title: Sensitivity enhancement of a dynamic mode microcantilever by stress inducer and mass inducer to detect PSA at low picogram levels.
abstract: We report two types of signal enhancement strategy derived from the origin of mechanical response, surface stress and mass, of the dynamic mode microcantilever for the detection of PSA at low picogram scales (low femtomolar concentration). The PSA detection at extremely low concentration levels is crucial to the early detection of relapses of prostate cancer after the radical prostatectomy and the detection of breast cancer in patient's serum. There is a clear need for the ultrasensitive detection of PSA via simple and rapid diagnostic tools. From the motives, to increase the sensitivity of the microcantilever, PSA polyclonal antibody (PSA pAb) as an additional surface stress inducer and PSA polyclonal antibody-conjugated silica nanoparticles (pAb-SiNPs) as a mass inducer have been applied to the PSA-captured microcantilevers. From two types of sandwich assay, we could confirm the sensitivity enhancement effects (2 approximately 4 times enhanced at the same concentrations) enough to detect PSA at low picogram levels (LOD of 1 pg/mL or below). Moreover, surface stress due to steric interactions between epitope-specific monoclonal antibodies was assessed to support a signal amplification strategy by stress inducer, and the reduction of signal enhancement due to stiffness increase by the mass inducer was studied to clarify the sensitivity enhancement of the microcantilever by mass inducer.
authors.affiliation: Nano-Bio Research Center, Korea Institute of Science and Technology, 39-1, Haweolgog-Dong, Seongbuk-Gu, Seoul, 136-791, Republic of Korea.
authors.forename: Sang-Myung
authors.initials: SM
authors.lastname: Lee
authors.forename: Kyo Seon
authors.initials: KS
authors.lastname: Hwang
authors.forename: Hyo-Jin
authors.initials: HJ
authors.lastname: Yoon
authors.forename: Dae Sung
authors.initials: DS
authors.lastname: Yoon
authors.forename: Sang Kyung
authors.initials: SK
authors.lastname: Kim
authors.forename: Yoon-Sik
authors.initials: YS
authors.lastname: Lee
authors.forename: Tae Song
authors.initials: TS
authors.lastname: Kim
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry; D004574:Electromagnetic Fields; D006801:Humans; D008297:Male; D053758:Nanoparticles; D036103:Nanotechnology; D017430:Prostate-Specific Antigen / Q000032:analysis*; D011468:Prostatectomy; D012822:Silicon Dioxide; D013314:Stress, Mechanical; D013499:Surface Properties
chemical_list: D000911:Antibodies, Monoclonal; D012822:Silicon Dioxide; D017430:Prostate-Specific Antigen