Yan Li

University of Jinan (Jinan, China), Chi-nan-shih, Shandong Sheng, China

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Publications (19)34.93 Total impact

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    ABSTRACT: In this contribution, mesoporous carbon nanospheres (MCN) were used to fabricate a label-free electrochemical immunosensor for breast cancer susceptibility gene (BRCAl). The detection platform was constructed by conjugation of anti-BRCA1 on glassy carbon electrodes which were modified by mesoporous carbon nanospheres-toluidine blue nanocomposite (MCN-TB)/room temperature ionic-liquid (RTIL) composited film. TB was adsorbed onto MCN and acted as a redox probe. The electroactivity of TB was greatly enhanced in the presence of MCN. The good conductivity of MCN and BMIM·BF4 could promote the electron transfer and thus enhance the detection sensitivity. Moreover, the large surface area of MCN and the protein-binding properties of BMIM·BF4 could greatly increase the antibody loading. The specific antibody-antigen immunoreaction on the electrode surface resulted in a decrease of amperometric signal of the electrode. Under optimized conditions, the amperometric signal decreased linearly with BRCAl concentration in the range of 0.01-15ngmL(-1) with a low detection limit of 3.97pgmL(-1). The immunosensor exhibits high sensitivity, good selectivity and stability.
    Analytica chimica acta 04/2013; 770:62-7. · 4.31 Impact Factor
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    ABSTRACT: For the specificity of prostate cancer markers, prostate specific antigen (PSA) has been widely used in prostate cancer screening, diagnosis, and treatment after monitoring. In normal male serum, PSA can only be detected in traces of 0-4 ng mL(-1). In this paper, we constructed an electrochemical immunosensor for PSA detection using a nanocomposite film of graphene sheets-methylene blue-chitosan (GS-MB-CS) as electrode material. The nanocomposite film showed high binding affinity to the electrode and was used to immobilize the antibody of PSA. The modification procedure was monitored by cyclic voltammetry (CV). An amperometric biosensor was easily developed based on the response of peak current to the capture of PSA induced by specific antigen-antibody reactions. Under optimum conditions, the amperometric signal decreased linearly with PSA concentration (0.05-5.00 ng mL(-1)). A low limit of detection (13 pg mL(-1)) and a high selectivity are obtained. Moreover, the prepared immunosensor was applied for the analysis of PSA in serum samples with satisfactory results. The proposed method may have a promising future in biochemical assays for high selectivity, good reproducibility, and stability.
    Analytical Biochemistry 03/2012; 422(1):22-7. · 2.58 Impact Factor
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    ABSTRACT: Bisphenol A (BPA), which could disrupt endocrine system and cause cancer, has been considered as an endocrine disruptor. Therefore, it is very important and necessary to develop a sensitive and selective method for detection of BPA. Herein, nitrogen-doped graphene sheets (N-GS) and chitosan (CS) were used to prepare electrochemical BPA sensor. Compared with graphene, N-GS has favorable electron transfer ability and electrocatalytic property, which could enhance the response signal towards BPA. CS also exhibits excellent film forming ability and improves the electrochemical behavior of N-GS modified electrode. The sensor exhibits a sensitive response to BPA in the range of 1.0×10(-8)-1.3×10(-6) mol L(-1) with a low detection limit of 5.0×10(-9) mol L(-1) under the optimal conditions. Finally, this proposed sensor was successfully employed to determine BPA in water samples with satisfactory results.
    Analytica chimica acta 01/2012; 711:24-8. · 4.31 Impact Factor
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    ABSTRACT: The unexpected discovery of graphene and especially the follow-up explosion of interest in its properties and applications marked the beginning of a new carbon era. Graphene is a real two-dimensional crystal (one-atom-thick) with high crystal quality and quite unusual electronic properties, and has shown great promise in a variety of applications, such as field-effect transistors, photovoltaic devices and biosensors. Besides the properties that make graphene as excellent transducer materials in biosensors, such as high electron transfer ability and specific surface area, several advantages of graphene over carbon nanotubes, one of its well-studied allotropes, are becoming apparent. Graphene shows super-quenching capability towards various organic dyes and quantum dots due to the long-range nanoscale resonance energy transfer. Graphene-based hybrid materials, especially nanoparticle-decorated graphene nanocomposites, have been widely used as electrode materials for the development of electrochemical biosensors. In this review, we outline the recent advances about the application of graphene-based materials in biosensors, with focus on fluorescence and electrochemical biosensors.
