Self-assembled Ag2S–Au Janus nanoparticles for targeted photo-responsive thermal ablation of cancer cells and bacteria

Abstract Janus nanoparticles (JNPs) represent one of the most complex nanoparticles, and achieving precise control over their synthesis remains a significant challenge. Here, we explore gold–silver sulfide (Au–Ag 2 S) JNPs for targeted anticancer and antibacterial therapies. Au–Ag 2 S JNPs were synthesized and characterized using transmission electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray powder diffraction, energy-dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy confirming their distinct dimeric structure with Au and Ag 2 S components. Surface modification with 1,2-Distearoyl-sn-glycero-3-phosphoethanolamine-Polyethylene Glycol (DSPE-PEG) and folic acid enhanced stability and enabled targeted delivery to cancer cells, resulting in AADF JNPs. AADF JNPs exhibited strong near-infrared (NIR-II) emission, ideal for in vivo imaging and photothermal therapy. In vitro studies demonstrated high biocompatibility and enhanced cellular uptake in 4T1 cancer cells compared to non-targeted JNPs. Upon laser irradiation, AADF JNPs effectively reduced 4T1 cell viability, demonstrating their phototherapeutic effect. Furthermore, AADF JNPs exhibited potent antibacterial activity against Escherichia coli and Staphylococcus aureus under NIR irradiation, it achieved 78% tumor cell killing and 99% bacterial eradication. These findings highlight the potential of AADF JNPs as a promising solution for targeted cancer and bacterial infection treatments.