3.1 Intracellular GSH changes
The one-dimensional fluorescence spectra of GSH (Figure 3) showed that the emission wavelengths of GSH detected by CQDs as probes were all around 465 nm; from 0 to 14 d, the measured GSH content changed slowly and increased significantly after 14 d, reaching the maximum on day 50. The two-dimensional correlation of GSH content was calculated, and the synchronous and asynchronous two-dimensional correlation fluorescence spectra of GSH were obtained. It can be seen that there is only one autocorrelation peak on the main diagonal, and there is no cross peak outside the main diagonal. The excitation wavelengths of CQDs as probes are all 370 nm, and the synchronous fluorescence change graph of GSH is completely synchronous, i.e. all peaks of the same substance belong to synchronous change. Since there is no obvious interference in the system, no cross peaks exist outside the main diagonal. In the two-dimensional asynchronous correlation fluorescence spectrogram, an asynchronous cross peak appeared at 465 nm outside the main diagonal, and excitation at 370 nm would get an emission peak at 465 nm, and the distribution of GSH content at different stages was clear.