Recent progress of UCNPs–MoS2 nanocomposites as a platform for biological applications

Composite materials can take advantages of the functional benefits of multiple pure nanomaterials to a greater degree than single nanomaterials alone. The UCNPs–MoS₂ composite is a nano-application platform that combines upconversion luminescence and photothermal properties. Upconversion nanoparticles (UCNPs) are inorganic nanomaterials with long-wavelength excitation and short-wavelength tunable emission capabilities, and are able to effectively convert near-infrared (NIR) light into visible light for increased photostability. However, UCNPs have a low capacity for absorbing visible light, whereas MoS₂ shows better absorption in the ultraviolet and visible regions. By integrating the benefits of UCNPs and MoS₂, UCNPs–MoS₂ nanocomposites can convert NIR light with a higher depth of detection into visible light for application with MoS₂ through fluorescence resonance energy transfer (FRET), which compensates for the issues of MoS₂'s low tissue penetration light-absorbing wavelengths and expands its potential biological applications. Therefore, starting from the construction of UCNPs–MoS₂ nanoplatforms, herein, we review the research progress in biological applications, including biosensing, phototherapy, bioimaging, and targeted drug delivery. Additionally, the current challenges and future development trends of UCNPs–MoS₂ nanocomposites for biological applications are also discussed.