Two-Dimensional Nanomaterial-Based Aptasensors: Graphene and MXenes as Emerging Biosensing Platforms

Recent advances in graphene- and MXene-based aptasensors have transformed biosensing by integrating the high specificity of aptamers with the unique physicochemical properties of two-dimensional (2D) nanomaterials. Graphene and its derivatives provide a large surface area, excellent conductivity, mechanical flexibility, and biocompatibility, enabling efficient aptamer immobilization, signal amplification, and sensor stability. MXenes, with their hydrophilic surfaces, high electrical conductivity, and versatile surface chemistry, offer ultrahigh sensitivity and tunability across diverse sensing platforms. This review presents a comparative analysis of graphene- and MXene-based aptasensors, covering synthesis and functionalization strategies, sensing mechanisms (electrochemical, fluorescent, colorimetric), and their integration for detecting biomarkers, pathogens, toxins, heavy metals, and small molecules. Particular attention is given to hybrid nanostructures, field-effect transistor (FET)-based devices, and nanocomposites that exploit synergistic effects to improve detection limits, selectivity, and real-time responsiveness. Critical challenges, including oxidation, nonspecific adsorption, reproducibility, large-scale fabrication, and device integration, are also addressed. Finally, we discuss future directions such as graphene–MXene heterostructures, machine learning-assisted signal processing, and wearable or implantable biosensors for personalized medicine and environmental monitoring. By consolidating current progress and highlighting knowledge gaps, this review aims to guide the design of next-generation aptasensors with real-world applicability.