Biomedical subjects

Yuan-Cheng Cao

Publications and source records attributed to Yuan-Cheng Cao.

6 recordsLinked to original sources

PubMed2007

Optimization of the methods for introduction of amine groups onto the silica nanoparticle surface.

The luminescent silica nanoparticle has attracted the researchers' concentration in bioanalysis recently. Its extensive application is based on the immobilization of various biomolecules such as deoxyribonucleic acid, antibody, and so forth onto the surface. By comparing different introduction methods of amine groups, it was confirmed that the "two-step" route is more preferable by adding tetraethyl orthosilicate and 3-aminopropyl-(triethoxyl)silane in sequence, to attain ideal amine-modified silica nanoparticles. On this basis, carboxyl groups were derived from amine groups on the nanoparticle surface and then were activated by 1-ethyl-3-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxy-succinimide. Finally, mouse monoclonal antihuman CD71 antibody (McAb CD71) and transferrin were effectively linked with the carboxyl groups and successfully labeled the receptors in the membrane of fibroblast cells, respectively.

Amines↗

PubMed2006

Preparation of Au coated polystyrene beads and their application in an immunoassay.

A novel immunoassay method based on polystyrene beads coated with Au nanoparticles (Au@PS) is described. Au nanoparticles were prepared by reductive reaction, and then deposited on the surface of polystyrene beads to form Au coatings. Results indicated that the Au coatings had good stability and that human IgG was immobilized at a concentration of 16 microg/g Au@PS. FITC-labeled rabbit-anti-human IgG and FITC-labeled rabbit-anti-goat IgG were employed to react with the human IgG on Au@PS. Fluorescence imaging results showed that the reaction had good immuno-specificity. In addition, further experiments at the single-bead level indicated that the linear range was 0.05-15 microg/ml, and that the FITC signal could be detected even when the target antibody concentration was as low as 0.01 microg/ml. The assay results were compared with an enzyme-linked immunosorbent assay (ELISA), and showed relatively good reliability.

Animals↗

PubMed2006

Characterization of the coupling of quantum dots and immunoglobulin antibodies.

Water-soluble quantum dots (QDs) were used to label goat anti-human immunoglobulin antibodies (Abs), and the labeling process was characterized by column purification. The QDs obtained in organic solvent were modified with mercaptoacetic acid (MAA) and became water-soluble. These water-soluble QDs were linked to the antibodies using the coupling reagents ethyl-3-(dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The linking process was shown to be effective by ultra-filter centrifugation and column purification. After comparing the quantities of Abs and water-soluble QDs involved in the linking reaction via column purification, it was found that a molar Abs:QD ratio of >1.2 resulted in most of the water-soluble QDs becoming covalently linked to the Abs. The circular dichroism (CD) spectra of Abs and QD-Ab conjugates were very similar to each other, indicating that the secondary structure of Abs remained largely intact after the conjugation. Finally, antigen (Ag)-antibody (Ab) recognition reactions perfomed on the surface of a glass slide showed that the conjugate retained the activity of Abs. This work lends support to the idea of linking biomolecules to QDs, and thus should aid the application of QDs to the life sciences.

Humans↗

PubMed2006

Preparation of silica encapsulated quantum dot encoded beads for multiplex assay and its properties.

Novel -COOH modified polystyrene beads were prepared by sulfonation grafting, and the surface area and pore volume are greatly improved in comparison with the swelling-treated beads. The optimization coating time is 4 h, and the corresponding -COOH content is approximately 2.1 mmol/g. The scanning electron microscope results show that the silica particles deposited on the beads and formed a silica shell that decreases the leakage of quantum dots (QDs) preferably and improves the bar code stability greatly. The anti-photobleaching of silica-coated beads was studied systemically, and the results show that the half-decay time (t1/2) of the coated beads increases to 537 s--seven times longer than that of the uncoated ones. Further DNA probe hybridization experiments indicated that the coding signal and target signal can be detected simultaneously and that the assays based on these probe-conjugated silica/QD/polystyrene beads have good specificity and sensitivity that can detect a concentration as low as 0.01 microg/ml target DNA in denatured calf thymus DNA solution, indicating that it is feasible to use this kind of bead for multiplex analysis.

DNA↗

PubMed2004

Synthesis, protein-binding ability and phytoalexin-elicitor activity of epoxyalkyl (1-->3)-beta-D-oligoglucosides.

We describe a approach for the synthesis of (1-->3)-beta-D-oligosaccharide derivatives 10-18. 1-9 were synthesized by treating peracetylated (1-->3)-beta-D-oligosaccharides with the corresponding alkenyl alcohols and Lewis acid (SnCl(4)) catalyst. Epoxidation of the corresponding alkenyl oligoglucosides took place by m-CPBA. NaOMe in dry methanol was used for the deacetylation of the blocked derivatives, to give 10-18 in an overall yields of 25-32%. In subsequent glucan-binding protein of soybean assays, we found that 16 was most active, with an IC(50) value of 9 mM. However, the activities of 17, 18, 13, 14, 15, 10, 11, and 12 were gradually decreased. At the same time, we found 16 was most active as compared to the other (1-->3)-beta-D- oligoglucoside derivatives in eliciting phytoalexin accumulation in soybean cotyledon tissue, and 16 was kept longer time than (1-->3)-beta-D-glucohexaose, which indicated 16 is much more stable than (1-->3)-beta-D-glucohexaose.

Epoxy Compounds↗

PubMedDate not supplied

Quantum dot optical encoded polystyrene beads for DNA detection.

A novel multiplex analysis technology based on quantum dot (QD) optical encoded beads was studied. Carboxyl functionalized polystyrene beads, about 100 microm in size, were precisely encoded by the various ratios of two types of QDs whose emission wavelengths are 576 and 628 nm, respectively. Then the different encoded beads were covalently immobilized with different probes in the existing of sulfo-NHS and 1-[3-(Dimethylamino) propyl]-3-ethylcarbodiimide methiodide, and the probe density could reach to 3.1 mmol/g. These probe-linked encoded beads were used to detect the target DNA sequences in complex DNA solution by hybridization. Hybridization was visualized using fluorescein isothiocynate-labeled DNA sequences. The results show that the QDs and target signals can be obviously identified from a single-bead-level spectrum. This technology can detect DNA targets effectively with a detection limit of 0.2 microg/mL in complex solution.

Base Sequence↗