title: Adsorption according to the Langmuir-Freundlich model is the detection mechanism of the antigen p53 for early diagnosis of cancer.
abstract: Biosensors for early detection of cancer biomarkers normally depend on specific interactions between such biomarkers and immobilized biomolecules in the sensing units. Though these interactions are expected to yield specific, irreversible adsorption, the underlying mechanism appears not to have been studied in detail. In this paper, we show that adsorption explained with the Langmuir-Freundlich model is responsible for detection of the antigen p53 associated with various types of cancers. Irreversible adsorption was proven between anti-p53 antibodies immobilized on the biosensors and the antigen p53, with the adequacy of the Langmuir-Freundlich model being confirmed with three independent experimental methods, viz. polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), nanogravimetry using a quartz crystal microbalance and electrochemical impedance spectroscopy. The method based on this irreversible adsorption was sufficiently sensitive (limit of detection of 1.4 pg mL(-1)) for early diagnosis of Hodgkin lymphoma, pancreatic and colon carcinomas, and bladder, ovarian and lung cancers, and could distinguish between MCF7 cells containing the antigen p53 from Saos-2 cells that do not contain it.
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, 13560-970 São Carlos-SP, Brazil. jucoatrini@yahoo.com.br.
authors.forename: Juliana Coatrini
authors.initials: JC
authors.lastname: Soares
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, 13560-970 São Carlos-SP, Brazil. jucoatrini@yahoo.com.br.
authors.forename: Andrey Coatrini
authors.initials: AC
authors.lastname: Soares
authors.affiliation: São Carlos Institute of Chemistry, University of São Paulo, 13560-970 São Carlos-SP, Brazil.
authors.forename: Paulo Augusto Raymundo
authors.initials: PA
authors.lastname: Pereira
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, 13560-970 São Carlos-SP, Brazil. jucoatrini@yahoo.com.br.
authors.forename: Valquiria da Cruz
authors.initials: Vda C
authors.lastname: Rodrigues
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, 13560-970 São Carlos-SP, Brazil. jucoatrini@yahoo.com.br.
authors.forename: Flavio Makoto
authors.initials: FM
authors.lastname: Shimizu
authors.affiliation: Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos-SP, Brazil.
authors.forename: Matias Eliseo
authors.initials: ME
authors.lastname: Melendez
authors.affiliation: Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos-SP, Brazil and Department of Pathology, Barretos Cancer Hospital, Barretos-SP, Brazil.
authors.forename: Cristovam
authors.initials: C
authors.lastname: Scapulatempo Neto
authors.affiliation: Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos-SP, Brazil.
authors.forename: André Lopes
authors.initials: AL
authors.lastname: Carvalho
authors.affiliation: Federal University of São Carlos, Sorocaba-SP, Brazil.
authors.forename: Fábio L
authors.initials: FL
authors.lastname: Leite
authors.affiliation: São Carlos Institute of Chemistry, University of São Paulo, 13560-970 São Carlos-SP, Brazil.
authors.forename: Sergio A S
authors.initials: SA
authors.lastname: Machado
authors.affiliation: São Carlos Institute of Physics, University of São Paulo, 13560-970 São Carlos-SP, Brazil. jucoatrini@yahoo.com.br.
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
mesh_terms: D000327:Adsorption; D000906:Antibodies / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D015374:Biosensing Techniques; D045744:Cell Line, Tumor; D058266:Dielectric Spectroscopy; D055088:Early Detection of Cancer; D006801:Humans; D061986:MCF-7 Cells; D009369:Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D013055:Spectrophotometry, Infrared; D016159:Tumor Suppressor Protein p53 / Q000276:immunology / Q000378:metabolism*
chemical_list: D000906:Antibodies; D015415:Biomarkers; D016159:Tumor Suppressor Protein p53