The ability to make an accurate diagnosis at the time of treatment is crucial for many diseases. However, current standard diagnostic procedures can only be performed in specialised healthcare facilities. To bring diagnostic methods from a specialised laboratory to the point of treatment, many alternative methods have been proposed. One of them is surfaceenhanced Raman scattering (SERS), which offers advantageous features such as high sensitivity in biotarget detection and higher accuracy. Here, we have developed an advanced SERS platform for the ultrasensitive, rapid and highly specific identification of tumour biomarkers in liquid biopsies. Our particular focus is on the detection of Thyroglobulin (Tg), the most important tumour biomarker for the diagnosis and prognosis of thyroid cancer. Specifically, SERS-active substrates fabricated by nanosphere lithography on chip or on tips of optical fiber (OF) were functionalized with Tg Capture antibodies. Gold nanoparticles were functionalized with Detection antibodies and conjugated with a Raman reporter. The sandwich assay platform was validated in the planar configuration and a detection limit of only 7 pg/ml was successfully achieved. The same approach has been successfully demonstrated on washout fluids from fine needle aspiration biopsies of cancer patients. Finally, the functionalization strategy was translated to the LOF-SERS platform and successfully used to detect Tg concentration. The proposed SERS-assisted immunoassay platform has proven to be highly versatile and can be used with both microfluidic chip POC devices and SERS-OF-based optrodes to perform sensitive, specific and rapid ex vivo assays for Tg detection in liquid intraoperative biopsies.
In this work, we propose a novel immunoassay platform for the detection of human Thyroglobulin (Tg) to be integrated with fine-needle aspiration biopsy for early identification of lymph node metastases in thyroid cancer patients. The sensing platform detects Tg (a well-known biomarker for the classification of metastatic lymph nodes related to thyroid cancer) by a sandwich immunoassay involving a self-assembled surface-enhanced Raman scattering (SERS) substrate assisted and empowered by functionalized gold nanoparticles enabling additional Raman signal amplification and improved molecular specificity. The sandwich assay platform was preliminary validated in a planar configuration and a detection limit as low as 7 pg/mL was successfully achieved. 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, optical fiber SERS optrodes were fabricated and successfully used to detect Tg concentration by applying the same bio-recognition strategy. 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.
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