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1.
Front Chem ; 9: 713104, 2021.
Article in English | MEDLINE | ID: mdl-34395382

ABSTRACT

In this work, a facile one-pot hydrothermal route was employed to synthesize a series of fluorescent carbon dots (CDs) by using 20 natural amino acids, respectively, as the starting materials. It was found that the CDs synthesized using phenylalanine could possess the intrinsic peroxidase-like activity that could effectively catalyze a traditional peroxidase substrate like 3, 3', 5, 5'- tetramethylbenzidine (TMB) in the presence of H2O2 to produce a blue solution; thereby, a catalytic sensing system for H2O2 has been developed. On the basis of this catalytic reaction, together with the fact that glucose oxidase (GOx) can catalyze the hydrolysis of glucose to generate H2O2, a sensitive catalytic sensing system for glucose could be further established. Furthermore, based on this catalytic reaction, taken together with the two enzymatic catalytic systems of acetylcholinesterase (AChE) and choline oxidase (CHO), a highly sensitive multi-catalytic sensing system could be successfully developed for organophosphorus (OPs) pesticides such as dimethoate, DDVP, and parathion-methyl. Limit of detections (LODs) of H2O2 and glucose were estimated to be 6.5 and 0.84 µM, respectively. The limit of detection of the sub-nM level could be obtained for tested dimethoate, DDVP, and parathion-methyl OPs pesticides. The established sensing systems can exhibit good practical application performance in serum and several fruit samples.

2.
Chemistry ; 27(28): 7646-7650, 2021 May 17.
Article in English | MEDLINE | ID: mdl-33871127

ABSTRACT

We show herein the phosphatase-like catalytic activity of coordination polymers obtained after adding Ag+ -ions to thiols bearing hydrophobic alkyl chains terminated with a 1,4,7-triazacyclononane (TACN) group. The subsequent addition of Zn2+ -ions to the self-assembled polymers resulted in the formation of multivalent metal coordination polymers capable of catalysing the transphosphorylation of an RNA-model compound (2-hydroxypropyl-4-nitrophenyl phosphate, HPNPP) with high reactivity. Analysis of a series of metal ions showed that the highest catalytic activity was obtained when Ag+ -ions were used as the first metal ions to construct the backbone of the coordination polymer through interaction with the -SH group followed by Zn2+ -ions as the second metal ions complexed by the TACN-macrocycle. Furthermore, it was demonstrated that the catalytic activity could be modulated by changing the length of the hydrophobic alkyl chain.

3.
Exp Ther Med ; 17(3): 1919-1929, 2019 Mar.
Article in English | MEDLINE | ID: mdl-30783469

ABSTRACT

The aim of the present study was to evaluate the potential use of 7 plasma miRNAs for liver fibrosis staging in patients with chronic hepatitis B virus (HBV) infection. Relative levels of miRNAs were measured using quantitative polymerase chain reaction and used to develop a diagnostic panel. A receiver operating characteristic (ROC) curve was drawn to evaluate the performance of individual miRNAs and the whole panel. It was identified that hsa-miR-122 exhibited significantly different expression levels between F4 and F3, F2, F1, and F0 fibrosis stages (P<0.05), and between F2 and F1 stages (P=0.045); hsa-miR-146a-5p, hsa-miR-29c-3p and hsa-miR-223 exhibited significantly different expression levels between F4 and F0 stages. ROC analysis revealed that hsa-miR-122-5p, hsa-miR-223 and hsa-miR-29c-3p identified patients with ≥F2 fibrosis with area under the curve (AUC) =0.745, 0.631 and 0.670, respectively. hsa-miR-122-5p identified patients with ≥F3 disease (AUC=0.783). hsa-miR-122-5p, hsa-miR-223 and hsa-miR-29c-3p identified patients with cirrhosis with AUC=0.776, 0.617 and 0.619, respectively. The miRNA panel exhibited a higher accuracy compared with individual miRNAs in discriminating between ≥F2, ≥F3 and F4 fibrosis stages with AUC=0.904, 0.889 and 0.835, respectively. hsa-miR-122-5p, hsa-miR-146a, hsa-miR-29c and hsa-miR-223 were positively correlated with fibrosis stage. hsa-miR-122-5p and hsa-miR-381-3p were negatively correlated with alanine aminotransferase, aspartate transaminase and HBV viral DNA load. These 7 miRNAs may serve as potential biomarkers of liver fibrosis in patients with HBV-associated fibrosis. The miRNA panel may serve as a novel non-invasive method for liver fibrosis staging.

