Analysis of quantum capacitive states as a signal amplification mechanism in biosensors and its application in microfluidics electrochemical chips for diagnosis of Monkeypox

• Grant number: 24/10062-8
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: September 01, 2025
• End date: January 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Analytical Chemistry
• Principal Investigator: Renato Sousa Lima
• Grantee: Juliana Naomi Yamauti Costa
• Host Institution: Centro Nacional de Pesquisa em Energia e Materiais (CNPEM)
• Associated research grant: 23/00246-1 - Miniaturized large-scale devices for in-situ analysis: fabrication, characterization and applications, AP.TEM

Abstract

This project aims to develop label-free electrochemical biosensors (BELFs) with the potential to enable accessible, rapid, quantitative, and accurate diagnosis of infections caused by Monkeypox (MPX) in clinical practice, whether in laboratories, hospitals, or at the point of need. To achieve this, we propose the development of reagentless quantum biosensors in a novel configuration of ultradense microfluidic electrochemical chips that meet three key requirements: (i) applicability in clinical practice at a low cost, (ii) high testing capacity (throughput), and (iii) the ability to generate highly accurate quantitative analyses in biological fluids.Focusing on generating ultrasensitive BELFs, we will develop biosensors on our chips based on quantum electrochemistry mechanisms. This approach involves the application of electroactive self-assembled monolayers (e-SAMs) covalently anchored to Au electrodes. The e-SAM consists of a redox probe (Fc) anchored to a peptide, which will also be used to functionalize the electrode with bioreceptors for MPX viruses (MPXV). Monoclonal antibodies will be employed for the recognition of A29 proteins (biomarkers) from these viruses. Regarding the detection principle, when a target molecule binds to the bioreceptor, a new redox equilibrium occurs within the molecular structure, leading to changes in electronic occupation that can be detected by monitoring quantum capacitance (Cq). This signal provides access to information about the quantum states of the molecular system, significantly amplifying the analytical signal. By applying this quantum mechanism, we expect to achieve detection limits in the pico- to attomolar range.Reagentless quantum biosensors have been extensively studied by the research group of Prof. Dr. Paulo Bueno (UNESP), who serves as a co-advisor for the candidate. Their advantages include eliminating the need for (i) secondary recognition elements, (ii) labeling molecules (such as fluorescent tags), and (iii) the addition of an external solution containing the redox probe. Thus, they are attractive candidates for point-of-care diagnostics. To validate the method developed in this project, real commercial samples of serum and saliva will be used for testing in complex media, as well as clinical samples available at the Adolfo Lutz Institute, obtained after project submission to the Plataforma Brasil and approval by the Ethics Committee. The samples will be quantified using the gold standard technique, real-time quantitative polymerase chain reaction (qPCR), and the results will be compared with those obtained from the biosensor developed here.It is important to highlight that this project goes beyond incremental studies related to advancing the technological maturity of the platform developed during the candidate's master's research. The implementation of the quantum biosensor on our chips will involve fundamental challenges, such as the evaporation of the (non-aqueous) medium used in these measurements, the inherent effects of using a two-electrode system, the surface functionalization of both electrodes, and the surface effects of thin films. These factors can critically impact reproducibility. Thus, in addition to developing a promising method for diagnosing infections caused by MPXV, another contribution of this doctoral project is the proposal of solutions to these challenges, allowing us to adapt the quantum biosensing architecture to our chips. This system will represent a potential platform for diagnosing other diseases by enabling accessible, rapid, and accurate analyses of various biomarkers.