title: In-situ quantitative analysis of a prostate-specific antigen (PSA) using a nanomechanical PZT cantilever.
abstract: We report on a novel technique of resonant frequency shift measurement based on a nanomechanical cantilever with a PZT actuating layer for label-free detection of a prostate-specific antigen (PSA) in a liquid environment. The nanomechanical PZT thin film cantilever is composed of SiO(2)/Ta/Pt/PZT/Pt/SiO(2) on a SiN(x) supporting layer for simultaneous self-exciting and sensing; it was fabricated using a standard MEMS (micro electromechanical system) process. The specific binding characteristics of the PSA antigen to its antibody, which is immobilized with Calixcrown self-assembled monolayers (SAMs) on a gold surface deposited on a cantilever, are determined to a high sensitivity. For the bioassay in a liquid environment, a liquid test cell with a 20 microl volume reaction chamber has been fabricated, using a bonding technique between poly(dimethyl siloxane) (PDMS) bilayers. An observed trend of resonant frequency change with respect to time could be explained by the binding kinetics due to the Langmuir isotherm and diffusion and by the effects of a small volume reaction chamber. In the saturated regimes, the resonant frequency of the cantilever increased with increase of the PSA concentration in the reaction chamber, showing that the trend of the resonance frequency change was similar to that of the fluorescence results. The saturated resonance frequency shift of the cantilever was proportional to the PSA antigen concentration of analyte solution.
authors.affiliation: Microsystem Research Center, Korea Institute of Science and Technology, Seongbuk-gu, Seoul 136-761, Republic of Korea.
authors.forename: Kyo Seon
authors.initials: KS
authors.lastname: Hwang
authors.forename: Jeong Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Jaebum
authors.initials: J
authors.lastname: Park
authors.forename: Dae Sung
authors.initials: DS
authors.lastname: Yoon
authors.forename: Jung Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Tae Song
authors.initials: TS
authors.lastname: Kim
mesh_terms: D000906:Antibodies / Q000032:analysis / Q000276:immunology; D000936:Antigen-Antibody Complex / Q000032:analysis / Q000276:immunology; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D017022:Flow Injection Analysis / Q000295:instrumentation / Q000379:methods; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D019563:Mechanics; D008832:Microchemistry / Q000295:instrumentation* / Q000379:methods; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation* / Q000379:methods; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods; D017430:Prostate-Specific Antigen / Q000032:analysis* / Q000276:immunology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012996:Solutions; D014159:Transducers; D014732:Vibration
chemical_list: D000906:Antibodies; D000936:Antigen-Antibody Complex; D012996:Solutions; D017430:Prostate-Specific Antigen