Green synthesis of zinc oxide nanoparticles using Bacillus subtilis ZBP4 and their antibacterial potential against foodborne pathogens

Microbial Nanotechnology for Precision Nanobiosynthesis: Innovations, Current Opportunities and Future Perspectives for Industrial Sustainability

A new area of biotechnology is nanotechnology. Nanotechnology is an emerging field that aims to develope various substances with nano-dimensions that have utilization in the various sectors of pharmaceuticals, bio prospecting, human activities and biomedical applications. An essential stage in the development of nanotechnology is the creation of nanoparticles. To increase their biological uses, eco-friendly material synthesis processes are becoming increasingly important. Recent years have shown a lot of interest in nanostructured materials due to their beneficial and unique characteristics compared to their polycrystalline counterparts. The fascinating performance of nanomaterials in electronics, optics, and photonics has generated a lot of interest. An eco-friendly approach of creating nanoparticles has emerged in order to get around the drawbacks of conventional techniques. Today, a wide range of nanoparticles have been created by employing various microbes, and their potential in numerous cutting-edge technological fields have been investigated. These particles have well-defined chemical compositions, sizes, and morphologies. The green production of nanoparticles mostly uses plants and microbes. Hence, the use of microbial nanotechnology in agriculture and plant science is the main emphasis of this review. The present review highlights the methods of biological synthesis of nanoparticles available with a major focus on microbially synthesized nanoparticles, parameters and biochemistry involved. Further, it takes into account the genetic engineering and synthetic biology involved in microbial nanobiosynthesis to the construction of microbial nanofactories.

Combinational antimicrobial activity of biogenic TiO2 NP/ZnO NPs nanoantibiotics and amoxicillin-clavulanic acid against MDR-pathogens

The development of effective strategies against multidrug-resistant (MDR) pathogens is an urgent need in modern medicine. Nanoantibiotics (nABs) offer a new hope in countering the surge of MDR-pathogens. The aim of the current study was to evaluate the antibacterial activity of two attractive nABs, TiO2 NPs and ZnO NPs, and their performance in improving the antimicrobial activity of defined antibiotics (amoxicillin-clavulanic acid, amox-clav) against MDR-pathogens. The nABs were synthesized using a green method. The physicochemical characteristics of the synthesized nanoparticles were determined using standard methods. The results showed the formation of pure anatase TiO2 NPs and hexagonal ZnO NPs with an average particle size of 38.65 nm and 57.87 nm, respectively. The values of zeta potential indicated the high stability of the samples. At 8 mg/mL, both nABs exhibited 100 % antioxidant activity, while ZnO showed significantly higher activity at lower concentrations. The antibiofilm assay showed that both nABs could inhibit the formation of biofilms of Acinetobacter baumannii 80 and Escherichia coli 27G (MDR-isolates). However, ZnO NPs showed superior antibiofilm activity (100 %) against E. coli 27G. The MIC values were determined to be 8 (1), 2 (2), and 4 (4) mg/mL for amox-clav, TiO2 NPs, and ZnO NPs against A. baumannii 80 (E. coli 27G), respectively. The results showed that both nABs had synergistically enhanced antibacterial performance in combination with amox-clav. Specifically, an 8-fold reduction in MIC values of antibiotics was observed when they were combined with nABs. These findings highlight the potential of TiO2 NPs and ZnO NPs as effective nanoantibiotics against MDR-pathogens. The synergistic effect observed when combining nABs with antibiotics suggests a promising approach for combating antibiotic resistance. Further research and development in this area could lead to the development of more effective treatment strategies against MDR infections.

