Flower-like gap-enhanced Raman tags wrapped with polydopamine-functionalized MoS2 nanosheets for phototheranostic nanoplatform

Phototheranostic nanoplatforms that perform simultaneous optical imaging and phototherapy through light activation are considered a promising approach for early diagnosis, surgical guidance, and precision treatment of cancer. In this work, we develop a novel flower-like gap-enhanced Raman tags (for brief, PMF-GERTs) wrapped with polydopamine (PDA)-functionalized molybdenum disulfide (MoS₂) nanosheets. In PMF-GERTs, 4,4′-biphenyldithiol (BPDT) Raman reporter molecules are embedded in the nanogap between the gold core and the flower-like shell, and PDA-functionalized MoS₂ nanosheets (PDA/MoS₂) were wrapped on the surface of the flower-shaped shell. Photothermal and photodynamic experiments show that PDA/MoS₂ nanosheets significantly improve the photothermal performance and photodynamic response ability of Raman tags in the NIR-II region. Under the irradiation of 1064 nm laser (1 W/cm²), the PMF-GERTs solution can heat up to 66 °C within 300 s, and the photothermal conversion efficiency reaches 43.6%. Moreover, PMF-GERT also has excellent photothermal stability and photodynamic properties and can perform effective phototherapy on 4T1 tumor cells. In Raman spectra and mapping imaging experiments, PMF-GERTs have strong enhanced Raman signals, lower detection thresholds and long-time physiological environment stability (72 h). In addition, PMF-GETRs also have excellent performance in simulating biological tissues and biological Raman mapping imaging. This novel Raman tag is expected to be used to develop phototheranostic nanoplatform that integrates Raman imaging diagnosis and photothermal and photodynamic therapy.

Graphical abstract