Researchers at China's Gannan Medical University and Shanghai University recently developed a Schottky junction-based nanocomposite that combines gold nanoparticles (AuNPs) with graphene oxide quantum dots (GOQDs), demonstrating a highly effective, antibiotic-free strategy for treating bacterial infections and accelerating wound healing.
The work addresses a known clinical challenge: the rapid rise of multidrug-resistant (MDR) bacteria driven by widespread antibiotic use. Conventional approaches - such as increasing antibiotic dosage or developing new drugs - are often limited by toxicity, long development timelines, and persistent resistance. As a result, non-invasive phototherapies, particularly photodynamic therapy (PDT) and photothermal therapy (PTT), are gaining attention as alternatives. However, each modality has intrinsic limitations: PDT efficiency is constrained by electron–hole recombination and oxygen availability, while PTT requires precise thermal control to avoid damaging healthy tissue. To overcome these constraints, the researchers engineered a hybrid nanostructure in which AuNPs and GOQDs form a Schottky junction - a metal–semiconductor interface that enables directional charge transfer.
Under 460 nm LED irradiation, GOQDs act as semiconducting photosensitizers, generating electron-hole pairs, while the AuNPs serve as electron sinks. This junction effectively suppresses charge recombination, prolonging carrier lifetimes and significantly enhancing reactive oxygen species (ROS) generation.
At the same time, the system improves photothermal performance. AuNPs exhibit localized surface plasmon resonance (LSPR) in the visible range, enabling efficient light absorption and conversion into heat, while GOQDs contribute broad optical absorption and high electron mobility. This dual contribution enhances light-to-heat conversion, with the nanocomposite reaching approximately 38.8°C after 10 minutes of illumination. The resulting localized hyperthermia increases bacterial membrane permeability, disrupts ionic balance, and accelerates cell death.
GOQDs also play a multifunctional role beyond charge transport. Their abundant surface functional groups improve dispersion stability, biocompatibility, and tissue affinity, ensuring effective interaction with biological environments.
Experimentally, the AuNPs/GOQDs nanocomposite demonstrated strong antibacterial performance against both Gram-positive and Gram-negative strains, achieving over 97% eradication of Staphylococcus aureus and Escherichia coli in vitro under light irradiation. High-resolution imaging confirmed that the combined ROS generation and photothermal effect led to membrane rupture, causing leakage of intracellular components such as DNA and proteins and resulting in irreversible bacterial cell death.
In vivo results further highlight the therapeutic potential. In a murine wound infection model, treatment with the light-activated nanocomposite achieved approximately 99% wound healing within 9 days, significantly outperforming control groups and individual components. Histological analysis revealed enhanced tissue regeneration, including thicker collagen deposition and reduced inflammation, consistent with improved healing dynamics.
Overall, the study demonstrates that integrating AuNPs and GOQDs into a Schottky junction-enabled platform enables synergistic PDT/PTT under a single light source. By combining enhanced ROS production, efficient photothermal conversion, and favorable biological interactions, this nanocomposite offers a promising drug-free approach for combating MDR infections and promoting wound repair, particularly in challenging cases such as burns, diabetic ulcers, and trauma-related injuries.
