Nanotechnology in agriculture, livestock, and aquaculture in China. A review

2.1 Nanotechnologies used for vegetables

The effects of nanotechnologies of TiO₂-ZnO compound on nitrate, nitrite, and vitamin C content were studied in vegetable. The nanotechnology device can reduce the nitrate and nitrite content of cabbage. And, the decrease was positively correlated to the treatment time. The nanotechnology device has no effect on the vitamin C content in vegetables (Zhang et al. 2008a).

2.2 Application of nanotechnologies in fruits

The superiority of nanotechnologies has been gradually acknowledged in the research fields of preservation of fruits and vegetables. Furthermore, the introduction of nanotechnologies into coating preservation of fruits and vegetables for fresh keeping has also been attempted (Ma and Gan 2004). The field of nanotechnologies in preservation of fruits and vegetables is still in its initial stage, so further investigation, discovery, and research breakthrough were required. Nanoparticle has a certain application prospect in the coating preservation of fruits. The effect of keeping nanoparticle complex latex fresh was investigated by coating loquat and cherry with hydrolyzed collagen/sodium alginate. Decay indexes, respiratory intensity, water losses, total acid, and soluble solid were detected during preservation. Experimental results demonstrated that the complex latex can reduce water losses and decay indexes of loquat and control its respiratory intensity. The complex latex using sodium hexametahposphate to disperse nano-SiOx was more effective than others. This was also confirmed in preservation experiment of cherries (Jia et al. 2008).

Nano-preserved fruit wax can improve fruit sensory quality. In the next 5 years, the handling after harvesting and waxing rate of China’s fruit will rise from the current 5 to 40 %. The estimation quantity of treatment fruit in 1 year may attain 24 million tons. However, the current annual demand of fruits with nanotechnology film coating in preservation is 48 thousand tons; thus, it has a broad market prospect. A new nano SiOx fruit preservation wax, which is based on the film-forming agent with natural animal and plant wax source, has been developed and used in China as fruit wax. Silicon nanoscale oxide (SiOx) and methyltrimethoxysilane are used as the O₂/CO control material, coupling agent, and dispersing agent, and imazalil and plant growth regulator are respectively applied as the anti-mildew and anti-staling agents. The product not only has effects of common fruit wax preservation, fresh keeping, inhibition of water evaporation, and protection from microbial invasion, but also strengthens control of breathing, metabolism regulation, and anti-mold, which can greatly improve the perceptual qualities and market competitiveness of fruits. At present, the new nano SiOx fruit wax has been widely applied in the fruit production regions of several provinces in China. Mass production was carried out for only 2 months, and 18 tons of fruit wax has been sold, and 18 thousand tons of fruit has been treated.

The products of nanotechnologies were used as fruit antiseptic. SiO₂ hydrosol can effectively inhibit the infection of cucumber gray mold fungus Botrytis cinerea. When the concentration of SiO₂ hydrosol is 1.0 g/L, the control efficiency is 93.5 %, which is close to that of 600 times of Dacotech (95.7 %). When the concentration of SiO₂ hydrosol is 2.0 g/L, the control efficiency is 98.9 %, which is significantly higher than that of Dacotech (Pu et al. 2005). Quasi nano-silver solution can be used as an antimicrobial preservative of tomato juice and tomato-carrot juice mixture (Zhang et al. 2003). Researchers have developed and produced a nano silicon oxide fruit wax for the first time in the world.

2.3 Application of nanotechnologies in rice and other food crops

The major research and application of nanotechnologies on crops are rice and wheat. Rice, wheat, and maize are the three major cereal crops in China. Rice (Oryzae sativa) is one of the most important crops in the world and is the staple food for over half of the world population. The total world production in 2011 was 722.8 million tons (Nair et al. 2013). Both hybrid rice seeds in southern China and conventional japonica rice seeds in northeastern China were soaked with nano-863-treated water. The seed germination and seedling quality were improved, and the yields were significantly increased (Deng 2003; Ma et al. 2007).

Nanotechnologies promoted the growth of rice. Nano-863-treated water was used by different researchers in different areas for soaking rice seeds, treatment of fertilizer, irrigation water, and pesticide preparation, and all of the results demonstrated that the nano-863-treated water showed enhancing effects on plant growth, development, and yield. Nanotechnologies used in rice production have comprehensive advantages, and in particular, it showed significant enhancing effects on rice growth in the early stages. Nanotechnologies showed enhancing effects on rice seed germination rate and germination states, promoting rice seedling quality and improving its capacity for anti-adversity. The growth process of rice was also in advance, and the yield increasing effect was significant. Therefore, it is an effective measure to cultivate multiple tillers and enhancing seedlings. In paddy field spraying with nano-863-treated water, the rice yield can be increased within a certain range. Compared with that of the control, the rice yield was increased by 342.0–970.5 kg/hm² (3.6–12.0 %) (He 2005; Gong and Dong 2012). The rice seed germination state and germination rate were increased significantly when Xinghe nano aerator was used to treat ten different rice varieties (Zhong et al. 2005). After soaking for 3 and 10 days, the germination states were respectively improved by 0.6–4.0 and 0.4–2.7 %. Compared with that of the clean water soaking of seeds, on the fifth day after seed soaking with Xinghe nano aerator, there were no differences in the shoot fresh weight and shoot length and width. However, on the tenth day, the shoot fresh weight, shoot length, and shoot width was increased by different degrees in the seven rice varieties among the ten with nanotechnology treatment. In addition, there were differences in the germination states, germination rate, shoot fresh weight, and shoot length and width of both different varieties and the same variety.

Rice variety of Nipponbare was treated with nano devices for pot experiments. The four nano devices were nano-863, nano ceramic, nano net, and nano film; clean water was used as the control. The results showed that the nano composite functional materials affected the metabolism of rice and promoted seed germination, plant growth, and development, which were most evident in the tillering stage. The biomass of rice in each treatment increased by 30.8–37.4 %, root weight increased by 12.3–35.2 %, and the total root length, surface area, and volume index were greatly increased. The difference of each index became small until the early booting stages, indicating that the enhancing effects of nanotechnologies in early rice seed germination and seedling were better than those of the late growth stage (Wang et al. 2011c); it also demonstrated that nanotechnologies can promote the metabolism of rice seeds and seedlings, early germination and rooting, increase in number of white roots, and increase in root absorption ability. Nanotechnologies also promoted the growth of rice, tillering occurred in advance 3 days than the control, and the number of tillers increased by 4.9–14.0 % (Table 2). The field experiment results demonstrated that rice seeds soaked with nano device could significantly increase rice production by more than 10 %. The tested results showed that the head rice ratio and gel consistency were respectively increased by 31.2 and 15.0 % after treatment with nano devices (Liu et al. 2007a; Wang et al. 2011c) (Table 2, Fig. 2).

