Thick-Shell CdSe/ZnS/CdZnS/ZnS Core/Shell Quantum\nDots for Quantitative Immunoassays

Abstract

Colloidal\nquantum dots (QDs) have been broadly applied as fluorescent\nlabeling materials in the fields of bio-imaging, sensing, and detection,\nin which the optical performances and stability of the utilized QDs\nare vital. Despite significant efforts in developing such materials,\nit is still challenging to fabricate QDs with high photoluminescence\nquantum yields (PL QYs) while concurrently possessing high particle\nand optical stabilities, limiting the further development of QD-based\nbiological labeling and detection techniques. Herein, we report a\nsynthesis of giant CdSe/ZnS/CdZnS/ZnS core/shell QDs with an ultrathick\nshell (∼36 monolayers) and high PL QYs (>80%). We further\nemploy\nthe as-synthesized QDs for C-reactive protein detection, which reach\nnearly a 3-fold enhancement in detection sensitivity (∼0.41\nng/mL) and a 2-fold increase in shelf life, in comparison to the traditional\nthick-shell QDs (<i>i.e.</i>, CdSe/CdS/ZnS core/shell QDs)\nor commercially available core/shell QDs. We postulate that the performance\nimprovements in protein detection are due to the use of the developed\ncore/shell QDs with high particle stability and PL QYs and large surface\narea (facilitating surface antibody coupling). Our study demonstrates\nthe viability of applying high-quality core/shell QDs for protein\ndetection with high sensitivity and accuracy.