One-pot hydrothermally synthesized mesostructured silicas for effective controlled drug-release applications

Mesoporous silica nanoparticles (MSNs) have captured the interest of researchers worldwide due to their unique properties (e.g., high surface area, uniform pores with tunable pore sizes) and application in various fields such as catalysis, drug delivery systems (DDS), etc. In particular, they offer numerous advantages over traditional nano-based formulations in the development of DDS. However, there are few key challenges involved with developing efficient DDS (such as achieving a high drug loading capacity and cost-effective manufacturing of the DDS). Drug-loaded mesostructured silica nanoparticles are typically synthesized in a two-step fashion – the first step involving synthesis of MSNs and the second step entailing the loading of drug into MSNs via physical adsorption of highly concentrated drug solutions onto the mesoporous framework. The current project aims to synthesize a novel DDS for controlled release antimicrobial drug delivery applications that employs the active drug as template in a facile single-step hydrothermal synthesis process, thereby addressing the above mentioned key challenges. Quaternary ammonium compounds (QACs) have been shown to exhibit broad-spectrum antimicrobial activity. In this work, mesostructured silica nanoparticles were synthesized by employing three different QACs - didecyldimethylammonium chloride (DDAC), cetylpyridinium chloride (CPC) and benzalkonium chloride (BAC) – as templates. Initial surface area measurements by physical adsorption of N2 gas on the three synthesized materials indicated the BAC-templated material to be having a high surface area (ca. 1,500 m2/g). Further characterization tests were carried out on this selected material in order to get a better understanding of its properties and also to investigate its potential usage as a DDS for antimicrobial applications. Drug release studies were carried out at physiologically relevant pH levels (5-8) to demonstrate the pH-responsive controlled release of BAC, and the results have been discussed. Microbiological assays demonstrate a significant time-dependent reduction in Staphylococcus aureus and Salmonella enterica viability.M.S.Includes bibliographical referencesby Anjani Gant