Jianmin Wu

Zhejiang University, Hang-hsien, Zhejiang Sheng, China

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Publications (26)112.59 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Small peptides in serum are potential biomarkers for the diagnosis of cancer and other diseases. The identification of peptide biomarkers in human plasma/serum has become an area of high interest in medical research. However, the direct analysis of peptides in serum samples using mass spectrometry is challenging due to the low concentration of peptides and the high abundance of high-molecular-weight proteins in serum, the latter of which causes severe signal suppression. Herein, we reported that porous semiconductor-noble metal hybrid nanostructures can both eliminate the interference from large proteins in serum samples and significantly enhance the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) yields of peptides captured on the nanostructure. Serum peptide fingerprints with high fidelity can be acquired rapidly, and successful discrimination of colorectal cancer patients based on peptide fingerprints is demonstrated.
    Analytica Chimica Acta 11/2014; · 4.52 Impact Factor
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    ABSTRACT: A chemiresistive sensor array consisting of nine different types of ionogels was constructed. The conductivity of each ionogel was very sensitive to stimulations of volatile organic compounds (VOCs). The sensing mechanism of the ionogel was based on the change in ion mobility in response to the absorption of VOCs. This mechanism significantly differed from the currently used chemiresistive sensors, usually relying on the modulation of charge densities. The ionogel sensor can produce a reversible and fast resistance response upon exposure to dosing gases cycled between the VOC sample and N2. The resistance response of ionogel had a linear relationship with the VOC concentration. Meanwhile, the ionogel sensor displayed selectivity to different types of VOCs because of the specific molecular interaction between ionic liquids and the target organic vapor. A chemiresistive sensor array comprising nine types of ionogel with diverse chemical structures can generate a pattern of cross-reactive responses to a specific vapor, thereby leading to the discrimination of VOCs in air samples using principal component analysis.
    Sensors and Actuators B Chemical 10/2014; 202:105–113. · 3.84 Impact Factor
  • Jie Tan, Linru Xu, Tong Li, Bin Su, Jianmin Wu
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    ABSTRACT: The electrochemiluminescence (ECL) of porous silicon (pSi) has attracted great interest for its potential application in display technology and chemical sensors. In this study, we found that pSi with a different surface chemistry displayed an apparently different dynamic ECL process. An image-contrast technology was established on the basis of the intrinsic mechanism of the ECL dynamic process. As a proof of principle, the visualization of latent fingerprints (LFPs) and in situ detection of TNT in fingerprints was demonstrated by using the ECL-based image-contrast technology.
    Angewandte Chemie 07/2014;
  • Jie Tan, Linru Xu, Tong Li, Bin Su, Jianmin Wu
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    ABSTRACT: The electrochemiluminescence (ECL) of porous silicon (pSi) has attracted great interest for its potential application in display technology and chemical sensors. In this study, we found that pSi with a different surface chemistry displayed an apparently different dynamic ECL process. An image-contrast technology was established on the basis of the intrinsic mechanism of the ECL dynamic process. As a proof of principle, the visualization of latent fingerprints (LFPs) and in situ detection of TNT in fingerprints was demonstrated by using the ECL-based image-contrast technology.
    Angewandte Chemie International Edition 07/2014; · 11.34 Impact Factor
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    ABSTRACT: Paper chips for immunoassay were patterned by screen printing of polydimethylsiloxane (PDMS) or wax pencil drawing. The methods for paper chip patterning are cheap, convenient, rapid and suitable for most laboratories. The whole time for patterning a paper chip is no more than 10 min. Visible immunoassay for the detection of bacteria (Escherichia coli ) has been realized using the paper chip, on which the antibody for capturing E. Coli was immobilized on the detection zones of the paper chip, while the detection antibody was labeled with gold nanoparticles (AuNPs) as a signal reporter. After an immunological reaction, the AuNPs bound on the paper chip can effectively catalyse the reduction of silver ions during the silver enhancing step, generating a visible result that can be read by naked eyes. The quantitative results can be acquired by scanning the silver stained paper chip with a commercial scanner/or digital camera. The density of E. coli in water samples can be measured after calibrating the gray value of silver stained spots with the logarithmic number of bacteria. The time and reagents consumed on the paper chip immunoassay is much smaller than those of conventional ELISA, while the sensitivity of the paper chip immunoassay is comparable to conventional ELISA. The technology proposed in this work displays a great potential in the in-situ analysis when daily monitoring of water quality are required.
