Positively Charged Semiconductor Conjugated Polymer Nanomaterials with Photothermal Activity for Antibacterial and Antibiofilm Activities In Vitro and In Vivo

Biofilm infections are associatedwith most human bacterial infectionsand are prone to bacterial multidrug resistance. There is an urgentneed to develop an alternative approach to antibacterial and antibiofilmagents. Herein, two positively charged semiconductor conjugated polymernanoparticles (SPPD and SPND) were prepared for additive antibacterialand antibiofilm activities with the aid of positive charge and photothermaltherapy (PTT). The positive charge of SPPD and SPND was helpful inadhering to the surface of bacteria. With an 808 nm laser irradiation,the photothermal activity of SPPD and SPND could be effectively transferredto bacteria and biofilms. Under the additive effect of positive chargeand PTT, the inhibition rate of Staphylococcus aureus (S. aureus) treated with SPPD and SPND (40 & mu;g/mL)could reach more than 99.2%, and the antibacterial activities of SPPDand SPND against S. aureus biofilmswere 93.5 and 95.8%. SPPD presented better biocompatibility than SPNDand exhibited good antibiofilm properties in biofilm-infected mice.Overall, this additive treatment strategy of positive charge and PTTprovided an optional approach to combat biofilms.