Fluorescence detection of valence speciation of Cr(III) based on the catechol oxidase mimic enzyme activity of CuSeNP nanozymes.

Copper selenide nanoparticles (CuSeNP) were synthesized using histidine, ethylenediamine, and sodium selenate as precursors by one-step microwave digestion methods. The as-prepared CuSeNPs exhibit excellent catechol oxidase mimic enzyme and catalase (CAT)-like activities. Dopamine (DA) can be oxidized to aminochrome with H2O2 by CuSeNPs, and the intermediate product aminochrome can further react with α-naphthol to yield a highly fluorescent derivative. It was confirmed that Cr(III) could adsorb on the surface of CuSeNPs and inhibit the production of semiquinone radicals in the reaction system, and the catalytic activity of CuSeNPs was inhibited. The detection mechanisms, kinetics, and catalytic properties of CuSeNPs were systematically investigated. As a result, a novel fluorescence method for the assay of Cr(III) was established. The feasibility of CuSeNP nanozyme in detecting speciation Cr(III) in food samples was explored with satisfactory results. It showed the obvious potential for developing effective and dependable fluorescent detection method for protecting food safety.

Metal-organic framework composite Mn/Fe-MOF@Pd with peroxidase-like activities for sensitive colorimetric detection of hydroquinone.

The construction of highly sensitive detection methods for hydroquinone (HQ) in environment and cosmetics is of great significance for environmental protection and human health. In this work, a novel detection method for HQ was successfully developed by constructing a metal-organic framework mimic enzyme colorimetric sensor (Mn/Fe-MOF@Pd1.0) with excellent peroxidase-like activity, which was synthesized by doping manganese ions into Fe-MOF by introducing bimetallic active centers, thereby improving the peroxidase-like activity of Fe-MOF, and the acid resistance and stability of Mn/Fe-MOF were improved by supporting palladium (Pd NPs). It is proven that Mn/Fe-MOF@Pd1.0 promoted the decomposition of hydrogen peroxide (H2O2) to generate active species, therefore, oxidized chromogenic substrate discoloration. On this basis, the detection of HQ based on the Mn/Fe-MOF@Pd1.0 colorimetric sensor was constructed, in which the limit of detection (LOD) was 0.09 µM in the linear range of 0.3-30 µM. Furthermore, Mn/Fe-MOF@Pd1.0 was successfully used for detecting HQ in hydroquinone whitening cream and actual water samples. The successful synthesis of Mn/Fe-MOF@Pd1.0 may provide new insights for further study of the enzyme-like activity of metal-organic framework composites, and the constructed facile and sensitive sensor system could broaden the application prospects of HQ detection.

RuO2/rGO heterostructures as mimic peroxidases for colorimetric detection of glucose.

The successful synthesis of ruthenium oxide/reduced graphene oxide (RuO2/rGO) heterostructures by one-pot hydrothermal method using graphene oxides and RuCl3 as precursors is reported. The heterostructures had high peroxidase-like (POD-like) activities, which catalyzes the oxidation of classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 to create a blue colored reaction product. The catalytic activity was significantly enhanced by the synergistic effect between RuO2 nanoparticles and rGO. RuO2/rGO had a low Km of 0.068 mM and a high vmax of 1.228 × 10-7 M·s-1 towards TMB in the TMB-H2O2 catalytic oxidation system. In addition, the POD-like activity originating from the electron transfer mechanism was confirmed by cytochrome C (Cyt C) oxidation experiment. A colorimetric method based on RuO2/rGO heterostructures was developed with good sensitivity and selectivity for glucose detection with a limit of detection of 3.34 µM and a linear range of 0-1500 µM. The RuO2/rGO heterostructures have potential applications in the biomedical areas, such as biosensor and diagnostics.

Colorimetric aptasensor for sensitive detection of quinclorac based on exonuclease III-assisted cyclic release of phosphorodiamidate morpholino oligomer mimic enzyme strategy.

