Tunable electrochemical synthesis of 3D nucleated microparticles like Cu-BTC MOF-carbon nanotubes composite: Enzyme free ultrasensitive determination of glucose in a complex biological fluid

The present study describes the fabrication of 3D nucleated microparticles like Cu-MOF (MPsLCu-MOF)-SWCNTs composite on glassy carbon electrode (GCE) by electrodeposition and applied as a sensor for the sensitive determination of glucose in human saliva samples. First, SWCNTs were deposited on GCE by potential cycling between 0.0 V to -1.0 V and then, Cu-MOF was electrodeposited on SWCNTs modified GCE using a ligand, 1,3,5-benzene tricarboxylic acid (BTC), triethylamine hydrochloride and copper salt. The SEM studies showed the formation of MPsLCu-MOF on SWCNTs as well as on bare GCE with 1 μm size. The impedance studies showed that the heterogeneous electron transfer rate constant of [Fe(CN)6]3-/4- was higher at SWCNTs-MPsLCu-MOF than bare GCE and SWCNTs and MPsLCu-MOF modified GCEs. Then, the composite electrode was utilized for non-enzymatic detection of glucose. The SWCNTs-MPsLCu-MOF modified electrode showed a well-defined sharp oxidation peak at 0.45 V with enhanced current than bare GCE and SWCNTs and MPsLCu-MOF modified GCEs. As the concentration of glucose increases from 10-160 × 10-6 M, the oxidation current also increases without shifting its oxidation potential. The present composite modified electrode was also used to determine glucose in the linear range of 20 × 10-9 M to 80 × 10-6 M by amperometry with a LOD of 1.72 × 10-9 M (S/N=3) and a superior sensitivity of 573 μA mM−1 cm−2. Finally, the composite fabricated electrode was exploited for real-time analysis of glucose in human saliva samples and satisfactory results were obtained.