Gold Nanoparticle Sensor for Homocysteine Thiolactone-Induced Protein Modification

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• 作者：Arther T. Gates ; Sayo O. Fakayode ; Mark Lowry ; Gabriela M. Ganea ; Abitha Murugeshu ; James W. Robinson ; Robert M. Strongin ; Isiah M. Warner
• 刊名：Langmuir
• 出版年：2008
• 出版时间：April 15, 2008
• 年：2008
• 卷：24
• 期：8
• 页码：4107 - 4113
• 全文大小：405K
• 年卷期：v.24,no.8(April 15, 2008)
• ISSN：1520-5827

文摘

Homocysteine thiolactone-induced protein modification (HTPM) is a unique post-translational protein modificationthat is recognized as an emergent biomarker for cardiovascular disease. HTPM involves the site-specific acylationof proteins at lysine residues by homocysteine thiolactone (HTL) to produce protein homocystamide, which has beenfound at elevated levels in patients with coronary heart disease. Herein, we report the development of a novel goldnanoparticle (GNP) biochemical sensor for detection of protein homocystamide in an in vitro serum protein-basedmodel system. Human serum albumin (HSA) and human sera were subjected to HTPM in vitro to produce HSA-homocystamide or serum protein homocystamide, respectively, which was subsequently treated with citrate-cappedGNPs. This GNP sensor typically provided instantaneous visual confirmation of HTPM in the protein model systems.Transmission electron microscopy images of the GNPs in the presence of HSA-homocystamide suggest that modification-directed nanoparticle assembly is the mechanism by which the biochemical sensor produces a colorimetric signal. Theresultant nanoparticle-protein assembly exhibited excellent thermal and dilutional stability, which is expected fora system stabilized by chemisorption and intermolecular disulfide bonding. The sensor typically provided a linearresponse for modified human sera concentrations greater than ~5 mg/mL. The calculated limit of detection andcalibration sensitivity for the method in human sera were 5.2 mg/mL and 13.6 AU · (g/mL)^-1, respectively.