Table 2

Number of rice tiller after treated with different nano biological assistant growth apparatus

Contents	T0/pure water (control)	T1/nano-863	T2/nanoceramic	T3/nanonet	T4/nanopiece
Tillers (no./hill)	10.31	10.88	11.75	11.38	10.81
Tiller increment %	–	5.5	14.0	10.4	4.9

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The other experiment results also demonstrated that the growth and development of crops could be promoted by seed soaking and paddy field irrigation with nano device-treated water. The increased extent of rice biomass was 5.6–18.6 %; 0.5–1.4 tillers were increased in each rice plant, with an increase extent of 4.8–14.0 %. Rice root was increased by 5.7–18.8 %. The increased biomass of maize was 12.6–16.5 %, of which chlorophyll content was increased by 6.3–11.0 %. The total absorption nitrogen, phosphorus, and potassium (NPK) of plant was increased, in which phosphorus absorption was particularly evident. The absorbed total phosphorus in rice was increased by 6.2–26.8 %, and that in maize was enhanced by 20.3–23.6 %. However, the nitrogen and potassium percentage contents of plants between each treatment group either did not change significantly or only reduced slightly. Only phosphorus percentage content was increased, the P₂O₅ contents of rice plants in each treatment group were enhanced by 0.3–7.6 %. The P₂O₅ contents of maize plants in each treatment group were enhanced by 6.1–8.7 %. These data suggest that nanotechnologies may increase the chlorophyll content of crops, which is conducive to the promotion of photosynthesis and increasing photosynthate. After treatment of nanotechnologies, the root was more developed and could absorb more nutrients, thereby increasing the biomass. The total absorption content of phosphorus and content of phosphorus in plants were both increased in the nitrogen, phosphorus, and potassium, which was closely related to the synergistic effect of nano device-treated water on phosphorus (Liu et al. 2007b) (Fig. 3).

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From the period of seedling establishment, the various growth stages of rice with nanotechnology treatment were 1–2 days earlier than those of the control group, and the seedling quality was better. Absorption of fertilizer, physiological activity, and function were improved in rice, and the growth vigor and stress resistance abilities were stronger than those of the control. The development process was accelerated, precocity was promoted, and yield was increased. The results of seed inspection and yield measurement demonstrated that the spike number, spike length, grain number per panicle, and 1000-grain weight of per unit area in the treatment areas were all significantly higher than those of the control (Zhang et al. 2007).

Nanotechnologies can influence the gene expression to a certain degree. The γ-ECS gene of which was expressed in leaves and roots, and the transcribing of γ-ECS gene in rice was slightly enhanced by spraying nano silicon on rice seedlings under cadmium (Cd) stress (Wang et al. 2013).

In wheat seeds treated with and without the 399-nm fertilizer, the germination rate were 94 % and 12 %, respectively. The radicle and plumule of the seeds treated without 399-nm fertilizer grew very slowly, while in the seeds treated with 399-nm fertilizer, the wheat seedlings have developed root system and are growing wel1. The epidermal cells of stem using 399-nm fertilizer are larger and the vascular bundles are more compact. Besides carbon and oxygen elements, the species and the percentage of elements contained in the wheat seedlings applied with 399-nm fertilizer are more than those without using 399-nm fertilizer (Liu et al. 2009a).

3.1 Application of nanotechnologies in chicken breeding

In recent years, nanotechnologies have been applied more and more in the field of animal breeding. Not only can it improve animal immunity and reduce the use of antibiotics, but also can reduce the manure odor of livestock and poultry, which is conducive to bring environment improvement.

The nano vitamin D3 and ordinary vitamin D3 were added to the feed of laying hens, respectively. On the condition of same feed dosage, the production performance and shinbone quality of hens which are feeding nano vitamin D3 were better than those of feeding ordinary vitamin D3 (Yang et al. 2014). Mannan oligosaccharides nano-liposomes can increase the average daily gain of healthy chickens, lower feed conversion. The average daily weight gain were significantly higher than flavomycin control group (P < 0.01). Thymus index was significantly lower than that of the control group. The nitric oxide levels of chicken plasma in mannan oligosaccharides nano-liposomes were significantly increased (P < 0.01) compared with control groups. Mannan oligosaccharides nano-liposomes can regulate the immune function of chicken and play the role of resisting disease and promoting growth (Hu et al. 2012). Nano-selenium has the advantages of high absorption rate, high security, high antioxidant capacity, high egg-laying capacity, and good growth performance, and the range between nutrition dose and toxic dose of nano-selenium is significantly wider than that of sodium selenite. The toxicity of nano-selenium is lower than that of selenomethionine, and its toxicity is currently the lowest of all selenium supplements (Cai et al. 2013).

Nano-863 was used to treat water and feed, which was then given to Israeli recessive white roosters. The results demonstrated that the daily weight increase in the experimental group was 27.9 % higher than that in the control group. The survival rate and economic benefit increased by 2 and 157.8 %, respectively. The ratio of feedstuff to weight increment was decreased by 18.8 %. The chickens in the experimental group were healthy and lively, their appetite was rich, and feathers were lustrous and smooth, while the chickens in the control group had fluffy feathers.

Nano Se has biological characteristics of high oxidation resistance, high immune regulating, high biological activity, and low toxicity. Previous research concerning nano Se in poultry production has mainly concentrated on the oxidation resistance and improvement of production performance of broilers. The addition of Se to the chicken feed is beneficial to the growth and disease resistance of the chickens. When the addition contents of Se in feed were 0.1, 0.2, 0.3, and 0.4 mg/kg, there were no significantly different effects among the three Se sources of sodium selenite (Na₂SeO₃), selenomethionine, and nano Se on the growth performance of broilers at the same levels (P > 0.05). However, when the addition amount of Se was 0.5 mg/kg, the growth performances of the broiler chickens in the nano Se group were significantly higher than those of the selenomethionine and sodium selenite group (P < 0.05). Similarly, when the addition contents of Se in feed were 0.1, 0.2, 0.3, and 0.4 mg/kg, there were no significant difference among the effects of the three Se sources on glutathione peroxidase (GPX) activity and total antioxidant capacity (T-AOC) of the sera and tissues of broilers at the same addition level (P > 0.05). However, when the addition amount of Se was 0.5 mg/kg, then the effects of selenomethionine and sodium selenite on the activity of glutathione peroxidase and total antioxidant capacity were dramatically reduced in comparison to those with the addition of 0.5 mg/kg of the same source of Se (P < 0.05); in addition, the levels of reactive oxygen species and content of malondialdehyde (MDA) were significantly increased (P < 0.05), while there were no significant changes in the nano Se group (Cai 2012).

