Biomedical subjects

Kemin Wang

Publications and source records attributed to Kemin Wang.

26 records · Page 2Linked to original sources

PubMed2003

Collection of trace amounts of DNA/mRNA molecules using genomagnetic nanocapturers.

The collection and then the separation of rare DNA/mRNA targets with single-base mismatches in a complex matrix is critically important in human disease diagnostics, gene expression studies, and gene profiling. The major result of this work is the development and application of a novel genomagnetic nanocapturer (GMNC) for the collection, separation, and detection of trace amounts of DNA/RNA molecules with one single-base difference. The GMNC is constructed by bioconjugating molecular beacon DNA probes onto magnetic nanoparticle surfaces. We have successfully applied the GMNC in artificial buffer solution samples and in cancer cell samples, both containing different proteins and random DNA sequences. Our method has three distinctly useful features: highly efficient collection of trace amount of DNA/mRNA samples down to femtomolar (10(-15) M) concentrations; excellent ability to differentiate single-base-mismatched DNA/mRNA samples by combining the exceptional specificity of molecular beacons and the separation power of magnetic nanoparticles; and real-time monitoring and confirmation of the collected gene products. The newly developed genomagnetic nanocapturers will be highly useful for the collection of trace amounts of DNA/mRNA targets in a variety of sample sources in forensic, medical, and biotechnological fields.

Actins↗

PubMed2003

Bioconjugated nanoparticles for DNA protection from cleavage.

We have developed a novel method to protect DNA from cleavage using bioconjugated nanoparticles. Positively charged amino-modified silica nanoparticles have been directly prepared using water-in-oil microemulsion. Plasmid DNA can be easily enriched onto the positively charged nanoparticle surface, and the DNA strands are well protected from enzymatic cleavage. When incubated with nuclease enzyme for enzymatic cleavage, free plasmid DNA strands are completely cleaved, while those on the nanoparticle surfaces are intact. Our results clearly demonstrate unique properties of nanomaterials when combined with biomolecules. Our simple bionanotechnology will be highly useful in DNA separation, manipulation, and detection, and possibly in genetic engineering and gene therapy, as plasmid DNA can be protected in cellular environments without any change in its property.

Animals↗

PubMed2003

Porphyrin assembly on beta-cyclodextrin for selective sensing and detection of a zinc ion based on the dual emission fluorescence ratio.

In the present paper, a new cyclodextrin/porphyrin supramolecular sensitizer for zinc ion has been proposed based on the porphyrin dual fluorescence emission ratio. In aqueous solution, meso-tetraphenylporphyrin shows weak fluorescence, while in the presence of alkylated beta-cyclodextrin, it exhibits significant fluorescence enhancement by forming a cyclodextrin/porphyrin inclusion complex. Furthermore, the formation of a supramolecular complex causes a remarkable increase of the porphyrin metalation rate following the porphyrin fluorescence emission changes at two different emission wavelengths. The fluorescence emission of tetraphenylporphyrin at 656-nm bands decreases while that at 606 nm increases upon zinc ion interaction. Thus, the inclusion complex can behave as a ratiometric fluorescent sensor. Theoretically derivative equations for fluorescent ratiometry have been proposed for the first time. The feasibility of the proposed method is demonstrated by the performance of fluorometric detection of zinc ion. With the optimum conditions described, zinc ion in aqueous solution can be determined from 5.0 x 10(-7) to 2.5 x 10(-4) M. As the porphyrin electronic absorption and fluorescence emission are located in the visible range, and the fluorescence changes upon zinc ion interaction show high selectivity over biologically relevant cations, the inclusion complex could be used for biomedical application.

Cyclodextrins↗

PubMed2003

Rayleigh light scattering study on the supramolecular interactions of beta-cyclodextrin derivatives with tetrakis(4-methoxylphenyl)porphyrin.

The supramolecular interactions of beta-cyclodextrin(beta-CD) and four kinds of alkylated beta-cyclodextrin (beta-CDs), i.e. heptakis (2,6-di-O-isobutyl)-beta-cyclodextrin (Ob-beta-CD), heptakis (2,6-di-O-n-octyl)-beta-cyclodextrin (Oc-beta-CD), heptakis (2,6-di-O-n-dodecyl)-beta-cyclodextrin (Od-beta-CD) and heptakis (2,6-di-O-n-hexadecyl)-beta-cyclodextrin (Oh-beta-CD) with tetrakis(4-methoxylphenyl)porphyrin (TMOPP) have been investigated by Rayleigh light scattering (RLS) technique. Beta-CDs form 2:1 inclusion complex with TMOPP following an obvious RLS enhancement of TMOPP. The inclusion abilities of different beta-CDs were compared. The results show that the inclusion ability of beta-CDs is related to the size of the alkylated substituent. Thus, a new mechanism of inclusion interaction has been proposed. The exact stoichiometric ratios and the association constants of the inclusion complexes have been examined by application of curve fitting method.

