Ultrasensitive electrochemical immunosensor system for the determination of CD133 biomarker

Cancer stem cells (CSCs) have recently emerged as important variables affecting the development or invasiveness of solid tumors. Prominin 1 (PROM1, CD133) is a frequently used CSC biomarker in various tumors, including lung cancer, and CD133 overexpression is linked to chemoresistance, cancer recurrence, and a poor prognosis. Furthermore, CD133 has a significant impact on tumor growth and metastasis. In this work, the detection of CD133 using a single-use multi-walled carbon nanotube (MWCNT)-supported immunoplatform was achieved for the first time. The immunoplatform was designed using an anti-CD133 antibody and the CD133 protein. Differential pulse voltammetry (DPV) measurements were performed between -0.20 V and 0.8 V using a 5.0 mM [Fe(CN)₆]^3-/4- redox probe. The optimization parameters influencing the immunoassay response were thoroughly evaluated, and an analytical assessment of the single-use immunoplatform for CD133 detection created with anti-CD133 was performed. The designed immunosensor exhibited a rapid response time (30 min). In addition, the limit of detection (LOD) was determined for the immunosensors developed using both the commercial CD133 antibody and the 7D7 monoclonal antibody (MoAb; anti-CD133 antibodies produced by the Faculty of Medicine), with values of 0.135 and 0.052 µg mL^-1 obtained, respectively, in standard solutions. The determination of CD133 in commercial serum samples was used to test the applicability of the developed immunoplatform in real samples, and the results were satisfactory. This study provides a rapid, selective, and sensitive platform for determining the CD133 biomarker, which can be used for the early detection of lung cancer and monitoring of its development. Moreover, in a next step, it could be integrated into the design of an interesting single-use device with point-of-care (POC) application feasibility for measurement of CD133 levels.