Jianbo Li

Based on magnetic graphene oxide highly sensitive and selective imprinted sensor for determination of sunset yellow

A new imprinted material based on β-cyclodextrin/ionic liquid/gold nanoparticles functionalized magnetic graphene oxide has been successfully synthesized and modified to the glassy carbon electrode surface to constructed imprinted electrochemical sensor to detect sunset yellow. The sensitivity and electrochemical response of the electrode can be improved by nanomaterials. The surface morphology and crystal structure of the hybrid nanomaterial has been characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy. The electrochemical behaviors of the hybrid nanomaterials based sensor were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. Under the optimized conditions, the proposed electrochemical sensor showed a fast rebinding dynamics, which was successfully applied to sunset yellow detection with a wide linear range from 5.0×10(-9) to 2.0×10(-6)mol L(-1) and a detection limit of 2.0×10(-9)mol L(-1). The electrochemical sensor has been successfully applied in the determination of SY in spiked water samples, mirinda drink and minute maid, and the recoveries for the standards added are 97-105%.

A sensitive and selective chemiluminescence sensor for the determination of dopamine based on silanized magnetic graphene oxide-molecularly imprinted polymer.

Based on silanized magnetic graphene oxide-molecularly imprinted polymer (Si-MG-MIP), a sensitive and selective chemiluminescence sensor for dopamine measurement was developed. Si-MG-MIP, in which silanes was introduced to improve the mass transfer, graphene oxide was employed to improve absorption capacity, Fe3O4 nanoparticles were applied for separation easily and molecularly imprinted polymer was used to improve selectivity, demonstrated the advantages of the sensor. All the composites were confirmed by SEM, TEM, XRD and FTIR. Under the optimal conditions of chemiluminescence, dopamine could be assayed in the range of 8.0-200.0 ng/mL with a correlation coefficient of linear regression of 0.9970. The detection limit was 1.5 ng/mL (3δ) and the precision for 11 replicate detections of 80.0 ng/mL dopamine was 3.4% (RSD). When the sensor was applied in determining dopamine in actual samples, recovery ranged from 94% to 110%, which revealed that the results were satisfactory.

The preparation of novel adsorbent materials with efficient adsorption performance for both chromium and methylene blue

The hydroxy-functionalized ionic liquids (ILs) modified with magnetic chitosan/grapheneoxide (MG-ILs-OH) were synthesized. The surface morphology of MG-ILs-OH was characterized by transmission electron microscopy, X-ray diffraction, thermo gravimetric analysis and Fourier transform infrared spectroscopy techniques. It was found that the adsorption kinetics is well fitted by a pseudo-second-order model and the adsorption isotherms agree well with the Langmuir model, and the MG-ILs-OH could be repeatedly used by simple treatment. The results showed that the addition of ILs-OH can largely increase the adsorption sites (hydroxy and amino groups) and adsorption properties. The MG-ILs-OH were used as adsorbent for the removal of methylene blue (MB) and Cr(VI) from simulated wastewater with a fast solid-liquid separation in the presence of external magnetic field. The maximum obtained adsorption capacities of MB and Cr(VI) were 243.31 and 107.99 mg/g, respectively. The application of MG-ILs-OH could effectively solve the problem that the adsorbent only adsorb similar adsorbate.

CdTe quantum dots@luminol as signal amplification system for chrysoidine with chemiluminescence-chitosan/graphene oxide-magnetite-molecularly imprinting sensor

A sensitive chemiluminescence (CL) sensor based on chemiluminescence resonance energy transfer (CRET) in CdTe quantum dots@luminol (CdTe QDs@luminol) nanomaterials combined with chitosan/graphene oxide-magnetite-molecularly imprinted polymer (Cs/GM-MIP) for sensing chrysoidine was developed. CdTe QDs@luminol was designed to not only amplify the signal of CL but also reduce luminol consumption in the detection of chrysoidine. On the basis of the abundant hydroxy and amino, Cs and graphene oxide were introduced into the GM-MIP to improve the adsorption ability. The adsorption capacities of chrysoidine by both Cs/GM-MIP and non-imprinted polymer (Cs/GM-NIP) were investigated, and the CdTe QDs@luminol and Cs/GM-MIP were characterized by UV-vis, FTIR, SEM and TEM. The proposed sensor can detect chrysoidine within a linear range of 1.0×10(-7) - 1.0×10(-5) mol/L with a detection limit of 3.2×10(-8) mol/L (3δ) due to considerable chemiluminescence signal enhancement of the CdTe quantum dots@luminol detector and the high selectivity of the Cs/GM-MIP system. Under the optimal conditions of CL, the CdTe QDs@luminol-Cs/GM-MIP-CL sensor was used for chrysoidine determination in samples with satisfactory recoveries in the range of 90-107%.

