A Direct Immunoassay Based on Surface-Enhanced Spectroscopy Using AuNP/PS-b-P2VP Nanocomposites

• Published in: Sensors (Basel, Switzerland) Vol. 23; no. 10; p. 4810
• Main Authors: Vieira, Moyra F, Bovolato, Ana Lívia de Carvalho, da Fonseca, Bruno G, Izumi, Celly M S, Brolo, Alexandre G
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 16.05.2023; MDPI
• Subjects: Acids; Adenosine Triphosphate; Antibodies; Antigens; Biomolecules; Biosensors; Carboxylic acids; Detectors; Dielectric films; Dielectric properties; direct immunoassay; Gold; gold nanoparticles; Humans; IgG antibody; Immunoassay; Immunoglobulin G; Immunoglobulins; LSPR sensor; Metal Nanoparticles; Muscle proteins; Nanocomposites; Nanoparticles; Polystyrene resins; polystyrene-b-poly(2-vinylpyridine); Polystyrenes; Polyvinyl pyridine; Principal components analysis; Red shift; Scanning electron microscopy; Sensors; SERS sensing; Spectrum Analysis; Thin films; United States > US; polystyrene-b-poly(2-vinylpyridine); SERS sensing; gold nanoparticles; LSPR sensor; direct immunoassay
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s23104810

A biosensor was developed for directly detecting human immunoglobulin G (IgG) and adenosine triphosphate (ATP) based on stable and reproducible gold nanoparticles/polystyrene-b-poly(2-vinylpyridine) (AuNP/PS-b-P2VP) nanocomposites. The substrates were functionalized with carboxylic acid groups for the covalent binding of anti-IgG and anti-ATP and the detection of IgG and ATP (1 to 150 μg/mL). SEM images of the nanocomposite show 17 ± 2 nm AuNP clusters adsorbed over a continuous porous PS-b-P2VP thin film. UV-VIS and SERS were used to characterize each step of the substrate functionalization and the specific interaction between anti-IgG and the targeted IgG analyte. The UV-VIS results show a redshift of the LSPR band as the AuNP surface was functionalized and SERS measurements showed consistent changes in the spectral features. Principal component analysis (PCA) was used to discriminate between samples before and after the affinity tests. Moreover, the designed biosensor proved to be sensitive to different concentrations of IgG with a limit-of-detection (LOD) down to 1 μg/mL. Moreover, the selectivity to IgG was confirmed using standard solutions of IgM as a control. Finally, ATP direct immunoassay (LOD = 1 μg/mL) has demonstrated that this nanocomposite platform can be used to detect different types of biomolecules after proper functionalization.