Highly adhesive carbon quantum dots from biogenic amines for prevention of biofilm formation

We demonstrate the synthesis of antibacterial carbon quantum dots (CQDs) through a one-step pyrolysis of biogenic polyamine (PA) and dopamine (DA) mixture. SPM/DA-CQDs synthesized from DA combined with spermine (SPM) exhibit effective antibacterial activity and high adhesion properties on glass and surfaces of polymeric contact lens material. The antimicrobial activity of SPM/DA-CQDs is primarily due to their ability to disrupt the bacterial membrane, and they possess wide spectrum antimicrobial activity against Gram-negative bacteria (Escherichia coli, Salmonella enterica serovar Enteritidis, and Pseudomonas aeruginosa) and Gram-positive bacteria (Staphylococcus aureus and its multidrug-resistant strain, methicillin-resistant S. aureus). The minimal inhibitory concentration (MIC) of SPM/DA-CQDs against the tested bacteria was > 17-fold and > 7-fold lower than those of CQDs prepared solely from spermine and dopamine, respectively. The great biocompatibility of our SPM/DA-CQDs is revealed from the in vitro cytotoxicity and hemolysis assays and in vivo evaluation of morphological and physiological changes of rabbit corneas. We further prepared SPM/DA-CQDs-coated coverslips and contact lenses, which display excellent stability and antibiofilm properties. Moreover, in vivo tests show that SPM/DA-CQDs suppress bacterial keratitis (BK) formation in a corneal-injured rabbit model. Our results indicate that SPM/DA-CQDs have great potential as a coating material for inhibition of biofilm formation on contact lenses, and broadly to protect medical devices from contamination.