Here, a colorimetric aptasensor was constructed for sensitively detecting quinclorac (QNC), a common herbicide. The aptasensor involved a novel amplification strategy and a classical strand displacement strategy. The amplification strategy, termed exonuclease III (Exo III)-assisted cyclic release of phosphorodiamidate morpholino oligomer (PMO) mimic enzyme strategy, was developed based on two new findings on PMO: 1) DNA hybridized with PMO could resist Exo III digestion; 2) a designed G-rich PMO (named P2) could bind to hemin to form a G-quadruplex PMOzyme with peroxidase-like activity. In this strategy, a designed DNA-PMO duplex (D1-P1) completely hybridized with DNA2 (D2) in the other designed DNA-PMO duplex (D2-P2) to trigger D2 degradation by Exo III and cyclic release of P2. After that, the hemin-binding P2 catalyzed colorless tetra-methyl benzidine (TMB) to blue TMB+. The cycle process was performed at high Exo III concentrations without strict control and with constant background signals. In that case, the developed strategy was sensitive, efficient, easy to operate, reliable, and ultralow background. Meanwhile, a QNC aptamer was used to develop the strand displacement strategy based on magnetic beads. The colorimetric aptasensor was sensitive and selective for QNC detection with a detection limit of 7.1 ng mL-1. It was successfully applied to detect QNC in soil and river water with good recovery rates (92-98%) and a relative standard deviation (n = 3) <5%. The success of this study could provide a general reference strategy for developing sensitive aptasensors and other nucleic acid-related sensors.

Colorimetric and Fluorescence Dual-Mode Biosensors Based on Peroxidase-Like Activity of the Co3O4 Nanosheets.

The mimic enzyme has become a research hotspot in recent years because of its advantages of high stability, convenient preparation, and low price. In this article, Co3O4 nanosheets synthesized by a simple hydrothermal method possess the characteristics of a peroxidase-like activity. The results demonstrated that 3,3',5,5'-Tetramethylbenzidine (TMB) could be oxidized by H2O2 to produce a typical blue product (oxTMB) which has a strong absorption at 650 nm wavelength with the help of the Co3O4 nanosheets. Thus, a simple and sensitive colorimetric detection method for H2O2 was established with a good linear relationship (2-200 µM) and a low limit of detection (0.4 µM). Meanwhile, the colorimetric product can effectively quench the fluorescence emitted by Ru(bpy)3 2+. Therefore, a colorimetric and fluorescence dual detection mode photochemical sensor for H2O2 detection is constructed based on the principle of the inner filter effect (IFE) between the colorimetric product (oxTMB) and Ru(bpy)3 2+. It can effectively avoid the false positive problem of a single detection mode. In the presence of glucose oxidase, glucose can be catalyzed to produce gluconic acid and H2O2; therefore, the sensor can also be used for the determination of glucose with a good linear relationship (0.02-2 µM) and a low limit of detection (5 nM). Experimental results showed that the sensor has a high sensitivity and strong anti-interference ability which can be used for the detection of actual samples.

Metal-organic framework as a mimetic enzyme with excellent adaptability for sensitive chemiluminescence detection of glutathione in cell lysate.

A novel [Co(L)(H2O)2] (1) was obtained by hydrothermal method and it exhibited a 1D chain with exposed carboxyl groups, the unique coordination mode made it have unusual physical and chemical stability. Meanwhile, 1 showed peroxidase-like and weak oxidase-like activity. 1 as a peroxidase mimic enzyme had an excellent affinity for the substrates luminol and H2O2. Compared with HRP, 1 had catalytic activity in a wide pH range and showed the best catalytic activity at pH 7.4. Meanwhile, the catalysis process of 1 was reversible and recyclable, and the catalytic activity remained stable after different pH and temperatures and long-time storage. Based on the inhibition of glutathione on luminol-H2O2-MOF 1 chemiluminescence signal, a chemiluminescence method for the determination of glutathione has been proposed with high sensitivity and selectivity and had been applied for detecting glutathione in cell lysate with satisfactory results.

Co-MOF-74 based Co3O4/cellulose derivative membrane as dual-functional catalyst for colorimetric detection and degradation of phenol.

Smart nanomaterials that can simultaneously detect and eliminate contaminants in water environment are significant for health protection. To achieve such goal, Co-MOF-74 was in-situ assembled on regenerated cellulose membranes followed by calcination process, thus achieving dual-functional Co3O4/cellulose derivative membrane (Co3O4/CDM) catalyst. The Co3O4 morphology was readily controlled by further recrystallization of the deposited MOF precursor. Combining the high enrichment ability of cellulose membrane and outstanding peroxidase-active of Co3O4, the fast color reaction for phenol was accomplished within 10 min by Co3O4/CDM with the assistance of H2O2 and 4-aminoantipyrine (4-AAP). Moreover, the Co3O4/CDM also portrayed an excellent degradation property for phenol elimination via sulfate radical-advanced oxidation processes (SR-AOPs). The degradation efficiency of phenol reached 93% in 20 min, and the possible mineralization mechanism was proposed based on the XPS and LC-MS analysis. Thus, Co-MOF-74 derived Co3O4/CDM shows excellent properties in aiding the colorimetric detection and degradation of phenol in aqueous solutions.

