Abhimanyu Kumar Singh

The green synthesis of nanomaterials has drawn researchers from all over the world over the past few decades in a huge surge of interest. The aim of this research was to use Kinnow peel extract to synthesize titanium dioxide (TiO ₂ ) nanoparticles (NPs) in an environmentally friendly and efficient manner. This method seeks to improve antioxidant qualities while using fewer hazardous chemicals in the production of NPs. Using ultraviolet visible (UV–Vis) spectroscopy, the formation of crystalline TiO ₂ NPs was first verified by a distinctive absorbance peak at 235 nm. Further characterization was performed using X–ray diffraction (XRD), field emission–scanning electron microscopy (FE-SEM), energy–dispersive X–ray spectroscopy (EDX), transmission electron microscopy (TEM), and Fourier transform infrared (FT–IR) spectroscopy. The antioxidant potentials of the green-synthesized TiO ₂ NPs were evaluated using DPPH and FRAP assays. The results demonstrated potent free radical scavenging activity, comparable to ascorbic acid, a well-known standard antioxidant. These findings suggest that TiO ₂ NPs possess effective antioxidant properties and highlighting Kinnow peel extract as an eco-friendly sustainable and alternative to conventional synthesis routes. Moreover, the study indicate that the green-synthesized TiO ₂ NPs could serve a promising candidate to replace the conventional antioxidant drugs, such as ascorbic acid.

In the current scenario, various industries such as pharmaceuticals, biomedical sectors, cosmetics, photovoltaics, and automotive utilize zinc oxide nanoparticles (ZnO NPs) widely due to their exceptional potentials and high surface area-to-volume ratio. However, researchers are still working to improve the potential of ZnO NPs as antimicrobial, anticancer, antioxidant, antidiabetic, etc. This chapter highlighted plants and microbial extract-based synthesis methods of ZnO NPs and comparative understanding established with laser ablation, chemical reduction, milling, and sputtering. In contrast, the green synthesis of ZnO NPs offers an eco-friendly and chemical-free approach for biological applications. The green synthesis method involves a range of extract compositions, including secondary metabolites flavonoids, enzymes, proteins, and sugars, which reduce and stabilize ZnO NPs, influencing their structure, shape, size, and morphology. Biologically synthesized ZnO NPs, due to their cost-effective and eco-friendly nature, are significant for medication distribution and sensing applications.

The over-production of free radicals in the body causes oxidant damage in the body. Currently, zinc oxide nanoparticles (ZnO NPs) are gaining attention of most scientists because of their excellent physical, chemical, and biological properties. In this work, the ZnO NPs were synthesized using the petal extract of C. officinalis L. An absorbance spectrum of the synthesized ZnO NPs was recorded using an ultraviolet-visible (UV–Vis) spectrophotometer. The absorbance band around 368 nm confirms the formation of ZnO NPs. The transmission electron microscopy (TEM) analysis clearly shows that the most of the ZnO NPs are spherical in shape with average particle size ∼ 16 nm. The field emission scanning electron microscope (FE-SEM) result demonstrates the spherical morphology with large agglomeration of the particles. The energy-dispersive x-ray spectroscopy (EDS) result confirms the presence of Zn in the synthesized NPs’. The x-ray diffraction (XRD) peaks represent the crystalline structure of the ZnO NPs with average particle size ∼ 27.22 nm. Fourier transform infra-red (FT-IR) spectrum of synthesized ZnO NPs was recorded in the range of 4000-500 cm⁻¹. The ester and carboxylic groups were found at 1017 cm⁻¹, 952 cm⁻¹, 688 cm⁻¹, 609 cm⁻¹, and 514 cm⁻¹ due to the presence of Zn-O band stretch in the FT-IR spectrum. Further synthesized material was evaluated by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay to evaluate its antioxidant activity. It showed that ZnO NPs exhibited significant antioxidant activity through scavenging DPPH free radicals. Thus, it could be seen that the synthesis of naturally occurring plant product ZnO NPs acts as an alternative chemical antioxidant. Hence, the herbal synthesized ZnO NPs are proven to be a potent antioxidant agent and can be used in several medicinal applications.