Combating multidrug resistance of breast cancer with ginsenoside Rh2-irrigated nano-in-thermogel

The emergence of multidrug resistance (MDR) is the leading cause of mortality in patients with breast cancer. Overexpressed P-glycoprotein (P-gp) that can pump out chemotherapeutics from multidrug-resistant cancer cells is the main cause of chemotherapy failure. P-gp inhibitors are hence increasingly used to sensitize chemotherapy to breast cancer with MDR by reducing the efflux of drugs. However, representative P-gp inhibitors usually have severe side effects and the effect of their release behavior on chemotherapy are neglected in current studies. We constructed a nano-in-thermogel delivery system with the sequential release of ginsenoside Rh2 (GRh2) and a chemotherapeutic drug in the tumor microenvironment as a drug compounding "reservoir" to combat MDR in breast cancer. Briefly, paclitaxel (PTX) and GRh2 were encapsulated in solid lipid nanoparticles (SLNs) and dispersed in a poloxamer-based thermogel (SLNs-Gel). GRh2 was used as an innovative and safe P-gp inhibitor to lower P-gp expression and cellular adenosine triphosphate context, thereby sensitizing PTX-resistant breast cancer cells (MCF-7/PTX) to PTX. Pharmacodynamic and in vivo safety studies confirmed that intratumoral injection of SLNs-Gel significantly suppressed the proliferation of PTX-resistant breast cancer and alleviated the PTX-induced hematotoxicity. The GRh2-irrigated nano-in-thermogel delivery system shows great potential in combating multidrug-resistant cancer.

Utilizing Cymbopogon Proximus Grass Extract for Green Synthesis of Zinc Oxide Nanorod Needles in Dye Degradation Studies

This study successfully synthesized zinc oxide nanorod needles (ZnO-NRNs) using an environmentally friendly method employing Cymbopogon Proximus extract. The resulting ZnO-NRNs exhibited exceptional physicochemical and structural properties, confirmed through various characterization techniques, including UV-Vis spectrophotometry, dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDX). The analysis revealed a hexagonal wurtzite structure with high crystallinity, a 3.6 eV band gap, and a notably blue-shifted absorption band. ZnO-NRNs showed impressive photocatalytic activity, degrading Rhodamine B dye by 97% under UV and visible sunlight, highlighting their photostability and reusability. This green synthesis process offers cost effectiveness and environmental sustainability for practical applications.

Large-scale production of myco-fabricated ZnO/MnO nanocomposite using endophytic Colonstachys rosea with its antimicrobial efficacy against human pathogens

In this study, a ZnO/MnO nanocomposite was myco-fabricated using the isolated endophytic Clonostachys rosea strain EG99 as the nano-factory. The extract of strain EG99, a reducing/capping agent, was successfully titrated with equal quantities of Zn(NO3)2·6H2O and Mn(NO3)2·6H2O (precursors) in a single step to fabricate the rod-shaped ZnO/MnO nanocomposite of size 6.22 nm. The ZnO/MnO nanocomposite was myco-fabricated in 20 min, and the results were validated at 350 and 400 nm using UV-Vis spectroscopy. In a 7-L bioreactor, an industrial biotechnological approach was used to scale up the biomass of this strain, EG99, and the yield of the myco-fabricated ZnO/MnO nanocomposite. A controlled fed-batch fermentation system with a specific nitrogen/carbon ratio and an identical feeding schedule was used in this production process. Higher yields were obtained by adopting a controlled fed-batch fermentation approach in a 7-L bioreactor with a regular feeding schedule using a nitrogen/carbon ratio of 1:200. Overall, the fed-batch produced 89.2 g/l of biomass at its maximum, 2.44 times more than the batch's 36.51 g/l output. Furthermore, the fed-batch's maximum ZnO/MnO nanocomposite yield was 79.81 g/l, a noteworthy 14.5-fold increase over the batch's yield of 5.52 g/l. Finally, we designed an innovative approach to manage the growth of the endophytic strain EG99 using a controlled fed-batch fermentation mode, supporting the rapid, cheap and eco-friendly myco-fabrication of ZnO/MnO nanocomposite. At a dose of 210 µg/ml, the tested myco-fabricated ZnO/MnO nanocomposite exhibited the maximum antibacterial activity against Staphylococcus aureus (98.31 ± 0.8%), Escherichia coli (96.70 ± 3.29%), and Candida albicans (95.72 ± 0.95%). At the same dose, Staphylococcus aureus biofilm was eradicated in 48 h; however, Escherichia coli and Candida albicans biofilms needed 72 and 96 h, respectively. Our myco-fabricated ZnO/MnO nanocomposite showed strong and highly selective antagonistic effects against a variety of multidrug-resistant human pathogens. Therefore, in upcoming generations of antibiotics, it might be employed as a nano-antibiotic.

