Three-dimensional macroscopic graphene supported vertically-ordered mesoporous silica-nanochannel film for direct and ultrasensitive detection of uric acid in serum.

Direct, rapid and sensitive detection of physiologically-relevant active small molecules (ASMs) in complex biological samples is highly desirable. Herein, we present an electrochemical sensing platform by combining three-dimensional macroscopic graphene (3DG) and vertically-ordered mesoporous silica-nanochannel film (VMSF), which is able to directly detect ASMs in complex samples with high sensitivity and no need of tedious pretreatment. Free-standing and macroscopic 3DG serves as the supporting electrode and O2-plasma treatment is proposed as a simple and green approach to improve its hydrophilicity and electrochemical activity. The plasma-treated 3DG (pl-3DG) is suitable for stable modification of VMSF using electrochemically assisted self-assembly (EASA) method, conferring the electrode (VMSF/pl-3DG) with excellent anti-fouling properties. As the proof-of-concept demonstration, VMSF/pl-3DG sensor exhibits fast and ultrasensitive determination of uric acid (UA) with ultralow limit of detection (LOD, 23 nM) owing to high active surface, unhindered mass transfer, good electrical transfer of 3DG and signal amplification of VMSF nanochannel. Direct determination of UA in biological sample (serum) is also realized without the need of tedious pretreatment.