A new composite of graphene and molecularly imprinted polymer based on ionic liquids as functional monomer and cross-linker for electrochemical sensing 6-benzylaminopurine

Molecularly imprinted polymers prepared using traditional functional monomers and cross-linkers exhibit slow binding kinetics, low electrocatalytic activity and adsorption capacity. Herein, we report a new composite of ionic liquid-based graphene and molecularly imprinted polymer (IL-GR-MIP) with high electrocatalytic activity and adsorption capacity to construct an effective electrochemical sensor for 6-benzylaminopurine (6-BAP). Our objective was to enhance the efficiency of the sensor by incorporating more IL in the MIP framework. We synthesized IL-GR-MIP using ionic liquid 1-vinyl-3-butylimidazolium tetrafluoroborate (IL₁) as functional monomer, ionic liquid 1,4-butanediyl-3,3'-bis-l-vinylimidazolium dibromide (IL₂) as cross-linker, 6-BAP as template, and GR as supporter. IL-GR-MIP was characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscope. Compared with GR-MIP composites based on methacrylic acid or IL₁ as functional monomer, N, N'-methylenebisacrylamide and ethylene glycol dimethacrylate as cross-linker, the IL-GR-MIP (prepared with ionic liquids as functional monomer and cross-linker) sensor exhibited highest peak current for 6-BAP. The results indicate the ability of IL₂ as cross-linker to enhance electrocatalytic activity and adsorption capacity for 6-BAP of IL-GR-MIP. Under the optimized conditions, the peak current of IL-GR-MIP sensor was linear to 6-BAP concentration in the range of 0.5-50 μM with a detection limit of 0.2 μM (S/N = 3). The IL-GR-MIP sensor exhibited good selectivity with the anti-interference ability of 1000-fold ascorbic acid in 6-BAP determination. Furthermore, we demonstrated practical applicability of IL-GR-MIP sensor in detecting 6-BAP in real samples with satisfactory results.

Constructed ILs coated porous magnetic nickel cobaltate hexagonal nanoplates sensing materials for the simultaneous detection of cumulative toxic metals

The different morphologies of magnetic nickel cobaltate (NiCo₂O₄) electrocatalysts, consisting of nanoparticles (NiCo₂O₄-N), nanoplates (NiCo₂O₄-P) and microspheres (NiCo₂O₄-S) were fabricated. It was found that the electrocatalytic properties of the sensing materials were strongly dependent on morphology and specific surface area. The porous NiCo₂O₄ hexagonal nanoplates coupled with ILs as modified materials (ILs@NiCo₂O₄-P) for the simultaneous determination of thallium (Tl⁺), lead (Pb²⁺) and copper (Cu²⁺), exhibited high sensitivity, long-time stability and good repeatability. The enhanced electrocatalytic activity was attributed to relatively large specific surface area, excellent electronic conductivity, and unique porous nanostructure. The analytical performance of the constructed electrode on detection of Tl⁺, Pb²⁺ and Cu²⁺ was examined using differential pulse anodic stripping voltammetry (DPASV). Under optimal conditions, the electrode showed a good linear response to Tl⁺, Pb²⁺and Cu²⁺ in the concentration range of 0.1-100.0, 0.1-100.0 and 0.05-100.0μg/L, respectively. The detection limits (S/N=3) were 0.046, 0.034 and 0.029μg/L for Tl⁺, Pb²⁺ and Cu²⁺, respectively. The fabricated sensor was successfully applied to detect trace Tl⁺, Pb²⁺ and Cu²⁺ in various water and soil samples with satisfactory results. Hence, this work provided a promising material for electrochemical determination of cumulative toxic metals individually and simultaneously.

Facile colorimetric detection of 6-benzylaminopurine based on p-aminobenzenethiol functionalized silver nanoparticles

A simple colorimetric assay has been developed to detect 6-benzylaminopurine (6-BA) in a complex environment by using the novel probe p-aminobenzenethiol functionalized silver nanoparticles (ABT-AgNPs).