Tailored upconversion nanomaterial: A hybrid nano fluorescent sensor for evaluating efficacy of lactate dehydrogenase inhibitors as anticancer drugs

High Lactate Dehydrogenase (LDH) activity, a distinct feature of cancer cells, is a possible causative factor for cancer cells to metastasize, infiltrate, invade, and deteriorate. The exploration of upconversion hybrid nano fluorescent sensor (HNFS) with the capability of evaluation the LDH inhibitors efficacy will be useful to accelerate the development of anti-cancer drugs from LDH inhibitors. Herein, we design an HNFS that can evaluate the inhibitors efficacy in vitro from the changes of the upconversion luminescence in the red-light region. HNFS is composed of two components: a Nile Blue A derivative (CPNB) that detects LDH activity, and tailored manganese doped upconverting nanoparticles that produce bright red emission which absorbs by CPNB via Forster resonance energy transfer. The cytotoxicity of HNFS in living cells (HeLa, A549 and Ges-1) was investigated by using the CCK-8 assay, which showed that HNFS possesses excellent biocompatibility. After incubating HNFS with three types of cells (A549, HeLa, and Ges-1), the mean fluorescence intensities of confocal images in vitro can illustrate the efficacy of LDH inhibitors to different cancer cells and distinguish healthy cells (Ges-1) from cancer cells (A549 and HeLa). Therefore, the systematic study of HNFS in vitro does encourage the potential applications of evaluating the LDH inhibitors efficacy in cancer cells.