Influence of the Molecular Orientation and Ionization of Self-Assembled Monolayers in Biosensors: Application to Genosensors of Prostate Cancer Antigen 3

Author(s)

Raymundo-Pereira, Paulo A. ^[1] ; Pedro, Rafael de Oliveira ^{[1, 2]} ; Carr, Olivia ^[1] ; Melendez, Matias E. ^{[3, 4]} ; Gobbi, Angelo L. ^[5] ; Piazzetta, Maria Helena de Oliveira ^[5] ; Carvalho, Andre L. ^[3] ; Reis, Rui M. ^{[3, 6, 7]} ; Miranda, Paulo B. ^[1] ; Oliveira Jr, Osvaldo N.

Affiliation

^[1] Univ Sao Paulo, Sao Carlos Inst Phys, BR-13566590 Sao Carlos - Brazil

^[2] Minas Gerais State Univ UEMG, Dept Chem, BR-38302192 Ituiutaba - Brazil

^[3] Barretos Canc Hosp, Mol Oncol Res Ctr, BR-14784400 Barretos - Brazil

^[4] Little Prince Coll, Pele Little Prince Res Inst, BR-80250060 Curitiba, Parana - Brazil

^[5] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Nanotechnol Natl Lab LNNano, BR-13083970 Campinas, SP - Brazil

^[6] Univ Minho, Sch Med, Life & Hlth Sci Res Inst ICVS, P-4710057 Braga - Portugal

^[7] ICVS 3Bs PT Govt Associate Lab, P-4806909 Braga - Portugal

• Document type: Journal article
• Source: Journal of Physical Chemistry C; v. 125, n. 1, p. 498-506, JAN 14 2021.
• Web of Science Citations: 0

Abstract

Electrochemical sensing depends on the immobilization of biorecognition elements and charge transfer to the electrode, which can be tuned and sometimes controlled using self-assembled monolayers (SAMs) as matrices. In this study, we show that an efficient immobilization of an ssDNA probe to detect the prostate cancer antigen 3 biomarker is achieved even for less organized SAMs provided that the terminal groups were ionized. These conclusions were reached by comparing the biosensors made with 11-mercaptoundecanoic acid (11-MUA) prepared in ethanol and thioglycolic acid (mercaptoacetic acid: MAA) prepared in ethanolic and aqueous solvents. The highest sensitivity with electrochemical impedance spectroscopy was observed for sensors assembled over MAA monolayers on gold prepared in ethanol and water (at pH 12.5), with limits of detection of 1.2 x 10(-9) and 1.7 x 10(-9) mol L-1, respectively. The biosensors made on MAA films prepared in water at pH 7.0 and 2.5 were not efficient because they are mostly terminated by protonated carboxylic acid groups, according to sum-frequency generation vibrational and polarization modulation-infrared reflection-absorption (PM-IRRAS) spectroscopies, which prevent an adequate attachment of the biomarker. Well-organized SAMs of 11-MUA also showed good detection performance, but the limit of detection was not as low, 2.1 x 10(-9) mol L-1, probably due to its long chains that decrease the charge transfer. Therefore, the matrix fabrication method can control the molecular assembly of biosensors and hence their performance. (AU)

• FAPESP's process: 16/01919-6 - Design and fabrication of nanostructured flexible devices for biomarkers detection
• Grantee: Paulo Augusto Raymundo Pereira
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/03503-4 - Molecular interaction between chitosan and cell membrane models investigated by non-linear vibrational spectroscopy
• Grantee: Rafael de Oliveira Pedro
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 18/22214-6 - Towards a convergence of technologies: from sensing and biosensing to information visualization and machine learning for data analysis in clinical diagnosis
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/02819-0 - Interaction of chitosans and surfactants with cell membrane models investigated by nonlinear vibrational spectroscopy
• Grantee: Paulo Barbeitas Miranda
• Support Opportunities: Regular Research Grants