3.2 Application of nanotechnologies in pig industry

Diarrhea is a common intestina1 disease with high morbidity and mortality, seriously affecting the growth performance and survival of piglets. Due to the restricted use of antibiotics, new feed additives or drugs have been paid more and more attention. Nano-zinc oxide and montmorillonite were widely used as anti-diarrhea agents in piglets (Qing and Xiao 2013). Microelements of Se and Zn are the essential elements for the animals (Zhang 1993; Bian et al. 2010); they are the important additives of feed and prevent diarrhea and death of weanling pigs, and promote healthy growth of fattening pigs. Generally, the Zn element was added in the feed with common high Zn. This leads to the high toxicity to the pig; in addition, the high Zn cannot be absorbed sufficiently and waste the Zn source. Even more serious was that a mass of Zn was discharged with the feces and results in environment pollution. The supplementation of 500 mg/kg of Zn as nano-ZnO was as effective as 2000 mg/kg of Zn from ZnO for enhancing growth performance and alleviating diarrhea as well as improving intestinal microflora and barrier function of weanling pigs (You et al. 2012). The weaned piglets of 24 to 26 days old were used for the test. The control group was fed with the basal diet; groups 1, 2, and 3 were fed with the basal diet adding 2800 g/t zinc oxide, 800 g/t fat-coated zinc oxide, and 500 g/t nano zinc oxide, respectively. The results showed that the pigs’ average daily gain raised 15.3, 9.9, and 14.7 %, the ratio of feed to gain reduced 9.6, 7.5, and 10.3 %, the diarrhea ratio reduced 66.7, 55.6, and 55.6 %, respectively; compared with the control group, all were significant (P < 0.05), but groups of 1, 2, and 3 have no significant differences in average daily gain, ratio of feed to gain, and diarrhea ratio (P > 0.05) among the zinc oxide, fat-coated zinc oxide, and nano zinc oxide. It implied that the fat-coated and nano zinc oxide were a practicable alternative to high-dosage zinc oxide (Ren et al. 2013)

At present, the Se sources most widely used in feed are sodium selenite, but its toxicity is high and the biological utilization rate is low. Furthermore, it has a prooxidant effect, thus causing adverse effects on animals and environments (Zhu and Jiang 2005). The effects of nano Se on fattening pig meat quality, growth, and antioxidant were explored with sodium selenite as the control. When the level of Se source was 0.4–1.0 mg/kg, then the growth performance of piglets, drip loss, glutathione peroxidase (GSH-Px) activity, T-AOC level, and muscle Se content of the longissimus in the nano Se group were significantly higher than those of the sodium selenite group, while the methane dicarboxylic aldehyde (MDA) and content of active oxygen in the nano Se group were significantly lower than those of the sodium selenite group (Xia et al. 2005, 2006).

As a fourth-generation trace element additive, nano zinc oxide (nano ZnO) possesses surface effect, volume effect, quantum size effect, and so on. These features provide broad application prospects in the feed industry. Nano ZnO can significantly improve animal production performance and reduce the diarrhea rate of piglets. It can also improve the absorption capacity of livestock and poultry intestines and stomach as well as absorption speed and rate, which greatly reduce ratios of feed to meat and feed to egg, thus reducing the production cost (Zhong and Chen 2005). High zinc diets can prevent diarrhea and improve the production performance of piglets, but when its addition dosage is large, it will lead to adversely affect the environment and the pigs’ health. Nano ZnO has a unique advantage of physical and chemical properties, and its required dosage in the feed is lower, but it can achieve the same effects as with a high zinc daily diet. Therefore, it can replace the ordinary Zinc oxide (Pan et al. 2005).

Supplementation of chitosan nanoparticle-loaded copper (CNP-Cu) increased average daily feed intake and average daily gain and decreased feed gain ratio and diarrhea rate, and the optimal supplemental level of chitosan nanoparticles loaded copper was 100 mg/kg (P < 0.05). These results suggest that supplemental chitosan nanoparticle-loaded copper has beneficial effects on immune and antioxidant function in weaned pigs, which also can increase growth performance and decrease diarrhea rate. Accordingly, chitosan nanoparticle-loaded copper has a potential to substitute antibiotics (Wang et al. 2011a). An effective DNA vaccine for foot and mouth disease (FMD) virus was prepared using mannosylated chitosan nanoparticles to form the foot and mouth disease VpVAC-VP 1-OmpA complex particles. The immunological evaluation indicated that the 20 μg of DNA vaccine complexed with mannosylated chitosan nanoparticles was found optimum in inducing the immune response in G pig (Nanda et al. 2012).

A certain amount of classical swine fever peptides was adsorbed on calcium phosphate nanoparticles and the adsorption reached 70 %. The calcium phosphate nanoparticles with classical swine fever was used as a vaccine adjuvant; antibody levels of calcium phosphate nanoparticles peptide vaccine group were higher than those of peptide alone group but lower than those of Freund’s adjuvant group. The increase of body temperatures postponed 16 h in calcium phosphate nanoparticle peptide vaccine group as compared with peptide alone group. It was showed that calcium phosphate nanoparticles played an adjuvant effect on classical swine fever peptide vaccine to a certain extent (Guo et al. 2012).

The effects of 0.3 % Cu(II)-exchange silicate nanoparticles on the growth performance, bacterium populations, and ammonia concentration in piggery were investigated. The two dietary treatments were basal diet (control group) and basal diet +0.3 % Cu(II)-exchange silicate nanoparticles. The results indicated that addition of 0.3 % Cu(II)-exchange silicate nanoparticles significantly increased the average daily gain by 12.1 % (P < 0.05) and decreased feed/gain by 11.0 % (P < 0.05). In feeding trial, ammonia concentration of the trial group during morning, afternoon, and evening decreased by 20.1, 23.1, and 21.2 % (P < 0.01) compared to the control group. And, the trial group significantly decreased salmonella and E. coli count by 6.0 and 8.0 % (P < 0.05) (Zhu et al. 2010b).

Nanotechnologies have broad application in the fields of sterilization. The sterilization rates of nano ZnO to S. aureus and E. coli were 98.9 and 99.9 % after 5 min of treatment, respectively, which were significantly higher than those of common ZnO (Zu et al. 1999). The inhibition zone diameter to the pathogenic bacteria of nano ZnO was twice that of the common ZnO. Under light conditions, the antibacterial effect of nano ZnO was better (Qu and Jiang 2004). Crystal zinc Bei (nano ZnO, 300 mg/kg) and high-dose ZnO (3000 mg/kg) were used to feed weaned piglets aged 21 days in the early stages. The nano ZnO and high-dose ZnO were all capable of improving the daily gain of piglet, and the nano ZnO group was 27.9 % higher than that of the high zinc group (P < 0.05). There were no significant differences in the feed meat ratio and diarrhea rate among various groups (P > 0.05). Comparative tests on the effects of added nano ZnO on production performance were conducted. Seventy-five piglets were divided into five groups, among which the fourth group was the high zinc group (Zn 3000 mg/kg), the fifth group (control group) was the normal zinc group (Zn 100 mg/kg), and the other three were “crystal zinc Bei” groups (group 1 with the addition of 250 mg/kg, group 2 with 375 mg/kg, group 3 with 500 mg/kg). The high zinc group and different concentrations of nano ZnO groups both could improve the daily gain of piglets. Compared with that of the normal zinc group, the weight of the high zinc group was increased by 13.5 %. The three concentrations of nano ZnO groups (with the addition nano ZnO of 250, 375, and 500 mg/kg) were respectively increased by 9.9, 18.1, and 11.6 %. The high zinc group and nano ZnO group could both decrease the ratio of feed and meat (P > 0.05). In respect to piglet diarrhea, the nano ZnO groups were significantly better than the normal zinc group (P < 0.05), of which the high zinc group reduced by 28.2 %, and nano ZnO groups respectively decreased by 19.5, 23.9, and 26.4 %. The nano ZnO groups and high zinc group showed good effects on the piglets’ daily weight gain, feed meat conversion ratio, and reduction rate of diarrhea, among which the 375 mg/kg nano ZnO group had the best effect on weight gain. However, with the increasing dose of nano ZnO, the diarrhea reduction rate effects on piglets showed a decreasing trend (Wang et al. 2003).

