Two-dimensional materials have emerged as promising candidates for glucose sensing due to their exceptional electrocatalytic properties, high surface-to-volume ratio, and tunable electronic structures. These materials enhance both enzymatic and non-enzymatic glucose detection mechanisms, offering improved sensitivity, selectivity, and potential for wearable integration.
Enzymatic glucose sensors rely on the catalytic activity of glucose oxidase (GOx) or other enzymes to selectively oxidize glucose, producing an electrochemically measurable signal. Two-dimensional materials such as graphene, transition metal dichalcogenides (TMDCs), and MXenes serve as efficient immobilization platforms for enzymes while facilitating electron transfer. Graphene’s high conductivity and large surface area improve enzyme loading and stability, leading to enhanced sensor performance. Functionalized graphene oxide (GO) further enhances biocompatibility and enzyme retention. TMDCs like MoS₂ exhibit excellent electrocatalytic activity when combined with GOx, with reported sensitivities exceeding 10 µA mM⁻¹ cm⁻² and detection limits below 1 µM. MXenes, such as Ti₃C₂Tₓ, provide hydrophilic surfaces that stabilize enzymes while maintaining rapid electron transfer kinetics.
Non-enzymatic glucose sensors eliminate the need for biological recognition elements by directly catalyzing glucose oxidation on the electrode surface. Two-dimensional materials enhance this process through their intrinsic catalytic properties and defect-rich surfaces. Noble metal nanoparticles supported on graphene or TMDCs exhibit high activity for glucose oxidation at lower overpotentials, reducing interference from other electroactive species. For example, Pt nanoparticles on reduced graphene oxide (rGO) demonstrate sensitivities of up to 100 µA mM⁻¹ cm⁻² in alkaline media. Transition metal oxides and hydroxides integrated with 2D materials, such as Ni(OH)₂/MoS₂ hybrids, also show excellent catalytic performance due to synergistic effects. These systems achieve sensitivities comparable to enzymatic sensors while offering superior long-term stability.
Interference rejection remains a critical challenge in glucose sensing, particularly in complex biological fluids where species like uric acid, ascorbic acid, and acetaminophen can generate false signals. Two-dimensional materials improve selectivity through several mechanisms. Surface modification with polymers or molecularly imprinted layers can selectively block interferents while allowing glucose diffusion. For instance, Nafion-coated graphene electrodes suppress ascorbic acid interference by electrostatic repulsion. Additionally, the electrocatalytic properties of 2D materials can be tuned to oxidize glucose at distinct potentials, minimizing overlap with interfering species. MnO₂ nanosheets integrated with carbon nanotubes shift the glucose oxidation peak to lower potentials, reducing interference from common electroactive molecules.
Wearable integration of 2D material-based glucose sensors requires flexibility, stability, and continuous monitoring capability. Flexible substrates such as polyimide or textile fibers are combined with 2D materials to create stretchable and conformal devices. Laser-scribed graphene electrodes patterned on elastomers exhibit stable performance under mechanical deformation, making them suitable for skin-mounted sensors. Transparent conductive films of TMDCs enable integration into contact lenses for tear glucose monitoring. Encapsulation strategies using ultrathin polymers or hydrophobic 2D layers like hexagonal boron nitride (hBN) protect the sensing elements from environmental degradation while maintaining signal integrity.
Real-time monitoring is facilitated by wireless data transmission and low-power operation. Two-dimensional materials contribute to miniaturized, energy-efficient sensor designs due to their high conductivity and compatibility with printed electronics. For example, graphene-based field-effect transistors (FETs) functionalized with glucose-binding aptamers provide label-free detection with low power consumption. Hybrid systems combining enzymatic and non-enzymatic principles further enhance reliability by cross-validating measurements.
Despite these advances, challenges remain in achieving clinical-grade accuracy and long-term stability in wearable formats. Enzyme degradation and biofouling in enzymatic sensors necessitate robust immobilization techniques, while non-enzymatic sensors require further optimization to operate reliably in physiological conditions. Advances in 2D material synthesis and device engineering continue to address these limitations, paving the way for next-generation glucose monitoring systems.
In summary, two-dimensional materials significantly enhance both enzymatic and non-enzymatic glucose sensing through improved electrocatalysis, interference rejection, and wearable integration. Their unique properties enable high-performance, flexible, and continuous monitoring solutions, driving progress toward personalized diabetes management. Future developments will focus on refining material interfaces, improving selectivity, and scaling production for widespread adoption.