β-Cyclodextrin/chitosan–magnetic graphene oxide–surface molecularly imprinted polymer nanocomplex coupled with chemiluminescence biosensing of bovine serum albumin

In this report, a sensitive and selective chemiluminescence (CL) biosensor for bovine serum albumin (BSA) coupled with a surface molecularly imprinted polymer nanocomplex using β-cyclodextrin/chitosan–magnetic graphene oxide as backbone material (β-CD/Cs–MGO–SMIP) was investigated. The material β-CD/Cs–MGO combined with β-cyclodextrin, chitosan and graphene oxide was used to provide multiple imprinting sites and a large surface area was characterized by SEM, XRD and FTIR. It was found that β-CD/Cs–MGO–SMIP followed the Langmuir isotherm equation and pseudo-second order sorption kinetics when binding the template. This material demonstrated fast mass transfer, a promoted rate of removal of the biomacromolecule and excellent recognition and adsorption ability for the imprinting cavities situated at the surface of β-CD/Cs–MGO, which enabled easy access to BSA. Subsequently, a highly sensitive CL biosensor for BSA was proposed based on the strong recognition effect between β-CD/Cs–MGO–SMIP and BSA which led to a high selectivity of the sensor, and the proposed biosensor could assay in the range 5.0 × 10−7 to 1.0 × 10−4 mg mL−1 with a detection limit of 1.1 × 10−7 mg mL−1. The obtained recoveries were between 94% and 106% when determining samples.

Bioreceptor multi-walled carbon nanotubes@Fe3O4@SiO2–surface molecular imprinted polymer in an ultrasensitive chemiluminescent biosensor for bovine hemoglobin

An ultrasensitive chemiluminescent biosensor with a high selectivity, based on a bioreceptor surface molecular imprinted polymer (SMIP) that used core–shell Fe3O4@SiO2–multi-walled carbon nanotube nanostructures (Fe3O4@SiO2/MWCNTs) as the backbone material, for bovine hemoglobin (BHb) determination was proposed. The Fe3O4@SiO2/MWCNTs were synthesized with a new method, and then were characterized using SEM, FTIR and XRD techniques. The adsorption ability of Fe3O4@SiO2/MWCNTs–SMIP was evaluated to be 91 mg g−1 following the Langmuir isotherm equation and it demonstrated an excellent recognition and adsorption ability for the imprinted sites located on the surface or near the surface of the Fe3O4@SiO2/MWCNTs. Under optimum conditions of CL, the detection range of BHb was from 5.0 × 10−10 to 7.0 × 10−7 mg mL−1 with a detection limit of 1.5 × 10−10 mg mL−1 (3δ). The proposed biosensor was successfully applied in the determination of BHb in real samples with high selectivity and sensitivity, and the recoveries were excellent and varied from 92% to 106%. Finally, the possible CL mechanism of the BHb in amplifying the CL signal of the luminol–NaOH–H2O2 system was discussed.

A novel ionic liquid functionalized graphene oxide supported gold nanoparticle composite film for sensitive electrochemical detection of dopamine

A simple and sensitive electrochemical sensor for detection of dopamine has been developed based on ionic liquid functionalized graphene oxide supported gold nanoparticles (GO-IL-AuNPs) coated onto a glassy carbon electrode. The prepared graphene oxide, ionic liquid functionalized graphene oxide and GO-IL-AuNPs were characterized in detail by scanning electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy. The electrochemical properties of the hybrid nanomaterials were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. Meanwhile, the activities of hybrid nanomaterials toward the oxidation of dopamine were analyzed via cyclic voltammetry and differential pulse voltammetry. The resulting sensor showed excellent electrocatalytic activity towards dopamine. Under the optimum conditions, differential pulse voltammetry was employed to detect ultra-trace amounts of dopamine, for which a wide linear range of 7 nM to 5 μM and a limit of detection 2.3 nM (S/N = 3) were obtained. The proposed sensor exhibited excellent accuracy and precision and the relative standard deviation (RSD) was less than 5%. The highly sensitive sensor was successfully used for accurate determination of the content of dopamine in practical samples.