The water and feedstuff were treated with nano-863 and to feed pigs, the pigs’ tempers were stable, their daily weight gain was 9.2 % higher than that of the conventional feed group (control), and the feed to gain ratio was decreased by 3.0 %. As the color of pigs’ hair is also more pleasant, the price of the treated pigs is 0.20 ¥/kg higher than that of the control due to the improvement of the meat. Under the same treatment, the daily weight gain of pigs on a pig breeding farm was 113 g higher than that of the control group (increased by17.3 %). The feed to gain ratio was decreased by 7.8 %. In addition, the cost of feed was reduced by 0.28 ¥ (7.6 %). The pigs in the test group liked to eat and sleep, their hair color was more lustrous, skin was ruddy, and fecal odor was reduced.

Montmorillonite disinfectant is produced by adsorption and ion exchange reaction among copper salt, iron salt solution, and nano montmorillonite. As calculated by weight percentage, the contents of copper and iron in montmorillonite were 1.5–6.5 %, in which the weight ratio between copper and iron was 1:0.25–0.50. The disinfectant has broad-spectrum antimicrobial function, durable effectiveness, preventing drug resistance, low production cost, safe operation, and an environment-deodorizing function; thus, it can effectively improve the economic benefits of breeding industry. It can be used for the disinfection of livestock, poultry, and hatching eggs, and their cultivation places and facilities.

The composite plastic film which contains Nano TiO₂ (1 % TiO₂ concentration) was used as an antibacterial agent. The sterilization rate on E. coli and S. aureus, and Bacillus subtilis var. reached 99.9 and 97.4 % after treating 24 h, respectively. TiO₂/SiO₂ composite particles exhibited a stronger antibacterial performance. The nano composite materials showed obvious sterilizing effect used for object surface treating agent even under low and normal lighting conditions, which provides the possibility for application of nano composite materials in animal breeding (Li et al. 2001). The resistance effects of new nano inorganic antimicrobial agent nano TiO₂ and nano ZnO on several pathogenic organisms were investigated. The test results on E. coli, S. aureus, B. subtilis, C. albicans, and Aspergillus niger demonstrated that the new nano TiO₂ and nano ZnO had high efficiency and broad-spectrum antibacterial ability and showed strong inhibitory effects on E. coli, S. aureus, B. subtilis, and C. albicans. The mass fraction concentration of 75 × 10⁻⁶ nano TiO₂ and nano ZnO inhibited and killed more than 99 % of E. coli, S. aureus, and C. albicans and more than 90 % of B. subtilis, the antibacterial ability of which on A. niger is stronger than the similar Japanese antibacterial agent AG300 and phenol. This indicates that the nano TiO₂ and nano ZnO antibacterial agents have strong inhibition and bacteria-killing abilities as well as efficient broad-spectrum antibacterial properties against gram-positive and gram-negative bacteria, bacillus, yeasts and molds, and other different types of bacteria (fungi) (Long et al. 2007).

4.1 Nanotechnologies and fishery industry

Nanoparticles of elements like selenium, iron, etc. sources supplemented in diet could improve the growth of fish. The technology can be applied for using in aquariums and commercial fish ponds to reduce the cost of water treatment. Researchers believe that nanotechnologies may have the potential to provide fishponds that are safe from disease and pollution. Another application possibility of nanotechnologies is the usage of different conservation and packaging techniques to provide seafood safety by delaying mildew and microbial spoilage (Can et al. 2011). Nano TiO₂ could achieve desirable sterilization efficiency on three bacteria of E. coli, Aeromonas hydrophila, and Vibrio anguillarum. In ultraviolet lights, 0.1 g/L nano TiO₂ could reach a sterilizing rate above 98 % after 2 h and it could still keep a sterilizing rate above 96 % after 2 h in the sun. The photocatalytic sterilization efficiency of nano TiO₂ was correlative with its concentration and reaction time. Without adequate concentration or reaction time, the sterilization would not be effective (Huang et al. 2010).

Nanotechnologies were widely used for water treating and breeding fish. The application of nanotechnologies in seawater shrimp aquaculture revealed that the nano device was capable of improving water quality, reducing the rate of water exchange, and improving shrimp survival rate and yield (Wen et al. 2003). Among several nano devices, nano net treatment was the best; the results showed a 100 % increase in survival rate of fish, while water nitrite and nitrate both decreased, with nitrite decreasing to as low as one fourth of the control group. Nanotechnologies also increased the water pH, and the water quality was improved significantly. It has shown a broad prospect in aquiculture (Liu et al. 2008b).

Another experiment of nano-863-treated water and breeding fish were performed; the effects on the quality of water were investigated. Without changing the water for 6 months, the contents of NH₃-N, NO₂-N, NO₃-N, and CD in the test groups were 0.58, 0.13, 0.89, and 8.95, respectively, all of which were lower than those of the control group with conventional water changing, i.e., 1.58, 0.28, 2.33, and 19.22. The pH value of the experimental group was 7.20, which was higher than that of the control group (5.60), indicating that nano-863 can improve water quality and is more conducive to the growth of fishes. Nano-863 was also used in shrimp farming in fisheries aquatic breeding farm. One million tailed shrimps were included in each of the experimental and control groups. Seven hundred thirty thousand tailed shrimps survived in the test group, while only 360 thousand survived in the control group; thus, the survival rate of the test group is twice that of the control group. Nano-863 can also enhance the activity and energy of water, enhance shrimp appetite, and promote growth and development; it also has very strong antibacterial and algae and disease protection efficacy.

The basal fish bait was used as the control, and different doses of sodium selenite, selenomethionine, and nano Se were added, to investigate the effects of Nile tilapia (Oreochromis niloticus) on growth performance. Regardless of the form of Se, low doses of Se (0.1 mg/kg) in feed had a growth-promoting effect on fish, but the effect was not significant (P > 0.05), while moderate doses of Se (0.5 mg/kg) in feed had a significant promoting effect on the growth of fish (P < 0.05). However, there was no dramatic difference between the three selenium sources of sodium selenite, selenomethionine, and nano Se (P > 0.05). When high doses of Se were placed in the feed (2.5 mg/kg), the effects of different Se sources on the growth performance of fish were different. High doses of sodium selenite induced no significant weight gain of fish in comparison with the control group (P > 0.05). However, high doses of nano Se had obvious promoting effects on the growth of fish. The Nile tilapia weight gain rate was 86.3 ± 4.7 %, which was higher than that of the control group (51.9 ± 4.8 %) (Deng and Chen 2003).

