Mesoporous Organosilica Nanoparticles Containing Superacid and Click Functionalities Leading to Cooperativity in Biocidal Coatings

Abstract

A superior degree of functionality in materials can be expected, if two or more operational entities are related in a cooperative form. It is obvious that, for this purpose, one is seeking materials with complex design comprising bi- or multiple functional groups complementing each other. In the current paper, it is demonstrated that periodically ordered mesoporous organosilicas (PMOs) based on co-condensation of sol–gel precursors with bridging phenyl derivatives RF1,2C6H3[Si(OisoPr)3]2 allow for rich opportunities in providing high-surface area materials with such a special chemical architecture. PMOs containing high density of thiol (≅ RF1) and sulfonic acid units (≅ RF2) were prepared as mesoporous nanoparticles via an aerosol-assisted gas-phase method and were tested for biocidal applications. Each of the mentioned organic groups fulfills several tasks at once. The selective functionalization of thiols located at the surface of the particles using click chemistry leads to durable grafting on different substrates like glass or stainless steel, and the intraparticle −SH groups are important regarding the uptake of metal ions like Ag+ and for immobilization of Ag0 nanoparticles inside the pores as an enduring reservoir for antibacterial force. The superacidic sulfonic acid groups exhibit a strong and instantaneous biocidal acitivity, and they are important for adjusting the Ag+ release rate. Biological studies involving inhibitory investigation tests (MIC), fluorescence microscopy (life/dead staining), and bacterial adhesion tests with Pseudomonas aeruginosa show that the organobifunctional materials present much better performance against biofilm formation compared to materials containing only one of the above-mentioned groups.