Laser-written nanometal-doped graphene on paper for Alzheimer’s multi-target sensing

Laser-induced graphene (LIG) is highly favored in the sensing field due to its outstanding physicochemical properties. However, conventional PI film substrates suffer from limited flexibility and weak adhesion, which causes LIG detachment and compromised sensing stability, restricting their sensing applications. Moreover, the traditional approach of doping metal nanoparticles into LIG through secondary laser processing faces challenges: scanning path deviations cause uneven distribution, while repeated laser exposure may damage the substrate. To overcome these limitations, we used one-step laser direct writing (LDW) to engrave PI paper pre-soaked in a metal chloride solution, directly inducing graphene formation and in-situ reducing metal nanoparticles (LIG-Metal) simultaneously. Using PI paper as the substrate enhances the electrode's flexibility and adhesion, thereby preventing detachment. The incorporation of metal nanoparticles greatly improves the sensitivity of paper-based LIG electrodes while expanding their modification potential for sensing applications. Additionally, plasma treatment further improves the hydrophilicity and stability of PI paper-based LIG electrodes. Using prepared gold nanoparticle-doped laser-induced graphene (LIG-Au) electrodes as extended gate (EG), we developed a portable, multi-target intelligent sensing system. This system enables real-time, wireless monitoring of peroxynitrite (ONOO⁻) and c-Abl dynamics in the brains of Alzheimer’s disease (AD) transgenic mice, while also facilitating multi-dimensional investigation of their interactions and pathological roles in AD progression.