The growing demand for non-invasive, real-time health monitoring has driven the development of graphene-based wearable biosensors for point-of-care (POC) diagnostics. This review explores the surface functionalization of graphene and its critical role in enhancing the performance of wearable biosensors for biomarker detection. Leveraging graphene's exceptional electrical, mechanical, and biocompatible properties, we discuss how surface functionalization-such as covalent and non-covalent functionalization, biomolecular probes, and passivation layers-enable highly sensitive and selective detection of biomarkers in biofluids. We categorize biomarkers based on their physical properties and explore various wearable designs, including patches, contact lenses, microneedles, and textiles, highlighting their integration into POC devices. Furthermore, we examine the challenges and opportunities in translating graphene-based sensors from the lab to real-world applications, emphasizing the importance of biocompatibility and surface functionalization for improved performance. By bridging the gap between material science and biomedical engineering, this review provides a roadmap for the development of next-generation graphene biosensors that could revolutionize personalized medicine and point-of-care diagnostics.

Recently, aptameric graphene field-effect transistors (GFET) have emerged in the field of in situ detection of cancer protein biomarkers, thanks to their advantages of fast response, high specificity, and sensitivity. However, factors such as non-usable have limited their productization process. Here, we propose a novel aptamer indirect functionalization method that enables the reconfigurable modification for aptamer probes on graphene surface thereby achieving reusable aptameric-GFET detection for protein biomarkers with the calibrated signals. Furthermore, a novel crosslinker, Tetrakis(4-carboxyphenyl)pophyrin (TCPP), is exploited for the signal amplification. Results show that our proposed reusable sensor can respond to carcinoembryonic antigen(CEA), a representative cancer protein biomarker, concentration change in 6-8 minutes with an estimated LOD of 1.09ng/ml in 1× PBS and the signal is increased by more than half compare to the conventional method. Dissociation occurs at the target temperature and signal degradation is less than 5% after 3 cycles and 20% after 14 days of storage and 10 cycles. Our work provides a novel strategy for measure CEA quantitatively and sensitively with rapid response, which hold great potential for a wide range of medical application and lead to powerful biomarkers detection devices in healthcare.