Fluorescence and photothermal dual-readout phthalocyanine-fluorescein conjugate for detection and photothermal sterilization of anaerobic bacteria

Abstract

Anaerobic bacterial infection is a common but serious side-effect of dental implant, therefore, the development of new type of antimicrobials that can be applied in situ surgery area to avoid post-operation infection is highly desired. Herein, photothermal agent of silicon phthalocyanine-fluorescein conjugate, SiPc-FITC, is constructed via covalent bond. Comparing with the great majority of organic photothermal agents that based on H-aggregation induced nanocomposites requiring time-consuming uptake by bacteria as well as blue-shifted absorption and fluorescence quenching, SiPc-FITC demonstrates remarkable photothermal conversion efficiency in monomeric state (η = 29.0%) in aqueous solution along with favorable fluorescence emission, which not only significantly accelerate uptake rate of SiPc-FITC but also simplify clinic formulation process. Antibacterial experiments showed that both Gram-positive and Gram-negative anaerobic bacteria were completely eliminated within a few minutes when SiPc-FITC was mixed with bacteria and immediately irradiated with an 808 nm laser. As the results, SiPc-FITC is a multifunctional photothermal bactericide that can be used for fluorescence and photothermal dual readout in situ NIR photothermal sterilization to prevent post-operative infection for dental implant.