Nano-bio effects: Interaction of ZnO and DNA-bases

The interactions between two heme proteins myoglobin (HMb) and horseradish peroxidase (HRP) with zinc oxide (ZnO) nanoparticles are investigated by using UV–vis absorption, steady state fluorescence, synchronous fluorescence, time-resolved fluorescence, FT-IR, atomic force microscopy (AFM) and circular dichroism (CD) techniques under physiological condition of pH∼7.4. The presence of mainly static mode in fluorescence quenching mechanism of HMb and HRP by ZnO nanoparticle indicates the possibility of formation of ground state complex. The processes of bindings of ZnO nanoparticles with the two proteins are spontaneous molecular interaction procedures. In both cases hydrogen bonding plays a major role. The circular dichroism (CD) spectra reveal that a helicity of the proteins is reduced by increasing ZnO nanoparticle concentration although the α-helical structures of HMb and HRP retain their identity. On binding to the ZnO nanoparticles the secondary structure of HRP molecules (or HMb molecules) remains unchanged while there is a substantial change in the environment of the tyrosin active site in case of HRP molecules and tryptophan active site in case of HMb molecules. Tapping mode atomic force microscopy (AFM) was applied for the investigation the structure of HRP adsorbed in the environment of nanoparticles on the silicon and on the bare silicon. HRP molecules adsorb and aggregate on the mica with ZnO nanoparticle. The aggregation indicates an attractive interaction among the adsorbed molecules. The molecules are randomly distributed on the bare silicon wafer. The adsorption of HRP in the environment of ZnO nanoparticle changes drastically the domains due to a strong interaction between HRP and ZnO nanoparticles. Similar situation is observed in case of HMb molecules. These findings demonstrate the efficacy of biomedical applications of ZnO nanoparticles as well as in elucidating their mechanisms of action as drugs in both human and plant systems.

Surface modification of zinc oxide nanoparticles by vinyltriethoxy silane (VTES)

Zinc Oxide (ZnO) nanoparticles were prepared using a simple green synthesis approach in an alkaline medium, from three different extracts of citrus peels waste. The synthesized nano-crystalline materials were characterized by using ultraviolet-visible spectroscopy (UV-vis), x-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), energy-dispersive x-ray spectroscopy (EDS), environmental scanning electron microscopy (ESEM), and transmission electron microscopy (TEM). UV-vis analysis of the nanoparticles showed broad peaks around 360 nm for the ZnO NPs (Zinc oxide nanoparticles) from three citrus peels’ extracts. ZnO NPs exhibited Zn–O band close to 553 cm−1, which further verified the formation of the ZnO NPs. A bandgap of 3.26 eV, 3.20 eV and 3.30 eV was calculated for the ZnO NPs from grape (ZnO NPs/GPE), lemon (ZnO NPs/LPE), and orange (ZnO NPs/OPE) peels extract, respectively. The average grain sizes of the ZnO nanoparticles were evaluated to be 30.28 nm, 21.98 nm, and 18.49 nm for grape (ZnO NPs/GPE), lemon (ZnO NPs/LPE), and orange (ZnO NPs/OPE) peel extract, respectively. The surface morphology and sizes of the nanoparticle were confirmed by ESEM and TEM analysis, respectively. Furthermore, the zeta potential of the as-prepared ZnO NPs from OPE, LPE, and GPE was −34.2 mV, −38.8 mV, and −42.9 mV, respectively, indicating the high stability of the nanoparticles. Cyclic voltammetric properties of the synthesized nanoparticles were investigated across extracts, and the results showed that the citrus peels extracts (CPE) mediated ZnO NPs modified screen plate carbon (SPC/ ZnO NPs/CPE) electrodes exhibited enhanced catalytic properties when compared with the bare SPCE. The electroactive areas computed from the enhancement of the bare SPCE was approximately three times for SPCE/ ZnO NPs/LPE, and SPCE/ZnO NPs/GPE, and two times for SPCE/ZnO NPs/OPE, higher than that of the bare SPCE. Comparison across the extracts suggested that the catalytic properties of the nanoparticles were unique in ZnO NPs from GPE.

