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1.
Biosens Bioelectron ; 20(10): 2157-62, 2005 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-15741091

RESUMO

We designed and fabricated the nanomechanical Pb(Zr0.52Ti0.48)O3 (PZT) cantilever; we demonstrated a novel electrical measurement, under a controlled ambient temperature and humidity, for label-free detection of a prostate-specific antigen (PSA); and we achieved a detection sensitivity as low as 10 pg/ml. For the fabrication of our nanomechanical PZT cantilevers, we used composite layers of Ta/Pt/PZT/Pt/SiO2 on a SiN(x) supporting layer for electrical self-sensing without external oscillators. This method allows PSA proteins to be detected via a simple electrical measurement of the resonant frequency change generated by the molecular interaction of the antigen (Ag) and the antibody (Ab). The resonant frequency shifted due to the specific binding of the PSA Ag to its Ab which is immobilized via calixcrown self-assembled monolayers on an Au surface deposited on a nanomechanical PZT cantilever. We determined the resonant frequency shift as the value of -172 Hz and -273 Hz, when the concentration of PSA Ag was 1 ng/ml, with the cantilever dimensions of 100 microm x 300 microm and 50 microm x 150 microm, respectively. Theoretical and experimental analysis suggests that the minimum detectable sensitivity for a resonant frequency shift due to a PSA Ag-Ab interaction depends on the dimensions of the nanomechanical PZT cantilever. These results also demonstrate that the experimentally measured resonant frequency shift is larger than that calculated theoretically due to the compressive stress of the PSA Ag-Ab interaction.


Assuntos
Biomarcadores Tumorais/sangue , Técnicas Biossensoriais/instrumentação , Eletroquímica/instrumentação , Imunoensaio/instrumentação , Nanotecnologia/instrumentação , Antígeno Prostático Específico/sangue , Transdutores , Técnicas Biossensoriais/métodos , Impedância Elétrica , Eletroquímica/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Imunoensaio/métodos , Masculino , Mecânica , Nanotecnologia/métodos , Antígeno Prostático Específico/imunologia , Neoplasias da Próstata/sangue , Neoplasias da Próstata/diagnóstico
2.
Biosens Bioelectron ; 20(2): 269-75, 2004 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-15308231

RESUMO

In this paper, we report the novel electrical measurement for the label-free detection of C-reactive protein (CRP) using resonant frequency shift in the monolithic thin film cantilever of micromachined Pb(Zr0.52Ti0.48)O3 (PZT) which was fabricated with the composition of SiO2/Ta/Pt/PZT/Pt/SiO2 on silicon nitride (SiNx) supporting layer for the dual purpose of electrical self-excitation and sensing. The specific binding characteristics of CRP antigen to its antibody, which is immobilized with Calixcrown SAMs on Au surface deposited on microcantilever, is determined in high sensitivity to the nanogram level per milliliter by measuring the resonant frequency shift. The nanomechanical PZT cantilever turns out a robust platform for the highly specific antigen-antibody interaction and provides with the novel tool for qualification and quantification of biomolecules without any sample labeling and bulky optical apparatus.


Assuntos
Técnicas Biossensoriais/instrumentação , Proteína C-Reativa/análise , Eletroquímica/instrumentação , Imunoensaio/instrumentação , Chumbo/química , Titânio/química , Transdutores , Zircônio/química , Técnicas Biossensoriais/métodos , Proteína C-Reativa/química , Proteína C-Reativa/imunologia , Materiais Revestidos Biocompatíveis/química , Eletroquímica/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Imunoensaio/métodos , Manufaturas , Membranas Artificiais , Miniaturização , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Coloração e Rotulagem
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