The present review emphasizes on the quantification of biogenic amines (BAs) which are regarded as a quality indicator of food freshness or spoilage and for evaluating microbial action while food processing. BAs have various potential adverse effects on human health and they are widely found in varying concentrations in different food stuffs. In the quest for a reliable method for their precise detection, BA biosensors have emerged as an efficient tool which enables rapid and accurate assessment in miniature form. Various combinations of amine oxidase enzymes have been used for the fabrication of biosensors in order to enhance specific biorecognition and signal transduction. This article also summarizes the widely employed components used in the construction of a pertinent biosensor and the research results conducted previously. The meticulous description regarding the choice of transducers and the significant role of mediators in a high response biosensor has been reviewed. Moreover, it also encompasses the utilization of highly attractive electrolytic characteristics of nanoparticles to enhance the specificity and accuracy of BA biosensors.

The importance of biological agents has been recognized as a promising tool for green synthesis of silver nanoparticles over conventional physiochemical methods that are laden with various type of drawbacks. The biomediated nanoparticles synthesis chiefly employing microorganisms and plants as nanofactories is gaining worldwide popularity over past few decades. Biosynthesized silver nanoparticles have demonstrated desirable physical and chemical and antimicrobial properties among other metallic nanoparticles. This article represents a comprehensive review of biosynthesis route for silver nanoparticles formation including the mechanism, extra- and intra-cellular types and remarkable outcomes of previously conducted research works on biosynthesis. Broad antimicrobial spectra including antibacterial, antifungal, antiviral, sporicidal of biosynthesized silver nanoparticles with major emphasis on their potential applications in biocatalysis, biosensing, food packaging and preservation, pest killing and plant growth promotion, biomedicine and diagnostics etc. have been discussed. Moreover, this article also encompasses meticulous description on challenges and future prospects of biosynthesis of nanoparticles.

Green technology in the material synthesis offer simple, safer, cost-effective means of producing nanoparticles (NPs) with high yield and purity than conventional physicochemical routes. Till date, various microbes and plants have been used to synthesize NPs. Among these, actinomycetes have been explored as distinctive nano-machineries for the synthesis of gold, silver and several types of metallic NPs by extra and intracellular means. Actinomycetes represent an appealing group of microbes for nanomaterials mainly due to their unique ability to produce different bioactive compounds and enzymes acting as strong reductants. NPs synthesized from actinomycetes have been extensively evaluated to achieve numerous applications. Characterization of NPs synthesized from actinomycetes has been performed by using techniques like FT-IR, TEM, UV-vis, SEM, AFM, XRD and DLS, etc. The present article has focused on reviewing the outcome of research works conducted on the actinobacterial synthesis of metallic NPs, their characterization and potential applications in different fields.

Biosynthesis of silver nanoparticles (AgNPs) using plant extracts has become a promising alternative to the conventional chemical synthesis approach. In this study, cost-effective synthesis of AgNPs was attempted using leaves extract of Litchi chinensis. Bio-reduction reaction for the synthesis of NPs was checked by confirming the presence of AgNPs in solution by UV-vis spectrophotometry and with further characterization by fourier-transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). Surface plasmon resonance (SPR) band showed absorption peak at 422 nm indicating the formation of AgNPs, and FTIR spectra confirmed the presence of biological molecules involved in AgNPs synthesis. TEM analysis revealed the spherical shape of AgNPs with particle size distribution in a range of 5–15 nm. Further, the biosynthesized AgNPs showed significant bactericidal and sporicidal activity against model spore former Bacillus subtilis. AgNPs at concentrations ranging from 25 to 100 µg/mL showed bactericidal activity with inhibition zone ranging from 4–19 mm and sporicidal activity at 100–200 µg/mL in a range of 4.46–61.6% with an exposure time of 2–8 h. These findings exhibit distinctive potential of biogenic AgNPs for their efficient use in developing novel bactericidal and sporicidal agent against spore forming bacilli.

The healthcare area is often reluctant to execute new technology unless they are proven to be safe, constructive and secure. Eventually, an aspiration stands for providing point-of-care testing service to allow a better estimation of the biochemical levels of a patient that entails an insistent remedial action. With increasing mortality rate due to cardiovascular diseases (CVDs) in present scenario, it has become the need of hour to develop more advance methods for their diagnosis, so that it can be determined at sensitive levels and can be prevented from being fatal. Elevated level of cholesterol in blood stream is one of the utmost risk factors which lead to CVDs. Discernible from the vast research in this field, worth of cholesterol biosensors is already recognized and flourished in the clinical analysis of brain and cardiac vascular diseases. It necessitates unremitting progress in the development of biosensing technology towards fabrication, miniaturization and multiplexing ability of cholesterol quantification devices so that they can endow with lab-on-chip-analysis systems to the medical field. Different strategies have been meticulously explored for the engineering of cholesterol biosensors utilizing nanocomposites, conducting polymers, nanotubes and nanoparticles. Foremost, this article reviews the contemporary evolution in cholesterol biosensors, which encompass various strategies for immobilization of enzymes and roles of various matrices and artificial mediators used for the biosensor fabrication. Still there remains an enormous challenge to congregate the demands of performance and yield in a cost effective manner for its application in successful treatments of CVDs.