    Analytical Letters - ANAL LETT. 01/2012;
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    ABSTRACT: A new method of simultaneous determination of Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ is proposed here by using the second-derivative spectrophotometry method. In pH=10.35 Borax-NaOH buffer, using meso-tetra (3-methoxyl-4-hydroxylphenyl) porphyrin ([T-(3-MO-4-HP)P]) as chromomeric reagent, micelle solution was formed after Tween-80 surfactant was added into the solution containing Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ ions. The original absorption spectrum of the above complexes was obtained after heating in the boiling water for 25 min. The second-derivative absorption peaks of five metal-porphyrin complexes can be separated from the original absorption spectrum by using chemometric tool. In this way, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ ions can be determined simultaneously. Under the optimal conditions, the linear ranges of the calibration curve were 0-0.60, 0-0.60, 0-0.40, 0-0.80 and 0-0.48 μg mL(-1) for Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+, respectively. The molar absorptivity of these color systems were 1.38×10(5), 1.01×10(5), 3.24×10(5), 1.07×10(5) and 1.29×10(5)Lmol(-1)cm(-1). The method developed in this paper has advantages in selectivity, sensitivity, operation and can effectively resolve spectra overlapping problem. This method has been applied to determine the real samples with satisfactory results.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2011; 79(5):1546-51. · 1.98 Impact Factor
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    ABSTRACT: BRCAl is an anti-oncogene in women, who are genetically predisposed to breast and ovary cancer. The detection of BRCA1 can offer an opportunity to characterize the function of genetic features in breast and ovarian cancer and to screen breast or ovarian cancer patients. In this study, we designed a new label and fabricated a novel sandwich-type electrochemical immunoassay for the ultrasensitive detection of BRCAl. Horseradish peroxidase (HRP) was entrapped in the pores of amino-group functionalized SBA-15 and the secondary antibody (Ab₂) combined with SBA-15 by covalent bond. Ionic liquid (IL) was added into the mixed solution of SBA-15/HRP/Ab₂ and application of IL increased the electrochemical activity of HRP and promoted electron transport. The synergistic effect between IL, SBA-15, Ab₂ and HRP could retain the bioactivity of HRP and Ab₂. The sensitivity of the sandwich-type immunosensor using SBA-15/HRP/Ab₂/BMIM·BF₄ as labels for BRCA1 detection was much higher than that using either SBA-15/HRP/Ab₂ or SBA-15/Ab₂ as labels. Under optimal conditions, the electrochemical immunoassay exhibited a wide working range from 0.01 to 15 ng/mL with a detection limit of 4.86 pg/mL BRCA1. The precision, reproducibility, and stability of the immunoassay were acceptable.
    Biomaterials 03/2011; 32(8):2117-23. · 8.31 Impact Factor
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    ABSTRACT: Interest in the interaction between cationic porphyrins, particularly derivatives of meso-tetra(N-methylpyridinium-4-yl) porphyrin(TMPyP), and DNA abounds because they are versatile DNA-binding agents that could find application in photodynamic therapy, cancer detection, artificial nucleases, virus inhibition and so on. The interaction of two water-soluble cationic porphyrins, meso-tetrakis(4-N, N, N-trimethylanilinium) porphyrin (TMAP) and 5-phenyl-10,15,20-tris[4-(N-methyl) pyridinium]porphyrin (TriMPyP), with calf thymus DNA (ctDNA) was studied by UV-Vis absorption spectroscopy, fluorescence spectroscopy and resonance light scattering technique. TriMPyP forms aggregate in water due to the molecular asymmetry while TMAP exists as monomers. At lower concentrations of ctDNA (R > 1, R = c(TMAP)/c(DNA) base pair), the interaction of TMAP with DNA leads to significant hypochromicity and bathochromic shift of absorption spectra. And the fluorescence of TMAP was quenched while it showed enhanced resonance light scattering signals. But the extent of enhancement of resonance light scattering signals is very small, so the aggregate of TMAP is not very high. These observations indicate the self-stacking of TMAP along the DNA surface. At higher concentrations of ctDNA (R < 1), TMAP association with DNA is via outside binding which is accompanied with hyperchromic effect and fluorescence enhancement while the resonance light scattering signals is reduced. DNA addition decreases the fluorescence intensity of TriMPyP and it shifts the peak to the higher wavelengths (red shift). The interaction with DNA promotes the aggregation of TriMPyP and no simple outside binding is observed even at higher concentrations of ctDNA. The steric effect of molecular distortion constrains the intercalation or further binding to DNA. The effect of ionic strength on the interaction was investigated at two DNA concentrations, 1.2 and 24.0 micromol x L(-1), for TMAP. The Interactions of both porphyrins with DNA show high sensitivity to ionic strength. By addition of NaCl, electrostatic attraction is decreased, resulting in the change of binding mode.