Salinity is an edaphic stress that dramatically restricts worldwide crop production. Nanomaterials and plant growth-promoting bacteria (PGPB) are currently used to alleviate the negative effects of various stresses on plant growth and development. This study investigates the protective effects of different levels of zinc oxide nanoparticles (ZnO-NPs) (0, 20, and 40 mg L−1) and PGPBs (no bacteria, Bacillus subtilis, Lactobacillus casei, Bacillus pumilus) on DNA damage and cytosine methylation changes in the tomato (Solanum lycopersicum L. ‘Linda’) seedlings under salinity stress (250 mM NaCl). Coupled Restriction Enzyme Digestion-Random Amplification (CRED-RA) and Randomly Amplified Polymorphic DNA (RAPD) approaches were used to analyze changes in cytosine methylation and to determine how genotoxic effects influence genomic stability. Salinity stress increased the polymorphism rate assessed by RAPD, while PGPB and ZnO-NPs reduced the adverse effects of salinity stress. Genomic template stability was increased by the PGPBs and ZnO-NPs application; this increase was significant when Lactobacillus casei and 40 mg L−1 of ZnO-NPs were used.A decreased level of DNA methylation was observed in all treatments. Taken together, the use of PGPB and ZnO-NPs had a general positive effect under salinity stress reducing genetic impairment in tomato seedlings.

A simple procedure was used to generate and decorate leather structures with different amounts from zinc oxide (ZnO) nanoparticles to produce multifunctional leather structure by pulsed laser ablation method in liquid media based on changing the ablation time in just one-pot method. The impact of varying concentrations of ZnO nanoparticles embedded on the surface of leather on water resistance, water vapor permeability, mechanical characteristics, and UV-shielding efficiency was examined by different characterization techniques like X-ray diffraction, surface area, UV-visible spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The results showed that the combination between the external functional groups of leather with ZnO nanoparticles was discovered. ZnO nanoparticles effectively coated the surface of leather tissue, as seen by SEM images, and their form a spherical morphology. Leather with ZnO nanoparticles added had the highest capacity to kill Escherichia coli bacteria, exceeding leather without modification and ZnO nanoparticles alone in 50-hr incubation. In addition, the incubation period had a substantial impact on the suppression of Staphylococcus aureus bacteria growth by leather samples.

This chapter focuses on zinc oxide (ZnO) nanoparticle (NP) synthesis using the co-precipitation method with the aqueous plant extract of Rubus fairholmianus. The synthesized NP was characterized by different techniques using ultraviolet-visible (UV-Vis) and Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The SEM results revealed that the ZnO NPs formed a spherical structure and accumulated in the form of flower-shaped bundles. The energy dispersive X-ray analysis (EDAX) report exhibited that the ZnO NPs contain weight percentages of 34.13% zinc and 65.87% oxygen. The ZnO NPs reported a total phenolic, tannin and flavonoid content of 412.82 ± 9.27 mg GAE/g, 99.38 ± 7.77 mg RE/g, and 25.06 ± 1.71 mg GAE/g, respectively. The ZnO NPs showed better antioxidant and anti-inflammatory activities. The erythrocyte membrane against hypotonic-induced lysis of 80.17% compared to the diclofenac standard. Hence the ZnO NPs of R. fairholmianus possess better pharmacological activities that could be used to develop potential drugs against chronic diseases.

Four bacterial strains were used for biosynthesis of zinc oxide (ZnO) nanoparticles (NPs), namely Bacillus tropicus SHJP5, Bacillus tropicus LKJP6, Aeribacillus composti SJP25, and Aeribacillus pallidus SJP28. The synthesized nanoparticles were characterized using UV‐Visible spectroscopy (UV‐Vis), Fourier transform infrared spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), Photoluminescence spectroscopy (PL), Thermogravimetric analysis (TGA), and X‐ray diffraction (XRD). The XRD pattern of NPs (bio‐synthesized) shows the polycrystalline hexagonal wurtzite structure with the three major planes (100), (002), and (001). The average crystallite size determined by the Debye‐Scherrer equation is between 8–54 nm. A reduction in crystallite size of as‐prepared nanoparticles was observed in the presence of bacterial strains. The FTIR analysis reveals the amide, carboxyl, and hydroxyl groups found on the surface of biosynthesized ZnO NPs. These groups behave as reducing and stabilizing agents. The UV‐Vis spectra reveal the absorption bands for control, SHJP5, LKJP6, SJP25, and SJP28 at 373, 363, 382, 358, and 380 nm respectively. The corresponding energy band gap was found to be 3.324, 3.415, 3.246, 3.463, and 3.263 eV respectively, with the decreasing size of the nanoparticles produced by bacterial strains. The FESEM analysis confirms the hexagonal structure of bio‐synthesized ZnO NPs. The nanoparticles have a uniform distribution of spherical shape except for the strain Aeribacillus pallidus LKJP6 which exhibits uniform and thin nanorods. Minimum inhibitory concentration (MIC) tests against E. coli (7.1 mg/ml) and S. aureus (3.2 mg/ml) verified the antibacterial activity of produced ZnO NPs. The use of isolated strains for the extracellular manufacture of ZnO NPs is encouraged in this work. To the best of our knowledge, this might be the first study that has been presented that shows the structural, optical, and surface morphology of a thermophilic bacterium, Bacillus tropicus SHJP5, Bacillus tropicus LKJP6, Aeribacillus composti SJP25, and Aeribacillus pallidus SJP28 for the biosynthesis of ZnO NPs in particular.

