Ultra-fast sustainable synthesis,optimization and characterization of guava phenolic extract functionalized nanosilver with enhanced biomimetic attributes

There had been some reports demonstrating the green synthesis of silver nanoparticles using guava (Psidium guajava (L.) extract); however, detailed and in-depth interrogation of the vital synthesis parameters for rapid, facile, efficacious synthesis at room temperature, and robust characterization of the as-prepared nanoparticle is currently lacking. This study presents a comprehensive delineation of the sustainable phyto-fabrication of biogenic guava phenolic extract functionalized silver nanoparticles (GVE-SNP) based on guava phenolic extract as the sole reductant/stabilizer, as well as the synthesis optimization, thorough physicochemical characterization and potential biological applications of the as-prepared nanosilver. The results revealed that successful synthesis of GVE-SNP was instantaneous and maximum intensity of the plasmonic peak at 425 nm was achieved in less than 10 min. GVE-SNP was found to present stable, well-dispersed, round, uniform, and crystalline nanoparticles of about 5.88 nm. The FTIR and RAMAN spectra indicated that GVE-SNP surface was properly capped by bioactives from GVE. The nanoparticles displayed potent radical scavenging activity against ABTS⁺ and DPPH. Also, GVE-SNP exhibited a significant and dose–response inhibitory effect against tyrosinase. Furthermore, the nanoparticles displayed good cytotoxicity against L929 fibroblast and were found to possess strong antimicrobial properties, inhibiting the growth of S. aureus and S. epidermidis.     

Determination of engineered nanoparticles on textiles and in textile wastewaters

Textile materials with engineered nanoparticles (ENPs) have excellent properties as they are antibacterial, antimicrobial, water resistant and protective. The textile industry has recognized the importance and the advantages of ENPs, so they comprise one of the fastest developing branches of processing.The most important sources of ENPs released to the environment from textiles are textile-industry wastewaters and waters from large hospital or hotel laundries. In addition, waste textile materials coated with ENPs present a threat to the environment, if such materials are not properly handled and disposed of after use.Currently, the toxicity and the potential harm of ENPs widely applied on textiles are not thoroughly investigated and/or eliminated. Consequently, there is an urgent need to define the most appropriate analytical methods for monitoring ENPs on textiles.This review presents the most important techniques for monitoring ENPs on textile materials and in textile-wastewater samples, from the perspective of protecting the environment and human health.     

Study of silver nanoparticle-hemoglobin interaction and composite formation

Nanoscience is now an expanding field of research and finds potential application in biomedical area, but it is limited due to lack of comprehensive knowledge of the interactions operating in nano-bio system. Here, we report the studies on the interaction and formation of nano-bio complex between silver nanoparticle (AgNP) and human blood protein hemoglobin (Hb). We have employed several spectroscopic (absorption, emission, Raman, FTIR, CD, etc.) and electron diffraction techniques (FE-SEM and HR-TEM) to characterize the Hb-AgNP complex system. Our results show the Hb-AgNP interaction is concentration and time dependent. The AgNP particle can attach/come closer to heme, tryptophan, and amide as well aromatic amine residues. As a result, the Hb undergoes conformational change and becomes unfolded through the increment of β-sheet structure. The AgNP-Hb can form charge-transfers (CT) complex where the Hb-heme along with the AgNP involved in the electron transfer mechanism and form Hb-AgNP assembled structure. The electron transfer mechanism has been found to be dependent on the size of silver particle. The overall study is important in understanding the nano-bio system and in predicting the avenues to design and synthesis of novel nano-biocomposite materials in material science and biomedical area.     

Green Synthesis and Characterization of Silver Nanoparticles Using Spondias mombin Extract and Their Antimicrobial Activity against Biofilm-Producing Bacteria

Multidrug resistant bacteria create a challenging situation for society to treat infections. Multidrug resistance (MDR) is the reason for biofilm bacteria to cause chronic infection. Plant-based nanoparticles could be an alternative solution as potential drug candidates against these MDR bacteria, as many plants are well known for their antimicrobial activity against pathogenic microorganisms. Spondias mombin is a traditional plant which has already been used for medicinal purposes as every part of this plant has been proven to have its own medicinal values. In this research, the S. mombin extract was used to synthesise AgNPs. The synthesized AgNPs were characterized and further tested for their antibacterial, reactive oxygen species and cytotoxicity properties. The characterization results showed the synthesized AgNPs to be between 8 to 50 nm with -11.52 of zeta potential value. The existence of the silver element in the AgNPs was confirmed with the peaks obtained in the EDX spectrometry. Significant antibacterial activity was observed against selected biofilm-forming pathogenic bacteria. The cytotoxicity study with A. salina revealed the LC50 of synthesized AgNPs was at 0.81 mg/mL. Based on the ROS quantification, it was suggested that the ROS production, due to the interaction of AgNP with different bacterial cells, causes structural changes of the cell. This proves that the synthesized AgNPs could be an effective drug against multidrug resistant bacteria.