Performance Optimisation of Molecularly Imprinted Polymers Nanoparticles Based Conductometric Biosensors for Cardiac Biomarker Detection

Over the past decades, cardiovascular diseases (CVDs) have become a major threat to human health across the globe increasing the patient mortality rate. Early diagnosis of the CVDs is important to increase the survival rate of the patients, and one of the key methods to achieve this is through the detection of cardiovascular biomarkers. The conventional methods for diagnosing CVDs via detecting cardiovascular biomarkers typically require bulky instruments in centralised laboratories which are expensive and time consuming. Alternatively, there is a growing interest in developing low-cost, hand-held, and robust biosensors for fast detection of cardiovascular biomarkers for optimal management of patients. The current study involves, fabrication of conductometric sensors with patterned gold electrodes on high resistive silicon (HR-Si) wafers. The immobilisation of artificial recognition element, also known as molecularly imprinted polymer nanoparticles (nanoMIPs) on (3-glycidyloxypropyl)trimethoxy silane (GPS) functionalised conductometric sensors provides reliable and accurate measurements of clinically significant levels of three selected cardiac biomarkers in human saliva using a label-free approach. The selected cardiac biomarkers used in this study include brain natriuretic peptide (BNP), N-terminal pro-brain natriuretic peptide (NT-proBNP), and cardiac troponin I (cTnI). The sensor performance in detecting the targeted cardiac biomarkers in both media of phosphate buffer solution (PBS) and artificial saliva is evaluated by testing them in ×1000 times diluted cardiac specific nanoMIPs in PBS at pH 7.4 with a 10 minutes of sample incubation. GPS silanisation is important for maximum binding of nanoMIPs onto the sensor surface with correct orientation facilitating the maximum binding of target cardiac biomarkers. The electrical resistance changes are measured within 3 minutes, upon interactions of cardiac nanoMIPs on the sensors with incoming cardiac biomarkers to evaluate the sensor performance. Cardiac nanoMIPs immobilised conductometric biosensors resulting in significant resistance changes with high sensitivity and selectivity in detecting the targeted cardiac biomarkers. The results also showed that these biosensors are also reusable for at least two cycles. These novel conductometric biosensors have the potential to reform cardiac diagnostics, enabling point-of-care testing and bringing diagnostics closer to the patients, thereby improving patient care and outcomes.<p></p>