4.
Org Biomol Chem ; 16(31): 5667-5676, 2018 08 08.
Article in English | MEDLINE | ID: mdl-30043797

ABSTRACT

Extending the research on 3,3',5,5'-tetramethylbenzidine (TMB) and its derivatives in analytical chemistry is important, considering that TMB is widely used as an enzyme catalytic substrate. In this work, two TMB derivatives, TMBS and TMBB, were synthesized via a facile and one-step condensation reaction between the -NH2 group of TMB and the -CHO group of salicylaldehyde or benzaldehyde. Because at low pH the two Schiff base compounds can release TMB which can emit strong fluorescence, the probes could show dual-modal signal responses, fluorescence and UV-vis absorption, towards the pH. Practical applications of pH sensing in Chinese rice vinegar and lemon juice samples were successfully demonstrated. On the basis of these findings, a catalytic chromogenic reaction was developed to monitor the pH with the naked eye, too. Furthermore, considering the chemical equilibrium reaction between CO2 and H2O and that glucose oxidase (GOD) can catalyse the dehydrogenation and oxidation reaction of ß-d-glucose to produce gluconic acid, both of which can result in lowering the pH values of the two Schiff base systems, highly sensitive and selective dual-modal sensing systems for detecting CO2 and ß-d-glucose have also been successfully established. Therefore, the two synthesized TMB derivatives can demonstrate their robust application potential.

5.
Anal Biochem ; 526: 58-65, 2017 06 01.
Article in English | MEDLINE | ID: mdl-28327452

ABSTRACT

A novel electrochemical sensor was presented for the determination of L-5-hydroxytryptophan (L-5-HTP) based on a graphene-chitosan molecularly imprinted film modified on the surface of glassy carbon electrode (GR-MIP/GCE). The morphology and composition of the imprinted film were observed in field emission scanning electron microscopy (FESEM), raman spectroscopy and fourier transform infrared (FTIR). The properties of the sensor were evaluated by electrochemical techniques. Under the optimal conditions, the peak currents of L-5-HIP were found to be linear in the concentration range of 0.05-7.0 µM, while the sensor also exhibited great features such as low detection limit of 6.0 nM (S/N = 3), superb selectivity against the structural analogues, good antidisturbance ability among coexisting components, excellent repeatability and stability. Moreover, the proposed method had been applied to the detection of L-5-HTP in human blood serum with a satisfactory recoveries ranging from 90.6% to 105.6%.


Subject(s)
5-Hydroxytryptophan/blood , Carbon/chemistry , Chitosan/chemistry , Graphite/chemistry , Molecular Imprinting/methods , Polymers/chemistry , 5-Hydroxytryptophan/chemistry , Biosensing Techniques/methods , Electrochemical Techniques/methods , Electrodes , Humans , Limit of Detection , Microscopy, Electron, Scanning , Spectrum Analysis, Raman
6.
Sci Rep ; 5: 15026, 2015 Oct 12.
Article in English | MEDLINE | ID: mdl-26456479

ABSTRACT

An important unresolved clinical issue is to distinguish hepatitis B virus (HBV) infection caused chronic hepatitis and their corresponding liver cirrhosis (LC). Recent research suggests that circulating microRNAs are useful biomarkers for a wide array of diseases. We analyzed microRNA profiles in the plasmas of a total of 495 chronic hepatitis B (CHB) patients, LC patients and healthy donors and identified 10 miRNAs that were differentially expressed between CHB and LC patients. Our logistic models show that three panels of miRNAs have promising diagnostic performances in discriminating CHB from LC. Blinded tests were subsequently conducted to evaluate the diagnostic performances in clinical practice and a sensitivity of 85% and specificity of 70% have been achieved in separating CHB from LC pateints. The expression levels of some circulating miRNAs were significantly correlated with HBV DNA load and liver function, such as prothrombin activity (PTA) and levels of alanin aminotransferase (ALT), albumin (ALB) and cholinesterase (CHE). Our results provide important information for developing novel diagnostic tools for distinguishing chronic HBV hepatitis and their corresponding cirrhosis.


