Monitoring in vitro neural stem cell differentiation based on surface-enhanced Raman spectroscopy using a gold nanostar array

The development of neurochips for non-invasive monitoring of neural stem cell stimulation is highly desirable and can enable the efficient optimization of tissue development protocols. Traditional methods, including cell staining and sorting, have long been used, but these techniques are time-consuming and may damage cells. Here, we have developed a cell-based chip to monitor the in vitro stepwise differentiation process of isolated mouse neural stem cells, the one-step differentiation of adult human neural stem cells (HB1.F3), and the electrochemical stimulation of rat pheochromocytoma PC12 cells. Results showed that each cell line exhibited a different behavior during differentiation. The DNA contents changed irregularly during the differentiation of HB1.F3 cells, while the percentage of proteins increased. In addition, the results revealed that the electrochemical stimulation of PC12 cells induced changes in the synthesis of DNA and proteins. The differentiation of isolated mouse neural stem cells showed a decrease in some peaks corresponding to the DNA content and an increase in the percentage of protein, in addition to the irregular behavior of some peaks related to both nucleic acids and proteins. The increase in protein percentage could indicate local variations in protein structure and a maturation shift. These results demonstrate that the SERS technique allows for more rapid biological sample analysis without time-consuming staining, enabling researchers to monitor engineered tissues and optimize culture conditions in a near real-time manner.