1 Introduction

The nanotechnology is a well growing area in research and have a wide range of application in different area and utilized in fabrication of nano scale materials by green route found as a safer, energy efficient, cost-effective, eco-friendly and less toxic. In the last few decades, nanotechnology is one of the most rapid growing areas in modern advanced material science and engineering and involved in fabrication of materials having nanoscale dimension in the range of 1-100 nm along with their applications in the area of electronic, optical, medicine, nutrition, energy, electronics, textiles, biomedical, catalytic, anticancer, antimicrobial, biosensing, wound healing and anti-inflammatory property [1,2,3,4,5,6,7,8,9,10]. The nanostructured materials have distinctive characteristic use in catalytic synthesis of pharmaceutical drugs due to their high surface area, small particles size known as “nano-effect” [10]. In the continuation, fabricated nanostructured materials based on reduction approach for industrial process required to minimize waste and enhance E-factors and atom efficiency [11, 12].

The survey of literature reaveld that synthesis of metal nanoparticles scoping are in nanoscience, different types of metals nanoparticles such as zinc oxide, copper oxide, silver nitrate and iron oxide are well reported [13,14,15,16]. In the continuation, the different approach applied for the fabrication of metals nanoparticles such as microwave irradiation, hydrothermal, decomposition and sol–gel [17]. Additionally, the chemical and physical approach use for synthesis of nanoparticles costly and time-consuming produced the hazardous chemical as well as waste materials. Therefore, greener approach advantageous way for the synthesis of nanoparticles to reduced the time, cost-effective, less toxic, one step synthesis and eco-friendly nature, the nanoparticles obtained by biological route from plant extract found a better option compared to chemical and physical approach and also non-toxic, biocompatible and drug carriers [18, 19]

The biological system associated in fabrication of biogenic synthesis of nanoparticles from plants and their derivatives, yeast, algae, fungi and bacteria [20,21,22,23,24,25,26,27,28]. In the continuation plant extract contain bioactive moieties such as alkaloids and phenolic compounds shows bioreduction mechanism, act as stabilizing and reducing agent [29,30,31]. In the recent years the survey of literature revealed that biogenic synthesis of ZnO NPs use to removed heavy metals as arsenic and sulphur from water sources and also in degradation of atmospheric pollutants [32, 33]. The metal zinc play a significantly role or biocompatibility, a second most essential trace elements after iron that found in human system and play a diverse role in body metabolic functions [34]. Hence ZnO NPs gained the importance due to wurzite structure, n-type semiconductor and hexagonal phase [35]. The previous year’s revealed that ZnONP widely known due to their chemical behavior and distinctive optical property having different application in diverse areas [1, 36,37,38,39]. Hence some study come in the light that ZnO NPs apply in additive, food, batteries, ferrites and fire retardants [40]. ZnO NPs use as cell imaging agent [41], biosensors [42], antidiabetic [43], well-functioning in area of nanogenerator [44], antimicrobial [45] and cosmetics [46] due to their novel physicochemical properties. ZnONPs effectively use in drug administration, antimicrobial, antioxidants and treatment of diseases [29, 32], mechanical actuators and piezoelectrically sensors [39, 40]. Henec ZnO nanoparticles light sensitive [47] and agriculture and food pathogen [48]. Hence the few papers come in the light regarding the biogenic synthesis of ZnO NPs from different part of plants are ecological approach that produce less toxic chemicals [44, 49]. Hence biosynthesis of ZnO NPs from plants Sargassum muticum, Aloe vera, Borassus flabellifer fruit Eichhornia cras sipes and also few fungal and bacterial like Escherichia coli, bacillus subtilis, Lactobacillus plantarum and Ureolytic bacteria [50].

The Evolvulus Alsinoides a family plant exhibited medicinal characteristics, E. Alsinoides is a tiny, haired, horizontal, small woody branched roots, and inhabitant in South America and broad in tropical and subtropical area of the world [51, 52]and used as medicine in ayurved in different form and fruitful for health care [53]. Hence the extract E. Alsinoides and its parts have medicinal value used in their treatment [54, 55]. Pharmacognostical in ethanobotanicals produced antioxidant potential [56] in vitro antioxidant potential [57, 58] and nickel oxide nanoparticles shown photocatalytic and anticancer activity [59]. In this study we use biogenic synthesis of ZnO NPs from aqueous extract of E. Alsinoides. The finally synthesized ZnO NPs characterized by physicochemical support such as UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (FE-SEM) and transmission electron microscopy (HR-TEM) respectively.

2 Experimental

2.1 Materials

2.1.1 Preparation of aqueous extract Evolvulus alsinoides

The fresh green leaves collected, washed, dried and crushed. Take the 20 g of it and grinded in to the powder form, kept it in 250 mL Er-lenmeyer flask taking 150 ml of distilled water and heat the reaction mixture at 90 °C and refluxed it for 1 h. The reaction mixture was kept at ordinary temperature 15 min, filtrate passed through Whatmann filter paper and use for further study.

2.2 Biosynthesis of ZnO NPs from aqueous extract E. alsinoides

The aqueous extract of E. alsinoides plant use in amount of 10 ml in a conical flask were heated under stirring at 50 °C for 10 min during this 50 mL of 91 mM zinc acetate use as precursor and its solution was added drop wise with constant stirring. The reaction mixture changed in light yellow colored product and left for 30 min to complete the reduction to zinc hydroxide and then centrifuge at 10,000 rpm for 10 min. The residual was dried at 40–50 °C and reduction of Zn2+ to Zn0 occurred due to the change in color of the solution from light yellow to cream. The UV–visible spectroscopy (Shimadzu, USA) observed a peak in the range of 265 nm favour the formation of ZnONPs.