This study presents a novel, eco-friendly synthesis route for zinc oxide (ZnO) nanoparticles using cladode extracts of Hylocereus undatus acting simultaneously as reducing and improving agents, in alignment with green chemistry principles. The synthesis involved the reaction of zinc sulfate heptahydrate with the plant extract, with the medium pH adjusted using sodium hydroxide (NaOH), followed by calcination at 300 °C, 400 °C, and 500 °C, and then by a washing step to enhance purity. Comprehensive characterization was performed using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrical impedance spectroscopy to investigate the structural, morphological, and dielectric properties of the nanoparticles. The sample calcined at 400 °C, followed by washing (HT400W), exhibits highly crystalline ZnO nanoparticles with a predominant wurtzite structure (93.15 wt% ZnO) and minimal impurities (6.85 wt% Na2SO4). SEM analysis indicated a flake-like morphology with nanoscale features (50-100 nm), while Raman spectroscopy confirmed enhanced crystallinity and purity post-washing. Additionally, the HT400W sample exhibited a dielectric constant (ε') of 16.96 and a low loss tangent (tan δ) of 0.14 at 1 MHz, suggesting superior energy efficiency for high-frequency applications. This green synthesis approach not only eliminates hazardous reagents but also delivers ZnO nanoparticles with good dielectric performance. Furthermore, this work demonstrates the efficacy of a sustainable biotemplate, offering an environmentally friendly approach for synthesizing ZnO nanoparticles with tailored physicochemical properties.

The present study investigates the effect of Silver doped zinc oxide (Ag-ZnO) and Zinc Oxide (ZnO) nanoparticles fuel additives on the performance and emission characteristics of diesel engine. The ZnO and Ag-doped ZnO nanoparticles (NPs) prepared by the hydrothermal method. After the preparation, the XRD pattern of ZnO and Ag-doped ZnO NPs revealed hexagonal wurtzite structure and calculated their crystallite size was 19 and 37 nm. FTIR spectra confirmed the presence of Ag and Zn-O vibration modes. The micrograph (or nano) of scanning electron microscopy and transmission electron microscopy shows the spherical shape with less agglomerated ZnO and Ag-doped ZnO NPs. Both ZnO and Ag-doped ZnO NPs were added in Pongamia B20 biodiesel blends with the various proportions as an additive. Furthermore, the experimentally measured results exhibited significant emission (CO, NOx) properties of biodiesel blends with the addition of ZnO and Ag-ZnO NPs in diesel engines.

The current paper explores the preparation of PVA nanocomposites by doping with zinc oxide (ZnO) nanoparticles using the method of coagulation and solvent casting technique. The dopant zinc oxide nanoparticle is prepared by simple precipitation method and is confirmed by the X-ray diffraction (XRD) studies. The XRD studies explore that the average particle size of the synthesized nanoparticles is 55 nm and show that the crystallinity factor of PVA nanocomposites is influenced by the interaction occurring between the PVA main chain and the ZnO nanoparticle. The FTIR spectroscopy suggests that the formulation of complexes occurring between the dopants and the PVA main chain is due to inter or intra molecular hydrogen bonding. UV-vis spectra explore the dramatic decrease in the optical energy gap of nanoparticles doped polymer composites and the variations of Urbach energy (Eu) related to crystallinity for various dopant concentrations. The mechanical properties of the PVA nanocomposites were explored using universal testing machine (UTM) that reflects that, for x=15% doping concentration, there is an increase in the tensile strength, stiffness, and Young’s modulus, whereas, for x=7.5% concentration, the percentage total elongation at fracture is found to be the maximum. The morphological behavior and homogenous nanoparticle distribution in the composites were examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDAX).

