Designing functionalized nanodiamonds with hyaluronic acid-phospholipid conjugates for enhanced cancer cell targeting and fluorescence imaging capabilities.

Nanomedicine aims to develop smart approaches for treating cancer and other diseases to improve patient survival and quality of life. Novel nanoparticles as nanodiamonds (NDs) represent promising candidates to overcome current limitations. In this study, NDs were functionalized with a 200 kDa hyaluronic acid-phospholipid conjugate (HA/DMPE), enhancing the stability of the nanoparticles in water-based solutions and selectivity for cancer cells overexpressing specific HA cluster determinant 44 (CD44) receptors. These nanoparticles were characterized by diffuse reflectance Fourier-transform infrared spectroscopy, Raman spectroscopy, and photoluminescence spectroscopy, confirming the efficacy of the functionalization process. Scanning electron microscopy was employed to evaluate the size distribution of the dry particles, while dynamic light scattering and zeta potential measurements were utilized to evaluate ND behavior in a water-based medium. Furthermore, the ND biocompatibility and uptake mediated by CD44 receptors in three different models of human adenocarcinoma cells were assessed by performing cytofluorimetric assay and confocal microscopy. HA-functionalized nanodiamonds demonstrated the advantage of active targeting in the presence of cancer cells expressing CD44 on the surface, suggesting higher drug delivery to tumors over non-tumor tissues. Even CD44-poorly expressing cancers could be targeted by the NDs, thanks to their good passive diffusion within cancer cells.