Characterization, antimicrobial, and antioxidant activities of silver nanoparticles synthesized by uricase from Alcaligenes faecalis GH3

A review of microbes mediated biosynthesis of silver nanoparticles and their enhanced antimicrobial activities

In recent decades, biosynthesis of metal and (or) metal oxide nanoparticles using microbes is accepted as one of the most sustainable, cost-effective, robust, and green processes as it does not encompass the usage of largely hazardous chemicals. Accordingly, numerous simple, inexpensive, and environmentally friendly approaches for the biosynthesis of silver nanoparticles (AgNPs) were reported using microbes avoiding conventional (chemical) methods. This comprehensive review detailed an advance made in recent years in the microbes-mediated biosynthesis of AgNPs and evaluation of their antimicrobial activities covering the literature from 2015-till date. It also aimed at elaborating the possible effect of the different phytochemicals, their concentrations, extraction temperature, extraction solvent, pH, reaction time, reaction temperature, and concentration of precursor on the shape, size, and stability of the synthesized AgNPs. In addition, while trying to understand the antimicrobial activities against targeted pathogenic microbes the probable mechanism of the interaction of produced AgNPs with the cell wall of targeted microbes that led to the cell's reputed and death have also been detailed. Lastly, this review detailed the shape and size-dependent antimicrobial activities of the microbes-mediated AgNPs and their enhanced antimicrobial activities by synergetic interaction with known commercially available antibiotic drugs.

Biosynthesis of metallic nanoparticles by bacterial cell-free extract

The biosynthesis of metallic nanoparticles (MNPs), encompassing noble metals, metal oxides, and sulfides, has gained significant attention in recent years due to their unique properties and wide-ranging applications. However, traditional chemical synthesis methods often involve extreme conditions, harsh chemicals, and negative environmental impacts. Consequently, developing a simple, non-toxic, and eco-friendly approach for MNP synthesis is paramount. One promising method that addresses these concerns is using a bacterial cell-free extract (CFE) as a mediator for biosynthesis. Compared with other biosynthesis production methods, the purification process of MNPs synthesized using bacterial CFEs is much simpler, and CFE production is easier to standardize and reproduce. Bacterial CFEs are rich in various biomolecules, including proteins, enzymes, and peptides, which serve as both reducing and oxidizing agents during MNP formation. These biomolecules act as capping agents, contributing to the stability and monodisperse nature of MNPs. Using bacterial CFEs for MNP synthesis offers several advantages. Firstly, it aligns with eco-friendly practices as a biosynthesis approach. The non-toxic process minimizes environmental damage. Additionally, bacterial CFEs are cost-effective, making large-scale production economically viable. This review provides insights into these mechanisms, highlighting the role of CFE biomolecules and their impact on MNP characteristics. It also investigates the correlation between synthesis parameters, morphologies, and physical, chemical, and biological properties, allowing for tailored MNP design through the biosynthesis conditions. Despite its advantages, bacterial CFE-mediated biosynthesis faces challenges. This review addresses these challenges and discusses potential solutions. It also explores future perspectives, emphasizing areas for further investigation and innovation. In summary, using bacterial CFEs to synthesize MNPs offers significant advantages over other methods. It ensures eco-friendly, non-toxic, and cost-effective production. The review emphasizes the mechanisms and biomolecules involved, showcasing the potential for tailored MNP design. It also addresses challenges and prospects, paving the way for advancements in this field. Furthermore, the originality of this work lies in the exploitation of bacterial CFEs as a highly efficient and scalable platform for MNP synthesis.

Recent trends in microbial nanoparticle synthesis and potential application in environmental technology: a comprehensive review

Microbial technology comprising environment in various aspects of pollution monitoring, treatment of pollutants, and energy generation has been put forth by the researchers worldwide in an eco-friendly manner. During the past few decades, this revolution has pronounced microbial cells in green nanotechnology, extending the scope, efficiency, and investment capita at research institutes, industries, and global markets. In the present review, initially, the source for the microbial synthesis of nanoparticles will be discussed involving bacteria, fungi, actinomycetes, microalgae, and viruses. Further, the mechanism and bio-components of microbial cells such as enzymes, proteins, peptides, amino-acids, exopolysaccharides, and others involved in the bio-reduction of metal ions to corresponding metal nanoparticles will be emphasized. The biosynthesized nanoparticles physicochemical properties and bio-reduction methods' advantages compared with synthetic methods will be detailed. To understand the suitability of biosynthesized nanoparticles in a wide range of applications, an overview of its blend of medicine, agriculture, and electronics will be discussed. This will be geared up with its applications specific to environmental aspects such as bioremediation, wastewater treatment, green-energy production, and pollution monitoring. Towards the end of the review, nano-waste management and limitations, i.e., void gaps that tend to impede the application of biosynthesized nanoparticles and microbial-based nanoparticles' prospects, will be deliberated. Thus, the review would claim to be worthy of unwrapping microorganisms sustainability in the emerging field of green nanotechnology.

Silver nanoparticles from insect wing extract: Biosynthesis and evaluation for antioxidant and antimicrobial potential

Silver nanoparticles (AgNPs) are among the most widely synthesized and used nanoparticles (NPs). AgNPs have been traditionally synthesized from plant extracts, cobwebs, microorganisms, etc. However, their synthesis from wing extracts of common insect; Mang mao which is abundantly available in most of the Asian countries has not been explored yet. We report the synthesis of AgNPs from M. mao wings extract and its antioxidant and antimicrobial activity. The synthesized AgNPs were spherical, 40–60 nm in size and revealed strong absorption plasmon band around at 430 nm. Highly crystalline nature of these particles as determined by Energy-dispersive X-ray analysis and X-ray diffraction further confirmed the presence of AgNPs. Hydrodynamic size and zeta potential of AgNPs were observed to be 43.9 nm and -7.12 mV, respectively. Fourier-transform infrared spectroscopy analysis revealed the presence of characteristic amide proteins and aromatic functional groups. Thin-layer chromatography (TLC) and Gas chromatography-mass spectroscopy (GC-MS) analysis revealed the presence of fatty acids in the wings extract that may be responsible for biosynthesis and stabilization of AgNPs. Further, SDS-PAGE of the insect wing extract protein showed the molecular weight of 49 kDa. M. mao silver nanoparticles (MMAgNPs) exhibit strong antioxidant, broad-range antibacterial and antifungal activities, (66.8 to 87.0%), broad-range antibacterial and antifungal activities was found with maximum zone of inhibition against Staphylococcus aureus MTCC 96 (35±0.4 mm) and Fusarium oxysporum f. sp. ricini (86.6±0.4) which signifies their biomedical and agricultural potential.

Bioavailability and antioxidant activity of nanotechnology-based botanic antioxidants

Botanic bioactive substances have issues with their solubility, stability, and oral bioavailability in the application, which could be improved by nanotechnologies. In another hands, green synthesis of nanoparticles (NPs) with plant extract is also a promising technology for preparation of NPs due to its safety advantage, yet the bioactive botanic substances that could be more than the assistant of the green synthesis of NPs. Based on the above concerns, this review summarized the preparation of botanic NPs with various plant extract, their solubility, stability, and oral bioavailability; specific attention has been paid to the botanic Ag/Au NPs, their capacity of antioxidant, bioavailability, antimicrobial, anti-inflammatory, and anticancer.