Investigation of the inhibited biotoxicity of heavy metals towards 5- formylcytosine in rice by hydrochar based on photoelectrochemical biosensor.

A photoelectrochemical (PEC) biosensor was constructed for 5-formylcytosine (5fC) nucleotide detection based on Ag2S@WS2 photoactive material and FeVO4 catalytic signal quenching. After Ag2S@WS2 was modified onto the ITO substrate surface, 5fC recognition reagent of Au@4-amino3hydrazino5mercapto-1,2,4-triazol (Au@AHMT) was further modified through electrostatic adsorption. Afterwards, based on the specific chemical reaction between -NH2 and -CHO, 5fC can be selectively recognized and captured. Subsequently, the nanoenzyme of FeVO4 was recognized based on the specific reaction between the phosphate group of 5fC nucleotide and Fe3+. Under the catalysis of FeVO4, the 4-chloro-1-naphthol in the detection solution can be oxidized to generate a precipitate, which will be retained on the electrode surface to inhibit the PEC signal. The developed method presented a widely dynamic range from 0.1 to 400 nM. The detection limit was 0.062 nM (3σ). This method also showed good detection selectivity, reproducibility and stability. The applicability was verified by investigating 5fC content change in genomic DNA of rice tissues after incubated with heavy metals. Moreover, the inhibited influence of hydrochar towards heavy metals was also assessed.

Histamine detection in fish samples based on indirect competitive ELISA method using iron-cobalt co-doped carbon dots labeled histamine antibody.

Due to complex matrixes and specific reagent deficiency, the rapid detection of histamine is still a challenge to date. Based on the high peroxidase-like activity of iron-cobalt co-doped carbon dots, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) was established for histamine detection using the mimic enzyme labeled with histamine antibody (His-Ab). Through the competitive binding of the labeled His-Ab to solid-phase and sample antigens, histamine content was detected with a linear range of 2.5-150 µg mL-1. The detection limit based on 3σ/K was 0.50 mg kg-1, which was much lower than those of commercial His-kit and HPLC methods. The ic-ELISA method was applied to histamine detection in fish samples with the recovery of (103.4 ± 0.5)%, which was in accord with those of commercial His-kit and HPLC methods. The results indicated that the established ic-ELISA method was suitable for rapid detection of histamine in fish samples with high accuracy, sensitivity and stability.

Multienzyme-Mimic Ultrafine Alloyed Nanoparticles in Metal Organic Frameworks for Enhanced Chemodynamic Therapy.

Nanozyme-based chemodynamic therapy (CDT) has emerged as an effective cancer treatment because of its low side effects and without the requirement of exogenous energy. The therapeutic effect of CDT highlights the pivotal importance of active sites, H2 O2 supplement and the glutathione (GSH) depletion of a nanozyme. The construction of a single kind of catalyst with multiple functions for the enhanced CDT is still a big challenge. In this work, seven types of bimetallic nanoparticles are synthesized using a metal-organic framework (MOF) as a stable host instead of a Fenton or Fenton-like ions supplier. Among them, Cu-Pd@MIL-101 with an alloy loading of 9.5 wt% modified by PEG (9.5% CPMP) is found to exhibit the highest peroxidase (POD) like activity combined with a superoxide dismutase (SOD) mimic activity and the function of GSH depletion. The in vivo results suggest that the stable and ultrafine nanoparticles possess favorable CDT effect for tumor and good biosafety as well as biocompatibility. This work has provided a credible strategy to construct nanozymes with an excellent activity and may pave a new way for the design of enhanced tumor CDT treatment.

Cyclodextrin-Modified CeO2 Nanoparticles as a Multifunctional Nanozyme for Combinational Therapy of Psoriasis.

