Highly efficient luminescent I-III-VI semiconductor nanoprobes based on template-synthesized CuInS₂ nanocrystals

CuInS₂ semiconductor nanocrystals (NCs) exhibit large absorption coefficient, size-dependent photoluminescence and low toxicity, making them excellent candidates in a variety of bioapplications. However, precise control of both their composition and morphology to improve the luminescent efficiency remains a great challenge via conventional direct synthesis. Herein, we present a novel low-temperature template synthesis of highly efficient luminescent CuInS₂ nanoprobes from In₂S₃ NCs via a facile cation exchange strategy. The proposed strategy enables synthesis of a series of CuInS₂ NCs with broad size tunability from 2.2 to 29.6 nm. Through rationally manipulating the stoichiometry of Cu/In, highly efficient luminescence of CuInS₂ with the maximum quantum yield of 28.6% has been achieved, which is about one order of magnitude improvement relative to that of directly synthesized NCs. By virtue of the intense emission of CuInS₂ nanoprobes, we exemplify their application in sensitive homogeneous biodetection for an important biomolecule of adenosine triphosphate (ATP) with the limit of detection down to 49.3 nM. Moreover, the CuInS₂ nanoprobes are explored for ATP-targeted cancer cell imaging, thus revealing their great potentials in the field of cancer diagnosis and prognosis.