Light-Induced Cell-Sheet Harvest on TiO₂ Films Sensitized with Carbon Quantum Dots

Carbon quantum dots (CQDs) have been incorporated as a sensitizer into TiO₂ films to regulate the light-induced cell-detachment performance. Depending on the amount of CQDs incorporated, nanodots or porous films are obtained. It was found that the right amount of CQDs incorporation significantly improves the cell-sheet detachment efficiency, and an intact cell sheet could be obtained after merely five minutes of UV illumination (365 nm, UV365), which is much faster than that from CQDs-free TiO₂ film. Furthermore, cell sheets on CQDs-sensitized TiO₂ films show improved viability, and alkaline phosphatase and collagen I activity either before or after light-induced detachment. The improved cell-detachment performance is ascribed to the effective inhibition of charge recombination of the TiO₂ film and the microstructure variations, which increase the negative surface potential and change the secondary structure of the adsorbed extracellular protein molecules; this results in a faster release of cells. It is suggested that the faster release reduces the possible detrimental impact on cell functions during detachment and helps in maintaining the excellent cellular activity. This study demonstrates that CQDs sensitization is an effective approach for optimizing the performance of light-induced cell-sheet harvest.