Polyphenol-Assisted Exfoliation of Transition Metal Dichalcogenides into Nanosheets as Photothermal Nanocarriers for Enhanced Antibiofilm Activity.

Transition metal dichalcogenide (TMD) nanosheets have evoked enormous research enthusiasm and have shown increased potentials in the biomedical field. However, a great challenge lies in high-throughput, large-scale, and eco-friendly preparation of TMD nanosheet dispersions with high quality. Herein, we report a universal polyphenol-assisted strategy to facilely exfoliate various TMDs into monolayer or few-layer nanosheets. By optimizing the exfoliation condition of molybdenum disulfide (MoS2), the yield and concentration of as-exfoliated nanosheets are up to 60.5% and 1.21 mg/mL, respectively. This is the most efficient aqueous exfoliation method at present and is versatile for the choices of polyphenols and TMD nanomaterials. The as-exfoliated MoS2 nanosheets possess superior biomedical stability as nanocarriers to load antibiotic drugs. They show a high photothermal conversion effect and thus induce a synergetic effect of chemotherapy and photothermal therapy to harvest enhanced antibiofilm activity under near-infrared (NIR) light. All these results offer an appealing strategy toward the synthesis and application of ultrathin TMD nanosheets, with great implications for their development.

Surface-Adaptive Gold Nanoparticles with Effective Adherence and Enhanced Photothermal Ablation of Methicillin-Resistant Staphylococcus aureus Biofilm.

Biofilms that contribute to the persistent bacterial infections pose serious threats to global public health, mainly due to their resistance to antibiotics penetration and escaping innate immune attacks by phagocytes. Here, we report a kind of surface-adaptive gold nanoparticles (AuNPs) exhibiting (1) a self-adaptive target to the acidic microenvironment of biofilm, (2) an enhanced photothermal ablation of methicillin-resistant Staphylococcus aureus (MRSA) biofilm under near-infrared (NIR) light irradiation, and (3) no damage to the healthy tissues around the biofilm. Originally, AuNPs were readily prepared by surface modification with pH-responsive mixed charged zwitterionic self-assembled monolayers consisting of weak electrolytic 11-mercaptoundecanoic acid (HS-C10-COOH) and strong electrolytic (10-mercaptodecyl)trimethylammonium bromide (HS-C10-N4). The mixed charged zwitterion-modified AuNPs showed fast pH-responsive transition from negative charge to positive charge, which enabled the AuNPs to disperse well in healthy tissues (pH ∼7.4), while quickly presenting strong adherence to negatively charged bacteria surfaces in MRSA biofilm (pH ∼5.5). Simultaneous AuNP aggregation within the MRSA biofilm enhanced the photothermal ablation of MRSA biofilm under NIR light irradiation. The surrounding healthy tissues showed no damage because the dispersed AuNPs had no photothermal effect under NIR light. In view of the above advantages as well as the straightforward preparation, AuNPs developed in this work may find potential applications as a useful antibacterial agent in the areas of healthcare.