Microfluidic platform development for electrochemical biosensing of cancer biomarkers

Cancer is one of the leading causes of death worldwide and it is responsible for lowering the average life expectancy, overall in the industrialized world. In particular, lung cancer represents the main cause of cancer death and a relevant pathology with considerable effects on the quality of life of patients and their families, with enormous costs and impacts on society. This is mainly due to the inadequacy of the diagnostic process with respect to the amount and complexity of information to be evaluated by the clinician (e.g. molecular information and its association with clinical and personal information). An early detection of this disease can possibly save many lives, which is why it is important to develop platforms that can make a rapid and reliable diagnosis. Biosensing is based on the detection of analytes thanks to the presence of a recognition element able to generate a specific and detectable signal due to the interaction with the analyte. Several approaches are possible to design a robust biosensor, among them electrochemical biosensing is recognized as one of the most promising being able to directly convert the bio-chemical signal due to the biological event (i.e., the analyte-recognition element interaction) into an electrical one. Given their versatility, electrochemical biosensors can be specifically designed for early stage diagnosis, making them able to identify those biomarkers that are produced at the very starting stage of the target disease. Further improvement of biosensors is possible coupling them to microfluidic platforms. Indeed, the ally of electrochemical biosensors and microfluidic devices can contribute to reduce the volume of reagents, to increase the device sensitivity and to simplify the final protocol, allowing to prepare the sample and to detect the analyte in the same device. Microfluidic approaches coupled with electrochemical techniques for the biosensing allow to transpose the detection from an in the lab to an out of the lab context, increasing therefore the accessibility of the analysis. Indeed, electrochemical techniques do not require trained personnel and guarantee faster response. In this work, a particular focus was placed on Angiopoietin-2 (Ang2), a specific biomarker for lung cancer. A Self-Assembled Monolayer (SAM) was grown on top of a Screen Printed Electrode (SPE) and a specific antibody (a-Ang2) for Ang2 detection was attached on top of it. Furthermore, a microfluidics-based biosensing device was designed with a CAD software and entirely built in polydimethylsiloxane (PDMS). Ang2 concentration was transduced into an electrical signal to be measured and evaluated. This was done thanks to two different electrochemical techniques: Electrochemical Impedance Spectroscopy (EIS) and Square Wave Voltammetry (SWV). In conclusion, after the device was validated trough electrochemical measurements, it was improved with a new design: device was enlarged, such that more SPEs can be hosted and multiplexed measurements can be carried out in real-time.