Adsorbent for resorcinol removal based on cellulose functionalized with magnetic poly(dopamine)

A simple chemical bonding method to synthesize magnetic cellulose-poly(dopamine) (Fe3O4@CMC@PDA) was reported. The adsorption behaviors of resorcinol in aqueous solution on Fe3O4@CMC@PDA were systematically investigated. As the results shown that, with the advantage of high surface area, abundant hydroxyl and amino groups of Fe3O4@CMC@PDA, and the magnetic property of Fe3O4, the resorcinol can be easily and rapidly extracted from the water by magnetic attraction under investigation. The adsorption equilibrium of Fe3O4@CMC@PDA for resorcinol corresponded with Freundlich isotherm, and the novel adsorbent exhibited better resorcinol removal efficiency in solutions with low pH. It was found that the resorcinol adsorption performance of Fe3O4@CMC@PDA strongly depends on their surface charge concentration and specific surface area. These results provide evidences for estimating and optimizing the removal of phenols from the wastewater by using of Fe3O4@CMC@PDA composites in the future.

An ultrasensitive chemiluminescence aptasensor for thrombin detection based on iron porphyrin catalyzing luminescence desorbed from chitosan modified magnetic oxide graphene composite

In this work, an ultrasensitive chemiluminescence (CL) aptasensor was prepared for thrombin detection based on iron porphyrin catalyzing luminol - hydrogen peroxide luminescence under alkaline conditions, and iron porphyrin was desorbed from chitosan modified magnetic oxide graphene composite (CS@Fe3O4@GO). Firstly, CS@Fe3O4@GO was prepared. CS@Fe3O4@GO has advantages of the good biocompatibility and positively charged on its surface of CS, the large specific surface area of GO and the easy separation characteristics of Fe3O4. GO, Fe3O4 and CS@Fe3O4@GO were confirmed by transmission electron microscopy (TEM), scanning electron microscope (SEM), fourier transform infrared (FTIR) and X-ray powder diffraction (XRD). Then, thrombin aptamer (T-Apt) and hemin (HM, an iron porphyrin) were sequentially modified on the surface of CS@Fe3O4@GO to form CS@Fe3O4@GO@T-Apt@HM. The immobilization properties of CS@Fe3O4@GO to T-Apt and adsorption properties of CS@Fe3O4@GO@T-Apt to HM were sequentially researched through the curves of kinetics and the curves of thermodynamics. When thrombin existed in solutions, HM was desorbed from the surface of CS@Fe3O4@GO@T-Apt@HM owing to the strong specific recognition ability between thrombin and T-Apt, causing the changes of CL signal. Under optimized CL conditions, thrombin could be measured with the linear concentration range of 5.0×10-15-2.5×10-10mol/L. The detection limit was 1.5×10-15mol/L (3δ) while the relative standard deviation (RSD) was 3.2%. Finally, the CS@Fe3O4@GO@T-Apt@HM-CL aptasensor was used for the determination of thrombin in practical serum samples and recoveries ranged from 95% to 103%. Those satisfactory results revealed potential application of the CS@Fe3O4@GO@T-Apt@HM-CL aptasensor for thrombin detection in monitoring and diagnosis of human blood diseases.

Biorecognition and highly sensitive determination of Ribonuclease A with chemiluminescence sensor based on Fe3O4/multi-walled carbon nanotubes/SiO2-surface molecular imprinting polymer

A chemiluminescence (CL) sensor with high sensitivity and selectivity has been developed for the determination of Ribonuclease A (RNase A). A new material Fe3O4/multi-walled carbon nanotubes/SiO2 (Fe3O4/MWCNTs/SiO2) was introduced into this sensor as a supporting material to prepare a surface molecular imprinting polymer (SMIP). In this work, Fe3O4 not only served as a backbone material in the preparation of the RNase A SMIP, but also as a separation reagent to allow the easy collection of the SMIP complex. Carbon nanotubes and SiO2 were also used as supporting materials to prepare SMIP for their large specific surface area. The Fe3O4/MWCNTs/SiO2 nanocomposite was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The adsorption ability of the Fe3O4/MWCNTs/SiO2-SMIP was calculated to be 102 mg g−1, which demonstrated the excellent recognition and adsorption ability of the imprinting cavities situated at or in the proximity of the surface of the Fe3O4/MWCNTs/SiO2. Under optimal conditions, the linear range of the sensor extended from 1.0 × 10−9 mg mL−1 to 1.0 × 10−7 mg mL−1 for RNase A and the detection limit was 3.2 × 10−10 mg mL−1 (3δ). The proposed sensor was successfully applied for the determination of RNase A in biological samples with recoveries from 93% to 105%.