Electrochemical chips with high testing capacity for the diagnosis of head and neck cancer metastasis

Abstract

Oral squamous cell carcinoma (OSCC) is the most common type of head and neck cancer and has a propensity for lymph node metastases, which decreases the 5-year survival rate of patients by up to 50%. The diagnosis of this carcinoma is made through tissue biopsy, a laborious, expensive, invasive method that does not allow the detection of lymph node metastasis in its initial stage. Thus, the medical procedure adopted consists of performing neck dissection surgery on the patient, removing all lymph nodes from the region of the neck even if metastasis has not been diagnosed. This surgery causes deformation of the patient's face, and difficulty in speaking and eating, irreversibly damaging the individual's life quality. Among all patients who undergo this procedure, ~70% are not under metastatic condition. Therefore, to avoid unnecessary surgical interventions, the accurate detection of lymph node metastasis in its initial stage is of pivotal importance. In this regard, the central problem of this project is the diagnosis of lymph node metastasis from OSCC in the clinical practice (in laboratories, hospitals, or at the point of need) in an accurate and fast way. As a solution, we propose a new electrochemical sensor assembly that (1) combines reproducibility and scale-up compatibility with low cost, as well as (2) allows serial analyses that will be performed to (3) detect two biomarkers of this metastasis in saliva; accordingly, we aim to address the yardsticks of real-world applicability, high testing capacity (throughput), and high accuracy, respectively.The devices will be prototyped using standard microfabrication techniques seeking to obtain readily marketable and reproducible sensors. Ultra-dense electrochemical chips will be generated (various sensors per area on a single chip), which will be possible due to two factors: (1) the electrodes consist of vertical nanofilms arranged in a mesh-like geometry and (2) each sensor is based on only 2 Au electrodes, i.e., the working and the quasi-reference electrodes that will be separated by a layer of SU-8 photoresist (~3 µm). The integration of a larger number of sensors on a single chip wafer is essential to make them cheaper and increase throughput through serial analysis. For these analyses, a simple electrical grounding step will be sufficient to eliminate interference between the solutions present in the sensors (crosstalk). Using antibodies as elements of recognition, label-free electrochemical biosensors will be developed to detect proteins collagen 6 (COL6A1) and cystatin B (CSTB) in saliva. According to studies conducted in CNPEM by the Dr.(a) Adriana F. P. Leme's group, with whom we will collaborate in this master's project, these proteins act as biomarkers for screening patients without and with lymph node metastasis.The microfabrication steps of the ultra-dense electrochemical chips have already been established in the group. Therefore, the specific objectives of this master's project are (i) the study of the experimental conditions to prepare the biosensors through electrochemical analyses and surface characterization techniques and (ii) the systematic evaluation of the analytical performance of these biosensors from serial analysis of biomarkers patterns diluted in electrolyte medium and in saliva (clinically relevant matrix).