Subject(s)
DNA, Viral/genetics , Hepatitis B virus/physiology , Hepatitis B, Chronic/diagnosis , Liver Cirrhosis/diagnosis , MicroRNAs/genetics , Adult , Alanine Transaminase/blood , Biomarkers/blood , Case-Control Studies , Cholinesterases/blood , DNA, Viral/blood , Diagnosis, Differential , Female , Gene Expression Profiling , Hepatitis B, Chronic/blood , Hepatitis B, Chronic/genetics , Humans , Liver Cirrhosis/blood , Liver Cirrhosis/genetics , Liver Function Tests , Logistic Models , Male , MicroRNAs/blood , Middle Aged , Prothrombin/metabolism , Sensitivity and Specificity , Serum Albumin/metabolism , Viral Load
7.
Biosens Bioelectron ; 61: 466-70, 2014 Nov 15.
Article in English | MEDLINE | ID: mdl-24934748

ABSTRACT

In this paper, a novel DNA-length-dependent fluorescent sensor was constructed based on the fluorescence resonance energy transfer. In the self-assembled multilayers (Quartz/GO/PDDA/Tx-DNA/PDDA/ZnO@CdS), ZnO@CdS and graphene oxide(GO) were employed as an energy donor and an energy acceptor, respectively. Single-stranded Tx-DNA (x represents different chain length of DNA) and poly(diallydimethylammonium) chloride (PDDA) were used as a linker. In the presence of complementary Px-DNA, the formation of double-stranded DNA leads to a change in chain length and achieves the purpose of changing the distance between ZnO@CdS and GO. Thereby, it enhances the efficiency of energy transfer between ZnO@CdS and GO resulting in the quench of fluorescence of ZnO@CdS, and thus different length DNA sequence was detected.


Subject(s)
Biosensing Techniques/instrumentation , DNA/analysis , Fluorescence Resonance Energy Transfer/instrumentation , Graphite/chemistry , Oxides/chemistry , Quantum Dots/chemistry , Equipment Design
8.
Anal Biochem ; 440(2): 220-6, 2013 Sep 15.
Article in English | MEDLINE | ID: mdl-23747534

ABSTRACT

A molecularly imprinted polymers (MIPs) microsensor was presented as a carbon fiber microelectrode (CFME) coating for specifically recognizing xanthine (Xan). The polymeric film was obtained based on the imprinted procedure of electropolymerization of pyrrole in the presence of the template molecule Xan by cyclic voltammetry, and template was removed by magnetic stirring. Under the optimum conditions, a satisfactory molecularly binding selectivity of Xan was obtained from the MIPs microsensor with an imprinting factor (IF) of 6.63 and a linear response to concentration in certain ranges. The ranges are from 4.0 × 10⁻6 to 6.0 × 10⁻5 M and from 8.0 × 10⁻5 to 2.0 × 10⁻³ M with a detection limit of 2.5 × 10⁻7 M. Meanwhile, good stability (relative standard deviation [RSD] = 3.2%, n = 10) and reproducibility (RSD = 2.0%, n = 10) were observed, and recoveries ranging from 96.9 to 102.5% were calculated when applied to Xan determination in real blood serum samples.


Subject(s)
Carbon/chemistry , Chemistry Techniques, Analytical/instrumentation , Molecular Imprinting , Polymers/chemical synthesis , Pyrroles/chemical synthesis , Xanthine/analysis , Carbon Fiber , Dielectric Spectroscopy , Electrochemistry , Microelectrodes
9.
Anal Biochem ; 426(1): 40-6, 2012 Jul 01.
Article in English | MEDLINE | ID: mdl-22484037

ABSTRACT

An improved imprinted film-based electrochemical sensor for urea recognition was developed using CdS quantum dots (QDs) doped chitosan as the functional matrix. The microstructure and composition of the imprinted films depicted by scanning electron microscopy (SEM), attenuated total reflection infrared (ATR-IR), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS) indicated the fabricated feasibility of the nanoparticle doped films via in situ electrodeposition. Differential pulse voltammetric responses under the optimal fabrication conditions showed that the sensitivity of CdS QDs-MIP (molecularly imprinted polymer) electrochemical sensor was enhanced from the favorable electron transfer and magnified surface area of CdS QDs with a short adsorption equilibrium time (7 min), wide linear range (5.0 × 10(-12) to 4.0 × 10(-10) M and 5.0 × 10(-10) to 7.0 × 10(-8) M), and low detection limit (1.0 × 10(-12) M). Meanwhile, the fabricated sensor showed excellent specific recognition to template molecule among the structural similarities and coexistence substances. Furthermore, the proposed sensor was applied to determine the urea in human blood serum samples based on its good reproducibility and stability, and the acceptable recovery implied its feasibility for practical application.


