Nanodiamonds as Raman probes for specifically targeted bioimaging: visualization and mechanism study of the biorecognition between nanodiamonds-EGF and EGFR

Abstract

Nanodiamonds (NDs), with many superior properties, have been utilized as multifunctional drug delivery platforms, which are suitable for cancer cell targeting, imaging and therapeutic applications. In this paper, NDs were modified with epidermal growth factor (EGF) molecules through the amide bonds, and used as cancer cell seeking probes with confocal Raman microscopy to visualize the specific targeting recognition of EGF ligands and their receptors (EGFR) that were over-expressed on HeLa cells. Relying on the characteristic Raman signal of NDs at 1332 cm⁻¹, Raman mapping was successfully utilized to reveal the specificity of EGF targeting ability under physiological conditions. Also, the specific recognition between EGF and its receptor was proven to be a dose-dependent process. Besides, the further influence of the specific recognition on HeLa cells such as the cell shape change and induced migration process was also investigated, and the related mechanism was discussed, showing that EGF recognition could change cell morphology and promote cancer cell migration, which might cause risks for the application of EGF molecules in targeting drug delivery systems. The present results provide a new perspective to evaluate and select suitable targeting molecules in future diagnostic and therapeutic applications.