title: Analysis of Scanning Electron Microscopy Images To Investigate Adsorption Processes Responsible for Detection of Cancer Biomarkers.
abstract: Adsorption processes are responsible for detection of cancer biomarkers in biosensors (and immunosensors), which can be captured with various principles of detection. In this study, we used a biosensor made with nanostructured films of polypyrrole and p53 antibodies, and image analysis of scanning electron microscopy data made it possible to correlate morphological changes of the biosensor with the concentration of cells containing the cancer biomarker p53. The selectivity of the biosensor was proven by distinguishing images obtained with exposure of the biosensor to cells containing the biomarker from those acquired with cells that did not contain it. Detection was confirmed with cyclic voltammetry measurements, while the adsorption of the p53 biomarker was probed with polarization-modulated infrared reflection absorption (PM-IRRAS) and a quartz crystal microbalance (QCM). Adsorption is described using the Langmuir-Freundlich model, with saturation taking place at a concentration of 100 Ucells/mL. Taken together, our results point to novel ways to detect biomarkers or any type of analyte for which detection is based on adsorption as is the case of the majority of biosensors.
authors.affiliation: São Carlos Institute of Physics, University of São Paulo , 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Valquiria da Cruz
authors.identifier: http://orcid.org/0000-0002-3738-3549
authors.initials: VD
authors.lastname: Rodrigues
authors.affiliation: São Carlos Institute of Physics, University of São Paulo , 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Cesar H
authors.initials: CH
authors.lastname: Comin
authors.affiliation: São Carlos Institute of Physics, University of São Paulo , 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Juliana Coatrini
authors.identifier: http://orcid.org/0000-0001-5455-1770
authors.initials: JC
authors.lastname: Soares
authors.affiliation: São Carlos Institute of Physics, University of São Paulo , 13560-970 São Carlos, São Paulo, Brazil.|Departament of Materials Engineering, São Carlos School of Engineering, University of São Paulo , 13563-120 São Carlos, São Paulo, Brazil.
authors.forename: Andrey Coatrini
authors.initials: AC
authors.lastname: Soares
authors.affiliation: Molecular Oncology Research Center, Barretos Cancer Hospital , 14784-400 Barretos, São Paulo, Brazil.
authors.forename: Matias Eliseo
authors.initials: ME
authors.lastname: Melendez
authors.affiliation: Molecular Oncology Research Center, Barretos Cancer Hospital , 14784-400 Barretos, São Paulo, Brazil.
authors.forename: José Humberto T G
authors.initials: JH
authors.lastname: Fregnani
authors.affiliation: Molecular Oncology Research Center, Barretos Cancer Hospital , 14784-400 Barretos, São Paulo, Brazil.
authors.forename: André Lopes
authors.initials: AL
authors.lastname: Carvalho
authors.affiliation: São Carlos Institute of Physics, University of São Paulo , 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Luciano da F
authors.initials: LD
authors.lastname: Costa
authors.affiliation: São Carlos Institute of Physics, University of São Paulo , 13560-970 São Carlos, São Paulo, Brazil.
authors.forename: Osvaldo N
authors.initials: ON
authors.lastname: Oliveira
mesh_terms: D000327:Adsorption; D014408:Biomarkers, Tumor / Q000032:analysis*; D015374:Biosensing Techniques; D008855:Microscopy, Electron, Scanning; D058525:Quartz Crystal Microbalance Techniques
chemical_list: D014408:Biomarkers, Tumor
keywords: Langmuir−Freundlich; SEM; circularity; head and neck cancer; image processing; imunnosensor; p53