    Guang pu xue yu guang pu fen xi = Guang pu 03/2009; 29(2):423-7. · 0.29 Impact Factor
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    ABSTRACT: In Tris-HCl buffer (pH 8.0), the fluorescence of Pyronine G emitted at 552 nm was quenched by nucleic acids when excited at 525 nm. Adding N, N-dimethylformamide (DMF) as a sensitive media can enhance the sensitivity greatly. Based on the fluorescence reactions sensitive fluorimetric methods for nucleic acids at nanogram levels were proposed. Under the optimum conditions, the calibration curves were linear in the range of 0.0032 - 2.5 microg mL(-1) for ct DNA and 0.0024 - 2.5 microg mL(-1) for hs DNA. The limits of determination were 3.2 ng mL(-1) and 2.4 ng mL(-1) respectively. This method has good selectivity and high sensitivity. It has been applied to the determination of DNA in the synthetic samples and real samples with satisfactory results.
    Annali di Chimica 06/2006; 96(5-6):273-84. · 0.99 Impact Factor
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    ABSTRACT: In this paper, the binding characteristics of human serum albumin (HSA) and m-nitrophenylfluorone (m-NPF)-molybdenum (Mo(VI)) complex have been studied by fluorophotometry. The binding constants are measured at different temperature. Based on the theory of Forster energy transfer, the binding distance and the energy transfer efficiency between m-nitrophenylfluorone-Mo(VI) complex and protein are obtained. According to the thermodynamic parameters, the main sort of binding force can be judged. The results indicate that HSA and m-NPF-Mo(VI) complex have strong interactions. The mechanism of quenching belongs to static quenching and the main sort of binding force is electrostatic gravitation.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 04/2006; 63(3):532-5. · 1.98 Impact Factor
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    ABSTRACT: A simple and sensitive method was conducted for the determination of trace amounts of proteins with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt (azophloxine, AP) using a Rayleigh light-scattering (RLS) technique. At pH 2.60 and in the presence of an emulsifier OP microemulsion, the RLS of AP can be greatly enhanced by proteins, owing to the interaction between AP and protein. The enhanced intensity is proportional to the concentration of proteins. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lys) and gamma globulin (gamma-G) have been tested. For example, the linear range of BSA was 0 - 0.06 microg mL(-1) with detection limits of 2.38 ng mL(-1). The method was applied to the analysis of protein in human urine and penicillin samples with satisfactory results. The relative standard deviation was in all instances less than 4.0%, and the recovery was in the range of 97.5 - 104%.
    Analytical Sciences 03/2006; 22(2):275-9. · 1.57 Impact Factor
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    ABSTRACT: The fluorescence spectral behavior of interaction of phenylfluorone(PF)-Mo(VI) and protein was investigated in Triton X-100 microemulsion medium at pH 2.0. A novel method for the determination of protein using phenylfluorone (PF)-Mo(VI) as a fluorescence spectrum probe was developed. Excitation and emission wavelengths are 465 and 525 nm, respectively. The effective factors and the optimum conditions have been studied, and the reducing value of fluorescence intensity is in proportion to the concentration of proteins in the range 0-6.00 microg x L(-1) for bovine serum albumin, 0-4.00 microg x L(-1) for human serum albumin, 0-5.00 microg x L(-1) for ovalbumin, and 0-4.00 microg x L(-1) for lysozyme. The Triton X-100 microemulsion was efficiently used to enhance the sensibility and stability of the system, and the limits of detection are 5.4, 5.2, 1.5 and 8.2 ng x L(-1), respectively. Most of foreign substances do not interfere with the determination, and this method has good selectivity and high sensitivity. It has been applied to the determination of proteins in the urine samples with satisfactory results.