    Talanta 03/2014; 120:135–140. · 3.50 Impact Factor
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    ABSTRACT: Serum peptides are becoming a rich source of disease biomarkers, therefore, preserving serum peptide information after sample collection is of great importance. This work demonstrates that nanoporous silicon microparticles can be successfully applied in the storage of peptide information.
    Chemical Communications 01/2014; · 6.38 Impact Factor
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    ABSTRACT: A label-free optical sensor was constructed by integrating pH sensing material and supported phospholipid bilayers (SPBs) in a microfluidic chip. The pH sensing material was composed of a double layer structure consisting of chitosan hydrogel and electrochemically etched porous silicon. The pH change in the microchip could induce a reversible swelling of the chitosan hydrogel layer and consequently caused a shift in effective optical thickness (EOT) of the double layer, which could be observed by Fourier transformed reflectometric interference spectroscopy (FT-RIS). After phospholipid bilayers (PLBs) were self-assembled on the sensing layer, the EOT almost remained constant during the cycling of pH from 7.4 to 6.2, indicating the blockage of H(+) translocation by the PLBs. For studying the behavior of ion channel protein, gramicidin A, a typical ion channel protein, was inserted in the SPBs for mimicking the ion transportation function of cell membrane. Due to the H(+) transportation capability of gramicidin A, the optical response to pH change could partially recover. In the presence of Ca(2+), the pore of the ion channel protein was blocked, causing a significant decrease in the EOT response upon pH change. The bio-functionalized microfluidic sensor fabricated in this work will provide a reliable platform for studying the function of ion channel protein, which is an important class of drug targets.
    Lab on a Chip 11/2013; · 5.70 Impact Factor
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    ABSTRACT: There have been great concerns about the persistence of steroid hormones in surface water. Since the concentrations of these compounds in water samples are usually at a trace level, the efficient enrichment of steroid hormones is vital for further analysis. In this work, a porous and hydrophobic polymer was synthesized and characterized. The composition of solvent used as porogen in the synthetic process was shown to have an effect on the morphology of the polymer, which was successfully used as a solid-phase extraction sorbent for simultaneously enriching steroid hormones in surface water samples. The recoveries of the steroid hormones on the custom-made polymer ranged from 93.4 to 106.2%, whereas those on commercialized ENVI-18, LC-18, and Oasis HLB ranged from 54.8-104.9, 66-93.6 and 77.2-106%, respectively. Five types of steroid hormones were simultaneously measured using HPLC-UV after they were enriched by the custom-made sorbents. Based on these findings, the SPE-HPLC method was developed. The limits of detection of this method for estriol, estradiol, estrone, androstenedione, progesterone were 0.07, 0.43, 0.61, 0.27 and 0.42 μg/L, respectively, while precision and reproducibility RSDs were below 6.40 and 7.49%, respectively. This article is protected by copyright. All rights reserved.
    Journal of Separation Science 08/2013; · 2.59 Impact Factor
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    ABSTRACT: For appropriate selection of antibiotics in the treatment of pathogen infection, rapid antibiotic susceptibility testing (AST) is urgently needed in clinical practice. This study reported the utilizing of microfluidic pH sensor for monitoring bacterial growth rate in culture media spiked with different kinds of antibiotics. The microfluidic pH sensor was fabricated by integration of pH sensitive chitosan hydrogel with PDMS microfluidic channels. For facilitating the reflectometric interference spectroscopic measurements, the chitosan hydrogel was coated on an electrochemically etched porous silicon chip, which was used as the substrate of the microfluidic channel. Real-time observing the pH change in the micro-channel can be realized by Fourier transformed reflectometric interference spectroscopy (FT-RIFS), in which the effective optical thickness (EOT) was selected as the optical signal for indicating the reversible swelling process of chitosan hydrogel stimulated by pH change. With this microfluidic pH sensor, we demonstrate that confinement of bacterial cells in nanoliter size channel allows rapid accumulation of metabolic products and eliminating the need for long time pre-incubation, thus reducing the whole detection time. Based on this technology, the whole bacterial growth curve can be obtained in less than 2 h, and consequently rapid AST can be realized. Compared with conventional methods, the AST data acquired from the bacterial growth curve can provide more detail information for studying the antimicrobial behavior of antibiotics during different stage. Furthermore, the new technology also provides a convenient method for rapid MIC determination of individual antibiotics or the combinations of antibiotics against human pathogen that will find application in clinical and point of-care medicine.
