GCE Surface Research Articles

Electrochemical detection of the oxidative damage of a potential pyrimido[5,4-g]pteridine-derived antitumor agent toward DNA.

In this work, we design and synthesize 2,2'-(7,9-dimethyl-2,4,6,8-tetraoxo-6,7,8,9-tetrahydropyrimido[5,4-g]pteridine-1,3(2H,4H)-diyl)bis(N,N-bis(2-chloroethyl)acetamide) (PT-MCA) as a novel DNA intercalator and potential antitumor agent. Electrochemical analysis reveals the redox process of PT-MCA on the electrode surface. The bioelectrochemical sensors are obtained by modifying the surface of GCE with calf thymus DNA (ctDNA), poly (dG), poly (dA), and G-quadruplex, respectively. The DNA oxidative damage induced by PT-MCA is investigated by comparing the peak intensity change of dGuo and dAdo and monitoring the peaks of the oxidation products of guanine and/or adenine (8-oxoGua and/or 2,8-oxoAde). UV-vis absorption and fluorescence spectra and gel electrophoresis are further employed to understand the intercalation of PT-MCA into DNA base pairs. Moreover, PT-MCA is proved to exhibit stronger anti-proliferation activity than mitoxantrone against both 4T1 and B16-F10 cancer cells. At last, the oxidative damage of PT-MCA toward ctDNA is not interfered by the coexistence of ions and also can be detected in real serums.

Electrochemical sensor for determination of methylprednisolone as an anabolic steroid used in doping

The current work was done to prepare an electrochemical sensor based on an MC/GCE (mesoporous carbon modified glassy carbon electrode) for determining the presence of methylprednisolone (MP) as a performance-enhancing anabolic steroid. Utilizing FE-SEM and XRD to characterize the shape and structure, it was discovered that the GCE surface was covered by a MC porous structure with a large effective surface area. MC can facilitate the process of electron transfer in electrochemical reactions and improve electrochemical reactivity, stability, and selectivity to determine MP, according to research on electrochemical properties using DPV measurements. The results revealed a steady linear range of 0.005–8 μM and a sensitivity value of 25.8389 µA/μM. Additionally, the MP sensor's detection limit was as low as 0.001 μM. The results showed very good conformity between the results of the two assays, and the RSD values (4.65–5.31 %) and recovery (96.00–99.40 %) values for DPV measurements were good enough. The proposed MP electrochemical sensor was applied to measure MP in blood serum samples taken from young volleyball players between the ages of 18 and 24. It demonstrated the MC/GCE results' desired accuracy and usefulness in determining the MP content of human blood serum.

ALP-Based Biosensors Employing Electrodes Modified with Carbon Nanomaterials for Pesticides Detection.

Due to the growing presence of pesticides in the environment and in food, the concern of their impact on human health is increasing. Therefore, the development of fast and reliable detection methods is needed. Enzymatic inhibition-based biosensors represent a good alternative for replacing the more complicated and time-consuming traditional methods (chromatography, spectrophotometry, etc.). This paper describes the development of an electrochemical biosensor exploiting alkaline phosphatase as the biological recognition element and a chemically modified glassy carbon electrode as the transducer. The biosensor was prepared modifying the GCE surface by a mixture of Multi-Walled-Carbon-Nanotubes (MWCNTs) and Electrochemically-Reduced-Graphene-Oxide (ERGO) followed by the immobilization of the enzyme by cross-linking with bovine serum albumin and glutaraldehyde. The inhibition of the biosensor response caused by pesticides was established using 2-phospho-L-ascorbic acid as the enzymatic substrate, whose dephosphorylation reaction produces ascorbic acid (AA). The MWCNTs/ERGO mixture shows a synergic effect in terms of increased sensitivity and decreased overpotential for AA oxidation. The response of the biosensor to the herbicide 2,4-dichloro-phenoxy-acetic-acid was evaluated and resulted in the concentration range 0.04-24 nM, with a limit of the detection of 16 pM. The determination of other pesticides was also achieved. The re-usability of the electrode was demonstrated by performing a washing procedure.

