1 Background

The growth of nanotechnology has paved the way for new innovations in various areas, including agriculture, food, medicine, textile, and electronics. Some of these are already been established and marketed while several others are still under their laboratory stage [1,2,3]. Various applications of nanotechnology and designed nanostructures may bring desirable advances to mankind and environment, but they may have health and ecological implications resulting into extensive risks to society. Owing to their adjustable physicochemical properties like thermal–electrical properties, melting point, catalytic behavior, and photo activity, nanomaterials have garnered prominent attention from the researchers worldwide [4, 5]. As per the definition given by ISO, nanomaterials are defined as “Material with any external nanoscale dimension or having internal nanoscale structure” [6, 7]. Based on the above definition, various structures of nanoscale dimensions are named as nanowires, quantum dots, nanoplates, etc. Based on the nature of base material used for the production, nanomaterials can be broadly categorized into 4 categories (Table 1).

Table 1 Categories of nanomaterials
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All these types of nanoparticles possess various advantageous characteristics which makes them highly useful for a range of applications Table 2 [8,9,10,11].

Table 2 Characteristic properties of nanomaterials
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Along with these positive attributes, nanotechnology might bring-in some significant negative implications on society, economy, and environment Table 3 [11,12,13]. These effects can be summed up in the following ways.

Table 3 Negative effects of nanotechnology on society
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Therefore, it is call of the hour to focus on finding new provisions of increasing the transparency and traceability of nanomaterials through precise assessments and management of all the risk factors associated [14,15,16]. This article aims to present a summary of existing applications, risks, and legislations as well as some further developments related to nanotechnology and nanostructures.

2 Main text

2.1 Applications, benefits, and services of nanotechnology

Nanotechnology is all about designing, characterization, application, production, and marketing of structures on nanoscale dimensions. The interdisciplinary field of nanotechnology is accepted as a window of new opportunities for providing solutions not only in the core technical areas but also promisingly addressing developmental issues like water treatment, eco-remediation, and sustainable energy [17,18,19,20]. The broad relevance of nanotechnology accentuates the manipulation, categorization, and creation of nanoscale materials [21, 22]. Nanotechnology has proven its relevance in almost every area of life, be it agriculture, medical, electronics, fashion, environment, or construction [23,24,25]. Nanomaterials are the natural or engineered substances with dimensions between 1 and 100 nm. Playing with matter on nanoscale is a revolutionary technology as nanosize exposes a unique world of physiochemical, biological, and toxicological properties. At nanoscale, it is the surface behavior along with quantum behavior that brings about remarkable changes in the properties of matter [16, 26, 27]. The quantum effect gives nanomaterials very diverse physical, chemical, thermal, electrical, optical, and magnetic properties. Materials gain strength and resistance at the nanoscale, their color and light reflecting characteristics get altered, and reduction of size increases the surface area which results in alteration of physiochemical properties of the particle which leads to increased mobility, reactivity, and better aggregation and dissolution properties [28]. The various applications of nanotechnology are summarized in Table 4.

Table 4 Applications of nanotechnology
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Nanosilver is used as an antimicrobial agent in cleaning sprays and for disinfecting the chopping boards, food containers, and refrigerator boxes. Nanoclay and nanocomposites are employed to decrease the costs and to increase the strength and shelf life of carbonated and noncarbonated drinks [71, 72]. Nanosensor-based packaging films are utilized for safe and hygienic packing and delivery of food items and improving their shelf life [73, 74]. Cost-effective nanopurification systems for water treatment can resolve the global problem of drinkable water. It is expected that by the year 2030, the world will observe an increase of 60% in the water demand globally [26, 27]. Silver- and chitosan-based nanofilters can play a substantial part in producing drinking water from sea water, thus providing solution to the increasing global demand of fresh water. Nano-based technologies will create enormous ecological paybacks in the area of water treatment through improving the analysis, monitoring, disinfection, desalination, water conservation, recycling, and sewerage systems [75,76,77,78]. After water and food resources, energy is proved to be the fundamental resource for mankind, and the ever rising demand for energy resources is expected to climb by 50% by the year 2025. Currently the major sources are the natural energy resources from fossil fuels which are expected to bear double the current burden by 2025 [79, 80]. Nanotechnology has the potential to provide solutions to the global energy demands through cost-effective nanofuel cells, hydrogen storage nanosystems, nanocoated solar cells, and reinventing the energy storage and energy distribution. Nanodevices can track alterations in the glucose level, cholesterol level, and carbon dioxide level of the body without extracting blood; nanobots can help repair or replace the damaged body tissues in injured body; nanosolutions can restore youth and health of aging skin. In the medical field, nanotechnology aids drug delivery methods, tissue engineering, treatment systems, regenerative medicines, cell repair, cancer detecting and treating cancerous patients, gene-therapy, etc. [81,82,83].

