Saimon Moraes Silva (La Sense) group

Detection of forever chemicals

We are developing a versatile biosensor system for rapid onsite detection and monitoring of toxic per- and poly-fluoroalkyl substances (PFAS) in contaminated waterways. PFAS are also known as the ‘forever chemicals’ and have become a major environmental pollutant that threatens human and ecological health; in Australia PFAS contamination is prevalent in both urban and rural areas, and all Australians are expected to have detectable levels of toxic PFAS in their blood. Current conventional PFAS detection methods rely on sample collection and transport to a centralized laboratory, which is expensive and time-consuming. Thus, there is a need for low-cost portable sensors for the on-spot monitoring of PFAS. In order to achieve specific molecular recognition for PFAS detection, we employ protein-based surface chemistries for specifically recognizing the target PFAS compounds.

Glucose meters are a great example of the impact that electrochemical biosensors, capable of functioning in whole blood, can have on the management of diseases. However, the success of these life-changing devices has not yet been expanded to the detection of many other relevant biomarkers. This is due to the issue of the nonspecific adsorption of unwanted biomolecules such as proteins or even whole cells on electrode surfaces, which leads to electrode fouling. Fouling blocks electron transfer pathways and eventually leads to sensor response loss (Figure 5A). The issue of biosensor fouling for the detection of glucose was solved because glucose is presented in high concentrations in blood and is a small molecule that can be filtered by using membranes permeable for glucose but stop other larger biomolecules from reaching the electrode. Nevertheless, a greater number of clinically appropriate biomarkers are the same size as the fouling species, for which semi-permeable membranes cannot be applied. Hence, one of the biggest obstacles to electrochemically detecting proteins in biological fluids remains the fouling of the electrode surface. Electrochemical biosensors that use DNA, antibodies, or other proteins as recognition elements, so-called affinity-based biosensors, offer a potential alternative for inexpensive, disposable, and sensitive multiplexed point-of-care diagnostics for home healthcare. An abundance of surface chemistries and assays reported in the literature have been successfully employed for affinity-based electrochemical biosensors. However, commercialization of such technology for clinical diagnostics has been hindered by their inability to maintain sensing functionality when exposed to biological fluids such as plasma or blood. This loss of functionality is also a result of the nonspecific adsorption of unwanted biomolecules on the electrode surfaces. To overcome these issues, we have developed an antifouling coating technology based on lubricin, a glycoprotein commonly found on the joints’ biological fluid and covering the cartilage surface in mammalian articular joints, that resulted in more stable and robust electrochemical sensors capable of efficiently functioning when challenged in complex samples such as highconcentration protein solutions, saliva, and even unprocessed whole blood.