Plant-mediated green synthesis of silver nanoparticles: Synthesis, characterization, biological applications, and toxicological considerations: A review

Green synthesis of multifunctional bamboo-based nonwoven fabrics for medical treatment

Medical nonwovens fabrics are pivotal materials in modern healthcare systems, and find extensively application in surgical gowns, masks, nursing pads, and surgical instrument packaging. As healthcare requirements evolve and medical technology advances, the demand for functional nonwoven medical devices is continuously increasing. In addition, numerous environmental challenges and the need to transition to a sustainable society have increased the popularity of studies on environmentally friendly multifunctional nonwoven materials prepared from biomass fibers. Therefore, in this study, ecofriendly bamboo fibers were used to fabricate multifunctional medical nonwoven materials with superhydrophobic, antibacterial, flame-retardant, and biocompatible properties. Specifically, ZIF-67 was grown in situ on natural bamboo cellulose fibers (BCFs) extracted from natural bamboo and coated with polydimethylsiloxane to construct an environmentally friendly and versatile nonwoven fabric. The treated nonwoven fabric exhibited superhydrophobicity with contact angle of 163° and possess excellent self-cleaning properties. The antibacterial activity of the samples was investigated by the plate-counting method; the results showed that the untreated BCFs did not exhibit antibacterial activity, whereas the treated bamboo nonwoven fabrics demonstrated significant antibacterial activity (p < 0.001), with an antibacterial rate of >99 % against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, and Candida albicans. In addition, when the samples were exposed to different temperatures (-4 and 50 °C) and humidities (0 % and 95 %), they demonstrated an antibacterial activity of >99 % against E. coli (F5,10 = 0.602; p = 0.670) and S. aureus (F4,10 = 0.289; p = 0.879). The heat release rate and smoke production rate of the nonwoven fabric decreased by 54.64 % and 93.18 %, respectively, compared to those of the BCFs, indicating excellent flame retardancy. The nonwoven fabric also exhibited satisfactory biocompatibility and breathability, ensuring user comfortability. This research not only has significant implications for producing low-cost, environmentally friendly, sustainable, and multifunctional medical products and openi up new pathways for the diversified utilization of bamboo, thereby expanding its applicability.

Radical scavenging potential of spectrophotometric, spectroscopic, microscopic, and EDX observed zinc oxide nanoparticles from leaves, buds, and flowers extract of Bauhinia Variegata Linn: A thorough comparative insight

The present study incorporated an environment-friendly and cost-efficient green synthesis method for fabricating zinc oxide nanoparticles (ZnO-NPs) using various parts (leaves, buds, and flowers) of Bauhinia Variegate Linn. UV-Spectrophotometric analysis was used to confirm the synthesis of ZnO-NPs, which showed an absorption band within 360-380 nm range. Further techniques like FT-IR spectroscopy and (SEM) scanning electron microscopy equipped with a novel EDX were also included to confirm the synthesis, size, and shape of ZnO-NPs. Results obtained by FT-IR showed that the phytochemicals present in the ethanolic extract successfully acted as a capping agent. SEM micrographs confirmed irregularly shaped nanoparticles with an average size of 70-80 nm. The presence of Zinc and Oxygen peaks in EDX also confirmed the successful synthesis of ZnO nanoparticles. The radical scavenging (antioxidant) potential of prepared nanoparticles was also evaluated by DPPH radical assay. The ZnO-NPs obtained from the ethanolic extract of buds showed the highest %RSA (86%) as compared to the flowers (79%) and leaves (76%). The current study findings showed the versatile morphology of all parts of the plant with significant antioxidant potential, establishing the use of Bauhinia Variegate in biological systems for various biomedical applications. RESEARCH HIGHLIGHTS: A thorough comparative analysis of the radical scavenging power of major parts of the Bauhinia Variegate, which is 1st of its kind. Extensive characterization using UV-Vis spectrophotometry, FT-IR, SEM, and EDX to observe the conformational and morphological changes. Analysis of the reduction potential of leaves, buds, and flowers of a single plant for future directions in green synthesis.

Biosynthesis of bacteriocin BacZY05-silver nanoconjugates and evaluation of their antibacterial properties

Bacteriocins are antimicrobial peptides produced by bacteria to prevent the growth of pathogens. Combining bacteriocins with metal nanoparticles, like silver nanoparticles (AgNPs), has developed into a viable strategy to get over bacteriocin limitations. In this study, bacteriocin BacZY05 was extracted from Bacillus subtilis ZY05 and purified using various techniques. The resulting purified bacteriocin was then combined with silver nanoparticles to form bacteriocin silver nanoconjugates (BacZY05-AgNPs). The physicochemical properties of the BacZY05-AgNPs were characterized using various analytical techniques. The mean diameter of the synthesized AgNPs was approximately 20-60 nm with an oval or spherical shape. The antimicrobial activity of the BacZY05-AgNPs was evaluated against several indicator strains by their zone of inhibition (ZOI), using the agar well diffusion method. Compared to bacteriocin (ZOI- 13 to 20 mm) and AgNPs (ZOI- 10-22 mm) alone, the antibacterial activity data demonstrated a 1.3-1.5-fold increase in the activity of bacteriocin-nanoconjugates (ZOI- 22 to 26 mm). For Staphylococcus aureus MTCC3103 and Klebsiella pneumoniae MTCC109, BacZY05-capped AgNPs exhibited the lowest minimum inhibitory concentration (MIC), measuring 10.93 µg/mL. For Salmonella typhi NCIM2501, the MIC was 28.75 µg/mL. The highest MIC value was 57.5 µg/mL for Escherichia coli DH5α and Vibrio cholerae MTCC3909. With BacZY05-capped AgNPs, the lowest minimum bactericidal concentration (MBC) of 28.75 µg/mL was observed for Staphylococcus aureus MTCC31003. In the cases of Salmonella typhi NCIM2501 and Klebsiella pneumoniae MTCC109 concentration was 57.5 µg/mL. Vibrio cholerae MTCC3909 and Escherichia coli DH5α had the highest MBC values at 115 µg/mL.

Environmentally friendly silver nanoparticles synthesized from Verbascum nudatum var. extract and evaluation of its versatile biological properties and dye degradation activity

In the present study, green synthesis of silver nanoparticles (VNE-AgNPs) via Verbascum nudatum extract was carried out for the first time. The synthesized AgNPs were characterized by different spectral methods such as UV-vis, FTIR, XRD, TEM, and EDAX. According to TEM analyses, the average size range of AgNPs was 17-21 nm, and the dominant peaks in the 111°, 200°, 221°, and 311° planes in the XRD pattern indicated the Ag-NPs FCC crystal structure. FTIR data showed that VNE-AgNPs interacted with many reducing, capping, and stabilizing phytochemicals during green synthesis. VNE-AgNPs had higher antibacterial activity against S. aureus and E. coli bacterial strains with a maximum inhibition zone of 21 and 18 mm, respectively, than penicillin 5 IU, used as a positive control in the study. The cytotoxic effect of VNE-AgNPs appeared at a concentration of 50 µg/mL in L929 cells and 5 µg/mL in cancer (A549) cells. When the impact of VNE-AgNPs and C-AgNPs on inflammation was compared, it was found that VNE-AgNPs increased TNF-α levels (333.45 ± 67.20 ng/mg-protein) statistically (p < 0.05) more than TNF-α levels (256.92 ± 27.88 ng/mg-protein) in cells treated with C-AgNPs. VNE-Ag-NPs were found to have a degradation efficiency of 65% against methylene blue (MB) dye within 3 h.