Fabrication of Graphene Oxide-Decorated Mesoporous NiFe2O4 as an Electrocatalyst in the Hydrogen Gas Evolution Reaction

An electrocatalyst for the hydrogen evolution reaction has been successfully synthesized from graphene oxide (GO) decorated with the mesoporous NiFe2O4. A high catalytic activity performance was reached by using the GCE surface as a conductor, and the synthesized composite contained GO/NiFe2O4. Based on the results, the as-prepared electrocatalyst exhibited a high overpotential for the HER reaction of 36 mV vs. RHE at a 10 mA current density, with an electrochemical active surface area (ECSA) of 3.18 × 10−4 cm2. Additionally, the electrocatalyst demonstrated a considerably good performance after the 9000 s stability test. It is believed that such an enhancement in electrocatalytic activity was due to the synergistic effect between the unique porosity feature of the mesoporous NiFe2O4, which may provide a more active surface, and the high conductivity of the GO.

Porous gold-curcumin nanocomposite for enhanced electrooxidation of glycerol and ethylene glycol

• Electrodeposited a thin film of gold-curcumin nanocomposite on the surface of GCE using a galvanostatic current. • Electrocatalytic oxidation of Gly and EG with a low activation energy of 20.7 and 49.7 kJ mol −1 , respectively. • Low onset potential during electrooxidation of Gly and EG at −0.17 V and −0.14 V, respectively. We report efficient electrocatalytic oxidation of glycerol (Gly) and ethylene glycol (EG) using a thin film of gold-curcumin (Au-CM) nanocomposite deposited on a glassy carbon electrode. The nanocomposite was synthesized using a galvanostatic technique in a two-electrode system with a very low current of 0.5 mA. Extensive characterization confirmed that the deposit consists of gold nanoparticles in a porous curcumin envelope. The Au-CM/GCE showed excellent catalytic activity for the electrocatalytic oxidation of Gly and EG with a low activation energy of 20.7 and 49.7 kJ mol –1 and a low onset potential of –0.17 V and –0.14 V, respectively.

SENSOR ELETROQUÍMICO PARA MONITORAMENTO DE SUOR

ABSTRACT Introduction: Attention is given to developing electrochemical sensors for the rapid and real-time measurement of lactate levels. The synthesis of electrochemical sensors is based on an electrode modified with a nanocomposite. Objective: Analyze an electrochemical sensor's feasibility for sports monitoring sweat in lactate. The Au@CNTs were the main focus of this study. Methods: The Au@CNTs composite was synthesized on the GCE surface and tested under pre-established protocols as a sensor. Results: The shape and structure of the modified electrodes were analyzed using SEM. The results showed that the Au@CNTs nanoparticles in the Au@CNTs nanocomposite were evenly distributed throughout the porous CNTs network. The performance of the developed sensor was measured using cyclic voltammetry and amperometry. The electrochemical biosensor responded linearly to lactate over phosphate buffer solution with a low detection limit and sensitivity. Conclusion: The experiment of this sensor evaluated lactate concentrations in real sweat samples that were exceptionally close to the injection amount, enabling it as an effective biosensor for the detection of lactate in sweat samples. Level of Evidence: Therapeutic Studies - Outcome Investigation.

Application of LTA zeolite-modified electrode for sensitive detection of retinoic acid in tap water.

An electrochemical method based on a Linde Type-A zeolite-modified glass carbon electrode (LTA/GCE) was introduced for the determination of retinoic acid (RA). LTA zeolite could be synthesized through a hydrothermal method and served as a commercial electrochemical sensor with high stability and sensitivity in electrochemical progress. The as-synthesized product was characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Under optimal conditions, a detection limit of 0.8 μM was obtained for RA with a linear range of 0.8-20.1 μM. This electrochemical method for determining RA was simpler and cheaper than previously reported methods. Furthermore, the modified electrode could be applied to the detection of RA in tap water, achieving a linear range of 1.4-15.0 μM with a detection limit of 1.4 μM and good recovery. The modified electrode designed by this method provided good selectivity, stability, and reproducibility for RA determination and reliable application for the analysis of RA in environmental water.

