Ag induced plasmonic TiO2 for photocatalytic degradation of pharmaceutical under visible light: Insights into mechanism, antimicrobial and cytotoxicity studies

Abstract

Global concerns include water scarcity and shortage, which are escalated by organic pollutants such as naproxen (NPX) that deteriorate drinking water and taint access to safe drinking water by humans. Moreover, NPX may cause gastrointestinal difficulties, cardiovascular risks, kidney damage, allergic reactions, liver toxicity, bleeding issues and pregnancy risks, hence it is essential to remove it in water. Ag-TiO 2 was synthesized by hydrothermal method for NPX degradation. Ag on TiO 2 reduced the band gap and surface area of TiO 2 and resulted in a plasmonic Ag-TiO 2 composite of 0.2 % Ag. The photocatalytic degradation of 0.2 % Ag-TiO 2 was 80 % in 180 minutes using a solar simulator during NPX degradation with a first order reaction rate that was 3.6 times faster than that of pure TiO 2 and the catalyst showed good stability for four cycles. The dual activity of Ag 0 surface plasmon resonance improved light absorption capability and enhanced charge transfer for increased photodegradation rate and stability. The antibacterial studies demonstrated that 0.2 % Ag-TiO 2 posted strong antibacterial properties under light irradiation and less in the dark, with a greater effect on gram-negative than gram-positive bacteria. The minimum inhibitory concentration (MIC) values of 620, 1250, 2500, 2500 µg/mL were attained against B. subtilis , S. aureus , E. coli and S. typhimurium bacteria, respectively. The low cell toxicity of 0.2 % Ag-TiO 2 was determined using human embryonic kidney (HEK293) cells with an inhibitory concentration (IC 50 ) of 61.09 ± 0.24 µg/mL under light irradiation. Radical trapping experiments demonstrated that hydroxyl radicals (OH • ) played a vital role during the degradation and bactericidal activity of NPX under light irradiation. This work advances new insights on the synthesis of less toxic nanoparticles with high photocatalytic and bactericidal activity for possible applications at industrial scale. • Ag-TiO 2 with 80 % NPX degradation efficiency was synthesized by hydrothermal method. • The anatase TiO 2 -based composite was stable after four cycles with increasing SPR due to Ag 0 • The as-synthesized composite had high gram-negative antibacterial properties and low cytotoxicity. • Mineralization of NPX and degradation pathway was proposed.