    Analytical Chemistry 01/2013; · 5.83 Impact Factor
  • Haijuan Zhang, Xiaobo Wang, Jianmin Wu
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    ABSTRACT: The image illustrates a natural phenomenon of droplet formation caused by the condensation of vapor on a nonwettable surface at temperature below the dew point. Real-time observing the light scattered from the droplets may lead to a new mechanism for vapor sensing. However, the dew point of organic vapor in an air sample is usually far below room temperature. The problem has been solved by J. Wu and co-workers using porous silicon infiltrated with ionic liquids, on which the organic vapor can be condensed into microdroplets at a temperature far above the dew point. This finding, described on page 3775, leads to the creation of novel optical vapor sensor, which combines the light scattering effect of droplets with the sharp spectral features of pSi photonic crystal.
    Small 12/2012; 8(24):3774. · 7.51 Impact Factor
  • Jiandong Feng, Jianmin Wu
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    ABSTRACT: Soft matter, easily deformed by weak interactions, can act as a sensing element based on stimuli-responsive conformational change. When combined with solid-state nanomaterials, the mechanical actuation is transformed into an optical or electrical signal. DNA molecules can control the pore accessibility of nanoporous gold, acting as a smart nanolock. Application in the screening of anticancer drugs is demonstrated.
    Small 09/2012; 8(24). · 7.51 Impact Factor
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    ABSTRACT: Cast-iron is one of the most popular materials used in water distribution system in China. However, the iron release problem it brings up during decades has been a tough question to researchers. Iron release is a process that pipe corrosion scale breaks and release iron ions into bulk water deteriorating water quality and causing colored water problem. Literature shows that some factors such as pH, residual chlorine, DO and velocity of the bulk contribute to iron release. In this study, experiments are conducted to explore the effects of major anions in drinking water such as chloride, sulfate, and nitrate on iron release. The factors are examined separately and synthetically to observe detailed effects as separate factors and as complicated components. Higher concentrations of solutions result in higher iron release while lower concentrations have opposite results in single-factor experiments. Results suggest that the ORP level and conductivity of bulk water both have relations to the iron release.
    Proceedings of the 2012 Second International Conference on Electric Technology and Civil Engineering; 05/2012
  • Chemistry - A European Journal 11/2011; 17(48):13400-4. · 5.93 Impact Factor
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    ABSTRACT: Interest in using nanoporous materials for sensing applications has increased. The present study reports a method of preparing well-ordered nanoporous gold arrays using a porous silicon (PSi) template. Gold nanolayer could be electrodeposited on the surface of the PSi template at low electrolysis currents in low concentration of chloroauric acid (HAuCl(4)) solution. Surface morphology characterizations and optical measurements revealed that a PSi-templated nanoporous gold (Au-PSi) array well replicated the nanoporous structure and retained the optical properties of PSi. Fourier transform reflectometric interference spectra showed that a characteristic blue-shifted effective optical thickness (EOT) was observed due to the low refractive index of the gold film. An optical DNA biosensor was then fabricated via the self-assembly of single-stranded DNA (ssDNA) with a specific sequence on the surface of Au-PSi. The attachment of ssDNA and its hybridization with target oligonucleotides (ODNs) persistently caused the blue shift of the EOT. Consequently, a relationship between the EOT shift and the ODN concentration was established. The mechanism of the optical response caused by DNA hybridization on the Au-PSi surface was qualitatively explained by the electromagnetic theory and electrochemical impedance spectroscopy (EIS). The lowest detection limit for target ODNs was estimated at around 10(-14) mol L(-1), when the baseline noise, a variation in the value of EOT is around 5 nm. The fabricated Au-PSi based optical biosensor has potential use in the discovery of new ODN drugs because it will be able to detect the binding event between ODNs and the target DNA.
    Biosensors & Bioelectronics 08/2011; 30(1):21-7. · 6.45 Impact Factor
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    ABSTRACT: An ammonia gas sensor chip was prepared by coating an electrochemically-etched porous Si rugate filter with a chitosan film that is crosslinked by glycidoxypropyltrimethoxysilane (GPTMS). The bromothylmol blue (BTB), a pH indicator, was loaded in the film as ammonia-sensing molecules. White light reflected from the porous Si has a narrow bandwidth spectrum with a peak at 610 nm. Monitoring reflective optical intensity at the peak position allows for direct, real-time observation of changes in the concentration of ammonia gas in air samples. The reflective optical intensity decreased linearly with increasing concentrations of ammonia gas over the range of 0-100 ppm. The lowest detection limit was 0.5 ppm for ammonia gas. At optimum conditions, the full response time of the ammonia gas sensor was less than 15s. The sensor chip also exhibited a good long-term stability over 1 year. Therefore, the simple sensor design has potential application in miniaturized optical measurement for online ammonia gas detection.