4.2 Nanotechnologies in controlling of aquatic diseases

The aquaculture industry has suffered tremendous losses due to disease caused by bacteria (Huang et al. 2010). At present, traditional disinfection and sterilization methods are mostly used to control aquatic diseases, and various chemical disinfectants, antibiotics, and sulfa drugs are frequently used in large quantities. The cost of these chemical drugs is quite high, stimulation is strong, efficiency is low, and there are numerous side effects; thus, various related problems cannot be fundamentally solved, leading in turn to many adverse effects (Yang 2003).

Not only is nano TiO₂ able to degrade the organic pollutants in water, but it also has the abilities of sterilization and disinfection. Under ultraviolet irradiation conditions, nano TiO₂ can produce highly active hydroxyl -OH, superoxide ion -O, peroxyl radical -OOH, and other free radicals with high oxidation capacity. These free radicals can interact with biomacromolecules, such as lipids, proteins, enzymes, and nucleic acid molecules in bacteria, viruses, and other microorganisms, which can destroy cell structures through a series of chain reactions so as to achieve the effects of sterilization and disinfection by protein denaturation and lipolysis of bacteria, and their sterilization efficiency is much higher than that of traditional bactericide (Yu et al. 2002; Sonawane et al. 2003; Zhao et al. 2000). In natural environments, nano TiO₂ shows strong sterilization effects only in the presence of sunlight. The catalytic effect of sunlight is similar to ultraviolet without the need for additional use of artificial light, which is conducive to the promotion and application of the technology in aquaculture industry.

The harmful and beneficial bacteria in aquaculture were detected by using copper-bearing montmorillonite (Cu²⁺-MMT) nanotechnologies (Liu et al. 2009c). The detected harmful bacteria were the aquatic animal intestinal pathogenic bacteria Aeromonas hudrophila, Vibrio parahaemolyticus, and Pseudomonas fluorescens. Probiotics were the intestinal Lactobacillus acidophilus and B. subtilis which isolated from silver carp and grass carp. The minimum inhibitory concentrations of copper-bearing montmorillonite on A. hydrophila and P. fluorescens were both 128 μg/mL. The minimum bactericidal concentrations were both 512 μg/mL. The minimum inhibitory concentration on V. parahaemolyticus was 64 μg/mL, and minimum bactericidal concentration was 256 μg/mL. The minimum inhibitory concentrations of copper-bearing montmorillonite on Bacillus and L. acidophilus were both 1024 μg/mL, and minimum bactericidal concentrations all were more than 1024 μg/mL. The above results indicated that copper-bearing montmorillonite showed strong antibacterial and bactericidal effects on the three aquatic pathogenic bacteria. Furthermore, the minimum inhibitory concentrations and minimum bactericidal concentrations of V. parahaemolyticus on copper-bearing montmorillonite were less than those of A. hydrophila and P. fluorescens, which demonstrated higher sensitivity and larger values of minimum inhibitory concentrations and minimum bactericidal concentrations on bacteria, illustrating that their influence was small.

5.1 Development of new type of nano pesticides

Jinggangmycin nanocapsules with Jinggangmycin as the core material were prepared by micro-emulsion polymerization. Against rice sheath blight pathogen (Rhizoctonia solani), indoor virulence test results showed that the half effect concentration value (EC₅₀) of Jinggangmycin nanocapsule was 4.23 μg/mL, with an efficacy 88-fold over the original drug. Field experiments showed that the control efficacy of Jinggangmycin nanocapsules was 1.2 times the original for the same concentration of 5 μg/mL (Lin et al. 2014).

5.2 Pesticides dilution with nanotechnologies treated water

Nano-863-treated water was then used to dilute pesticide for spraying; the treated leaves of plant in the treatment group were tender and green and did not turn yellow in the cold weather. The disease-resistant and cold-resistant effects were significant enhanced and show no appearance of blight. The evident yield-increasing effects were also achieved in balsam pear, pepper, corn, and other crops. After the nano-863-treated water was applied, the crop root system was well developed, drought resistance was significantly improved, and lodging-resistant ability was increased. It was also found that carbon nanotubes may promote the absorption of moisture by tomato seeds, thus improving the seed germination rate and promoting growth (Khodakovskaya et al. 2009).

5.3 Nanotechnologies in inhibition of pathogens

5.4 Nanotechnology application in plant protection

Nanotechnology approaches on plants allow more efficient and sustainable food production by reducing the chances of disease and pest incidence in plants (Nair and Kumar 2013). Historically, various fields, such as medicine, environmental science, and food processing, have employed the successful and safe use of nanotechnologies. However, their use in agriculture, especially for plant protection and crop production, is currently an under-explored area in the research community. Preliminary studies show the potential of nanotechnologies in improving seed germination and growth, plant protection, pathogen detection, and pesticide/herbicide residue detection (Khot et al. 2012).

The development of nanotechnology in conjunction with biotechnology has significantly expanded the application domain of nanotechnologies in various fields. In addition, a variety of carbon-based, metal- and metal oxide-based dendrimers (nano-sized polymers), and bio-composites nanomaterials (Environment Protection Agency, EPA 2007; Nair et al. 2010) are currently being developed. Their types include single-walled and multi-walled carbon nanotubes (SWCNT/MWCNT), such as nanoparticle of magnetized iron, aluminum, copper, gold, silver, silica, zinc and zinc oxide, titanium dioxide, cerium oxide (Ce₂O₃), etc. General applications of these materials are found in water purification, wastewater treatment, environmental remediation, food processing and packaging, industrial and household purposes, medicine, and smart sensor development (Jain 2005; Wei et al. 2007; Byrappa et al. 2008; Zhang and Webster 2009; Gao and Xu 2009; Qureshi et al. 2009; Lee et al. 2010; Zambrano-Zaragoza et al. 2011; Bradley et al. 2011). The majority of applications in these areas have focused on the significance of the nanotechnologies for improving efficiency and productivity. These materials are also used in agriculture production and crop protection (Bouwmeester et al. 2009; Nair et al. 2010; Sharon et al. 2010; Emamifar et al. 2010).

5.5 Nanotechnologies on microorganisms and insects

6.1 Effects of nano fertilizer on rice crop

Comparing with the normal urea treatments, the tiller numbers, SPAD values, and accumulation amounts of dry matter are increased significantly under the nanometer urea treatments with the same nitrogen rate. Meanwhile, the grain yields of the nanometer urea treatments are larger than those of the normal urea treatments when the nitrogen rates are from 0 to 90 kg/ha, while the grain yields and agronomic efficiency of nitrogen fertilizer of the nanometer urea treatments are increased significantly when the nitrogen rates are further increased, and the grain yield is increased by 10.2 % and agronomic efficiency of nitrogen fertilizer is increased by 44.5 % in their maxima. Based on the developed model between the yield and the fertilizer rate, the agronomic efficiencies of the normal urea are only 58.3–87.6 % of those of the nanometer urea when the nitrogen rates are from 90 to 244.9 kg/ hm² and the nanometer urea can save 12.4–41.7 % of nitrogen. It is suggested that the nanometer urea treatment with N 244.9 kg/hm² is the perfect treatment for high-grain-yield cultivation and has the highest grain yield of 11,174.7 kg/hm² and a much higher agronomic efficiency of nitrogen fertilizer, and the nanometer urea treatment with N 180 kg/hm² is the perfect treatment for safe cultivation and has much higher grain yield and agronomic efficiency of nitrogen fertilizer (Wang et al. 2010c). The same results were obtained by others experiments (Wang et al. 2011d; Li 2013).

