Surface-Engineered WS₂ Nanohybrids for Implications in Biomedicine

Transition metal dichalcogenides (TMDs) nanosheets, known for their distinctive structural and physicochemical characteristics, have become valuable tools in various biomedical fields, including drug delivery and tissue engineering. Here, we have developed a facile approach to synthesize surface-modified TMD nanosheets that exhibit several smart properties, such as near-infrared (NIR) light-responsiveness, ultrasound-responsiveness, and bactericidal behavior. The surface modification was performed using a redox reaction, which decorated liquid-exfoliated, 2D, ultrathin nanosheets of tungsten disulfide (WS₂) with silver nanospheres. TEM and AFM images, along with analytical techniques such as XPS, FTIR, powder-XRD, UV-vis, and Confocal Raman spectroscopy, confirmed the binding of silver to the nanosheets, resulting in heterostructured nanohybrids (nWS₂). Additional structural information about this surface-engineered material was obtained using synchrotron radiation-based instrumentation techniques, including X-ray absorption fine structure spectroscopy (XAFS). Moreover, we demonstrate that nWS₂ nanohybrids are capable of inhibiting biofilms of methicillin-resistant Staphylococcus aureus (MRSA), a widely prevalent causative agent of healthcare-associated bacterial infections. The nanohybrids can also convert incident near-infrared (NIR) light to thermal energy and exhibit enhanced bactericidal potential. 1 mg/mL of nWS₂ was able to increase suspension temperatures by 30 °C. A colony forming unit assay with NIR-exposed nWS₂ showed antibiotic-free prevention of MRSA growth. Next, we develop a nWS₂-integrated polymeric hydrogel system capable of 3D-biopriting hydrogel structures with user-defined geometry for tissue engineering applications. Finally, we evaluate the in vitro cytocompatibility and in vivo biocompatibility of this nanocomposite hydrogel platform by subcutaneously implanting it in immunocompetent mice. Histological staining revealed excellent host-tissue integration, vasculogenesis, and a minimal immune response around the implant's periphery. Taken together, we envision surface-engineered WS₂ nanosheets, alone or in combination with hydrogels, as a high-performance multifunctional biomaterial for implications in biomedicine.