Active-site-rich binary metal oxides integrated organic–inorganic hybrid nanocomposite: Electrochemical simultaneous detection of multi-drugs of isoprenaline and resorcinol in real samples

In recent years, awareness on human health is increasing, which also increased the use of drugs to efficiently cure or halt the disease. Besides their certain beneficiary effects, it also triggers some alarming conditions in the body when the drug crosses a certain limit. Therefore, there is a need to develop efficient methods to detect the amount of the drug in the human body. In this work, for the first time, we developed a novel zinc manganate incorporated on polydopamine encapsulated reduced graphene oxide hybrid nanocomposite (rGO-pDA-ZnMnO3 HNC) efficient electro-catalyst for the simultaneous electrochemical detection of multi-drugs of Isoprenaline (IP) and Resorcinol (RC). The incorporation of the ZnMnO3 on rGO-pDA sheets indicates excellent conductivity due to its enhanced active sites and high surface area. The rGO-pDA-ZnMnO3 HNC was drop-casted on the surface of GCE and used as a superior electro-catalyst for individual and simultaneous detection of multi-drugs using CV and DPV. The DPV results showed excellent electrochemical performance, like IP and RC in linear ranges (LR) of 0.004 – 85.99 and 0.04 – 27.9 µM and lower limit values (LOD) of 3.1 and 7.1 nM, respectively. Further, the modified GCE has excellent interference capability, repeatability, and stability. Finally, the practical impact was demonstrated in real-time samples of human urine, tap water, and hair dyes. Remarkably, the recovery rate of IP and RC is ∼99 % and ∼98 %, respectively with RSD of less than 3 %, which authenticates the usefulness of the proposed sensor for real-time applications.

Highly efficient detection of Pb(II) ion in water by polypyrrole and metal-organic frame modify glassy carbon electrode

Since lead is teratogenic, carcinogenic and mutagenic, people pay increasing attention to lead contamination in water environment. In this work, a novel electrochemical sensor was developed to detect Pb(II) ion in water by PPy, MOFs and bismuth film (BF) modify GCE. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, electrochemical impedance spectroscopy, contact angleanalyses, cyclic voltammetry and differential pulse anodic stripping voltammetry were used to characterize the BF-PPy/UIO-66-NH 2 /GCE surface, revealing the physical and electrochemical properties of the electrode. MOFs increased the specific surface area and adsorption site of the electrode. The PPy enhanced the conductivity of the composites materials. MOFs and PPy synergistically promoted the electrochemical performance of the electrode. The deposition potential, deposition time, solution pH and Bi (III) concentration were optimized to determine the optimal detection condition. The electrode has a wide linear range (0.5 to 10 μg/L) with a low detection limit (0.05 μg/L). This electrode also has good anti-interference, repeatability and stability. Besides, it has been successfully applied to the detection of actual water samples. The recovery rates ranged from 95.4 % to 102.8 % with a relative standard deviation (RSD) less than 4.40 %. Our results provide an insight on efficient and rapid detection of Pb(II) ions in water environment in the future. • MOFs and polypyrrole synergistically promoted the electrochemical performance. • The fabricated BF-PPy/UIO-66-NH 2 /GCE shows a low Pb(II) detection limit. • This sensor was applied to the detection of Pb(II) in tap water and groundwater.