Nowadays, the current synthesis techniques used in industrial production of nanoparticles have been generally regarded as nonenvironmentally friendly. Consequently, the biosynthesis approach has been proposed as an alternative to reduce the usage of hazardous chemical compounds and harsh reaction conditions in the production of nanoparticles. In this work, pure, iron (Fe)-doped and silver (Ag)-doped zinc oxide (ZnO) nanoparticles were successfully synthesized through the green route using Clitoria ternatea Linn. The optical, chemical, and physical properties of the biosynthesized ZnO nanoparticles were then analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis diffuse reflectance spectroscopy (DRS), zeta potential measurement, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and surface analysis. The biosynthesized ZnO nanoparticles were crystallized with a hexagonal wurtzite structure and possessed smaller particle sizes than those of commercially or chemically produced samples. The existence of biomolecules to act as reducing and stabilizing agents from C. ternatea Linn aqueous extract was confirmed using FTIR analysis. The biosynthesized ZnO nanoparticles mainly comprised of negatively charged groups and responsible for moderately stable dispersion of the nanoparticles. All these properties were favorable for the sonocatalytic degradation of Congo red. Sonocatalytic activity of ZnO nanoparticles was studied through the degradation of 10 mg/L Congo red using ultrasonic irradiation at 45 kHz and 80 W. The results showed that the sonocatalytic degradation efficiency of Congo red in the presence of biosynthesized ZnO nanoparticles prepared at 50 °C for 1 h could achieve 88.76% after 1 h. The sonocatalytic degradation efficiency of Congo red in the presence of Ag-doped ZnO was accelerated to 94.42% after 10 min which might be related to the smallest band gap energy (3.02 eV) and the highest specific surface area (10.31 m2/g) as well as pore volume (0.0781 cm3/g). Lastly, the biosynthesized ZnO nanoparticles especially Ag-doped ZnO offered significant antibacterial potential against Escherichia coli which indicated its ability to inhibit the normal growth and replication of bacterial cells. These results affirmed that the biosynthesized ZnO nanoparticles could be used as an alternative to the current chemical compounds and showed a superior sonocatalytic activity toward degradation of Congo red.

Biosynthesis of zinc oxide nanoparticles from Azadirachta indica for antibacterial and photocatalytic applications

We presented a low-cost, eco-friendly, and efficient bacterium-mediated synthesis of zinc oxide nanoparticles (ZnO-NPs) utilizing Paraclostridium benzoelyticum strain 5610 as a capping and reducing agent. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, energy-dispersive X-ray, and UV-vis spectroscopy were used to physiochemically characterize the biosynthesized ZnO-NPs. A major narrow peak at 441 nm was observed using UV-visible spectroscopy, verifying the presence of nanoparticles. According to SEM and TEM studies, the average dimensions of ZnO-NPs was 50 nm. The crystal size of 48.22 nm was determined by XRD analysis. FTIR analysis confirmed the presence of various reducing metabolites on the surface of ZnO-NPs. The synthesized nanoparticles were investigated for biological activity against Helicobacter suis, Helicobacter bizzozeronii, Helicobacter felis, and Helicobacter salomonis. Helicobacter suis was the most vulnerable strain, with an inhibitory zone of 19.53 ± 0.62 mm at 5 mg/mL dosage. The anti-inflammatory and the findings of the rat paw edema experiments revealed that the bacterium-mediated ZnO-NPs had a strong inhibitory action. In the arthritis model, the solution of ZnO-NPs showed 87.62 ± 0.12% inhibitory effect of edema after 21 days when linked with that of the standard drug. In the antidiabetic assay, ZnO-NPs sharply reduced glucose level in STZ-induced diabetic mice. In this study, the particle biocompatibility by human red blood cells was also determined. Keeping in view the biological importance of ZnO-NPs, we may readily get the conclusion that Paraclostridium benzoelyticum strain 5610-mediated ZnO-NPs will be a prospective antidiabetic, antibacterial, antiarthritic, and anti-inflammatory agent in vivo experimental models and can be used as a potent antidiabetic drug.

The important contribution of DNA to modern day nanobiotechnology is sometimes ascribed to its potential role as a programmable building block for the assembly of nanomaterials. In this work, our density functional theory (DFT) based study explores the possibilities of using complexes of DNA bases (viz., adenine (A), thymine (T), guanine (G), and cytosine (C)) as well as DNA base pairs (such as A-T, C-G, and G4-quadruplex) with the gold cluster Au3 as a model catalyst system for oxidation of CO to CO2. The complexes are energetically stable, and our calculated binding energies of the gold cluster–DNA base complexes are found to match closely with the experimentally obtained heat of desorption of DNA bases on Au films. Our results also reveal that the oxidation of CO on these complexes takes place exclusively via an Eley–Rideal (E-R) type of mechanism whereas both E-R and Langmuir–Hinshelwood (L-H) mechanisms for this reaction are observed for a bare Au3 cluster. More interestingly, the CO oxidation reaction on the gold cluster (in the complexes) is found to be more facile, with a lesser activation barrier and higher heat of formation of the products, as compared to that of a pristine Au3 cluster. Our results suggest that DNA base–gold cluster complexes can be an attractive and efficient catalytic model system that can have wider ramifications. Since the nanoscale gold is already known as a potential catalyst for variety of chemical reactions, our approach will richly supplement to the expanding horizons of catalysis involving gold.

Direct electrocatalytic and simultaneous determination of purine and pyrimidine DNA bases using novel mesoporous carbon fibers as electrocatalyst