    Guang pu xue yu guang pu fen xi = Guang pu 02/2006; 26(1):109-12. · 0.29 Impact Factor
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    ABSTRACT: In this paper, the interaction between 2-sulfophenylazo-rhodanine and protein was investigated by Rayleigh light-scattering technique. Based on this, a novel method for the determination of protein was developed. The effects of different conditions, such as acidity and media, were investigated thoroughly, and the optimum conditions were confirmed. Bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion, which is introduced into the protein determination, markedly increased the sensitivity of the system by changing the microenvironment. In pH 2.80 Britton-Robinson buffer solution in the presence of AOT microemulsion, the detection limits of bovine serum albumin, human serum albumin, ovalbumin, and gamma-globulin are 5.4, 4.5, 9.8, and 10.1 ng/mL, respectively. The method developed in this paper has been applied to the determination of protein in milk powder with satisfactory results.
    Journal of AOAC International 01/2006; 89(5):1353-9. · 1.23 Impact Factor
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    ABSTRACT: In the present paper, the spectral behavior of cadmium with trimethoxyphenylflurone (TM-PF) in microemulsion was studied. In the buffer medium of borax-NaOH at pH 10.40, cadmium (II) reacts with TM-PF to form a stable 1:2 complex. Its apparent molar absorptivity is 6.10 x 10(4) L x mol(-1) x cm(-1) at 560 nm. Beer's law is obeyed in the range of 0-0.60 microg x mL(-1). The coexistent metal ions can be separated, and cadmium can be enriched by sulfhydryl dextrane gel (SDG), greatly improving the selectivity and sensibility of the system. The method possesses high sensitivity as well as h igh selectivity, and can be used to determine trace amount of cadmium in environmental samples successfully.
    Guang pu xue yu guang pu fen xi = Guang pu 12/2005; 25(11):1853-6. · 0.29 Impact Factor
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    ABSTRACT: The concentration of protein in body fluids is an important measure in disease diagnosis and in analytical biochemistry. Searching for a sensitive and rapid method for proteins is an ongoing subject of investigation. We describe the reaction of dibromomethyl carboxyazo-Pb(II) with proteins found in urine. In a buffer containing of HCl and KCl at pH 1.80, dibromomethyl carboxyazo-Pb(II) complex combined with proteins to form a colored compound. The reaction was completed in 2 min and remained stable for 80 min. Under optimum conditions, the product of reaction between protein and dibromomethyl carboxyazo-Pb(II) absorbed at 530 nm and was linear in the range of 0-50 microg/ml of BSA. Moreover, the maximum binding number was defined to express the binding ability of dibromomethyl carboxyazo-Pb(II) to protein under a given set of conditions. The method was applied to the determination of urine proteins. The recovery of protein from human urine was 97.6-103% and the precision was <4.8%. Results compared favorably to the Biuret and Bradford protein methods on 50 urine samples. This method had high sensitivity and specificity and may be applicable to clinical analysis.
    Clinica Chimica Acta 12/2005; 362(1-2):79-84. · 2.85 Impact Factor
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    ABSTRACT: In this paper, the binding characteristics of bovine serum albumin (BSA) and phenylfluorone (PF)-molybdenum (Mo(VI)) complex have been studied by fluorophotometry. The binding constants are calculated at different temperatures. The binding distance and the energy transfer efficiency between PF-Mo(VI) complex and protein are obtained on the basis of the theory of Forster energy transfer. DeltaH and DeltaS are calculated to be -7.11 kJ mol-1 and 70.30 J mol-1 K-1, which indicate that electrostatic force plays major role in the interaction of PF-Mo(VI) complex and BSA. The experimental results show that BSA and PF-Mo(VI) complex have strong interactions and the mechanism of quenching belongs to static quenching.
