Boosting Antibacterial Efficacy of Silicon Quantum Dots through Chiral Surface Engineering

The rise of antibiotic-resistant bacteria poses a severe global health threat, driving the urgent need for alternative antimicrobial strategies. Nanomaterials, particularly silicon quantum dots (SiQDs), offer promising potential due to their multimechanistic antibacterial action and lower risk of inducing resistance. However, the practical application of conventional SiQDs is often constrained by a limited antibacterial efficacy. In this work, chiral SiQDs (D-SiQDs and L-SiQDs) were synthesized via a one-step polymerization method using (3-aminopropyl)trimethoxysilane (APTMS) and d- or l-cysteine as raw materials. Their antibacterial activity was evaluated against Gram-positive S. aureus and Gram-negative E. coli. D-SiQDs exhibited antibacterial activity against S. aureus and E. coli, achieving sterilization rates of 95% at concentrations of 50 μg/mL and 250 μg/mL, respectively, significantly outperforming achiral SiQDs (1 mg/mL and 2 mg/mL). Thus, the chiral introduction significantly enhanced the antibacterial activity of SiQDs. Mechanistic studies revealed that D-SiQDs caused more severe membrane damage, nucleic acid leakage, and ATP depletion in S. aureus. Furthermore, when applied to polypropylene fabrics, D-SiQDs confer excellent antibacterial properties while showing minimal cytotoxicity. This work highlights the significant role of chirality in enhancing the antibacterial performance of nanomaterials and presents chiral SiQDs as a highly promising, biocompatible alternative to conventional antibiotics for anti-infective applications.