2.3 Characterization of biosynthesized ZnO NPs

The green synthesized ZnO NPs exhibited UV–vis absorption spectrum from 200 to 500 nm recorded using Shimadzu UV–vis spectrophotometer (UV-1800, Japan). The UV–vis spectrum divulge peak at 264 nm support in fabrication of ZnO NPs (Fig. 1), Fourier transform infrared spectroscopy [FTIR, Perkin Elmer 1750], technique confirm the presence of bioactive functional in aqueous extract of Evolvulus alsinoides plant, a peak shows at 467 cm−1 support the fabrication of ZnO NPs. The SEM and TEM of ZnO NPs showed spherical shape and size range 100 nm. X-ray diffraction with a CuKα radiation provide the XRD pattern and also given the crystalline nature of ZnO NPs.

Fig. 1
figure 1

UV–vis spectrum of ZnO NPs

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3 Result and discussion

3.1 UV–vis spectroscopy

The recent research describe the biosynthesized of ZnO NPs have UV–vis absorption spectrum in the range 200-800 nm recorded using Shimadzu UV–vis spectrophotometer (UV-1800, Japan). UV–vis spectrum of shown a peak at 264 nm demonstrated the develop of ZnO NPs (Fig. 1).

3.2 Fourier transforms infrared spectroscopy (FTIR)

FTIR techniques support to identify the bioactive constituents seen on the surface of ZnO NPs (Fig. 2) obtained from aqueous extract of Evolvulus alsinoides. The FTIR analysis describes the absorption peaks of ZnONPs as 3856, 3419, 2934, 2348, 1571, 1412, 1014, 923, 649 and 467 cm−1. Hence the weak peak observe at 3856 to N–H stretching vibration, 3419 cm−1 related to O–H vibration of alcohol and phenolic compounds, long chain unsaturated fatty acids, octadecanoic acids, squalene (triterpine) is a phenolic compounds, piperine, n-hexdecanoic acid and cholesterol [60]. In the continuation, the other peak observes at 2934 cm−1 (asymmetric C-H stretching bibration), peak1412 cm-1 are assigned to the vibration of the double covalent bond in olefins respectively and 1014 cm-1 may be attribute to- CH3 in the region. This is due to aqueous extract of Evolvulus alsinoids and effect of phytochemicals (squalene, piperine & unsaturated fatty acids) function as reducing agent and also reduced zinc acetate salt. Hence a prominent band at 467 cm−1 shown ZnO NPs formation. The bioactive moieties found as surfactant connected with surface of ZnO NPs and stabilize by electrostatic stabilization and realize that aqueous extract of Evolvulus alsinoids has potentiality to reduced and stabilized ZnO NPs.

Fig. 2
figure 2

FTIR spectrum of ZnONPs

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3.3 X-ray diffraction (XRD)

X-ray diffraction analysis revealed that the synthesized ZnO NPs obtained at nanoscale materials having crystalline nature and diffracto grom shown in Fig. 3 exhibited the peaks resemble to the refraction plane 100, 002, 101, 110, 103, 112, peaks observe at 31.84°, 34.52°, 36.33°, 47.63, 56.71°, 62.96, 68.13° and 69.18°, use Cu Kα radiation having wavelength λ = 0.1541 nm in range 2θ = 20–90° The peak in XRD pattern match with those in the standard reference file ( JCDPS) indication the formation of ZnONPs [61, 62].

Fig. 3
figure 3

XRD pattern of prepared ZnONPs

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3.4 Field-emission scanning electron microscopy, FE- SEM

FE-SEM and morphological study very essential to identification the structural information of synthesized ZnONPs and images be taken at divergent magnification and morphology given Fig. 4. In Fig. 4a image found the accumulation and cluster and randomly distributed form observed in ZnO NPs.

Fig. 4
figure 4

a SEM photograph of ZnONPs b TEM photograph of ZnONPs

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3.5 High-resolution transission electron microscopy, HR-TEM

HR-TEM analysis a authentic technique to determine size and shape of synthesized ZnO NPs and provide the direct information regarding the particles size distribution and shape of nanoparticles (Fig. 4). Additionally, the TEM image shows the spherical in shape and size range 100 nm of the biogenic synthesized ZnO NPs.

4 Conclusion

Nanoscience and nanotechnology play a role with the area of synthesis, exploration, characterization and applications of nanostructure and nanosize materials. Current research carried out to bio synthesis of ZnO NPs using aqueous extract of Evolvulus alsinoides and act as stabilizing and capping agent. In this regards, the biosynthesized ZnO NPs using extract of E. alsinoides a clean, less toxic, environmentally desirable approach. The characterized of ZnO NPs were done by spectral studies like UV–vis specta, FTIR, XRD FE-SEM, HR-TEM respectively. The green synthesized ZnO NPs observe a peak at 264 nm, nanostructure as crystalline and obtained spherical in shape with size range 100 nm found as stable ZnO NPs and this work is not reported earlier. It is hopeful that accomplishment of this approach on a large scale, industrial application, medicine and health care.