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- Liquid Redox Probe-Free Plastic Antibody Development for Malaria Biomarker RecognitionPublication . Glória, Juliane Corrêa; Oliveira, Daniela S.; Gandarilla, Ariamna Dip; Barcelay, Yonny Romaguera; Mariúba, Luis André Morais; Nogueira, Paulo Afonso; Brito, Walter Ricardo; Moreira, Felismina T. C.; Moreira, Felismina; DOS SANTOS OLIVEIRA, DANIELAMalaria is a major public health challenge worldwide and requires accurate and efficient diagnostic methods. Traditional diagnostic approaches based on antigen–antibody interactions are associated with ethical and economic concerns. Molecularly imprinted polymers (MIPs) offer a promising alternative by providing a complementary polymer structure capable of selectively binding target molecules. In this study, we developed a liquid, redox-probe-free, MIP-based electrochemical biosensor to detect the Plasmodium falciparum malaria marker histidine-rich protein (HRP2) at the point-of-care (PoC). The imprinting phase consists of the electropolymerization of the monomer methylene blue (MB) in the presence of the target protein HRP2 at the working electrode (WE) of the modified carbon screen printed electrode (C-SPE). Subsequent removal of the protein with proteinase K and oxalic acid yielded the MIP material. The sensor assembly was monitored by cyclic voltammetry (CV), Raman spectroscopy and scanning electron microscopy (SEM). The analytical performance of the biosensor was evaluated by square-wave voltammetry (SWV) using calibration curves in buffer and serum with a detection limit of 0.43 ± 0.026 pg mL–1. Selectivity studies showed minimal interference, indicating a highly selective assay. Overall, our approach to detect the HRP2 infection marker offers simplicity, cost-effectiveness and reliability. In particular, the absence of a redox solution simplifies detection, as the polymer itself is electroactive and exhibits oxidation and reduction peaks.
- An Innovative Approach for Tailoring Molecularly Imprinted Polymers for Biosensors—Application to Cancer Antigen 15-3Publication . Oliveira, Daniela dos Santos; Oliveira, Andreia Sofia Rodrigues; Mendonça, Patrícia Vitorino; Coelho, Jorge Fernando Jordão; Moreira, Felismina Teixeira Coelho; Sales, Maria Goreti Ferreira; Moreira, Felismina; DOS SANTOS OLIVEIRA, DANIELAThis work presents a novel approach for tailoring molecularly imprinted polymers (MIPs) with a preliminary stage of atom transfer radical polymerization (ATRP), for a more precise definition of the imprinted cavity. A well-defined copolymer of acrylamide and N,N′-methylenebisacrylamide (PAAm-co-PMBAm) was synthesized by ATRP and applied to gold electrodes with the template, followed by a crosslinking reaction. The template was removed from the polymer matrix by enzymatic/chemical action. The surface modifications were monitored via electrochemical impedance spectroscopy (EIS), having the MIP polymer as a non-conducting film designed with affinity sites for CA15-3. The resulting biosensor exhibited a linear response to CA15-3 log concentrations from 0.001 to 100 U/mL in PBS or in diluted fetal bovine serum (1000×) in PBS. Compared to the polyacrylamide (PAAm) MIP from conventional free-radical polymerization, the ATRP-based MIP extended the biosensor’s dynamic linear range 10-fold, improving low concentration detection, and enhanced the signal reproducibility across units. The biosensor demonstrated good sensitivity and selectivity. Overall, the work described confirmed that the process of radical polymerization to build an MIP material influences the detection capacity for the target substance and the reproducibility among different biosensor units. Extending this approach to other cancer biomarkers, the methodology presented could open doors to a new generation of MIP-based biosensors for point-of-care disease diagnosis.
- Molecularly imprinting for ca 15-3 protein detection: a promising biosensor for advanced point-of-care applicationsPublication . Oliveira, Daniela; Barcelay, Yonny Romaguera; Moreira, Felismina(Introduction) Cancer is a public health problem worldwide. Early detection is crucial to improve survival rates [1]. Non-invasive, fast rapid, and low-cost diagnostic methods are urgently needed. Biosensors are a promising alternative to traditional methods such as ELISA, enabling point-ofcare (PoC) analyses. These require biorecognition elements with high selectivity and stability to meet current requirements in PoC diagnostics [2]. This work aims to create an electrochemical biosensor that can detect CA 15-3 with high sensitivity and selectivity. The biosensor consists of molecularly imprinted polymer (MIP) as the biorecognition element, and it is assembled via electrochemical polymerization of a mixture of 3-acrylamidopropyl trimethylammonium chloride (AMPTMA) in the presence of CA 15-3. Electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were employed to evaluate the biosensor's electrochemical performance during its optimization and construction. CA 15-3 was successfully detected in a wide concentration range from 0.001 to 100 U mL-1 in just 20 minutes, with an R2 of 0.994. The MIP sensor showed minimal interference with other cancer proteins. This device offers rapid, sensitive, and cost-effective detection of CA 15-3, making it suitable for clinical PoC application.