    International Journal of Biological Macromolecules 11/2005; 37(1-2):69-72. · 2.60 Impact Factor
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    ABSTRACT: The interaction and absorption spectral behavior of o-chlorophenylfluorone (o-CPF)-Mo(VI) and protein are studied in OP microemulsion medium. Under the optimum condition, the molar absorptivity of o-CPF-Mo(VI)-BSA system at 532 nm is 6.12 x 10(6) L x mol(-1) x cm(-1), and Beer's law is obeyed in the range of 0-14 microg x mL(-1) of BSA. Moreover, the binding number between the complex and BSA determined by molar ratio and slope ratio methods is 91. The mechanism of interaction of BSA and o-CPF-Mo (VI) is also discussed. OP microemulsion media introduced into the protein determination increased markedly the sensitivity of the system. The result of experiment indicates that the method possesses a high sensitivity as well as a high selectivity. It can be used to determine protein in human urine with satisfactory results.
    Guang pu xue yu guang pu fen xi = Guang pu 08/2005; 25(7):1110-3. · 0.29 Impact Factor
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    ABSTRACT: A new highly sensitive, stable, and accurate fluorometric method for the determination of indium(III) has been established in cetyltrimethylammonium bromide(CTMAB) microemulsion media. The excellent color-forming reagent 2,6,7-trihydroxy-9-(3,5-dibromo-4-hydroxyphenyl) fluorone (DBH-PF) reacts with indium(III) to form a purple complex with a 3 : 1 (ligand to metal) ratio in HAc-NaAc buffer solution at pH 4.94. The emission peak occurs at 556 nm with excitation at 525 nm. Indium(III) can be determined in the linear range of 0.005–0.30 µg mL−1 with a detection limit of 0.0029 µg mL−1. Foreign ions are eliminated by preconcentration and separation with sulfhydryl dextranegel (SDG). The proposed method has been satisfactorily examined for the determination of indium(III) in ore and sludge samples. The relative standard deviations are in all instances less than 3.0%, and the recoveries are between 94.7, and 99.5%.
    Journal of Analytical Chemistry 01/2005; 60(9):868-873. · 0.62 Impact Factor
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    ABSTRACT: In this paper, the binding reaction of Dahlia Violet and nucleic acids by the method of spectrophotometry is studied. At pH 6.1–6.9, the binding reaction is completed within 2 min at room temperature, and causes an absorbance decrease at the wavelength of the maximum absorption of the dye, i.e., 586 nm. Under optimum conditions, the calibration linearity for calf thymus deoxyribonucleic acid (ct DNA) and fish sperm deoxyribonucleic acid (fs DNA) are in the range of 0.4–11 µg mL and 0.4–13 µg mL, respectively, and their detection limits are, correspondingly, 0.06 µg mL and 0.38 µg mL. In addition, the binding number (n) of the dyes and DNA was studied by two methods: the molar ratio method and the graphical method of Rosenthanl. The values of n measured by the two methods are similar and each base pair of the nucleic acid can bind three molecules of Dahlia Violet. Moreover, the association constant (K) was estimated by the graphical method of Rosenthanl. Compared with some existing assays, the new method is sensitive, stable, simple, and relatively free from interference of co‐existing species. The analytical results of synthetic samples are satisfactory, with recoveries of 95.6%–102% and the relative standard deviations are lower than 4.2%.
    Instrumentation Science & Technology 01/2005; 33(4):437-448. · 0.43 Impact Factor
  • Bin Du, Dan Wu, Qin Wei, Yan Li
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    ABSTRACT: A simple, rapid, highly sensitive, and selective method for detecting protein in biological samples has been developed, which is based on the interaction between protein and m‐nitrophenylfluorone‐Mo(VI) complex as a spectral probe. The optimum condition for the reaction is investigated. Bovine serum albumin (BSA) obeys Beer's law up to 10 µg · mL, having a molar absorption coefficient of 8.51×10 L · mol · cm at 535 nm. Many amino acids and metal ions do not interfere. The results of determination for biological samples are comparable to those obtained by the Bradford method. Meanwhile, the binding number is also determined.
    Instrumentation Science & Technology - INSTRUM SCI TECHNOL. 01/2005; 33(6):715-725.