    Analytica chimica acta 01/2011; 685(1):58-64. · 4.31 Impact Factor
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    ABSTRACT: A simple, rapid and sensitive synchronous fluorescence method is put forward for the determination of enrofloxacin (ENRO) in the pharmaceutical formulation and its residue in milk based on the yttrium (III)-perturbed luminescence. When Y(3+) is added into the ENRO solution, the fluorescence of ENRO is significantly enhanced. The synchronous fluorescence technology is employed in the method to determine trace amount of ENRO residue in milks. The synchronous fluorescence intensity of the system is measured in a 1-cm quartz cell with excitation wavelength of 328 nm, Δλ=80 nm. A good linear relationship between the fluorescence intensity and the ENRO concentration is obtained in the range of 1.0 × 10(-9) to 2.0 × 10(-6)mol L(-1) (r(2)=0.9992). The limit of detection (LOD) of this method attains as low as 3.0 × 10(-10) mol L(-1) (S/N=3). The selectivity of this method is also very good. Common metal ions, rare-earth ions and some pharmaceuticals, which are usually used together with ENRO, do not interfere with the determination of ENRO under the actual conditions. The proposed method can be applied to determine ENRO residue in milks, and limit of quantification (LOQ) determined in the spiked milk is estimated to be 2.8 × 10(-8) mol L(-1) (10 μg L(-1)). Moreover, this method can be used as a rapid screening for judging whether the ENRO residues in milks exceed Minimal Risk Levels (MRLs) or not. In addition, the mechanism of the fluorescence enhancement is also discussed in detail.
    Talanta 10/2010; 82(5):1858-63. · 3.50 Impact Factor
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    ABSTRACT: A new molecularly imprinted polymer (MIP) targeting to quinolones (Qs) and tetracyclines (TCs) was synthesized using itaconic acid (ITA) and ciprofloxacin (CIP) as a functional monomer and template molecule, respectively. Factors affecting the overall performance of MIP were investigated, and the results showed that Fe(3+) ion play a vital role in the formation of MIP with high molecular imprinting effect. Meanwhile, the chelating ability of monomer, species of template molecule, as well as the molar ratio of monomer and template also contribute to the performance of the obtained MIP. Cyclic voltammetry verified that, with the participation of Fe(3+) ions, a ternary complex of ITA-Fe(3+)-CIP could be formed before polymerization. Compared with conventional MIP prepared from commonly used monomer, methacrylic acid (MAA), the new MIP show significantly enhanced molecular imprinting effect and higher capacity for specific adsorption of target compounds as revealed by static and dynamic binding experiments. The MIP was successfully used as solid-phase extraction (SPE) adsorbent for enriching a broad spectrum of antibiotics containing beta-diketone structure from surface water sample. HPLC detection showed that high recovery rate (78.6-113.6%) was found in these spiked antibiotics, whereas recovery rate for the non structurally related drugs, epinephrine (EP) and dopamine (DOPA), was very low (4.7-7.6%) on the MIP cartridges. The results demonstrate that the MIP prepared by the strategy proposed in this work, could specifically target to a series of structurally related antibiotics containing beta-diketone structure.
    Journal of Chromatography A 10/2010; 1217(52):8205-11. · 4.61 Impact Factor
  • Changlun Tong, Zhou Hu, Jianmin Wu
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    ABSTRACT: Characterization of the interaction between methylene blue (MB) and calf thymus deoxyribonucleic acid (ctDNA) was investigated by UV absorption spectra, fluorescence spectra, fluorescence polarization and fluorescence quenching experiments by ferrocyanide. The above results indicated that the binding modes of MB to ctDNA were relative to the molar ratio gamma (gamma=[DNA]/[MB]). At low gamma ratios (gamma < 4), remarkable hypochromic effect with no shift of lambda(max) in the absorption spectra of MB was observed in the presence of increasing amounts of ctDNA, the fluorescence of MB was efficiently quenched by the ctDNA bases and the fluorescence polarization of MB was slightly increased, which indicated that MB cations bound to phosphate groups of ctDNA by electrostatic interaction and then stacked on the surface of ctDNA helix. While at high gamma ratios (gamma > 6), besides the fluorescence of MB was quenched efficiently by the ctDNA bases, a red shift (about 3 nm) in the absorption spectra of MB was observed and the fluorescence polarization of MB was obviously increased, which indicated the intercalation binding that MB molecules were intercalated into the space of two neighbouring DNA base pairs was the preferred mode. Effects of K(4)Fe(CN)(6) on the fluorescence quenching of the MB-ctDNA system at low and high gamma ratios were also performed. The results showed that at gamma = 1.7, the quenching effect by ferrocyanide was higher than that of pure MB, while at gamma = 13.6 a decreased quenching of the fluorescence intensity was observed as compared with that of pure MB, which further proved the above conclusion. In addition, the mechanisms of the hypochromic effect and the fluorescence quenching were also discussed in detail.
