Encapsulation of Biosynthesized Nanosilver in Silica Composites for Sustainable Antimicrobial Functionality

Abstract

Silver nanoparticles (AgNPs) have become known as a broad‐spectrum antimicrobial agent. The antimicrobial activity of AgNPs is dependent on the particle size and the dispersion status. In this study, a simple and effective approach is developed for sequestering the biosynthesized AgNPs in silica composites during the gel formation of MCM‐41. Composites with different Ag concentrations of 0.034% (Ag1@MCM‐41), 0.151% (Ag2@MCM‐41), and 0.369% (Ag3@MCM‐41) are synthesized and then heated at 400 °C to produce Ag1@MCM‐41H, Ag2@MCM‐41H, and Ag3@MCM‐41H, respectively. The samples are characterized by flame atomic absorption spectrometry, Fourier‐transform infrared spectroscopy, X‐ray diffraction, N2 physisorption, scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The AgNPs are confirmed to be highly dispersed in the amorphous silica framework. The antimicrobial activity of the AgNP–silica samples is investigated against Staphylococcus aureus, Escherichia coli, and Candida albicans using the cup–plate and the plate‐count techniques. The results show an excellent antimicrobial effect of these samples against the studied microorganisms. Importantly, the AgNP–silica samples are found to be stable up to 58 months under ambient conditions. These stable and powerful antimicrobial composites provide a more practical and effective strategy for combating biomedical pathogens and public health threats.

Synthesis, characterization, and evaluation of biological activities of new 4′‐substituted ruthenium (II) terpyridine complexes: Prospective anti‐inflammatory properties

“…The experiment was carried out at least three times and the mean of reading was recorded. [37,38] 3 | RESULTS AND DISCUSSION…”

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“…Interestingly, the results show an excellent antimicrobial effect of these materials against S. aureus, E. coli, and Candida albicans applying either static (cup-plate) or dynamic (CFU) techniques [36]. In this sense, the use of silica-based materials for stabilizing nanoparticles for biological applications is of special interest due to their biocompatibility, high chemical and thermal stability, and hydrophilic nature [36,39,41]. Furthermore, the surface area of silica-based materials is typically large, allowing better contact between the microorganisms and the functionalized AuNPs, consequently achieving much higher antimicrobial activity than conventional AgNPs.…”

“…To prevent agglomeration, various strategies have been developed including capping, organic caging, and encapsulation [33]. Among them, encapsulation is an effective approach for stabilizing nanoparticles due to several merits such as simplicity, providing extremely long-term stability, shelf-storing ability, and maintaining high activity even at a low concentration of nanoparticles [34][35][36]. The encapsulating materials may include various inorganic oxides, carbon, clay, silica, and metal-organic frameworks, which endows the metal nanoparticles with additional functionality [34,[36][37][38][39].…”

“…Among them, encapsulation is an effective approach for stabilizing nanoparticles due to several merits such as simplicity, providing extremely long-term stability, shelf-storing ability, and maintaining high activity even at a low concentration of nanoparticles [34][35][36]. The encapsulating materials may include various inorganic oxides, carbon, clay, silica, and metal-organic frameworks, which endows the metal nanoparticles with additional functionality [34,[36][37][38][39]. For instance, the antibacterial properties of Ag NPs encapsulated in chitosan-4-((E)-2-(3-hydroxynaphthalen-2-yl) diazen-1yl) benzoic acid were evaluated against S. aureus and E. coli [41].…”

“…Additionally, biosynthesized AgNPs were encapsulated in silica composites during the gel formation of MCM-41. Interestingly, the results show an excellent antimicrobial effect of these materials against S. aureus, E. coli, and Candida albicans applying either static (cup-plate) or dynamic (CFU) techniques [36]. In this sense, the use of silica-based materials for stabilizing nanoparticles for biological applications is of special interest due to their biocompatibility, high chemical and thermal stability, and hydrophilic nature [36,39,41].…”