Hybrid rice is very important in China rice production, the current growth area of hybrid rice account for more than 56 % of rice planting area in China (Yuan 2014). Compared with the normal synergistic fertilizer of 100 % efficient fertilization, the nano-synergistic fertilizer had obvious yield-increasing effect on hybrid rice. The nano-synergistic fertilizer could increase the yield by 4.4–10.4 % with 60 % fertilization, 9.5–21.1 % with 70 % fertilization, and 4.7–15.8 % with 100 % fertilization. So, the nano-synergistic fertilizer could reduce the amount of fertilizer 30–40 % and has obvious yield-increasing effect. The mechanism of nano-synergistic fertilizer on hybrid rice showed that nano carbon mixed with water became the superconductor, which increased the electric potential of soil. The nano carbon soil made the soil colloid recombinant and release large amounts of nutrient elements. The nano-synergistic fertilizer made the outflow quantity of NH4 reduce in hybrid rice root, increase the absorption quantity of NO3⁻, and promote the absorption of nitrogen ion in root system on soil (Zhang et al. 2012).

Nano fertilizer also can promote the growth and increase the yield of rice. The survey results of yields in various treatment groups displayed the following trends: 100 % nano fertilizer treatment > 100 % conventional fertilization treatment > 70 % nitrogen amount of nano fertilization treatment > 70 % total nano fertilization treatment > 70 % nitrogen amount of conventional fertilization treatment > 70 % total conventional fertilization treatment > no nitrogen fertilizer + nano fertilizer > nano fertilizer > no nitrogen fertilizer > blank control. With the same amounts of phosphorus and potassium fertilizer, the nitrogen use efficiency of the 70 % nitrogen nano fertilization treatment was shown to be 11.6 % higher than that of the conventional fertilization. The yield of single application nano fertilizer treatment was 32.3 % higher than that of the blank control, indicating that the nano fertilizer promoted the growth of rice (Zhang et al. 2010).

Total nitrogen concentration increased sharply after nano urea fertilizer application. At the same nitrogen rate, the total nitrogen concentration in the nano urea treatments decreased significantly faster than those of the common urea (control). The safe drainage water time was 11.5–15.9 days after nano urea application whereas 12.5–17.3 days after common urea application, it means that the nano urea is easier and quickly absorbed than common urea. N loss in nano urea treatment was 70.6–74.3 % of N loss in control treatments. Rice grain yield and N agronomic efficiency of nano urea treatments were higher than those of the control. Of the nano urea N, 225 kg/hm² was recommended as the best rate for achieving high-yield, high-N efficiency, and safe cultivation technique in hybrid rice production (Wang et al. 2011c).

6.2 Effects of nano fertilizer on other crops

Nano-carbon was proved to be non-toxic materials. When 5 to 50 nm of carbon was added to the fertilizer, nano-fertilizer was formed. The experiments of nano-fertilizer efficiency on radish, cabbage, eggplant, pepper, tomato, celery, and leek crops were carried out. The results indicated that the nano-fertilizer promoted the growth of the crops and made the yield increase 20 to 40 %, and the vegetables come into the market 5 to 7 days ahead of time. After fertilization the radish grew to 83 cm in 38 days, eggplant reached 1.2 kg in 20 days and so on. Nano-fertilizer also could improve the quality of the vegetables; the content of vitamin C in chili increased 1.5 times (Liu et al. 2009b).

Compared to common fertilizer, the nano-synergistic fertilizer increased the rice yield of 10.3 %, the spring maize of 10.9–16.7 %, the soybean of 28.8 %, and increased the soybean oil content of 13.2 %, and had important significance of cultivating non-genetically modified soybeans. The nano-synergistic fertilizer also had the function of promoting the maize precocity. The input-output ratio of nano-synergistic fertilizer reached 1.0:13.5, and increased income 2777.5 ¥/hm² compared with the common fertilizer (Liu et al. 2008c).

The determination results of the nutritional index of different vegetables showed difference. The application of nano-synergistic fertilizer in radish may either increase or decrease the contents of amino acids, in which the contents of cystine, proline, leucine, phenylalanine. and methionine increased by 11.1–140.0 %, while those of tyrosine, arginine, histidine, valine, and lysine decreased by 11.1–30.0 %. After applying of nano-synergistic fertilizer in eggplant, the contents of other amino acids all increased, and the increase amplitude was 11.5–42.9 %, with the exception that the content of cystine decreased by 16.7 %. The content of pepper amino acid decreased by 42.9–72.7 % after use of nano-synergistic fertilizer, while vitamin C content increased by 155.7 %, indicating that the nano carbon had a strong activation potassium function and the quality of the pepper was improved and also its storability. The amino acid content of celery treated with nano synergistic ammonium bicarbonate was shown to be 15.4–70.0 % higher than that with urea treatment. The overall increased level of amino acid suggested that the nano-synergistic fertilizer could improve the quality and nutritional value of celery (Liu et al. 2009b). In addition, nano fertilizer also showed varying degrees of enhancing effects on the germination, growth, and yield of peanut (Liu et al. 2005a) and wheat (Liu et al. 2008d).

7.1 Detection of diseases

Due to the advantages of simple, rapid, non-pollution, and the results are liable to be decided, the nanotechnologies, as rapid detection and diagnosis methods, are widely used in the fields of medical science clinical examination, food safety test, and animal epidemic surveillance, such as various kinds diseases of bovine and swine, e.g., foot-and mouth disease, bovine leukemia virus, bovine akabane virus; hog cholera virus, swine pseudorabies virus, or porcine parvovirus (Wang et al. 2012a, b)

A nanotechnology of “quick test chip of double function for capture and detection of bacteria” was developed, which may perform rapid screen and detection of bacteria. In the past, the detection of bacteria in blood of patients with sepsis needs 2–5 days, whereas using the quick test chip to detect the bacteria in the blood of patients with sepsis, it can be finished in 30 min, for an increase in detection speed of about a hundred times (Nature, Communications, 2011-11-15).

Animal infectious disease not only affects the animal farming economy, but it also poses a threat to human health. Shrimp white spot virus was detected by means of dot immunogold filtration assay and the gold test strip method, in which the detection limit of the gold test strip method was 1.0 μg/mL, and after the use of silver enhancement, the detection limit achieved 0.01 μg/mL. The immunochromatographic strip was used for the detection of classical swine fever virus, and the results of which could be detected in 10–15 min (Lai et al. 2003), according to the test results, swine fever immunization can be reasonably guided to establish appropriate immunization procedures rapidly. The rabbit anti-avian influenza antibodies of H5 and H9 subtype virus was purified, which were used to produce immunogold probes with the prepared colloidal gold. The modified percolation method was then used to detect avian influenza subtype viruses H5 and H9 in the tested materials safely and quickly. The examination results could be obtained in 3 min, and the respective detection sensitivities were 1.62 and 1.25 μg/mL (Liu et al. 2005b).

