Clay-based photothermal agents for antibacterial applications

Official URL: https://risc01.sabanciuniv.edu/record=b2771015_(Table of contnets)

Light-to-heat conversion nanoparticles with effective photothermal activity play an important role in the design of photothermal materials that are remotely heated by light. In this thesis, novel clay-based photothermal agents and their utilization as a light-activated antibacterial coating for air filters were presented. By coating them with polydopamine (PDA), a photothermal polymer, halloysite nanotubes (HNTs) were turned into nano-heaters that can be remotely activated by near infrared (NIR) light. HNT-PDA nanohybrids were investigated in terms of their light-activated temperature elevations and were demonstrated to heat up proportionally to the amount of PDA coating on HNTs upon exposure to NIR light. The stability and reusability of the v photothermal activity of the HNT-PDA nanohybrids upon multiple NIR irradiation cycles were studied. Staphylococcus aureus (S. aureus) treated with HNT-PDA nanohybrids were shown to be physically disrupted upon NIR irradiation resulting in 6.3 log reduction in viability in 5 min irradiation. As a demonstration of the potential use of HNT-PDA nanohybrids in antibacterial applications, their utilization as coatings on air filtration membranes for turning them into light-activated antibacterial air filters was studied. A commercial HEPA filter was spray-coated with HNT-PDA nanohybrids resulting in air filters, which can be heated to temperatures sufficient to kill microorganisms when exposed to NIR light. HNT-PDA nanohybrids coated HEPA filters treated with S. aureus presented a 3.4 log killing activity after 20 min NIR irradiation. Furthermore, it was observed that the S. aureus biofilm established on the filter surface was eradicated via NIR light exposure. The HNT-PDA coating on the air filter was shown not to negatively affect the filtration performance The HNT-PDA coated air filters presented excellent aerosol filtration efficiency in addition to their bioaerosol removal and deactivation performance. The novel clay-based photothermal agents presented in this thesis have a strong potential for utilization as light-activated antibacterial agents in various applications.