title: An optical biosensing platform for proteinase activity using gold nanoparticles.
abstract: The surface plasmon resonance (SPR) wavelength of colloidal gold nanoparticles (AuNPs) can vary when the AuNPs aggregate, have different sizes or shapes, or are modified with chemical molecules. In this study, an optical biosensing platform for a proteinase activity assay was established based on the SPR property of AuNPs. The 13-nm AuNPs were modified with gelatin (AuNPs-gelatin) as a proteinase substrate and subsequently modified with 6-mercaptohexan-1-ol (MCH) (AuNPs/MCH-gelatin). After proteinase (trypsin or gelatinase) digestion, the AuNPs lose shelter, and MCH increases the attractive force between the modified AuNPs. Therefore, the AuNPs gradually move closer to each other, resulting in AuNPs aggregation. The AuNPs aggregation can be monitored by the red shift of surface plasmon absorption and a visible color change of the AuNPs is from red to blue. Such a color change can be observed with the naked eye. For detection, the absorption ratio, A(625)/A(525), of the reacted AuNPs solution can be used to estimate quantitatively the proteinase activity. A linear correlation has been established with trypsin activity at concentrations from 1.25 x 10(-1) to 1.25 x 10(2) U and matrix metalloproteinase-2 activity at concentrations from 50 ng/mL to 600 ng/mL.
authors.affiliation: Department of Biological Science and Technology, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Yao-Chen
authors.initials: YC
authors.lastname: Chuang
authors.forename: Jung-Chun
authors.initials: JC
authors.lastname: Li
authors.forename: Sz-Hau
authors.initials: SH
authors.lastname: Chen
authors.forename: Ting-Yu
authors.initials: TY
authors.lastname: Liu
authors.forename: Ching-Han
authors.initials: CH
authors.lastname: Kuo
authors.forename: Wei-Ting
authors.initials: WT
authors.lastname: Huang
authors.forename: Chih-Sheng
authors.initials: CS
authors.lastname: Lin
mesh_terms: D015374:Biosensing Techniques; D004591:Electrophoresis, Polyacrylamide Gel; D006046:Gold; D053758:Nanoparticles; D055095:Optics and Photonics; D010447:Peptide Hydrolases / Q000378:metabolism*; D013056:Spectrophotometry, Ultraviolet; D020349:Surface Plasmon Resonance
chemical_list: D006046:Gold; D010447:Peptide Hydrolases