SERS assisted sandwich immunoassay platforms for ultrasensitive and selective detection of human Thyroglobulin

• DOI: 10.1016/j.bios.2023.115322
• Publication Date: 2023-04-15T15:00:41Z
• Authors: S. Spaziani; G. Quero; S. Managò; G. Zito; D. Terracciano; P.E. Macchia; F. Galeotti; M. Pisco; A.C. De Luca; A. Cusano
• Keywords: Immunoassay; Sandwich immunoassay; Liquid biopsy; Metal Nanoparticles; Biosensing Techniques; Spectrum Analysis, Raman; Thyroglobulin; Human thyroglobulin; 3. Good health; Human thyroglobulin; Lab on fiber; Liquid biopsy; Sandwich immunoassay; SERS probes; Surface-enhanced Raman scattering; SERS probes; Human thyroglobulin; Lab on fiber; Liquid biopsy; SERS probes; Sandwich immunoassay; Surface-enhanced Raman scattering; Humans; Surface-enhanced Raman scattering; Surface -enhanced Raman scattering, SERS probes, Lab on fiber, Sandwich immunoassay, Human thyroglobulin, Liquid biopsy; Gold; Lab on fiber; Surface -enhanced Raman scattering

We developed an immunoassay platform for the detection of human Thyroglobulin (Tg) to be integrated with fine-needle aspiration biopsy for early detection of lymph node metastases in thyroid cancer patients. The sensing platform detects Tg by a sandwich immunoassay involving a self-assembled surface-enhanced Raman scattering (SERS) substrate assisted by functionalized gold nanoparticles that provide additional Raman signal amplification and improved molecular specificity. Specifically, the SERS-active substrates were functionalized with Tg Capture antibodies and fabricated either on-chip or on optical fiber tips by nanosphere lithography. Gold nanoparticles were functionalized with Detection antibodies and conjugated with 4-mercaptobenzoic acid, which serves as a Raman reporter. The sandwich assay platform was validated in the planar configuration and a detection limit as low as 7 pg/mL was successfully achieved. Careful morphological examination of the SERS substrates before and after Tg measurements further assessed the effective capture of nanoparticles and correlated the average nanoparticle coverage with the Tg concentration obtained by SERS measurements. The sandwich assay was successfully demonstrated on washout fluids of fine needle aspiration biopsies from cancer patients and confirmed the high specificity of the proposed methodology when complex biological matrices are considered. Finally, SERS optrodes were fabricated and successfully used to detect Tg concentration by applying the same bio-recognition strategy and Raman interrogation through an optical fiber. This opens the possibility of transferring the Tg detection approach to the optical fiber tip to develop point-of-care platforms that can be directly integrated into fine needle aspiration biopsies.