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    Green synthesis of silver nanoparticles from Hibiscus tiliaceus L. Leaves and their applications in dye degradation, antioxidant, antimicrobial, and anticancer activities
    (Elsevier BV, 2024-05) Konduri, Vinay Viswanath; Kalagatur, Naveen Kumar; Gunti, Lokanadhan; Mangamuri, Usha Kiranmayi; Kalagadda, Venkateswara Rao; Poda, Sudhakar; Krishna, Suresh Babu Naidu
    The present study reports the green synthesis of silver nanoparticles (AgNPs) from aqueous extract of Hibis cus tiliaceus L. leaves and their application in dye degradation, antioxidant, antimicrobial, and anticancer activities. Analysis using Fourier transform infrared (FT-IR) spectroscopy revealed that plant metabolite func tional groups had a role in the reduction and stability of AgNPs, and X-ray crystallography (XRD) demon strated that the AgNPs were in crystal form. The UV vis spectroscopy, dynamic light scattering (DLS), and zeta potential investigations revealed that the AgNPs were formed with an average size of 88.10 nm in colloi dal form and were stable (-49 mV). The field emission scanning electron microscopy (FE-SEM) and high-reso lution transmission electron microscopy (HR-TEM) confirmed the shape and size of the AgNPs as spherical with a particle size of 30 - 35 nm, respectively. The AgNPs exhibited potential antioxidant activity by total antioxidant, DPPH, and reducing power assays. The biosynthesized AgNPs displayed a wide range of antibac terial activity on Gram-ve and Gram+ve bacteria by the zone of inhibition assay. AgNPs showed good antican cer activity on MCF-7 cells with an IC50 value of 65.83 mg/mL. Furthermore, AgNPs acted as potential catalysts in combination with the reducing agent sodium borohydride (NaBH4) for the degradation of methylene blue (MB), methylene orange (MO), and methylene green (MG) dyes. The degradation efficiency of catalyst AgNPs in the attendance of NaBH4 for 15 min was noted to be 12.8 %, 26.92 %, and 47.56 % for MO, MB, and MG, respectively. The study concluded that green synthesized AgNPs could be highly applicable as an antioxidant, antimicrobial, and anticancer agents in the biomedical field. Furthermore, AgNPs could be helpful in the remediation of dye effluents.
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    Biogenic metallic nanoparticles as enzyme mimicking agents
    (Frontiers Media SA, 2023-03) Ngcongco, Khanyisile; Krishna, Suresh Babu Naidu; Pillay, Karen
    The use of biological systems such as plants, bacteria, and fungi for the synthesis of nanomaterials has emerged to fill the gap in the development of sustainable methods that are non-toxic, pollution-free, environmentally friendly, and economical for synthesizing nanomaterials with potential in biomedicine, biotechnology, environmental science, and engineering. Current research focuses on understanding the characteristics of biogenic nanoparticles as these will form the basis for the biosynthesis of nanoparticles with multiple functions due to the physicochemical properties they possess. This review briefly describes the intrinsic enzymatic mimetic activity of biogenic metallic nanoparticles, the cytotoxic effects of nanoparticles due to their physicochemical properties and the use of capping agents, molecules acting as reducing and stability agents and which aid to alleviate toxicity. The review also summarizes recent green synthetic strategies for metallic nanoparticles.
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    Biosynthesis and characterization methods of copper nanoparticles and their applications in the agricultural sector
    (Elsevier, 2022-01-15) Reddy, Bhagavanth; Mangatayaru, Girija K.; D, Madhusudan Reddy; Krishna, Suresh Babu Naidu; Golla, Narasimha; Kamel A, Abd-Elsalam
    This book provides information on the design and application of ecologically safe formulations, for protecting cultivated crops against insects and pathogen-causing diseases, plant science, antimicrobial applications and agroecosystem ...
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    Green synthesis of gold nanoparticles using marine algae and evaluation of their catalytic activity
    (SpringerOpen, 2016) Ramakrishna, M.; Babu, Dandamudi Rajesh; Gengan, Robert Moonsamy; Chandra, S.; Rao, G. Nageswara
    The hazardous effects of current nanoparticle synthesis methods have steered researchers to focus on developing newer eco-friendly methods for synthesizing nanoparticles using non-toxic chemicals. Owing to the diverse applications of nanoparticles in various fields such as catalysis, medicine, diagnostics, and sensors, several novel green approaches have been explored for synthesiz-ing nanoparticles using different natural sources such as plants, algae, bacteria, and fungi. Hence, in the present work, a green method for the synthesis of gold nanoparti-cles (AuNPs) under ambient conditions using aqueous extracts of marine brown algae is reported and the syn-thesized AuNPs were evaluated for their catalytic effi-ciency. The aqueous extracts of algae comprise reducing as well as capping agents required for the formation of AuNPs. The Fourier transform infrared spectra of the extracts revealed the presence of compounds having hydroxyl groups that are largely responsible for the reduction of auric chloride to AuNPs at room temperature. Results from high-resolution transmission electron micro-scopy and dynamic light scattering studies suggested that most of the biosynthesized AuNPs are nearly spherical in shape with an average size in the range of 27–35 nm. High negative values of zeta potential measurement confirmed the stability of AuNPs. Moreover, the reduction kinetics of AuNPs studied by UV–visible spectrophotometry showed that they have good catalytic efficiency in the degradation of dyes as well as reduction of nitro compounds in the presence of sodium borohydride as reducing agent. This simple process for the biosynthesis of gold nanoparticles is rapid, cost-effective and eco-friendly. The formation of AuNPs was observed with the change of pale yellow gold solution to ruby red color of gold nanoparticles and con-firmed by surface plasmon spectra using UV–visible spectroscopy. Nanoparticles synthesized through such environmentally benign routes can be used for synthesizing many other metal nanoparticles as well as for a wide range of biomedical applications, for commercial production on a large scale and also can be used as efficient catalysts for different organic reactions.