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Projeto de investigação
Nanomaterials and biosensors for health applications
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A dual-signal sensor based on molecularly imprinted photonic polydopamine for detection of the oxidative stress biomarker allantoin
Publication . Suleimenova, Akmaral; Marques, Ana C.; Frasco, Manuela F.; Fortunato, Elvira; Sales, M. Goreti F.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; International Society of Electrochemistry (ISE) | Elsevier
A novel biomimetic detection method is presented allocating two transducer principles in a molecularly imprinted polymer (MIP)-based sensor. The device was constructed on a transparent three-electrode system of conductive indium tin oxide (ITO) fabricated by laser direct writing on glass substrates. The sensing layer was prepared by electropolymerizing dopamine in the presence of allantoin, on colloidal silica particles that exhibited a structural color due to the short-range ordered structure. This opto-electrochemical dual-signal output was successfully developed for the detection of the oxidative stress biomarker allantoin. The analytical properties were evaluated by electrochemical impedance spectroscopy and reflectance analysis of the structural color. The sensor showed a linear response over a wide range of allantoin concentrations (0.1 nmol L−1 to 10000 nmol L−1) measured in synthetic urine. As expected, the lowest limit of detection in urine (0.012 nmol L−1) was achieved with the electrochemical signal. In addition, other urinary oxidative stress metabolites tested as interferents, namely uric acid and 8-hydroxy-2′-deoxyguanosine, had no effect on the dual-signal detection of allantoin. The biomimetic and cost-effective properties of the materials in combination with the improved analytical properties of opto-electrochemical detection provide a sensor platform with great potential for the screening of oxidative stress biomarkers in urinalysis.
An ultrasensitive paper-based SERS sensor for detection of nucleolin using silver-nanostars, plastic antibodies and natural antibodies
Publication . Suleimenova, Akmaral; Frasco, Manuela F.; Sales, M. Goreti F.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); Elsevier
A state-of-the-art, ultrasensitive, paper-based SERS sensor has been developed using silver nanostars (AgNSs) in combination with synthetic and natural antibodies. A key component of this innovative sensor is the plastic antibody, which was synthesized using molecularly imprinted polymer (MIP) technology. This ground-breaking combination of paper substrates/MIPs with AgNSs, which is similar to a sandwich immunoassay, is used for the first time with the aim of SERS detection and specifically targets nucleolin (NCL), a cancer biomarker. The sensor device was carefully fabricated by synthesizing a polyacrylamide-based MIP on cellulose paper (Whatman Grade 1 filter) by photopolymerization. The binding of NCL to the MIP was then confirmed by natural antibody binding using a sandwich assay for quantitative SERS analysis. To facilitate the detection of NCL, antibodies were pre-bound to AgNSs with a Raman tag so that the SERS signal could indicate the presence of NCL. The composition of the sensory layers/materials was meticulously optimized. The intensity of the Raman signal at ∼1078 cm−1 showed a linear trend that correlated with increasing concentrations of NCL, ranging from 0.1 to 1000 nmol L−1, with a limit of detection down to 0.068 nmol L−1 in human serum. The selectivity of the sensor was confirmed by testing its analytical response in the presence of cystatin C and lysozyme. The paper-based SERS detection system for NCL is characterized by its simplicity, sustainability, high sensitivity and stability and thus embodies essential properties for point-of-care applications. This approach is promising for expansion to other biomarkers in various fields, depending on the availability of synthetic and natural antibodies.
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Fundação para a Ciência e a Tecnologia
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PD/BD/142776/2018