In the recent decade, zinc oxide nanoparticles (ZnO NPs) have been widely explored owing to their versatile properties and prodigious demands in the drug delivery, medical, energy storage, cosmetics, and the healthcare sectors. Therefore, the current work opts for an environmentally benign method to prepare ZnO NPs. The leaf extract of Calendula officinalis L. acts as a reducing agent for the metal ions; therefore, in the current research, ZnO NPs were prepared via green route by using Calendula officinalis leaf extract. Furthermore, the ZnO NPs were analysed with different spectroscopic techniques to confirm the structure and stability of nanomaterials. The prepared ZnO NPs were characterized by XRD, FE-SEM, FT-IR and UV–Vis studies. Also, the antioxidant and antimicrobial properties of the synthesized ZnO NPs were investigated. The XRD result of synthesized ZnO NPs showed the crystalline size 28.23 nm with wurtzite hexagonal structure along with the most intense peak (101). Following preliminary confirmations of the intended ZnO NPs, both big and small agglomerated forms were observed in the FE-SEM, which is often used to determine their exterior assembly. Further, the results of Fourier transform infrared spectroscopy (FT-IR) indicated the formation of pure ZnO NPs with an absorption peak of the Zn–O bond between 4000 cm⁻¹ and 500 cm⁻¹ and no discernible peak in the monitoring range. The UV–Vis spectrum of the green synthesized ZnO NPs were revealed two prominent absorption peaks at 355 nm and 370 nm with energy band gap of 2.986 eV. Using the 1, 1-di phenyl-2-picrylhydrazyl (DPPH) test, the antioxidant activity of the described ZnO NPs was assessed. It demonstrated how, ZnO NPs significantly increased their antioxidant activity by scavenging 1, 1-di phenyl-2-picrylhydrazyl (DPPH) free radicals. It could be seen that synthesis of the naturally occurring plant product ZnO NPs have been acting as an alternate of chemical antioxidant. The antimicrobial analysis was also performed with the help of disk diffusion method where three multi-drug resistant human pathogens namely Staphylococcus aureus, Klebsiella pneumoniae and E.coli were used. The Zone of Inhibition diameter values are 35.2 mm ± 0.9, 23.6 mm ± 0.1 and 13.5 mm ± 0.1, respectively, which showed that the ZnO NPs was highly effective against S. aureus. Thus, the green synthesis method of ZnO NPs using leaf extract of Calendula officinalis is evidence that it is superior and environmentally friendly method for the preparation of ZnO NPs and hence it can be utilized in various nano-medicine approaches.

Rapidlyincreasing population, the demand for food has increased substantially. To overcome food deficits, an increase in agricultural production is needed, and for sustainability, the qualities of crops as well as maintaining the fertility of the soil are challenging situations. Soil contains limited amount of macro, micronutrients and innumerable amounts of soil microflora, which helps in crop production. Since the mid-19th century, a plethora of chemical fertilizers have been extensively used to improve crop production, but over time, they have shown disastrous effects on the soil compositionand profile. In the current alarming scenario, a new technology arearising, namely nanotechnology, in the field of agriculture. Nano-chemicals can play a paramount role in sustainable agriculture. This reviewsummarizes a variety of nanomaterials as pesticide, fertilizers and control of attack of fungus and bacterial diseases. Here discussed a range of nanomaterials including Ag, Fe, Cu, Si, Se, Al, Zn, ZnO, TiO₂ and carbon nanotubes non-propitious effectsof biomagnification. This review alsodiscussesthe several mechanisms which show how nanomaterials does work as nanofertilizer, nano pesticides, and control bacterial and fungal diseases along with the advantages and disadvantages in the sustainable approach of agriculture. Furthermore, it discusses the synergistic effect of nanomaterials and conventional approach involved in agriculture practices. Nano-fertilizers and nano-biofertilizers are new tools that have evolved for the sustainableagricultural and food security.