2.2 Market needs of nanomaterials

The growing acceptance of nanotechnology by the society is creating the demand for nano-inspired goods. This is also highlighting the necessity of understanding the potential effects these products would be having on environment, eco-balance, animals, and human beings. In the year 2019, the global market of nanomaterials was estimated to be 8.5 billion US dollars and is anticipated to grow with an annual rate of 13.1% from the year 2020 to the year 2027 [84,85,86,87]. This rise in market share of nanotechnology is attributed to the rapid acceptance and adoption of nanostructures in aerospace applications, medical and health sectors, food and packaging industry, agriculture and farming, sports, cosmetics, constructions, paints and coatings, electronics, environmental remediation power and energy sectors, etc. The key factor for this growing market of nanomaterials is the characteristic physical, chemical, and biological properties of metal nanoparticles. Copper, silver, platinum, gold, aluminum, palladium, zinc, tellurium, titanium metals, and their oxide-based nanoparticles along with carbon-based nanostructures are broadly being used in various consumer products.

Revenues in $ billions

Annual growth rate 2000–2010

Annual growth rate 2010–2013

Estimated growth for year 2020

Estimated growth for year 2030

World

25%

48%

3000

30,000

USA

24%

38%

750

7500

  1. Source: data from Roco et al. and from Lux Research [88, 89]

The area of nanotechnology is continuously attracting investments from all over the world with the USA and China leading the list. This inflow of funds is rendering the process of integration of manufactured nanomaterials into the finished market product. With this interest and funding, it is expected that the market for nanotechnology will expectedly grow with 17% CAG rate in the span of 7 years from the year 2018 to 2025. The optimistic market trend reflects the balanced collaborations between research, industry, and society.

2.3 Sources and synthesis of nanomaterials

As nanomaterials have proven their worth in almost every aspect of societal problems, we need to get them extracted naturally or produced synthetically (Table 5) [96, 97].

Table 5 Sources of nanomaterials
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Nanoparticles can be synthesized through various physiochemical or biological methods (Fig. 1). The physical methods of synthesizing nanoparticles are enormously expensive whereas chemical routes pose serious environmental risks along with the issues of slow growth rate and inaccuracy in the structure of the designed nanoparticle. Nanomaterials are being synthesized as per the following two approaches [98,99,100,101]:

  • Bottom-up approach—this approach begins with initial structures at atomic level. It is a cost-effective method for large scale productions.

  • Top-down approach—this approach begins with the initial structures at macroscopic level. It is a slow method and not cost-effective for large scale productions. Hydrothermal synthesis

Fig. 1
figure 1

Nanoparticle synthesis

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Synthesizing nanoparticles from chemical solutions can be achieved by the following routes [54, 102, 103]:

  • Colloid-based synthesis

  • Microemulsion-based synthesis

  • Hydrothermal-based synthesis

  • Solvothermal synthesis

  • Chemical vapor-deposition synthesis

  • Thermal-decomposition synthesis

  • Pulsed laser-ablation synthesis

  • Template-based synthesis

  • Combustion

  • Gas phase methods

  • Microwave synthesis

  • Conventional sol-gel method

In order to minimize the environmental risks from physiochemical synthesis, researchers are looking out for sustainable and green synthesis of nanoparticles. The green methods are comparatively faster in terms of reaction rate and are cost effective and less hazardous to the environment. Green synthesis of nanoparticles involves mixing of appropriate amount of metal ions with plant extracts or microorganisms under requisite conditions (Fig. 2) [26, 27].