Subject(s)
Chitosan/chemistry , Electrochemical Techniques , Quantum Dots , Urea/analysis , Adsorption , Cadmium Compounds/chemistry , Gold/chemistry , Humans , Molecular Imprinting , Sulfides/chemistry , Urea/blood
10.
Guang Pu Xue Yu Guang Pu Fen Xi ; 31(2): 431-5, 2011 Feb.
Article in Chinese | MEDLINE | ID: mdl-21510397

ABSTRACT

In the present paper, the authors studied the effects of anionic polyelectrolyte sodium polystyrene sulfonate (PSS) on the cationic dye thioflavin T (ThT) fluorescence spectra in aqueous solution. The influencing factors of the formed thioflavin T excimer in the existence of PSS were investigated. Experimental results show that PSS could increases the local concentration of ThT by electrostatic attraction, therefore enhances excimer formation of thioflavin T. The fluorescence intensity of ThT monomer and excimer (I(M) and I(E)) changes regularly along with the change in temperature; ln(I(E)/I(M)) and 1/T have good linear relationship. Hereby we have developed a new type of fluorescence ratiometric sensor for temperature which could be recognized by naked eye, and it could effectively eliminate environmental effects such as instability of exciting light intensity and photobleaching, therefore improve the accuracy of identification.

11.
Guang Pu Xue Yu Guang Pu Fen Xi ; 29(6): 1643-6, 2009 Jun.
Article in Chinese | MEDLINE | ID: mdl-19810550

ABSTRACT

From the digital images of the red complex which resulted in the interaction of nitrite with N-(1-naphthyl) ethylenediamine dihydrochloride and P-Aminobenzene sulfonic acid, it could be seen that the solution colors obviously increased with increasing the concentration of nitrite ion. The JPEG format of the digital images was transformed into gray-scale format by origin 7.0 software, and the gray values were measured with scion image software. It could be seen that the gray values of the digital image obviously increased with increasing the concentration of nitrite ion, too. Thus a novel digital imaging colorimetric (DIC) method to determine nitrogen oxides (NO(x)) contents in air was developed. Based on the red, green and blue (RGB) tricolor theory, the principle of the digital imaging colorimetric method and the influential factors on digital imaging were discussed. The present method was successfully applied to the determination of the daily changes curve of nitrogen oxides in the atmosphere and NO2- in synthetic samples with the recovery of 97.3%-104.0%, and the relative standard deviation (RSD) was less than 5.0%. The results of the determination were consistent with those obtained by spectrophotometric method.

12.
Guang Pu Xue Yu Guang Pu Fen Xi ; 28(9): 2165-8, 2008 Sep.
Article in Chinese | MEDLINE | ID: mdl-19093585

ABSTRACT

The fluorescence spectra of the succinic acid (7-hydroxy-coumarin) ester (SCE) of different concentration in water and ethanol solvents were studied. It was found that the peak wavelength changes not only with solvent, but also with the concentration. These phenomena of spectra have been discussed on the basis of solvent properties and dimerisation of SCE in hydrogen bonding solvents. The author thought that there are dimerisation phenomena in the SCE solutions at high concentration. The formation of dimer was caused by the aid of hydrogen bonding between SCE and solvent or between SCE themselves. Its acidic dissociation constant at excited state was determined based on the changes of the fluorescence spectra in water. And a simple and sensitive fluorescence quenching method for the determination of trace iron was developed. The method is based on the reaction of SCE with iron in hydrochloric acid medium. The fluorescence intensity was measured with excitation and emission wavelengths of 347 and 457 nm, respectively. The linear range for the determination of iron was 0.66-6.59 microg x L(-1). The detection limit was 51 ng x L(-1). The author contrasted SCE with 7-hydroxy-coumarin to determine Fe3+, and found the sensitivity of SCE is 10(4) higher than that of 7-hydroxy-coumarin. To our thinking there is a carboylate group in SCE, whose coordinate force with iron is stronger than hydroxide radical in 7-hydroxy-coumarin.


Subject(s)
Coumarins/analysis , Iron/analysis , Spectrometry, Fluorescence , Coumarins/chemistry , Ethanol/chemistry , Hydrogen-Ion Concentration , Iron/chemistry , Models, Chemical , Solvents/chemistry , Trace Elements/analysis , Water/chemistry
13.
Guang Pu Xue Yu Guang Pu Fen Xi ; 27(10): 2102-6, 2007 Oct.
Article in Chinese | MEDLINE | ID: mdl-18306805

ABSTRACT

Quartz substrate was modified with self-assembled monolayer of gamma-aminopropyl-triethylsilane by aqueous phase silanization, giving an homogenous surface terminated with amino groups. Colloidal gold nanoparticles were further assembled on this functionalized monolayer substrate, forming a gold nanoparticles/APES/quartz nanocomposite structure. Flourescent reagent morin was assembled onto the self-assembled multilayer films of gold nanoparticles via DL-cystenine (Cys) intermediate. The morin-modified self-assembled multilayer films of gold nanoparticles could detect triphenyltin fluorimetrically with high sensitivity, and the detection limit was as low as 1.297 x 10(-8) mol x L(-1). The effects of various factors such as concentration of solution, pH, and assembling time were investigated. The response mechanism behind caused the enhancement of relative fluorescence intensity was also discussed.

