A facile synthesis of biocompatible, glycol chitosan shelled CdSeS/ZnS QDs for live cell imaging

We here report a facile synthesis of chitosan shelled quantum dot (QD/fGC) that holds essential properties requisite for biological applications, such as excellent water solubility, super colloidal stability, and low nonspecific adsorption as well as ease of functionalization. In this method, the amphiphilic glycol chitosan fragment (MW 1.0-1.7 kDa) was assembled on the top of CdSeS/ZnS nanocrystal through hydrophobic interaction in aqueous solution, without displacing the native coordinating ligands, which result in a higher quantum yield of about 0.26, 46% of the uncoated CdSeS/ZnS QDs in chloroform (0.57). In addition, the prepared QD/fGC composes an individual semiconductor core and presents an extremely small size of about 6.03 ± 1.50 nm (n = 399) in diameter. By conjugation with bioactive amines via 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-based hydroxyl activation approach, the functionalized QD/fGC presented excellent recognition of specific cells in fluorescent imaging. Our work provides a new general method of chitosan modification of hydrophobic nanoparticles for biomedical applications.