Cu2+@NMOFs-to-bimetallic CuFe PBA transformation: An instant catalyst with oxidase-mimicking activity for highly sensitive impedimetric biosensor

In this work, a facile impedance biosensor was constructed for sensitive assaying of miRNA-10b based on the Cu2+ modified NH2-metal organic frameworks (NMOF@Cu2+) coupling with a three-dimensional (3D) DNA walker signal amplification strategy. Specifically, abundant Cu2+ can adhere to the MOF via the coordination reaction between NH2 and Cu2+, which can be applied as a skeleton to produce CuFe Prussian blue analogue@NMOF (CuFe PBA@NMOF) just in time. Meanwhile, the carboxyl group, which is rich in the organic ligands of the NMOF, can be used to assemble DNA strands (complementary strand, CS) (CS-NMOF@Cu2+) for biorecognition reaction. With the introduction of the target, a 3D DNA walker was triggered to shear out large amounts of assistant strands (AS), which were then anchored on the surface of GCE. Afterward, CS-NMOF@Cu2+ can be assembled on the GCE by hybridization with AS. Eventually, abundant CuFe PBA@NMOF were generated in situ on the electrode with the help of K₃[Fe(CN)6], which can catalyze the 4-chloro-1-naphthol (4-CN) precipitation without H2O2, thereby increasing the resistance of the platform. Under the optimal conditions, the EIS biosensor presents reliable analytical performance in a wide linear range from 0.8 pM to 250 pM with a low detection limit of 0.5 pM.

A novel comparative study for electrochemical urea biosensor design: Effect of different ferrite nanoparticles (MFe2O4, M: Cu, Co, Ni, Zn) in urease immobilized composite system

A new enzymatic electrochemical biosensor has been developed with the PANI/Nafion composite system containing ferrite nanoparticles with four different transition metals. The ferrite nanoparticles containing copper, cobalt, nickel, and zinc metals were synthesized by the co-precipitation method and their surfaces were modified with tetraethoxysilane and (3-aminopropyl) triethoxysilane to obtain –NH2 function in order to develop the purposed sensing system. The modified and unmodified ferrite nanoparticles were characterized by physically, chemically, and morphologically. Ferrite nanoparticles with suitable for enzyme immobilization were integrated on the GCE surface and covered with PANI/Nafion. According toelectrochemical measurements, it was determined that copper ferrite nanoparticles, which have the lowest bandgap value, significantly increased the biosensor performance. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to monitor biosensor production and evaluate its performance. A detection limit of 0.17 µM and a wide linear range of 0.5–45.0 µM were obtained for the urea detection with the DPV method with the sensing system (Nf/PANI/CuF/Urs). The biosensor has been successfully applied to soil and milk samples with high accuracy. In addition, it has been determined that the proposed method has good reproducibility, selectivity, and stability.

MIL‐53(Fe)/rGO: A new material applied in an electrochemical sensor for detection of Cd(II) ions in aqueous solutions

AbstractA metal organic framework/reduced graphene oxide nanocomposite is fabricated using an effective two‐step protocol. X‐ray diffraction and scanning electron microscopy results demonstrate that the MIL‐53(Fe) is formed on the reduced graphene oxide's surface with an average particle size of 1.13 μm. A glassy carbon electrode modified with MIL‐53(Fe)/rGO is obtained by drop‐casting of the nanomaterial onto the GCE's surface, and this result is proven by electrochemical measurements. The glassy carbon electrode modified with MIL‐53(Fe)/rGO is used as an electrochemical sensor for detection of Cd2+ in aqueous solutions by a differential pulse voltammetry technique. The sensor shows outstanding merits including the ability of direct detection, a rapid detection time, and a quite high sensitivity. The relationship between the sensor's output signal and the concentration of Cd2+ ions is linear in the concentration range from 1.0 to 7.0 μM. The sensor has a detection limit of 698 nM.