    Journal of Fluorescence 10/2009; 20(1):261-7. · 1.79 Impact Factor
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    ABSTRACT: Post-column identification of target compounds in complex samples is one of the major tasks in drug screening and discovery. In this work, we demonstrated that double layer porous silicon (PSi) attached with affinity ligand could serve as a sensing element for post-column detection of target molecule by Fourier transformed reflectometric interference spectroscopy (FTRIFS), in which trypsin and its inhibitor were used as the model probe-target system. The double layer porous silicon was prepared by electrical etching with a current density of 500 mA/cm(2), followed by 167 mA/cm(2). Optical measurements indicated that trypsin could infiltrate into the outer porous layer (porosity 83.6%), but was excluded by the bottom layer (porosity 52%). The outer layer, attached with trypsin by standard amino-silane and glutaraldehyde chemistry, could specifically bind with the trypsin inhibitor, acting as a sample channel, while the bottom layer served as a reference signal channel. The binding event between the attached trypsin and trypsin inhibitor samples could be detected by FTRIFS in real-time through monitoring the optical thickness change of the porous silicon layer. The baseline drift caused by sample matrix variation could be effectively eliminated by a signal correction method. Optical signals had a linear relationship with the concentration of trypsin inhibitor in the range of 10-200 ng mL(-1). The FTRIFS biosensor based on double layer porous silicon could be combined with a UV detector for screening the target molecule from complex component mixtures separated by a LC column. Using an LC-UV-FTRIFS system, a fraction containing a trypsin inhibitor could be separated from a soybean extract sample and identified in real-time.
    Biosensors & Bioelectronics 10/2009; 25(5):1056-63. · 6.45 Impact Factor
  • Jianmin Wu, Mingming Luan, Jiayin Zhao
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    ABSTRACT: Silica gel bead coated with macroporous chitosan layer (CTS-SiO(2)) was prepared, and the metal immobilized affinity chromatographic (IMAC) adsorbents could be obtained by chelating Cu(2+), Zn(2+), Ni(2+) ions, respectively on CTS-SiO(2), and trypsin could be adsorbed on the IMAC adsorbent through metal-protein interaction forces. Batch adsorption experiments show that adsorption capacity for trypsin on these IMAC adsorbent variated with change of pH. The maximal adsorption reached when the solution was in near neutral pH in all three IMAC adsorbents. Adsorption isothermal curve indicated that maximal adsorption capacity could be found in the Cu(2+)-CTS-SiO(2) with the value of 4980+/-125 IUg(-1) of the adsorbent, while the maximal adsorption capacity for trypsin on Zn(2+) and Ni(2+) loaded adsorbent was 3762+/-68 IUg(-1) and 2636+/-53 IUg(-1), respectively. Trypsin immobilized on the IMAC beads could not be desorbed by water, buffer and salt solution if the pH was kept in the range of 5-10, and could be easily desorbed from the IMAC beads by acidic solution and metal chelating species such as EDTA and imidazole. The effect of chelated metal ions species on CTS-SiO(2) beads on the activity and stability of immobilized trypsin was also evaluated and discussed. Trypsin adsorbed on Zn-IMAC beads retained highest amount of activity, about 78% of total activity could be retained. Although the Cu-IMAC showed highest affinity for trypsin, only 25.4% of the calculated activity was found on the beads, while the activity recovery found on Ni-IMAC beads was about 37.1%. A remarkable difference on stability of trypsin immobilized on three kinds of metal ion chelated beads during storage period was also found. Activity of trypsin on Cu-IMAC decreased to 24% of its initial activity after 1-week storage at 4 degrees C, while about 80% activity was retained on both Ni-IMAC and Zn-IMAC beads. Trypsin immobilized on Zn-CTS-SiO(2) could effectively digest BSA revealed by HPLC peptide mapping.
    International Journal of Biological Macromolecules 12/2006; 39(4-5):185-91. · 3.10 Impact Factor