PURPOSE: Reactive oxygen species (ROS)-induced oxidative stress plays a key role in the pathogenesis and progression of psoriasis by causing inflammation. Antioxidative strategies eradicating ROS may serve as effective and easy treatment options for psoriasis, while nanozymes with intrinsic antioxidant enzyme-like activity have not been explored for psoriasis treatment. The aim of this study is to fabricate ß-cyclodextrins (ß-CDs)-modified ceria nanoparticles (ß-CDs/CeO2 NPs) with drug-loaded and multimimic-enzyme activities for combinational psoriasis therapy. METHODS: The ß-CDs/CeO2 NPs were synthesized by a hydrothermal method using unmodified ß-CDs as a protecting agent. The structure, size and morphology were analyzed by dynamic light scattering, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. Considering the superoxide dismutase (SOD)- and catalase-mimetic activities, the in vitro antioxidant activity of the ß-CDs/CeO2 NPs was investigated. After dithranol (DIT) was loaded, the drug-loading capacity and release profile were determined by UV-visible light spectrophotometer and high-performance liquid chromatography. The anti-psoriatic efficacy was studied in the imiquimod (IMQ)-induced mouse model on the basis of morphological evaluation, psoriasis area and severity index calculation (PASI), and inflammatory cytokine expression. RESULTS: The average particle size of the blank ß-CDs/CeO2 NPs was 60.89±0.32 nm with a polydispersity index (PDI) of 0.12, whereas that of the DIT-loaded NPs was 79.38±1.06 nm with a PDI of 0.27. TEM results showed the as-prepared NPs formed a uniform quasi-spherical shape with low polydispersity. XPS indicates synthesized NPs have a mixed Ce3+/Ce4+ valence state. FTIR spectroscopy confirmed the presence of ß-CDs and DIT in the NPs. Inhibition of superoxide anion rate by NPs could be reached to 79.4% in the presence of 200 µg/mL, and elimination of H2O2 efficiency reached about 50% in the presence of 40 µg/mL, demonstrating excellent superoxide dismutase- and catalase-mimicking activities, thereby providing remarkable cryoprotection against ROS-mediated damage. Furthermore, ß-CDs on the surface endowed the NPs with drug-loading function via host-guest interactions. The entrapment efficiency and drug loading of DIT are 94.7% and 3.48%, respectively. The in vitro drug release curves revealed a suitable release capability of DIT@ß-CDs/CeO2 NPs under physiological conditions. In IMQ-induced psoriatic model, the DIT@ß-CDs/CeO2 NPs exhibited excellent therapeutic effect. CONCLUSION: This study may pave the way for the application of nanozyme ß-CDs/CeO2 NPs as a powerful tool for psoriasis therapy.

Low-background electrochemical biosensor for one-step detection of base excision repair enzyme.

We develop a low-background electrochemical biosensor for one-step detection of uracil DNA glycosylase (UDG) based on the host-guest interaction and iron-embedded nitrogen-rich carbon nanotube (Fe-N-C) that mimics enzyme-mediated electrocatalysis to achieve signal amplification. In this work, Fe-N-C is initially immobilized on a glassy carbon electrode, followed by the immobilization of ß-cyclodextrin (ß-CD). We construct the signal probes by assembling the methylene blue (MB)-labeled hairpin DNAs onto the surface of Au nanoparticles (AuNPs) to form the MB-hairpin/AuNP probes. Due to the steric effect of AuNPs and the stem-loop structure of hairpin DNA, MB is prevented from entering the cavity of ß-CD on the electrode. In contrast, UDG enables the removal of uracil from the U•A pairs in the stem of hairpin DNA probe to generate apurinic/apyrimidinic (AP) sites, leading to the assembly of MB-hairpin/AuNP probes on the electrode based on host-guest reaction between ß-CD and MB. Meanwhile, L-cysteine (RSH) is oxidized by O2 to disulfide L-cystine (RSSR) and H2O2. In the presence of H2O2, Fe-N-C catalyzes the oxidation of MB to generate an amplified electrochemical signal. Notably, the Fe-N-C-catalyzed oxidation of MB is mediated by the oxidation of RSH by O2 instead of external H2O2, greatly simplifying the experimental procedures and improving the electrochemical signal. Due to the introduction of host-guest recognition, this electrochemical biosensor displays a low-background signal and high signal-to-noise ratio, enabling the one-step sensitive measurement of UDG with a detection limit of 7.4 × 10-5 U mL-1. Moreover, this biosensor can measure UDG in crude cell extracts and screen the inhibitors, providing a new platform for biomedical research.

One step preparation of CN-WS2 nanocomposite with enhanced photoactivity and its application for photoelectrochemical detection of 5-formylcytosine in the genomic DNA of maize seedling.