A poly(neutral red)/porous graphene modified electrode for a voltammetric hydroquinone sensor

In this work, a glassy carbon electrode was modified with poly(neutral red)/porous graphene (PNR/P-Gr/GCE). The electrode was developed for use in an electrochemical sensor to determine hydroquinone (HQ) in skin whitening creams. The electrode was prepared by drop casting P-Gr on the GCE surface, followed by electro-polymerization of neutral red in deep eutectic solvent (DES) without an acid dopant. The fabrication of the electrode was optimized and then characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). The electrochemical properties of the electrode were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The PNR/P-Gr/GCE was used to determine HQ by adsorptive stripping differential pulse voltammetry (AdSDPV). Under optimal detection conditions, the electrode was 2 and 5 times more sensitive toward HQ than a P-Gr/GCE and an unmodified electrode, respectively. The developed electrode determined HQ concentrations from 0.005 to 70 µg mL−1 and exhibited a detection limit of 1.7 ng mL−1. The preparation of the electrode showed good repeatability (RSDs between 2.19 and 3.83%, n = 15), reproducibility (RSD < 1.87%, n = 6), and anti-interference properties. The proposed method successfully quantified HQ in skin whitening creams with recoveries between 89 ± 2 and 105.1 ± 0.2%. There was no significant difference at a 95% confidence level between the results obtained using the proposed method and those from UV-derivative spectrophotometry. This electrode presents a promising approach to HQ determination in skin whitening creams.

Mechanism and kinetics of Gold Nanoparticles Electrodeposited from Au (III) Ions Dissolved in a Deep Eutectic Solvent and Its Analytical Performance Towards Dopamine Quantification

The mechanism and kinetics of the electrochemical nucleation and growth of gold nanoparticles, AuNPs, onto a glassy carbon electrode, GCE, from Au(III) dissolved in the reline deep eutectic solvent, DES, at 70 °C, were assessed, for the first time. From the potentiodynamic technique it was found that gold electrodeposition onto the GCE substrate (Au(III)DES + 3e− (GCE) = Au(s)/GCE) is a diffusion-controlled process that requires of an overpotential nucleation to occur. The potentiostatic current density transients, recorded at different applied overpotentials, during the electrodeposition of AuNPs were described by a mechanism where multiple nucleation of 3D gold centers with mass-transfer controlled growth, occurs simultaneously with Au(III) adsorption (at the early stages) and the DES residual water reduction on the growing surfaces of the Au nuclei. From this analysis the diffusion coefficient of Au(III) ions was estimated as (2.56 ± 0.12) × 10−9 cm s−1 and it was found that the number density of Au nuclei, N s, depends exponentially on the applied overpotential while the nucleation frequency, A, was practically constant and the water reduction contribution increases linearly. From SEM images and EDX spectrum of the GCE surface, electrodeposited with gold (GCE/AuNPs), it was found that the Au deposit was formed by aggregates, (183 ± 37) nm average size, of AuNPs (of ca 50 nm diameter) and a density of (1.8 ± 0.3) × 109 aggregates cm−2. The GCE/AuNPs was used for the Dopamine, DA, electrochemical quantification in the presence of uric acid, UA, with the following analytical performance: sensitivity of (32.49 ± 0.37) μA mM−1 and (28.6 ± 0.2) μM detection limit.

Hybrid nanostructures of WS2 nanoflowers on N, B co-doped rGO for sensitive amperometric detection of Nilutamide

A sensitive amperometry technique is employed for the detection of Nilutamide (NLM, anticancer drug) in practical biological fluids based on the development of WS2 nanoflowers on the N, B-rGO matrices. A simple hydrothermal approach is used to create an efficient two-dimensional (2D) hybrid material comprising WS2 nanoflowers on nitrogen, boron doped reduced graphene oxide (WS2/N, B-rGO) nanocomposite for the electrochemical detection of NLM. Different analytical and spectroscopic approaches were used to confirm the successful synthesis of WS2/N, B-rGO. This synthesized material is modified on the GCE surface and acts as an electrochemical sensor for the detection of NLM, and it shows a wide linear range of 0.01–250 μM and 0.003 μM of a lower limit of detection. Furthermore, the nanocomposites have a lot of dedicated sites and greater surface area, thus improving the channels between the electrocatalyst and the electrolyte. By measuring the NLM concentration in a biological sample, WS2/N, B-rGO/GCE possesses a novel strategy for improving electrochemical activity, and it was subsequently used in practical applications.