14.
Luminescence ; 20(4-5): 331-3, 2005.
Article in English | MEDLINE | ID: mdl-16134221

ABSTRACT

In this paper, an internal conversion (IC) fluorescence probe N-(o-boronic acid)benzyl-1-naphthylamine (BBNA) was prepared from 1-naphthylamine and 2-formylbenzeneboronic acid. The fluorescence parameters of BBNA were investigated in a variety of solvents. When BBNA interacted with D-fructose in phosphate buffer solution of 30% MeOH, pH 8.21 (v/v), the fluorescence intensity increased and emission maximum red-shifted slightly with increasing D-fructose concentration. In the presence of D-fructose, the fluorescence quantum yield of BBNA increased with increasing solvent polarity, suggesting that internal conversion (IC) occurred with BBNA. The binding force of BBNA with d-fructose was the strongest, and the stability constant (K) of D-fructose was 99.9 mol/L. Therefore, a selective recognition system based on IC was constructed for D-fructose.


Subject(s)
Fluorescent Dyes/analysis , Fluorescent Dyes/chemistry , Glucans/analysis , Glucans/chemistry , 1-Naphthylamine/analogs & derivatives , 1-Naphthylamine/analysis , 1-Naphthylamine/chemistry , Boronic Acids/analysis , Boronic Acids/chemistry , Fructose/chemistry , Fructose/pharmacology , Hydrogen-Ion Concentration , Molecular Structure , Photochemistry , Spectrometry, Fluorescence
15.
Talanta ; 62(5): 1035-40, 2004 Apr 19.
Article in English | MEDLINE | ID: mdl-18969394

ABSTRACT

Fluorescent reagent sodium 1-naphthylamine diacetate (NADA) was assembled onto gold electrodes via its electrostatic interaction with cysteine (Cys) that was directly assembled on the gold electrode surface. Formation of the self-assembled bilayers was confirmed and primarily characterized by cyclic voltammetry and X-ray photoelectron spectra (XPS). The Cys modification of the gold electrode prevented direct adsorption of NADA onto the gold electrode and hence eliminated fluorescence quenching by gold. Strong fluorescence was observed from the NADA self-assembled bilayers at gold surface and was highly efficiently quenched by Cu(2+) that allowed for an extremely highly sensitive detection of Cu(2+) with a detection limit of 0.2ppt and quantitative detection range of 0.5-9ppt. The fluorescence from NADA/Cys/Au can be easily regenerated and therefore the present report showed a reusable method for immobilizing reagent in fabricating fluorescent chemosensors.

16.
Org Biomol Chem ; 1(4): 728-32, 2003 Feb 21.
Article in English | MEDLINE | ID: mdl-12929462

ABSTRACT

N-(substituted-benzoyl)-1-aminonaphthalenes and N-(substituted-benzoyl)-2-aminonaphthalenes (1-NBAs and 2-NBAs) with varied substituents at the para- or meta-position of benzoyl phenyl ring were prepared to probe the difference between 1-aminonaphthalene (1-AN) and 2-aminonaphthalene (2-AN) as electron donors, using benzanilide-like charge transfer as a probe reaction. An abnormal long-wavelength emission was found for all of the prepared aminonaphthalene derivatives in cyclohexane and was assigned to the CT state by the observation of a substantial red shift with increasing solvent polarity or with increasing electron-withdrawing ability of the substituent. The CT emission energies were found to follow a linear relationship with the Hammett constant of the substituent and the value of the linear slope for 1-NBAs (-0.45 eV) was higher than that of 2-NBAs (-0.35 eV), the latter being close to that of the aniline derivatives (BAs, -0.345 eV). This pointed to a higher extent of charge separation in the CT state of 1-NBAs in which a full charge separation was established by the reduction potential dependence of the CT emission energy with a linear slope of -1.00. The possible contribution of the difference in the steric effect and the electron donating ability of the donors in 1-NBAs and 2-NBAs was ruled out by the observation that the corresponding linear slopes of benzoyl-substituted BAs remained unchanged when para-, meta-, ortho-, or ortho,ortho-methyls were introduced into the aniline moiety. It was therefore concluded that 1-AN enhanced the charge transfer in 1-NBAs and the proximity of its 1La and 1Lb states was suggested to be responsible. Results showed that the charge transfers in 1-NBAs and 2-NBAs were not the same and 1-AN and 2-AN as electron donors were different not only in electron donating ability but in shaping the charge transfer pathway as well.

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