Vitex Negundo-Fe3O4-CuO green nanocatalyst (VN-Fe3O4-CuO): synthesis of pyrazolo[3,4-c]pyrazole derivatives via the cyclization of isoniazid with pyrazole and their antimicrobial activity, cytotoxicity, and molecular docking studies

In this study, we developed a novel pyrazolo[3,4-c]pyrazole derivative with antibacterial and antifungal activities that shows great potential for treating infectious diseases. To evaluate the binding affinity of 1AJ0 and 1AI9 proteins for developing potent antibacterial and antifungal compounds, we used the Vitex negundo (VN) leaf extract as the capping and reducing agent and reacted it with Fe2O3 and Cu(OAc)2 solutions to synthesize the VN-Fe3O4-CuO nanocatalyst. The newly synthesized compounds were confirmed using Fourier transform infrared spectroscopy, transmission electron microscopy, UV-visible spectroscopy, and X-ray diffraction analyses. Antibacterial screening revealed that compound 1g was highly active against Escherichia coli (MIC: 1 μg mL-1) and was much more effective than the standard ciprofloxacin. Compound 1b showed a higher antifungal activity than clotrimazole against Candida albicans (MIC: 0.25 μg mL-1) and cytotoxic activity against MCF-7 cancer cell lines. Compounds 1a-1l were exhibited low cytotoxicity activity compared to the standard doxorubicin (LC50: 21.05 ± 0.82 μg mL-1). To further support the discovery of new active antibacterial agents, compounds 1g and 1b and proteins 1AJ0 and 1AI9 were examined using the AutoDock Vina program and were compared with the standards ciprofloxacin and clotrimazole. With the 1AJ0 protein, compound 1g had a higher docking score (-3.7 kcal mol-1) than ciprofloxacin (-5.6 kcal mol-1), and with the 1AI9 protein, compound 1b had a higher docking score (-4.8 kcal mol-1) than clotrimazole (-4.4 kcal mol-1). Additionally, molecular dynamics simulation was used to investigate the most probable binding mode of compounds 1b and 1g with 1AI9 and 1AJ0, respectively. The VN-Fe3O4-CuO catalyst was used to prepare pyrazolo[3,4-c]pyrazole derivatives, which were successfully characterized and screened for antimicrobial and cytotoxic activities, molecular docking, and molecular dynamics simulation studies.

Response surface methodology based optimization of keratinase from Bacillus velezensis strain ZBE1 and nanoparticle synthesis, biological and molecular characterization

The increasing demands of keratinases for biodegradation of recalcitrant keratinaceous waste like chicken feathers has lead to research on newer potential bacterial keratinases to produce high-value products with biological activities. The present study reports a novel keratinolytic bacterium Bacillus velezensis strain ZBE1 isolated from deep forest soil of Western Ghats of Karnataka, which possessed efficient feather keratin degradation capability and induced keratinase production. Production kinetics depicts maximum keratinase production (11.65 U/mL) on 4th day with protein concentration of 0.61 mg/mL. Effect of various physico-chemical factors such as, inoculum size, metal ions, carbon and nitrogen sources, pH and temperature influencing keratinase production were optimized and 3.74 folds enhancement was evidenced through response surface methodology. Silver (AgNP) and zinc oxide (ZnONP) nanoparticles with keratin hydrolysate produced from chicken feathers by the action of keratinase were synthesized and verified with UV-Visible spectroscopy that revealed biological activities like, antibacterial action against Bacillus cereus and Escherichia coli. AgNP and ZnONP also showed potential antioxidant activities through radical scavenging activities by ABTS and DPPH. AgNP and ZnONP revealed cytotoxic effect against MCF-7 breast cancer cell lines with IC50 of 5.47 µg/ml and 62.26 µg/ml respectively. Characterizations of nanoparticles were carried out by Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray, X-ray diffraction, thermogravimetric analysis and atomic force microscopy analysis to elucidate the thermostability, structure and surface attributes. The study suggests the prospective applications of keratinase to trigger the production of bioactive value-added products and significant application in nanotechnology in biomedicine.