Analytical Sciences

Protein-Functionalized Gold Nanoparticles for Antibody Detection Using the Darkfield Microscopic Observation of Nanoparticle Aggregation

Ken YOSHIMURA,* PATMAWATI,** Mizuo MAEDA,*** Noriho KAMIYA,** and Tamotsu ZAKO*

*Department of Chemistry and Biology, Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo, Matsuyama, Ehime 790-8577, Japan
**Department of Applied Chemistry, Graduate School of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395, Japan
***Bioengineering Laboratory, RIKEN Cluster for Pioneering Research, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

Gold nanoparticles (AuNPs) are commonly used in biosensing applications. In this study, AuNPs were synthesized by using reduced bovine serum albumin (rBSA) as the reducing agent. The rBSA conjugated with AuNPs via Au-Sulfur interactions to form rBSA-functionalized AuNPs (rBSA-AuNPs). The interaction of the rBSA moieties on the rBSA-AuNP surface with an anti-BSA antibody (anti-BSA) led to AuNP aggregation, which enabled the successful detection of anti-BSA at a concentration as low as 20 nM through darkfield microscopy (DFM). This study demonstrates the potential applications of protein-functionalized AuNPs in the bioanalysis of substances through DFM.

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