Fast and Efficient Voltammetric Detection of L-Tryptophan in Dietary Supplements Using Carbon Electrodes Modified with Poly(L-Arginine)

Tryptophan (TRYP) is an essential amino acid that plays several key roles in different physiological processes, ranging from acting as a building block for protein synthesis to being involved in neurotransmission and cellular signaling.1 Humans can only obtain TRYP from food intake,1 and therefore this compound is frequently added to dietary supplements. Considering the potential toxic effects that arise from TRYP overdoses,2 an efficient quality control should be performed on products containing TRYP in their formulations. In this way, this work proposes an efficient voltammetric sensor as a cost-effective and feasible tool to detect TRYP in commercial supplements. The sensor was based on glassy carbon electrodes modified with poly(L-arginine) (GCE/p-ARG), which was electrochemically synthesized in situ from L-arginine monomers.3 The conditions for p-ARG electropolymerization were optimized through multivariate statistical approaches in order to enhance the electrode’s sensing capability. Cyclic voltammetry and electrochemical impedance spectroscopy analysis in the presence of [Fe(CN)6]3-/4- redox probe showed that p-ARG significantly improved the electron transfer at the electrode surface. TRYP was irreversibly oxidized on GCE/p-ARG displaying a peak at +0.73 V (vs. Ag/AgCl), which was more intense than the anodic peak showed by the bare GCE. This was due to the presence of p-ARG on the GCE surface, which enabled the occurrence of multiple interactions that favoured TRYP detection. The amino acid oxidation followed a diffusion-controlled mechanism and showed to be dependent on the supporting electrolyte pH. A linear relationship between the anodic peak current (obtained through square wave voltammetry) and the TRYP concentration was observed in the range from 1.0 to 7.0 μmol L-1. Limits of detection and quantification were found to be equal to 0.30 and 0.91 μmol L-1, respectively. The developed electroanalytical method was successfully applied to detect TRYP in dietary supplements, with good precision and accuracy. In conclusion, it can be stated that the GCE/p-ARG is a promising candidate for food and pharmaceutical industry to enable cheap, fast, and reliable quality control of TRYP-based commercial products. References M. Platten, E. A. A. Nollen, U. F. Röhrig, F. Fallarino, and C. A. Opitz, Nature Reviews Drug Discovery, 18, 379–401 (2019).Y. Xia, F. Zhao, and B. Zeng, Talanta, 206 (2020).J. Soleymani et al., Materials Science and Engineering C, 77, 790–802 (2017).

Real-time electrochemical quantification of H2O2 in living cancer cells using Bismuth based MOF

Metal-organic frameworks (MOFs) are receiving significant attention as supporting materials to load or encapsulate metal nanoparticles for electrochemical sensing applications owing to their porous structure and large surface area. In this work, Ag nanoparticles were incorporated upon Bi- terephthalic acid MOF (Bi-BDC) support and used as a viable electrochemical probe for hydrogen peroxide (H2O2) detection for the first time. Interestingly, the Ag-Bi-BDC (s) MOF modified GCE surface revealed remarkable electrocatalytic activity towards H2O2 detection as compared to its individual constituents. The enhanced current response towards the reduction of H2O2 is due to the synergistic combination of the strong binding interaction of the analyte on Ag-Bi-BDC (s) MOF surface through Bi3+ sites and the increased local availability of adsorbed H2O2 molecules, assisted by the high porosity of the MOF, and excellent catalytic activity of Ag particles. The fabricated sensor exhibited two linear ranges covering over four orders of magnitude with sensitivities of 886 and 13.9 μA mM−1cm−2. Besides, the proposed sensor also displayed a shorter response time (t < 1.8 s) and a lower detection limit of 20.1 nM which surpasses the previously reported similar works. Furthermore, the effect of interfering species on the reduction peak current response were studied and showed excellent selectivity for H2O2. The developed sensor also possesses good repeatability, reproducibility, and stability. Finally, the fabricated sensor exhibited good real time application in detecting H2O2 secreted from THP-1 and AtT-20 cancer cells. Hence, Ag incorporated Bi-BDC (s) MOF/GCE may be used as an alternative potential sensor material for enhanced electrochemical detection of hydrogen peroxide and other similar molecules.