Fig. 2
figure 2

Green synthesis method

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2.4 Risks of nanotechnology

Anticipated benefits of nanotechnology integrate enhanced efficiency, improved bio-accessibility, and sophisticated packaging. These novel products or constituents may pretense a threat to humans and environment. There are global efforts for addressing and regulating the manufacturing and secure management/applications of nanotechnologies either by advices and supervision or by legislations [104, 105]. Presently, there is no law wholly committed to the directives focusing towards nanotechnologies in any of the countries globally [106, 107]. Existing laws are being considered as adequate and precise enough for regulating the uses of nanotechnology [108, 109] though some modifications have been recommended by numerous policy-making bodies like various NGOs and the European parliament [110, 111]. The call for supplementary directions to evaluate the impending hazards and for suggestions to guarantee the secure utilization of nanotechnology is being recognized, and quite a few specialist organizations are working actively in this area, for instance the Organization for Economic Cooperation and Development (OECD), the International Standard Organization (ISO), or the US Food and Drug Administration (FDA) [112, 113]. The recent review article presents a sketch of the assessment of disputes and threat issues related to nanomaterials and indicates that these characteristics are straightly linked to the methods used for their synthesis. Important dictatorial concerns are to be analyzed for nanomaterials which comprise of a description of the term “nanomaterial,” listing processes, precise information necessities for risk-assessment, management and terms to boost the clearness, and recording of the marketable usages, as cataloging or informing to a record for goods containing [114,115,116]. The general characteristics of nanoparticles and their effects are summed up in Table 6.

Table 6 General characteristics and risks of nanoparticles
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2.5 Nanomaterial toxicity

The environment and an individual get the exposure to nanoparticles either during natural processes [28, 129] or during their manufacture, distribution, usage, clearance, and waste management. Nanoparticles get released in the environment either accidently or gradually during their synthesis, transport, storage, applications, or disposal methods. In some applications, like nanoremediation, significant amount of nanoparticles are deliberately being introduced to detoxify and transform the environment. The nanoscale dimension of these particles aids their movement in various body parts causing different types of cancers, swelling and damage of organs, protein denaturation and asthmatics attacks, etc. The enhanced surface area and great tendency to bind facilitates the adsorption and transportation of pollutants through long distances over a longer period of time.

There is not much information available about the effects of nanoparticles on the environment. Further research is required to mend the knowledge and information gap about the characteristic behavior of nanoparticles in soil, air, and water and their accumulative properties in food-chains.

Since nanotechnology is still in its nascent stage, there are questions about the effect of industrial and commercial use of nanotechnology on environment and organisms. During their production, nanoparticles might get released in the air, water, or soil in turn affecting the environment and organisms [130, 131]. The regular assessment of nanoparticles is very much necessary because every application of them creates a new environmental impact. The eco-toxicological effects and the consequences of accumulation of nanoparticles in organisms need more and more research. The alien matters to the human body are normally trapped by the skin and hairs of the organs, while human gastrointestinal tract and the lungs are most susceptible to the infections [132, 133]. Nanoparticles if inhaled by the organism can readily get to the heart, liver, and blood cells through the bloodstream. The tiny dimensions of nanoparticles can facilitate irreparable oxidative strain, denaturation of protein, internal organ injury, agitation of phagocyte functions and asthmatic and cancerous infections, and production of neo-antigens causing organ magnifications and non-functioning. It is being observed that many of the nanoparticles are non-hazardous, whereas some have the tendency of having positive health effects. As per the data available, the toxicity of nanomaterials is based on a variety of characteristics [134,135,136].

  1. i.

    Their dosage and the time of exposure effect

  2. ii.

    The concentration and aggregation property effect

  3. iii.

    The crystal structure, shape, and size effect

  4. iv.

    The surface fictionalization and area effect

Various policies in the form of rules, laws, and legislations are being taken into practice by some organizations to reduce or evade the risks linked with nanomaterials. However, there are not distinct legal definitions, regulations, and protocols for creation, management, cataloging, testing, and evaluating the effects of nanoparticles on environment. The toxicity listing of nanomaterials is an extremely stipulated study area in current times [137, 138]. Nanoparticles, if inhaled by the organism can readily get to the heart, liver, and blood cells through the bloodstream. The tiny dimensions of nanoparticles can facilitate irreparable oxidative strain, denaturation of protein, internal organ injury, agitation of phagocyte functions and asthmatic and cancerous infections, and production of neo-antigens causing organ magnifications and non-functioning. It is being observed that many of the nanoparticles are non-hazardous, whereas some have the tendency of having positive health effect.

3 Conclusion

Nanotechnology innovations are still in laboratory stage, generally incoherent from the public and areas where these are ultimately being practiced. Consequently, the people interact with technological advances merely as customers, for their commercialization, and when there is a conflict with the social values, the technology faces resistance. For the broad acceptance of nanotechnology, it is very much necessary to have a balance between the production, marketing, usage, risk assessment, and management of nanoparticles. Without proper regulations and legislations, the usages of nanotechnology may lead to serious grievances causing irreparable damage to the environment and mankind. More and more research and progressive work is still needed to find new cost-effective green synthesis routes, legislation bound usages, and risks and hazard assessment and their solutions. Imparting these points will result into the successful nanoinventions.