Low-toxicity PEG-coated SERS silver nanocubes for diagnosing esophageal cancer

The early detection of esophageal cancer is crucial for enhancing patient survival. Surface-enhanced Raman scattering (SERS), renowned for its precise detection capabilities of low-concentration molecules and organisms, holds immense promise for early diagnosis. However, the use of silver nanoparticles to enhance the Raman signal can disrupt the detection process. To address this problem in this study, we synthesized polyethylene glycol (PEG)-coated silver nanocubes (PEG-AgNCs) as stable, label-free, and low-toxicity nanoprobes for detecting esophageal cancer. AgNCs with sharp corners and edges are selected as the SERS substrate to increase the strength of the Raman signal. To minimize the toxicity of AgNCs, the surface is coated with PEG, which exhibits outstanding biocompatibility. The SERS effectiveness of PEG-AgNCs was evaluated using 4-mercaptobenzoic acid as a Raman probe molecule, and the toxicity of PEG-AgNCs at different concentrations was investigated using human keratinocytes (HaCaT) and human esophageal carcinoma cells (TE-1). Results showed that PEG-AgNCs can effectively reduce the toxicity of AgNCs while maintaining a strong SERS signal. Remarkable differences in Raman spectra were observed between HaCat and TE-1 cells within the spectral range of 588-768 cm-1, indicating the potential of PEG-AgNCs in the early detection of esophageal cancer using Raman detection. Our study highlights the potential of developing low-toxicity SERS biosensors for biological and chemical analyses.