An electrochemical immunosensor based on a nano-ceria integrated microfluidic chip for interleukin-8 biomarker detection

Abstract

Interleukin-8 (IL8) is an important cytokine that plays a significant role in tumor growth and angiogenesis across various malignant tumors, including oral squamous cell carcinoma (OSCC). It is an important biomarker for oral cancer; therefore, its early and accurate detection in bodily fluid reduces morbidity and mortality rates in cancer patients. The work presents the development of a label-free microfluidic miniaturized electrochemical immunosensor for IL8 biomarker detection at low concentration in saliva samples. A rapid, sensitive and selective biosensing platform was developed for IL8 detection using a nano-ceria integrated microfluidic system. The synthesized nano-ceria particles (8.13 nm) were employed to enhance the electrochemical biosensing signal and sensitivity of the biosensor due to their high catalytic properties and large surface area. For this, microfluidic chip was prepared by Indium tin oxide (ITO) (3 × 4 cm) containing three electrode patterns of working, reference and counter electrode. These electrode patterns were developed using a maskless photolithography technique and a polydimethylsiloxane (PDMS) mold created a 200 μm wide microchannel which was bound to the susbtrate using plasma treatment. Spectroscopy and microscopy techniques were used to confirm the synthesis of nano-ceria. Furthermore, electrode surface modifications were achieved by immobilization of chemically activated antibodies of IL8, as verified by Fourier transform-infrared spectroscopy (FT-IR). Furthermore, differential pulse voltammetry (DPV) was utilized to investigate electrochemical parameters and conduct biosensing studies. The developed electrochemical microfluidic biosensing platform works for an IL8 antigen in the concentrations ranging from 0.004 to 10 ng mL⁻¹ with a limit of detection (LOD) and limit of quantification (LOQ) of 0.0001 ng mL⁻¹ and 0.0006 ng mL⁻¹, respectively. Moreover, the developed electrochemical biosensing platform was validated using human saliva samples, achieving percentage recovery within an acceptable range.