Response Surface Methodology Based Desirability Function Approach To Investigate Optimal Mixture Ratio of Silver Nanoparticles Synthesis Process

Biogenic Synthesis of Silver-Core Selenium-Shell Nanoparticles Using Ocimum tenuiflorum L.: Response Surface Methodology-Based Optimization and Biological Activity

Bimetallic nanoparticles (BNPs) have shown better biological potential compared to their monometallic counterparts owing to the synergistic effect produced by these alloys. In this study, selenium-capped silver nanoparticles (Ag@Se NPs) were synthesized using an Ocimum tenuiflorum extract. These BNPs were characterized using UV-visible, Fourier transform infrared spectroscopy, nanoparticle tracking analysis, electron microscopy and energy dispersive x-ray analysis. Response surface methodology was used to understand how extract volume and temperature influenced the zeta potential, hydrodynamic size and NP concentration. The phytoconstituents were identified using gas chromatography-mass spectrometry (GC-MS) and molecular docking studies were performed on B-DNA to determine possible genotoxicity. Antioxidant activities, in vitro cytotoxicity (3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay), and genotoxicity (Allium cepa root cells) of these BNPs, were also evaluated. A surface plasmon resonance band around 420 nm confirmed BNP formation with significant quantities of silver and selenium. The Ag@Se NPs displayed good stability, dispersity, antioxidant activity, and compatibility at low concentrations but showed significant cytotoxicity and genotoxicity at high concentrations. Molecular docking analysis showed weak interactions between the plant constituents and B-DNA, suggesting no genotoxicity. These results provide an insight into the conditions required for optimal production of eco-friendly Ag@Se NPs with interesting biological properties.

Photoacoustics for listening to metal nanoparticle super-aggregates

Photoacoustic signal detection has been used to build a new strategy to determine the mesoscale self-assembly of metal nanoparticles in terms of size distribution and aggregate packing density (metal nanoparticle filling factor). A synergistic approach integrating photoacoustic signal and theoretical studies, validated by conventional light scattering and electron microscopy techniques, allows us to obtain a well-defined morphological interpretation of nanoparticle-based super-aggregates. By pumping light in a complex system, the acousto-thermal effect was listened to, providing information on the aggregation phenomena. Super-aggregates of covalently interconnected silver nanoparticles (AgNPs) functionalized with an organometallic dithiol are identified in solution, as a proof of concept for the versatility of the photoacoustic approach. According to our results, tiny AgNPs (size less than 10 nm) assembled into a 3D-network of super-aggregates (SA-AgNPs) with sizes in the range 100-200 nm and a filling factor in the range of 30-50%. Low-cost, rapid, and easy photoacoustic measurement in the low frequency range (less than 100 Hz) was revealed to be an innovative method to characterize the fundamental structure/property correlation of metal nanoparticle super-aggregates. This morpho-optical approach, which uses the absorption and scattering properties of nanoparticles in the liquid phase, opens new perspectives for advanced biomedical and structural applications.

Flacourtia indica based biogenic nanoparticles: development, characterization, and bioactivity against wound associated pathogens

Surface engineered nanoparticles (NPs) are of great attention due to their targeted medical applications. The nature of the functionalized surface plays a vital role in achieving the required functionalities of engineered NPs. Owing to the biofilm formation capabilities of wound associated pathogens, impaired wound healing is a major complication in the medical field. In this context, herein, we report the biogenic synthesis of Flacourtia indica (FI) based NPs, i.e., FI-AgNPs using the aqueous leaf extract of this anti-bacterial herb. The newly developed FI-AgNPs were characterized using various analytical and imaging techniques such as UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The FI-AgNPs showed potent anti-microbial activity and anti-biofilm potential which were examined through a test tube adherence method and congo red agar method. It has been observed that synthesized FI-AgNPs inhibit the formation of a biofilm of observed bacteria, even at a minimum concentration of 80 μgml−1. These findings suggest that synthesized FI-AgNPs could be used against wound associated microbes, especially bacterial coating on medical devices, to prevent antibiotic-resistant biofilm infections. Further development and research are obligatory to decode this skill into preventive and therapeutic strategies.