Surface Modification of a Stable CdSeZnS/ZnS Alloy Quantum Dot for Immunoassay

Quantum dots (QDs) are powerful materials in various bioapplications based on their excellent optical and electronic properties. For the application of various fields of QDs, surface modification of QDs is necessary. However, surface modification in QDs may result in a reduction in quantum yield (QY). This reduction of QY causes many weaknesses in the biological application of QDs. In this study, CdSeZnS/ZnS alloy QDs were used to prepare antibody-conjugated QDs for a sandwich immunoassay. The alloy QDs displayed a QY of 84.5% that was maintained at 83.0% (98.2% of QY was maintained) after surface modification with the anti-rabbit IgG as a model study. Surface-modified QDs successfully detected their corresponding target through antibody-antigen binding. The limit of detection was <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mn>1.1</a:mn> <a:mo>×</a:mo> <a:msup> <a:mrow> <a:mn>10</a:mn> </a:mrow> <a:mrow> <a:mn>2</a:mn> </a:mrow> </a:msup> </a:math> ng mL-1 for rabbit IgG.