Carbon nitride and WS2 nanocomposite (CN-WS2) with excellent photoelectric activity was prepared by one-step thermal polymerization. By the new strategy of simultaneously loading C and N elements on pure WS2, the formation of CN-WS2 brings high mobility, ultra-fast charge carrier separation and transport, and slows down the recombination rate of electrons and holes. Then, a novel photoelectrochemical biosensor was constructed for 5-formylcytosine detection based on CN-WS2 composite, aldehyde reaction probe (ARP) and ZnFe2O4, where CN-WS2 composite was employed as photoactive material, ARP was used as 5-formylcytosine capture reagent, and ZnFe2O4 was adopted as artificial mimic enzyme. Under the catalysis effect of ZnFe2O4, 4-chloro-1-naphthol was quickly oxidized by H2O2 to produce the insoluble substance of benzo-4-chlorohexadienone, which would be deposited on the electrode surface and caused a decreased PEC response. Under optimal experimental conditions, the biosensor showed low detection limit of 3 pM. This method can also discriminate 5-formylcytosine with other cytosine derivatives. More importantly, the applicability of this method was demonstrated by assessing the effect of antibiotics on the content of 5-formylcytosine in the root, stem and leave of maize seedlings.

Double-integrated mimic enzymes for the visual screening of Microcystin-LR: Copper hydroxide nanozyme and G-quadruplex/hemin DNAzyme.

Recently, mimic enzymes have obtained particular interest by their high activity, stability, and biocompatibility. In this work, by coupling copper hydroxide nanozyme and G-quadruplex/hemin DNAzyme to form a double-integrated mimic enzyme, a visual, sensitive and selective immunosensor was established to detect microcystin-LR (MC-LR). In this immunoassay, the microplates were modified with core-shell silica/nickel silicate as the substrate to capture MC-LR antigens. Then, Cu(OH)2 nanocages with fine regulation were used as the label to capture the secondary antibody for immunoreaction and the DNA primer for propagation, followed by using hybridization chain reaction to amplify the DNA primer, thus numerous DNAzymes (G-quadruplex/hemin) can be formed on the surface of Cu(OH)2 nanocages with the aid of hemin. Such double-integrated mimic enzyme including Cu(OH)2 nanozymes and DNAzymes showed excellent peroxidase activity for the chromogenic reaction of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), which realized the visual detection of MC-LR in the range from 0.007 to 75 µg/L with the detection limit of 6 ng/mL, and thus provided the probability for the portable assessment of MC-LR in real sample.

Internal Light Source-Driven Photoelectrochemical 3D-rGO/Cellulose Device Based on Cascade DNA Amplification Strategy Integrating Target Analog Chain and DNA Mimic Enzyme.

In this work, a chemiluminescence-driven collapsible greeting card-like photoelectrochemical lab-on-paper device (GPECD) with hollow channel was demonstrated, in which target-triggering cascade DNA amplification strategy was ingeniously introduced. The GPECD had the functions of reagents storage and signal collection, and the change of configuration could control fluidic path, reaction time and alterations in electrical connectivity. In addition, three-dimentional reduced graphene oxide affixed Au flower was in situ grown on paper cellulose fiber for achieving excellent conductivity and biocompatibility. The cascade DNA amplification strategy referred to the cyclic formation of target analog chain and its trigger action to hybridization chain reaction (HCR), leading to the formation of numerous hemin/G-quadruplex DNA mimic enzyme with the presence of hemin. Subjected to the catalysis of hemin/G-quadruplex, the strong chemiluminiscence of luminol-H2O2 system was obtained, which then was used as internal light source to excite photoactive materials realizing the simplification of instrument. In this analyzing process, thrombin served as proof-of-concept, and the concentration of target was converted into the DNA signal output by the specific recognition of aptamer-protein and target analog chain recycling. The target analog chain was produced in quantity with the presence of target, which further triggered abundant HCR and introduced hemin/G-quadruplex into the system. The photocurrent signal was obtained after the nitrogen-doped carbon dots sensitized ZnO was stimulated by chemiluminescence. The proposed GPECD exhibited excellent specificity and sensitivity toward thrombin with a detection limit of 16.7 fM. This judiciously engineered GPECD paved a luciferous way for detecting other protein with trace amounts in bioanalysis and clinical biomedicine.

Impedimetric aptasensor for nuclear factor kappa B with peroxidase-like mimic coupled DNA nanoladders as enhancer.

