Self-assembled gold nanonetwork/diamond-like carbon nanofilm: Synthesis, characterization, and biosensing application

In recent years, the synthesis of functional materials based on metal/carbon composites has gained significant attention. However, the development of simple and one-step preparation methods for such materials remains a considerable challenge. This study presents a novel and straightforward self-assembly approach for the fabrication of a porous gold nanonetwork/diamond-like carbon (GNN/DLC) nanofilm for the first time. The proposed method enables the direct formation of the nanofilm in the synthesis solution, which can be transferred onto rigid or flexible substrates using a modified Langmuir–Blodgett (LB) technique. Comprehensive physicochemical analyses revealed that the GNN/DLC structure contains oxygen-containing functional groups, hydrophobic methyl groups, a sp³/sp² ratio of 1.16, and exceptional conductivity (1.4 × 10³ S cm⁻¹). Optical analysis demonstrated bandgap energies of 1.42 eV and 3.87 eV, indicating that the interaction between oxygen-containing functional groups in the DLC matrix significantly influences the electronic properties of the nanofilm. Electrochemical studies confirmed that the GNN/DLC nanofilm functions as a highly sensitive electrode material for biosensor applications. The fabricated biosensor platform, modified with GNN/DLC, successfully detected the target microRNA miR-410-5p using differential pulse voltammetry (DPV), with a detection range of 0.3 fM to 100 fM and a low detection limit (LOD) of 0.27 fM. These findings highlight the potential of GNN/DLC nanofilms in biosensor construction. Additionally, the prepared GNN/DLC nanofilm is expected to find future applications in catalysis, gas storage and separation, energy systems, and biomedical technologies.