A novel carboxymethyl chitosan–quantum dot-based intracellular probe for Zn2+ ion sensing in prostate cancer cells

In this paper, we fabricated novel carboxymethyl chitosan-coated CdTe quantum dots (CMC–CdTe QDs) via the electrostatic interaction between amino groups in the carboxymethyl chitosan polymeric chains and carboxyl groups of the CdTe QDs. Carboxymethyl chitosan on the surface of CdTe QDs had strong binding ability with Zn2+, resulting in the obvious enhancement of the photoluminescence of CdTe QDs. The photoluminescence intensity of CMC–CdTe QDs probe was proportional to the concentration of Zn2+ in the range of 5.0 × 10−6 to 5.0 × 10−3 mol l−1. The detection limit for Zn2+ was 4.5 × 10−6 mol l−1. The experimental results indicate that the CMC–CdTe QDs possess favorable cell compatibility, good sensitivity and selectivity for intracellular Zn2+ sensing, and are promising candidates for cellular imaging and sensing in prostate cancer cells. The present study also provides an approach for the further development of nanoprobes dedicated to intracellular sensing.