At present, based on gold labelling, studies mainly focus on rapid detection on pathogenic microorganisms. The earliest immune colloidal gold technique basing on immunomagnetic separation technology was used, which was applied successfully in the detection of 01 population of comma bacillus (Vibrio choleras). The oligonucleotide microarray technology with nitrocellulose membrane as the carrier and nano gold coloring, which showed high sensitivity and specificity for E. coli, Salmonella, Shigella, V. cholerae, V. parahaemolyticus, proteus, Listeria monocytogenes, Bacillus cereus List Rand, Clostridium botulinum, and Campylobacter jejuni (Hong et al. 2005). Rapid detection of E. coli using an integrated handheld Spreeta TM SPR sensor was conducted, and then the colloid gold antibody as the secondary antibody was introduced; it expanded the detection signal and extended the binding process of the colloid gold antibody with microorganisms, which increased the detection precision from 10⁶ to 10¹ CFU/mL (Yin et al. 2005). V. cholerae in aquatic products by using colloid gold immunochromatography assay was investigated (Xie et al. 2005), the results illustrated that the V. cholerae contents in the enrichment medium was 1 CFU/mL, which can be detected by enrichment of bacteria at 12 h using a colloidal gold immunochromatography diagnostic kit. The detection of V. cholerae in aquatic products by the conventional method requires a long time, of which the enrichment culture time is 8–16 h, isolation and culture time is 14–20 h, and preliminary report time need more than 30 h. According to traditional isolation, culture, and identification technologies, Lester bacteria detection requires 1–2 weeks, while only 10 min is needed to obtain the test results when using the immune colloidal gold chromatography method, the sensitivity of which reaches 87.5 %.

A nanometer polymerase chain reaction (nano-PCR) assay was developed to detect the Africa swine fever virus. The amplification was efficiently enhanced with the gold nanoparticles as thermal mediator in the amplification system, and the sensitivity of the nano-PCR was more than 1000 times than that of conventional PCR with a detection 1imit of ten copies and had no cross-reactions with E. coli, porcine pseudorabies virus, porcine circovirus type II, classical swine fever virus, porcine reproductive and respiratory syndrome virus, porcine Teschovirus 8, and encephalomyocarditis virus (Cui et al. 2012).

7.2 Detection of mycotoxins

Mycotoxins are toxic secondary metabolites produced by fungi. The ingestion of contaminated food or feed by humans or animals will induce poisoning or disease. The application of immune technology in mycotoxin detection showed high sensitivity and strong specificity; thus, it is suitable for food and feed examinations. The colloidal gold immunochromatographic assay was used for detecting 50 ng/mL of botulinum toxin B, the result could be obtained within 10 min when the silver enhancement is used, the detection limit may reach 50 pg/mL, and there is no cross reaction with botulinum toxin A and E. A colloidal gold test strip for the rapid detection of ochratoxin A was developed, and the detection limit was shown to be much lower than that of the current limited requirements of ochratoxin in China (Lai et al. 2008). An immunogold test strip for the detection of aflatoxin B was successfully developed by Sun (Sun et al. 2006), in which the minimum detection limit was 2.5 ng/mL and the content of aflatoxin B in food could be qualitatively or semi-quantitatively detected.

Magnetic separation technology (MST) refers to the rapid isolation of targeted biological targets using superparamagnetism of magnetic nanomaterials and by the surface modification of nanoparticles and attaining specific interaction between functionalized magnetic nanoparticle surface lands and receptors (Safarik and Safarikova 2002). The application of fast detection techniques of food based on the magnetic separation technology mainly included rapid separation and enrichment of microorganisms and rapid extraction and separation and purification of nucleic acid and protein (Weng et al. 2009). There has also been an extensive application of nanotechnologies in food safety and rapid detection (Zhou 2012).

7.3 Detection of pesticide residues and degradation

Modern agriculture may not be operated without pesticides. Pesticides control crop diseases and insect pests and safeguard grain yield; meanwhile, they also lead to many negative effects. Pesticide residues are pressing issues affecting the environment and safety of agricultural products (Huang et al. 2014).

Pesticide residues in food are the economic and market problem and are directly related to the health of consumers. The disadvantage of the current determination method of pesticide residues in food is a lack of the sensitivity, fast, secure, and economical method. Application of nanoparticles in analysis of pesticide residues in food may overcome the disadvantages of the current a determination method, is the research focus of analytical chemistry, and obtains an amount of innovative research achievement. Combined with biology, immunology, electrochemistry, and material technology, nanotechnologies are important tendency for analysis of pesticide residues in food (Wang et al. 2011b).

The analysis of pesticide residues is affected by a series of problems, including complex background of sample ingredients, cumbersome pretreatment process, much time consume, low concentration of tested components, limited qualitative ability of analytical instrument, and low detection sensitivity of instruments. At present, there are many determination methods to detect the agrochemicals; the main methods are chemical method, gas chromatographic method (GS), high-performance liquid chromatography (HPLC), etc. The more precise testing methods were developed in recent years, i.e., gas chromatography-mass spectrum (GC-MS) and liquid chromatography-mass spectrum (LC-MS). A novel nanotechnology used for agrochemicals detection was widely applied. They are gold nanoparticles, carbon nano tube, quantum dots (QD), magnetic nanoparticles (MNP), TiO₂, SiO₂, ZnO nanoparticles and nanofiber, etc. (Yun et al. 2013). Rapid detection using gold nanoparticle can efficiently solve the above problems. Nano gold immunochromatographic and nano gold filtration assay were used for the detection of residual pesticide carbaryl, and the entire detection process required only 5 min, the respective detection limits of which were 100 and 50 μg/L. A mature detection product was developed and commercialized in China, such as the carbofuran rapid test strip.

A rapid detection method for melamine in milk and eggs using Au nanoparticles as colorimetric probe has been established. The melamine can be detected after extraction and centrifugation separation with 10 % trichloroacetic acid and chloroform. The proposed method could be used to detect melamine in milk and eggs with a detection limit of 0.1 and 2.5 mg/L (S/N = 3), and the recovery are 95.0–105.0 and 98.0–104.0 %, respectively (Sun et al. 2012). A new resonance Rayleigh scattering method was developed using gold nanoparticles as spectral probe and was used for the determination of melamine in milk. The detection limit was 2.7 × 10⁻⁸ mol/L. It was identified that this method is practical, simple, sensitive, and selective (Zeng et al. 2011). With multi-walled carbon nanotubes, solid-phase extraction cartridge is efficient for the clean-up of the sulfonamides in animal tissues or products, and the method is simple, accurate, and suitable for the quantification of the sulfonamides residues (Zhao et al. 2014).

