Author(s): Sousa, Mariana ; Pereira, Ana Cláudia ; Correia, Bárbara ; Carmo, Anália do ; Matos, Ana Miguel ; Cruz, Maria Teresa ; Moreira, Felismina
Date: 2025
Persistent ID: https://hdl.handle.net/1822/96956
Origin: RepositóriUM - Universidade do Minho
Subject(s): Colorimetric; Glutaraldehyde; Paper-based; Protein; SARS-CoV-2
The COVID-19 pandemic highlighted the need for rapid, cost-effective tools to monitor transmission and immune response. We developed two novel paper-based colorimetric biosensors using glutaraldehyde as a protein dyeits first use in this context. Glutaraldehyde reacts with amino groups to generate a brown color, enabling detection of SARS-CoV-2 antibodies. Wathman filter paper was functionalized with (3-aminopropyl)triethoxysilane (APTES) to immobilize virus-like particles (VLPs) and nucleocapsid protein (N-protein) as biorecognition elements. Upon incubation with antibody-containing samples, glutaraldehyde enabled colorimetric detection using RGB analysis in ImageJ software. Both sensors showed a linear correlation between antibody concentration and RGB values in buffer and serum. The VLP sensor responded linearly within the range of 1.020 µg/mL (green coordinate) in 500-fold diluted serum and the N-protein sensor from 1.040 µg/mL (blue coordinate) in 250-fold diluted serum. Both sensors demonstrated good selectivity, with glucose causing up to 18% interference. These biosensors represent a paradigm shift, as they provide a sensitive, user-friendly, and cost-effective option for semi-quantitative serological analysis. Furthermore, their versatility goes beyond the detection of SARS-CoV-2 antibodies and suggests broader applicability for various molecular targets.
