High-Quality CuInS₂/ZnS Quantum Dots for\nIn vitro and In vivo Bioimaging

Abstract

The exploration of biocompatible quantum dots (QDs) for\nbiomedical\nimaging is currently one of the fastest growing fields of nanotechnology.\nThis strategy overcomes the intrinsic toxicity of well-developed II–VI\nand other semiconductor QDs (Cd, Hg, Pb, Se, Te, As, etc.) that remains\na major obstacle to their clinical use. In this report, we synthesized\nhigh-quality CuInS₂/ZnS (CIS/ZnS) QDs without using conventional\ntoxic heavy metals. These QDs exhibited improved photoluminescence\n(PL) properties, with tunable emission peaks ranging\nfrom 550 to 800 nm and a maximum PL quantum yield (QY) up to 80%.\nNext, we explored the effective loading of the prepared oil-soluble\nCIS/ZnS QDs using biodegradable folate-modified N-succinyl-N′-octyl\nchitosan (FA-SOC) micelles. Targeting efficacy of the resulting QDs-loaded\nmicelles to tumors using in vitro and in vivo optical imaging techniques\nwas also investigated. The results show that the micelle platform\nallowed successful formulation of these oil-soluble QDs in water,\nwhile retaining the morphology, crystal structure, and PL of the initial\nCIS/ZnS QDs. This study demonstrates the versatility of using the\nbiocompatible CIS/ZnS QDs across different spatial scales (in vitro\ncell imaging and in vivo small animal imaging) for multicolor biological\nimaging applications.