D-cysteine-Derived Carbon Dots for Selective Discrimination, Imaging, and Synergistic Elimination of Gram-Positive Bacteria and Fungi

Microbial infections pose a significant threat to public health, exacerbated by the escalating issue of antibiotic resistance resulting from their overuse. Chiral carbon dots (CDs) not only inherit the antibacterial properties of CDs but also demonstrate highly selective chiral bactericidal activity. This study focuses on the development of chiral CDs synthesized from D- and L-cysteine, to selectively identify and synergistically eradicate Gram-positive bacteria and fungi. Chiral CDs exhibit high efficacy in staining Gram-positive bacteria and fungi while demonstrating minimal to no fluorescence with Gram-negative bacteria, attributable to variances in the membrane structures of these pathogens. D-CDs exhibit stronger fluorescence signals and greater antibacterial efficacy against Gram-positive bacteria and fungi compared to L-CDs. Under dual light irradiation, D-CDs bolster antibacterial activity through a triple-modal mechanism, involving membrane disruption in the absence of light, singlet oxygen generation during photodynamic therapy, and elevated temperature during photothermal treatment. Animal studies additionally showcase that D-CDs notably enhanced the healing of wounds infected with S. aureus under laser light exposure. This investigation underscores the chiral-specific imaging and antibacterial potentials of D-CDs, paving the way for the advancement of chiral nanomaterials in bacterial diagnostics and therapy. D-cysteine derived carbon dots are developed for selective discrimination, imaging, and synergistic elimination of Gram-positive bacteria and fungi, surpassing their enantiomers through an advanced tri-modal approach incorporating chemical, photodynamic, and photothermal therapies. image