A new synthetic approach for high surface area mesoporous silica and its use towards sustainable antifouling materials †

For the first time, a silica gel was obtained by hydrolysis of tetraethyl orthosilicate in the presence of resorcinol. This simple method gave a nano-silica with high specific surface area (1000 m² g⁻¹) and narrow pore size distribution. Resorcinol cannot form a self-assembled structure such as a micelle. Therefore, the formation mechanism of this new silica differs from that of mesostructured silica. A possible explanation for the role played by resorcinol was given. Then, as an application of this new silica gel, a set of quaternary ammonium salt (QAS)-based silanes were synthesized and tested for their antibacterial activity against the Pseudomonas delhiensis PS27 strain earlier described for its resilience towards adverse and stressful environmental conditions. Therefore, the novel nano-silica alongside the most active QAS-based silane was successfully prepared and further incorporated into a polydimethylpolysiloxane (PDMS) polymer matrix. The resulting film exhibited significant antibiofilm activity, inhibiting bacterial cell attachment onto the QAS-silica/PDMS composite surface without killing planktonic cells. In contrast, the composite material prepared using commercially available silica gel did not show antibiofilm activity. This finding suggests a different role in activity when the QAS-based silane is covalently attached to very high surface area silica.