Electrochemical detection of DNA damage caused by novel potential 2-nitroimidazole naphthalimide-based hypoxia tumor-targeting agent with mimimum side effects

In this work, we designed and synthesized two novel 2-nitroimidazole-naphthalimide-derived antitumor agents N-(2-(naphthalimide)ethyl)-2-(2-nitroimidazole)acetamide (D-2) and N-(2-(5-nitro-naphthalimide)ethyl)-2-(2-nitroimidazole)acetamide (D-5). The oxidative damage induced by the interaction between D-2 (D-5) and DNA was investigated by CV and DPV. The efficient electrochemical biosensors were prepared through modifying GCE with calf thymus DNA, poly dA and poly dG, respectively. The redox mechanism of D-2 (D-5) on GCE surface involved the reduction of 2-nitro group on imidazole ring and the oxidation of methylene linked naphthalimide skeleton and 2-nitroimidazole. The results of voltametric evaluation of interaction between antitumor agent and DNA/GCE revealed the oxidative damage of DNA caused by D-2 (D-5). In addition, UV–vis absorption and fluorescence spectra were investigated to further distinguish the interaction mode between D-2 (D-5) and DNA, implying the intercalation mode of D-2 (D-5) toward base pairs of DNA with a high affinity. At last, D-2 and D-5 were proved to have significantly better cell selectivity than mitonafide, the fact indicated that D-2 and D-5 had the potential for becoming lead antitumor agents and eliminating the side effects toward normal cells.

A “two-step” assay based on electro-activation for rapid determination of methylglyoxal in honey and beer

Methylglyoxal (MGO), a dicarbonyl compound in living organism, food and environment, has been associated with disease diagnosis and human health. The current electrochemical detection methods rely on the use of advanced materials. In this work, a non-advanced materials “two-step” assay including electrode electro-activation and MGO detection was developed. In the section of electro-activation, an activation method of GCE for MGO detection was established; and the composition changes on GCE surface caused by electro-activation, including functional groups and surface defects, have been carefully studied. The effect of carbonyl and surface defects induced by electro-activation on MGO detection was discussed. In section of MGO detection, the raise of background current caused by electro-activation was minimized by background subtraction; and the effect of interferences can be weakened by adjusting pH. The MGO signal on proposed activated GCE improved 20-fold than bare GCE. The recoveries were 72.38–109.16% in honey and beer, and RSDs were 0.24–9.63% without significant difference with HPLC method and comparable with advanced material modified sensors.

An innovative electrically conductive biopolymer based on poly(β‐cyclodextrin) towards recognition of ascorbic acid in real sample: Utilization of biocompatible advanced materials in biomedical analysis

In this study, a sensitive platform was designed for the electrocatalytical oxidation and recognition of ascorbic acid (AA) based on poly(β-cyclodextrin) modified glassy carbon electrode (p(β-CD-GCE). Electropolymerization of β-CD on the surface of GCE was performed on the potential range of -1 to 1.5V. So, a novel biopolymer was prepared on the surface of GCE towards sensitive recognition of AA in human plasma samples. The developed platform has good sensitivity and accuracy for electrooxidation and detection of AA with lower limit of quantification (LLOQ) of 1nM and linear range of 1nM to 100 mM. Moreover, the designed electrochemical sensor was employed for the analysis of AA on human plasma samples with high sensitivity. Based on advantages of p(β-CD) prepared by electropolymerization procedure (green, fast, homogeny, and efficient eletrocatalytical behaviour), this conductive biopolymer showed excellent analytical behaviour towards electrooxidation of AA. It is expected that the prepared polymeric interface is able to use in the analysis of biological species in clinical samples.