Ti3C2Tx MXene has gained significant attention for biosensor and supercapacitor applications because of 1) its metallic conductivity, large surface area, and reversible surface redox reactions led to high pseudocapacitance and high-rate performance; 2) the unique 2D morphology and high biocompatibility drive great motivation to design advanced nanohybrid systems with bio-receptors; 3) the high density of surface functional groups offers improved biomolecule loading and flexibility for further functionalization. In this thesis, biosensors and electrochemical energy storage devices based on Ti3C2Tx MXene are proposed. Specifically, Ti3C2Tx nanosheets were uniformly functionalized with aminosilane to provide a covalent binding for the immobilized bio-receptor (anti-CEA) for label-free ultrasensitive detection of cancer biomarker (CEA). [Ru(NH3)6]3+ is discovered as the preferable redox probe for biosensing. The fabricated MXene-based sensor exhibits a more comprehensive linear detection range and high sensitivity. Further, Ti3C2Tx nanosheets were introduced as the transducer, and Ti3C2Tx /Prussian blue (Ti3C2Tx/PB) composite was synthesized for sensitive detection of hydrogen peroxide. Meanwhile, a one-step patterning process for highly conductive nitrogen-doped laser-scribed graphene (N-LSG) has been developed. Working electrodes (Ti3C2Tx/PB/N-LSG) were extended by using different enzymes for corresponding biomarker detection, namely glucose, lactate, and alcohol. The enzyme/Ti3C2Tx/PB/N-LSG electrodes exhibit significantly improved electrocatalytic activity and outperform previously reported on-chip graphene-based biosensors. Further, a stretchable, wearable, and multifunctional Ti3C2Tx-based biosensor were designed for durable and sensitive detection of biomarkers in sweat. A unique modular design enabled a simple exchange of the specific sensing electrode to target the desired analytes, while an implemented three-phase interface design for the constant supply of oxygen led to superior sensor performance and stability. As expected, during in-vitro perspiration monitoring of human subjects, the physiochemistry signals (glucose and lactate level) could be measured simultaneously with high sensitivity and good repeatability, outperforming traditional reported graphene/PB- and CNTs/PB-based biosensors. Finally, we developed an in-plane hybrid microsupercapacitor, employing battery-type CuFe-Prussian blue analog (CuFe-PBA) as the positive electrode and pseudocapacitive Ti3C2Tx as the negative electrode. Due to the excellent match of the two types of high-rate performance materials in proton-based electrolyte, the designed on-chip device achieved excellent electrochemical performance.
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|KAUST Research Repository