title: Bioassay of prostate-specific antigen (PSA) using microcantilevers.
abstract: Diagnosis and monitoring of complex diseases such as cancer require quantitative detection of multiple proteins. Recent work has shown that when specific biomolecular binding occurs on one surface of a microcantilever beam, intermolecular nanomechanics bend the cantilever, which can be optically detected. Although this label-free technique readily lends itself to formation of microcantilever arrays, what has remained unclear is the technologically critical issue of whether it is sufficiently specific and sensitive to detect disease-related proteins at clinically relevant conditions and concentrations. As an example, we report here that microcantilevers of different geometries have been used to detect two forms of prostate-specific antigen (PSA) over a wide range of concentrations from 0.2 ng/ml to 60 microg/ml in a background of human serum albumin (HSA) and human plasminogen (HP) at 1 mg/ml, making this a clinically relevant diagnostic technique for prostate cancer. Because cantilever motion originates from the free-energy change induced by specific biomolecular binding, this technique may offer a common platform for high-throughput label-free analysis of protein-protein binding, DNA hybridization, and DNA-protein interactions, as well as drug discovery.
authors.affiliation: Department of Mechanical Engineering, University of California, Berkeley, CA 94720, USA.
authors.forename: G
authors.initials: G
authors.lastname: Wu
authors.forename: R H
authors.initials: RH
authors.lastname: Datar
authors.forename: K M
authors.initials: KM
authors.lastname: Hansen
authors.forename: T
authors.initials: T
authors.lastname: Thundat
authors.forename: R J
authors.initials: RJ
authors.lastname: Cote
authors.forename: A
authors.initials: A
authors.lastname: Majumdar
mesh_terms: D015374:Biosensing Techniques; D002624:Chemistry, Clinical / Q000379:methods*; D004247:DNA / Q000378:metabolism; D006801:Humans; D007834:Lasers; D008297:Male; D008954:Models, Biological; D010958:Plasminogen / Q000378:metabolism; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis; D011485:Protein Binding; D012680:Sensitivity and Specificity; D012709:Serum Albumin / Q000378:metabolism; D013997:Time Factors
chemical_list: D012709:Serum Albumin; D010958:Plasminogen; D004247:DNA; D017430:Prostate-Specific Antigen