Gold nanostructured laser-scribed graphene: A new electrochemical biosensing platform for potential point-of-care testing of disease biomarkers

Improvements in the laser-scribed graphene (LSG)-based electrodes are critical to overcoming limitations of bare LSG electrodes in terms of sensitivity, direct immobilization of detection probes for biosensor fabrication, and ease of integration with point-of-care (POC) devices. Herein, we introduce a new class of nanostructured gold modified LSG (LSG-AuNS) electrochemical sensing system comprising LSG-AuNS working electrode, LSG reference, and LSG counter electrode. LSG-AuNS electrodes are realized by electrodeposition of gold chloride (HAuCl 4 ) solution, which gave~2-fold enhancement in sensitivity and electrocatalytic activity compared to bare LSG electrode and commercially available screen-printed gold electrode (SPAuE). We demonstrate LSG-AuNS electrochemical aptasensor for detecting human epidermal growth factor receptor 2 (Her-2) with a limit of detection (LOD) of 0.008 ng/mL and a linear range of 0.1–200 ng/mL. LSG-AuNS-aptasensor can easily detect different concentrations of Her-2 spiked in undiluted human serum. Finally, to show the LSG-AuNS sensor system's potential to develop POC biosensor devices, we integrated LSG-AuNS electrodes with a handheld electrochemical system operated using a custom-developed mobile application. Schematic illustration of the developed LSG-AuNS aptasensor and its integration into a POC device. We observed Spiky and Christmas tree-like gold structures on the LSG electrode surface. • Nanostructured gold modified laser-scribed graphene biosensing system is developed. • A 2-fold enhancement in sensitivity is achieved compared to commercially available SPAuE. • The aptasensor for Her-2 with a 0.008 ng/mL detection limit is developed. • The aptasensor showed a good selectivity and is capable of Her-2 detection in undiluted serum. • POC biosensor device for Her-2 detection is demonstrated.