When nano TiO₂ powder or hydrogel was added in treating agent, both may more efficiently degrade the residues of chlorpyrifos in apple and plum. The photocatalytic effect of TiO₂ hydrogel was shown to be stronger than that of nano TiO₂ powder. It was confirmed that nano TiO₂ may effectively degrade chlorpyrifos in vegetable, with a degradation rate of reaching 70.2 % (Wang et al. 2007). TiO₂ can also degrade dimethoate and dichlorvos in aqueous solutions under different conditions. There have been more and more research and application of nanotechnologies in wastewater treatment of insecticide factories (Ren 2004), sewage treatment in dyeing and printing factories (Zhang and Zhu 2011), and indoor air purification (Yang 2011).

The effects of temperature on the photocatalytic degradation of 11 organophosphorus pesticides residues in the vegetable were investigated. The Chinese cabbage was treated by nanotechnology device (TiO₂-ZnO compound) at different temperatures. The results showed that the degradation rate increased with the temperature decreasing from 30 °C to 0 °C. The longer the treatment time, the higher degradation rates of the pesticide residues, and the increases of the degradation rate tend to flat after 1 h treatment. The 400-W power of ultraviolet mercury lamp irradiation can increase the degradation rates of the organophosphorus pesticide residues in the vegetables (Zhang et al. 2008b).

7.4 Nanotechnologies used in environmental protection

Along with the acceleration of industrialization progress, the environment pollution is increasingly severe in China. It is the basic state policy to strengthen the environmental protection and taking effective measures to reduce pollution and protect the environment is instant. First of all, it has to strengthen the monitor and detection, and then the effective measures can be made and implemented. A new type of sensor which is made of nanomaterials possesses high sensitivity and precision; it can be sued in the survey of hazardous substance in the environment and biodiversity.

Nanotechnologies can reduce greenhouse gas emissions and make the air clean (Xiang et al. 2005); it also can be used in sewage treatment (Sun et al. 2011; Ma et al. 2012), including surface water (Wilcoxon 2000) and ground water (Elliott and Zhang 2001). The removal ratio of formaldehyde in the TiO₂/vacuum ultraviolet process was much higher than that in the TiO₂/ultraviolet or vacuum ultraviolet photolysis process. Deposition of Au nanoparticles on TiO₂ significantly improved the separation of photogenerated electrons and holes. Accordingly, in the vacuum ultraviolet photocatalysis, Au/TiO₂ not only increased the removal ratio of formaldehyde, but also significantly decomposed the ozone. The concentration of residual O₃ was decreased 32 %. Moreover, Au/TiO₂ film was stable in the vacuum ultraviolet photocatalysis process (Li et al. 2010).

Nano-activated carbon fibers can be used in the treatment of piggery wastewater and removing nitrogen and phosphorus. The equipment is simple and the running costs are low, and the ecological benefits are obvious. The rates of removal of total nitrogen reached 59.7–75.4 %, chemical oxygen demand (CODcr) 58.7–71.6 %. In the whole process, nano-activated carbon fibers can keep good performance in the treatment (Zhao et al. 2013). Activated carbon supported platinum catalysts (Pt/AC) can be used for the efficient removal of formaldehyde in air (Huang et al. 2013).

Magnetic nanospheres coated with polystyrene (Fe₃O₄@PS) which was round shape with diameter of 55 ± 11 nm and can remove the organochlorine pesticides from aqueous solutions. The pesticides could be effectively adsorbed and the adsorption equilibrium time was less than 20 min. The sorbent of Fe₃O₄@PS showed a good performance with more than 93.3 % pesticides removal in treating actual water samples (Lan et al. 2014). The nanotechnologies have bright application prospect in eliminating the heavy metal pollution (Singh et al. 2011; Chrysoehoou et al. 2012) and remediation contaminated soil (Gao and Zhou 2013; Satapanajaru et al. 2008; Wang et al. 2010b).

The biofilters with nano-ecobase could remove the nitrite effectively. The mean ammonia and nitrite removal rates were 93.5 and 69.3 %, respectively. The highest ammonia removal rate was 94.6 % at 30 °C, dissolved oxygen concentration of 5.43 mg/L, and hydraulic retention time of 0.33 h. The highest nitrite removal rate was 71.5 % at 21 °C, dissolved oxygen concentration of 6.40 mg/L, and hydraulic retention time of 0.33 h. The optimum operating conditions of the nano-ecobase were 30 °C, dissolved oxygen concentration of 6.40 mg/L, and hydraulic retention time of 0.33 h (Song et al. 2012).

8.1 Effects of nanotechnologies on human health

There are four pathways by which nanoparticle may enter the human body: inhalation, swallowing, absorption from skin, and deliberate injection during medical processes (or release from implants). Due to the fact that the particle diameter of nanoparticles is extremely small, once they have entered the human body, they have a high degree of mobility. In some cases, they can even cross the blood-brain barrier.

The potential danger to human and animals of nanoparticles does not allow neglect. Researchers from Missouri University of USA found in their recent study that the residue in fruits of nanoparticles can enter into the human body. It also is possible to get in to the spleen, brain, liver, heart, etc., vitals, through blood and lymphatic system. It was demonstrated that the nanoparticle residue is very difficult to be cleared away by common methods of rinsing. Therefore, they appeal that nanotechnologies should be used with caution in food wrappages (http://phys.org/print296407164.html).

8.2 Nanotechnologies and environmental issues

Nanomaterial size, shape, specific surface area, and surface modification will all affect toxicity. In addition, environmental characteristics, such as pH value, temperature, and light density, will also affect the toxicities of nanotechnologies. The same nanomaterial, but with different diameter, length, crystal structure, and surface modification, will have different toxicities.

8.3 Social risks of nanotechnologies

As a new pollutant, nanotechnologies have been given increasing amounts of attention. Researches by scholars from around the world on the ecological toxicity of nanotechnologies have mainly concentrated on the particle properties of nanomaterials and their environmental characteristics, but there has been little research performed on the relationship between the ecological characteristics of the tested species and toxicity of nanomaterials.

Nanotechnologies show broad application prospects in chemistry and chemical engineering, biomedical, composite materials, information technology, catalysts, and other aspects, due to their small size effect, surface effect, quantum size effect, and macroscopic quantum tunneling effect (Krrlik and Biffis 2001; Long and Yang 2001; Kong et al. 2000). Nanotechnologies have been widely used, but at the same time will inevitably be released into the environment, which causes adverse effects on the ecological system. The toxicities of nanoparticle and nanomaterials on the entire ecosystem have been observed, and there have been large numbers of ecotoxicological research reports on these emerging contaminants.

Among the researches on different nanotechnologies, 31 % were on the nano TiO₂, followed by nano Co (18 %), nano ZnO (17 %), nano Ag (13 %), single-wall carbon nanotubes (9 %), and nano CuO (9 %) (Kahru and Dubourguier 2010). Studies on the ecological toxicity of nanotechnologies have mainly concentrated on nanomaterial properties, such as particle size, specific surface area, zeta potential, and interaction between nanotechnologies and the environment (such as light intensity, pH value) (Yang et al. 2010; Yin et al. 2011; Vecitis et al. 2010; Jin et al. 2010; Li et al. 2011b), while there has been little research on the effects of nanotechnologies on the entire ecosystem, such as on ecosystem diversity (Song et al. 2011).