IN SITU NANOCOATING ON PYROLYZED PAPER: A PIONEERING STRATEGY TO PROVIDE SENSITIVE ELECTROCHEMICAL ASSAYS IN BIOLOGICAL FLUIDS

IN SITU NANOCOATING ON PYROLYZED PAPER: A PIONEERING STRATEGY TO PROVIDE SENSITIVE ELECTROCHEMICAL ASSAYS IN BIOLOGICAL FLUIDS

• Autor
• Ítalo R. S. Bezerra
• Co-autores
• Caroline Y. N. Nicoliche , Aline M. Pascon , Ana C. H. Castro-Kochi , Gabriel R. Martos , Jefferson Bettini , Wendel A. Alves , Murilo Santhiago , Renato S. Lima
• Resumo

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  The analytical performance of electrochemical biosensors is significantly reduced when subjected to complex biological media (such as plasma and serum), which is due to the non-specific adsorption of biomolecules, especially proteins. Therefore, numerous studies in the literature report the use of semipermeable layers (e.g., polyethylene glycol)¹ to avoid this biopassivation on the surface of the electrodes. Although these strategies have been promising as anti-biofouling (a-BF) strategies, these semipermeable layers are mostly detrimental to the sensitivity of the devices as they act as high impedance layers that inhibit redox reactions on the electrode, decreasing the electrochemical signal. In addition, these layers may have low durability, reproducibility, and scalability.^2,3 To solve this problem, our research group studied the use of pyrolyzed graphitic paper (PGP) in combination with the addition of a neutral surfactant, polysorbate 20, commercially known as Tween^® 20 (T20). Such an off-the-shelf polysorbate provides the in-situ formation of a hydrophilic nanocoating on the electrode (2 nm according to transmission electron microscopy assays) that prevents biopassivation while providing the gradual capillarity-assisted penetration of the sample through the paper pores. These cooperative effects lead to a gradual increase in the electrochemical responses. While state-of-the-art a-BP strategies compromise sensitivity, our approach leads to peak currents that are up to 12.5 times greater than the original faradaic currents after 1-h exposure to unprocessed human plasma. The nanointerface was strictly characterized using a set of microscopic and spectroscopic techniques. Further, the clinical performance of the device was successfully challenged in clinically important samples, i.e., sera from healthy individuals and patients infected with the Coronavirus disease 2019 (COVID-19), for screening purposes. For these assays, we adapted the approach to develop an electrochemical impedance spectroscopy-based affinity immunosensor by anchoring the Spike (S) protein on gold nanoparticles (AuNPs). S protein was used as bioreceptor for selectively targeting SARS-CoV-2 virus antibodies. The serum samples could be distinguished from each other with 100% accuracy. Such results were recently published in the literature.⁴ The scalability and simplicity of the platform combined with its unique ability to operate in biofluids with an enhanced sensibility may help to pave the way for a new generation of electrochemical biosensors capable of translating field-deployable analyses and mass screening into the real world. This multidisciplinary work originated from a collaboration among research groups with expertise in distinct science areas, including electrochemistry, nanomaterials, microfabrication, and microscopy.

• Palavras-chave
• biosensor, complex sample, SARS-CoV-2, COVID-19, point of care
• Modalidade
• Pôster
• Área Temática
• Materias Funcionais Avançados