Dental caries is a major lifestyle concern as dental components affect the face of an individual. The issue of tooth decay occurs in every age group throughout the globe. Researchers are probing incipient implements and techniques to develop filling agents for decayed teeth. Zinc oxide (ZnO) powder is utilized mostly as a filling agent. Nanotechnology enhanced the efficiency of compounds of metal oxides utilized for dental caries. The present study aims to investigate the properties of ZnO nanoparticles (NPs) synthesized chemically (using ZnCl₂ and NaOH) as well as biologically (using aqueous leaf extract of Murraya paniculata). The XRD patterns confirm that ZnO NPs have a hexagonal crystalline structure with particle sizes of 47 nm and 55 nm for chemically and biologically synthesized NPs, respectively. The FE-SEM data confirm the nanorod and spherical/cubical shape morphologies for the chemically and biologically synthesized ZnO NPs, respectively. FTIR data show the peaks between 4000 and 450 cm⁻¹ of the functional groups of –OH, C-O, –C-H-, and Zn-O bonds. The UV–Vis absorption study indicates a peak around 370 nm and a hump around 360 nm corresponding to the chemically and biologically synthesized ZnO NPs, respectively. An antibacterial bioassay was performed and compared with commercially available ZnO bulk powder against tooth decaying pathogens, viz., Streptococcus mutans, Staphylococcus aureus, E. coli, and Lactobacillus fermentum, and found that both ZnO NPs had results closer to those of the standard drug (rifampicin). Thus, the synthesized ZnO NPs may be utilized as nano-drugs for the application of tooth decaying filling agents. Even biologically synthesized ZnO NPs may be considered more environmentally friendly and less toxic to human health concerns.

Impurity-free, controlled synthesis of iron oxide nanoparticle, in ultrapure water and chitosan, using laser ablation technique and its application for type II diabetes management through oral delivery of insulin-loaded iron oxide–chitosan nanocomposite is presented. The purity of the nanoparticle is monitored by laser-induced breakdown spectroscopy technique. The synthesized iron oxide nanoparticle was characterized by UV/Vis absorption spectroscopy, and morphological study was performed by scanning electron microscope. The intensity of absorption peak and wavelength corresponding to peak of the nanoparticle prepared in water and chitosan is dependent on the laser energy used for ablation purpose. Red shift in the absorption peak wavelength was observed by increasing laser energy. In addition to red shift, an increase in intensity of absorption peak was also seen when ablating laser energy was increased. The appearance of a weak peak around 295 nm was observed in iron oxide–chitosan nanocomposite. The spherical shape of the nanoparticle synthesized at the lower laser energy has gradually changed to triangular and irregular shaped structures as ablating laser energy was increased. The spherical nanoparticles loaded with insulin were used for oral delivery for diabetic management. The iron oxide–chitosan nanocomposite loaded with insulin has resulted in reduction in blood glucose level in mild diabetic, subdiabetic, and severely diabetic rats; more than 51 % reduction in blood glucose level, compared to the control group, has been achieved in the present work.

Colloidal silver nanospheres, nanorings, and nanonetworks were synthesized by the nanosecond pulsed laser ablation of a silver metal plate in a pure distilled water (at room temperature) using the fundamental (1064 nm), second harmonic (532 nm), and third harmonic (355 nm) wavelengths of the Nd:YAG laser, respectively. The products were characterized by means of both transmission electron microscopy (TEM) and optical absorption spectroscopy. The TEM data show the formation of silver nanospheres, nanorings, and nanonetworks. On the other hand, optical spectra reveal the occurrence of the red shift of the peak associated with the surface plasmon resonance (SPR) of silver nanorings and nanonetworks. A possible explanation for the formation of above stated silver nanostructures is being discussed.