Antimicrobial activity of TiO2:Ag nanocrystalline heterostructures: Experimental and theoretical insights

Abstract

We report the synthesis and characterization of silver-decorated titanium dioxide (TiO 2 :Ag) nanoparticles, as well as a discussion of their antimicrobial activity. This material was synthesized by microwave-assisted hydrothermal treatment and characterized by complementary techniques. The minimum inhibitory concentration and minimum bactericidal/fungicidal concentration of TiO 2 :Ag nanoparticles against planktonic and biofilm-forming strains of methicillin-resistant Staphylococcus aureus, Candida species (spp.) and the total biofilm mass were determined. The basis of the biological activity of TiO 2 :Ag was investigated by electronic analysis of the material using theoretical quantum chemical calculations. In the proposed mechanism of action, the impregnated semiconductor donates electrons to the forbidden band gaps in the metal, generating point defects, with partially located electrons and holes at the surface, initiating a radical process involving the solvent and biological target. Our results suggest that this TiO 2 :Ag nanomaterial has potential for use in the development of new therapeutic agents.

Photocatalytic Activity of Ag-TiO2 Composites Deposited by Photoreduction under UV Irradiation

“…Furthermore, Figure 6 shows that Ag-TiO 2 thin films showed an important increase in the photocatalytic activity under UV (near 35%); these results could be due to the silver aggregates deposited on the TiO 2 surface that can accumulate charge and accept electrons inside the semiconductor. The accumulation of electrons can reduce the carrier's recombination increasing generation of reactive oxygen species, and besides, Ag particle on TiO 2 can change and a collective oscillation can be generated, which is known as localized surface plasmon resonance (SPR) [49]; according to other reports, silver particles exhibit collective oscillation of their electrons in the conduction band, and it is suggested that the association between the semiconductor and the metal can increase photocatalytic activity, which coincides with the results obtained in this work [50]. Pseudo-first-order model was applied to kinetic data of Figure 6.…”

Tuning the Morphological, Optical, and Antimicrobial Properties of α-Ag2WO4 Microcrystals Using Different Solvents

“…MICs were recorded as the lowest concentrations of each solution to achieve complete inhibition of growth (without visible growth by visual inspection). 43,44 MFCs/MBCs were determined by inoculating 25 μL aliquots, taken from 10-fold serial dilutions (10 −1 to 10 −8 ) of each well, on plates containing SDA for C. albicans and Mueller−Hinton agar for MRSA and E. coli, in duplicate. After the cells were incubated at 37 °C for 24−48 h, the CFU/mL was calculated and log 10 -transformed.…”

Functional Antimicrobial Surface Coatings Deposited onto Nanostructured 316L Food-Grade Stainless Steel

“…As a result of this, the metal may inject electrons into the semiconductor, creating points defects with partially located electrons and holes on its surface. This involves the formation of superoxides, hydrogen ions (H+), and/or OOH* radicals, a consequence of electron-hole reactions, causing protein inactivation and cellular death (apoptosis) [ 67 , 68 ]. Consequently, it can be said that this association can be extremely effective in preventing biofilm formation and decreasing the number of bacteria [ 69 ].…”