In this work, we developed a sensitive and universal aptasensor for nuclear factor kappa B (NF-κB) detection based on peroxidase-like mimic coupled DNA nanoladders for signal amplification. The dsDNA formed by capture DNA S1 and NF-κB binding aptamer (NBA) was firstly assembled on electrode surface. The presence of target NF-κB then led to the leave of NBA from electrode surface and thus provided the binding sites for immobilizing initiator to trigger in situ formation of DNA nanoladders on electrode surface. Since the peroxidase-like mimic manganese (III) meso-tetrakis (4-Nmethylpyridyl)-porphyrin (MnTMPyP) interacts with DNA nanoladders via groove binding, the insoluble benzo-4-chlorohexadienone (4-CD) precipitation derived from the oxidation of 4-chloro-1-naphthol (4-CN) could be formed on electrode surface in the presence of H2O2, resulting in a significantly amplified EIS signal output for quantitative target analysis. As a result, the developed aptasensor showed a low detection limit of 7pM and a wide linear range of 0.01-20nM. Featured with high sensitivity and label-free capability, the proposed sensing scheme can thus offer new opportunities for achieving sensitive, selective and stable detection of different types of target proteins.

A novel impedimetric immunosensor based on AgI mimic enzyme nanomaterial for detecting carcinoembryonic antigen / 第二军医大学学报

Objective Todesign a novel impedimetric immunosensor basedon AgI mimic enzyme nanomaterial for detecting carcinoembryonic antigen (CEA) in serum with high sensitivity. Methods A novil chitosan modified AgI (CS-AgI) nanomaterial was synthesized and was characterized by transmission electron microscope (TEM) and Fourier transform infrared spectroscopy (FTIR). Then by utilizing CS-AgI labeled CEA antibody as tags, we prepared a novel impedimetric immunosensor on the gold electrode using the sandwich-type immunoassay. The electrochemical propertiesof the prepared impedimetric immunosensor were observed by electrochemical workstation and the concentration of CEA in sample was quantitatively analyzed. Results The synthesized CS-AgI nanoparticles were spherical in shape, with the particle size being 100 nm; the particles were employed to construct immunosensor as signal markers. The immunosensor had an excellent electrochemical performance in detection of CEA under PBS base solution of pH = 7, and its AC impedance response increased with the increase of the logarithm of CEA concentration, exhibiting a good linear relationship in the range of 0. 1ng/mL to 80ng/mL (r = 0.996), with a detection limkof 0. 05 ng/mL. Conclusion Based on AgI mimic enzyme nanomaterial, the impedance immunosensor prepared in this study shows a high sensitivity in detecting CEA; meanwhile, t has acceptable selectivity, repeatability and stability, providing an experimental evidence for early diagnosis and treatment of cancer.

Colorimetric determination of sarcosine in urine samples of prostatic carcinoma by mimic enzyme palladium nanoparticles.

The proposed palladium nanoparticles (Pd NPs), which with the catalytic activity similar to the horseradish peroxidase (HRP) mimic enzyme, can effectively catalyze the H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine sulfate (TMB) accompanied with a color change from colorless to blue in solution. And as a result, the sensitive detection of sarcosine can be realized by the naked eye observation and ultraviolet spectrophotometry, using Pd NPs as catalyst and TMB as the substrate of the simulation enzyme catalytic reaction. Under the optimal condition, the catalytic system of Pd NPs mimic enzyme can be used for the detection of sarcosine. It has been found that the color change could be clearly observed with the naked eyes, and the absorbance intensity at 653 nm showed a fine linear fitting with the concentration of sarcosine in the range from 0.01 µM to 50 µM, and the detection limit (3σ/S) for sarcosine was calculated to be 5.0 nM. In order to evaluate the feasibility and reliability, the method was also used for analyzing concentrations of sarcosine in human urine samples from diagnosed prostate cancer patients and healthy donors. It is expected to provide a convenient and efficient method for indirect evaluation for the diagnosis of prostatic carcinoma (PCa).

Studies on Elimination of H_2O_2 by D-glucosamine-Cu (Ⅱ) Complex / 中国海洋药物

Objective To study the catalytic capability of glucosamirie-Cu( Ⅱ) complex for decomposition of H2O2 and its relative factors. Methods Glucosamine-Cu( Ⅱ ) complex was prepared by the reaction of D-glucosamine hydrochloride with Cu2+ in aqueous solution, then added it into H2O2 solution. The concentration of H2O2 was determined by titrimetric analysis in a regular interval of time, the rate of decomposition of H2O2 was obtained in various conditions. Results Strong catalytic capability of glucosamine-Cu( Ⅱ ) complex was obtained at 30℃ pH 6. 5, the rate of decomposition was over 90% after 12h, and was almost 100% after 24h. Conclusion The complex of glucosamine-Cu( Ⅱ ) showed good catalytic capability for decomposition of H2O2.