Cyclodextrins↗

PubMed2003

Separation and determination synchronously by multichannel mode-filtered light capillary electrochromatography.

Mode-filtered light capillary electrophoresis (CE) was developed for capillary electrochromatography (CEC) by applying annular columns of different size (250, 320, and 530 micro m) and a bovine serum albumin (BSA)-modified chiral stationary phase. BSA was encapsulated on the pretreated surface of an optic fiber and the inner wall of a capillary using sol-gel technique with a resultant larger active stationary phase area. The coating was examined by atomic force microscopy (AFM) and Fourier transform infrared (FT-IR). The separation of DL-tryptophan (10 mM) was investigated under different voltage/current conditions.

Animals↗

PubMed2003

Mixed C18 and C1 modification on an optical fiber for chromatographic sensing.

An optical fiber-chromatographic sensor, aiming at simultaneous and selective response to multiple components following a chromatographic separation, is described. We report an improved approach for immobilization of octadecyl (C(18)) and methyl (C(1)) moieties as stationary phase on an optical fiber suitable as a sensing phase for organic solutes. By this approach, the stability and lifetime of the sensing layer as well as the detectability and retention behavior of the chromatographic sensor could be improved. Infrared spectroscopy was employed to confirm the presence of C(18) and C(1) moieties on the modified surface of the optical fiber. The chromatographic sensor was applied, with good sensitivity and chemical selectivity, to the simultaneous separation and detection of bromobenzene and toluene, using water as the mobile phase.

Biosensing Techniques↗

PubMed2002

A selective optode membrane for histidine based on fluorescence enhancement of meso-meso-linked porphyrin dimer.

A plasticized polymer film, poly(vinyl chloride) (PVC) incorporated with a specific porphyrin dimer, is shown to exhibit significant and analytical usefulness for optical response toward histidine. The porphyrin dimer containing a free-base porphyrin and a covalently linked metalloporphyrin is shown to be weakly fluorescent as a result of the photoinduced intramolecular electron transfer from the inner free-base porphyrin in singlet excited state to a low-spin cobalt(II). The fluorescence enhancement of the membrane by histidine is based on favorable extraction of histidine into the bulk organic membrane and complexation with the inner metallopophyrin moiety and inhibiting the electron transfer process. With the optode membrane described, histidine in a sample solution from 0.0045 to 1.53 mM can be determined. The calibration curve of the optode membrane for histidine shows a good correlation with the mathematically derived formalism and, thus, confirms the theoretically expected behavior. The sensor presented exhibits high selectivity toward histidine over several amino acids and common inorganic anions. The optical selectivity coefficients obtained for histidine over other biologically relevant amino acids and anions are shown to meet the selectivity requirements for the monitoring concentration levels of histidine in biological samples. The selective characteristic of the sensor has been discussed in the view of the coordination chemistry of metalloporphyrin.

Algorithms↗

PubMedDate not supplied

Photostable luminescent nanoparticles as biological label for cell recognition of system lupus erythematosus patients.

In this article, we report a method for cell recognition of system lupus erythematosus (SLE) patients that uses photostable luminescent nanoparticles as biological labels. The luminescent silica nanoparticles are prepared with a water-in-oil microemulsion (W/O) technique. The silica network is produced by the controlled hydrolysis of tetraethylorthosilicate (TEOS) in water nanodroplets with the initiation of ammonia (NH3.H2O). A luminescent compound, tris(2,2'-bipyridyl)dichlororuthenium(II)hexahydrate [Ru(II)(bpy)3]2+, is doped inside as a luminescent signaling element, and the most appropriate dye concentration for the preparation of the nanoparticles with a size of 28 +/- 4 nm has been determined. The luminescent silica nanoparticles are covalently immobilized with goat anti-human immunoglobulin G (IgG), which can recognize SmIgG+ B lymphocytes. We have used antibody-labeled nanoparticles to recognize target SmIgG+ B lymphocytes isolated from the circulating blood of SLE patients. It has been observed that a bioassay based on fluorescent nanoparticles can identify target cells selectively and efficiently. And fluorescent nanoparticle labels also exhibit high photostability. The experiment results have shown that this cell recognition method was an effective one as further proof of the diagnosis of SLE.

2,2'-Dipyridyl↗