Junjie Fei

Carbon nanomaterial based electrochemical sensors for biogenic amines

AbstractThis review describes recent advances in the use of carbon nanomaterials for electroanalytical detection of biogenic amines (BAs). It starts with a short introduction into carbon nanomaterials such as carbon nanotubes, graphene, nanodiamonds, carbon nanofibers, fullerenes, and their composites. Next, electrochemical sensing schemes are discussed for various BAs including dopamine, serotonin, epinephrine, norepinephrine, tyramine, histamine and putrescine. Examples are then given for methods for simultaneous detection of various BAs. Finally, we discuss the current and future challenges of carbon nanomaterial-based electrochemical sensors for BAs. The review contains 175 references. FigureThis article reviews recent advances in the use of carbon nanomaterials (CNs) for the electroanalytical measurements of biogenic amines.

Electrochemical determination of toxic ractopamine at an ordered mesoporous carbon modified electrode.

A sensitive electrochemical sensor was developed to detect toxic ractopamine using ordered mesoporus carbon (OMC) modified glass carbon electrode (OMC/GCE). Cyclic voltammetry was used to investigate the electrochemical behaviours of ractopamine on OMC/GCE. The results indicated that the OMC modified electrode can remarkably enhance electrocatalytic activity towards the oxidation of ractopamine with a great increase of peak current. The oxidation mechanism was studied and the results showed that the oxidation of ractopamine involved two protons and two electrons of its two phenolic hydroxyl groups. The signal for the determination of ractopamine was recorded using differential pulse voltammetry (DPV) and the optimisation for the experimental conditions was also conducted. The results showed that the response of the sensor to concentration of ractopamine displayed a linear correlation over a range from 0.085 μM to 8.0 μM with a detection limit of 0.06 μM, demonstrating favourable sensitivity and selectivity for the detection of ractopamine. Finally, the method was successfully applied for the determination of ractopamine in pork samples with satisfying recoveries in the range of 96.6-104.5% and excellent RSD of less than 5%.

Real-Time Monitoring ATP in Mitochondrion of Living Cells: A Specific Fluorescent Probe for ATP by Dual Recognition Sites

Adenosine triphosphate (ATP) is mainly produced in the mitochondrion and used as a universal energy source for various cellular events. Various fluorescent probes for ATP have been established successfully, but most of them are not appropriate for monitoring the fluctuation of the mitochondrial ATP level. Herein, a fluorescent probe named Mito-Rh is first synthesized and used to recognize ATP in mitochondrion. In the probe, rhodamine, diethylenetriamine, and triphenylphosphonium are selected as fluorophore, reaction site, and mitochondrion-targeting group, respectively. Probe Mito-Rh shows high sensitivity to ATP with 81-fold fluorescence enhancement, and the detection range (0.1-10 mM) can match the concentration level of ATP in the mitochondrion. Moreover, Mito-Rh provides excellent selectivity toward ATP over other biological anions (ADP, AMP, GTP, CTP, UTP) owing to a concurrent effect of dual recognition sites (hydrogen bond and π-π stacking). In particular, the probe can localize in mitochondrion specifically and demonstrates utility in the real-time detection of mitochondrial ATP concentration changes.

Facile and Sensitive Near-Infrared Fluorescence Probe for the Detection of Endogenous Alkaline Phosphatase Activity In Vivo

Alkaline phosphatase (ALP) is an essential enzyme and widely distributes in a variety of tissues. To date, various nanomaterial and small-molecule fluorescent probes for ALP have been constructed successfully, but the emission wavelengths of these probes are in the ultraviolet or visible range, which is not beneficial for bioimaging. Herein, a hemicyanine-based near-infrared (NIR) fluorescent probe named CyP is first synthesized and used to detect ALP activity. The characteristics of probe CyP are as follows: (1) The probe possesses a facile structure, which can be obtained by easy synthetic steps. (2) The fluorescence emission of the sensing system is at 738 nm belonging to NIR region, which is suitable for bioimaging in vivo. (3) The probe exhibits high sensitivity to ALP with 10-fold fluorescence enhancement and low detection limit (0.003 U/mL) can match the level of ALP in vivo. (4) The fluorescent change of the probe is attributed to the fact that ALP-catalyzed cleavage of the phosphate group in CyP induces the transformation of CyP (fluorescence off) into CyOH (fluorescence on), which is proved by HPLC, 31P NMR, MS, and DFT calculation. (5) The NIR fluorescent probe is applied for the detection of endogenous ALP activity in various biological samples such as cell, tissue, and living animal with satisfactory results.

ADSORPTIVE STRIPPING VOLTAMMETRIC STUDY OF SCANDIUM–ALIZARIN COMPLEXAN COMPLEX AT A CARBON PASTE ELECTRODE

ABSTRACT A highly selective, sensitive, rapid and economic adsorptive stripping voltammetric method has been developed for the determination of ultra trace amount of scandium at a carbon paste electrode (CPE) in the current paper. The Sc(III)−alizarin complexan (ALC) complex is adsorbed at the electrode in a mixed buffer solution (pH 5.4) containing 0.04 M acetate and 0.016 M biphthalate, yielding one peak corresponding to the reduction of ALC in the complex at −0.60 V (vs. SCE). The second-order derivative linear scan voltammograms of the complex are recorded by use of model JP−303 polarographic analyzer from −0.10 to −1.10 V. A linear relationship between the second order derivative peak current and Sc(III) concentration in the range of 1.0 × 10−9 to 6.0 × 10−7 M is observed. The detection limit for Sc(III) is 6.0 × 10−10 M. A relative standard deviation of 4.34% is given for ten determinations of 6.0 × 10−8 M Sc(III). The method has been applied to the determination of the trace Sc(III) in the mineral samples with satisfactory results.

Determination of Trace Aluminum by Anodic Adsorptive Stripping Voltammetry Using a Multi-Walled Carbon Nanotube Modified Carbon Paste Electrode

The adsorptive voltammetric behavior of the aluminum (Al)-alizarin violet (AV) complex in 0.2 mol L−1 HAc-NaAc buffer (pH 4.5) at a multi-walled carbon nanotube modified carbon paste electrode (MWCNT/CPE) was investigated. The results showed that the complex can be adsorbed on the surface of the MWCNT/CPE, yielding one oxidation peak at 530 mV (vs. SCE). The proposed method exhibits good linearity over the range from 1.0 × 10−9 mol L−1 to 1.0 × 10−7 mol L−1, and a low detection limit of 6.0 × 10−10 mol L-1 for 120 s accumulation was obtained under optimum conditions.