Quantum dot-crosslinked light-guiding hydrogels for sensing folate receptor-overexpressed cancer cells

Abstract In this study, we report quantum dots (QDs)-crosslinked light-guiding hydrogels, which are used to detect folate receptor (FR)-overexpressed cancer cells. The QDs are modified by folic acid (FA). In order to avoid fluorescence quenching, the covalent bond is used to cross-link FA modified QDs (FA-QDs) with hydrogels. The fluorescence stability of the prepared FA-QDs-doped light-guiding hydrogels (FQLH) is outstanding. Cancer cells with overexpression of FR (breast cancer cells, MCF-7; cervical cancer cells, HeLa), cancer cells without expression of FR (lung cancer cells, A549), and normal cells (mouse embryonic fibroblast, 3T3) are used to test the sensing characteristics of FQLH. After FQLH is inserted into the MCF-7 solution, the fluorescence intensity increases linearly with time, and the result of the HeLa solution is similar. But there is no similar response into the A549 solution or 3T3 solution, which shows that FQLH can effectively and specifically detect FR-overexpressed cancer cells. Simultaneously, the MCF-7 as an example is studied in detail. The results show that the concentration of MCF-7 can be measured based on the rate of increased fluorescence intensity. The minimum detection concentration is 1.0 × 104/mL. Moreover, detection of other cancer cells can be achieved by doping the hydrogels with the corresponding targeted modified QDs. In addition, the prepared FQLH has excellent mechanical and light-guiding performance (loss is less than 0.0165 dB/mm), and it is promised to be implanted into the human body to achieve real-time detection in vivo，which shows a great potential in cancer detection and therapy.