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Cardiovascular disease (CVD) is the leading cause of death worldwide. More than 85% of CVD-related deaths are due to acute myocardial infarction (AMI), which is more commonly known as heart attack. Affordable and early diagnosis of AMI has the potential to save millions of lives each year; unfortunately, conventional methods are ineffective for early diagnosis due to their poor sensitivity. Highly sensitive and accurate analytical tools to measure cardiac biomarkers are demanded in hospitals for rapid AMI screening. This dissertation aims to develop cardiac biosensors with the aid of functional nanomaterials. Porous carbon nitride (PCN), an updated version of graphitic carbon nitride (GCN) and its functional derivatives, was designed, synthesized, characterized, and used to fabricate electrochemical aptasensors and field effect transistor (FET) aptasensors for cardiac biomarkers. The first part of this dissertation introduces the fabrication and characterization of laser-scribed graphene (LSG) and the effects of deposition of PCN nanosheet materials on LSG surfaces. The properties of PCN were further improved through decorating the nanosheet materials with metal nanoparticles. Moreover, a point-of-care platform, called KAUSTat, was created by integrating the LSG biosensor with a custom-made potentiostat and smartphone application. This device demonstrated exceptional diagnostic potential for usage in hospitals and resource-limited locations by replacing expensive medical apparatus with simple and practical smart systems, which could aid in the early diagnosis of AMI. The second part of this dissertation includes the fabrication and characterization of amorphous indium gallium zinc oxide (IGZO) and PCN materials using semiconducting metal-oxide bio-FET as a cardiac biosensor for the for the rapid detection of cardiac biomarkers. The IGZO bio-FET surface was engineered based on PCN for successful immobilization of the recognition aptamers. We demonstrate a transistor-based biosensor that paves the way for a rapid and inexpensive detection of biomarkers. In contrast to existing FET biosensors, which have low sensitivity and struggle to work with biological samples, the developed Bio-FET sensors exhibited good selectivity and sensitivity for low concentrations of the cardiac biomarker. The biosensor holds potential for the rapid, sensitive diagnosis of AMI. |
