Papers by Keyword: Colloidal Gold

Abstract: A rapid and sensitive competitive immunochromatographic assay for aflatoxin B₁ (AFB₁) based on colloidal gold-antibody probe was developed. The limit of detection for AFB1 standard solution was 0.5ng/ml and for foodstuff sample was 10μg/Kg. Other aflatoxins including AFM₁, AFB₂, AFG₁, and AFG₂ have less cross-reactivity to the strip. The storge life of the strip was at least 12 monthes. The method was well agreement with the ELISA method by testing food samples. This method is suitable for rapid testing of AFB₁ on site.

Abstract: Porcine Epidemic Diarrhea Virus (PEDV) infection has caused huge economic losses, but no serological method is available for batch detection of field samples. The aim of the study was to develop a method for large-batch detection of PEDV infection. Colloidal gold-labeled staphylococcal protein A (SPA) was sprayed on glass fibers to prepare a conjugate pad. The recombinant N protein of PEDV was blotted on the test line of the nitrocellulose (NC) membrane, and pig IgG was streaked on the control line of the NC membrane. The immunochromatographic strip was used for detection of antibodies against PEDV. The results showed that the strip test was simple and the results could be determined within 10 min with naked eyes. The test strip was highly specific for pig serum against PEDV and no cross-reaction was observed. The test strip had close similarity with ELISA. Storage at room temperature for 6 months did not affect the specificity and sensitivity obviously. A total of 320 clinical pig sera were detected by both ELISA and the developed test strip, and the coincidence was 96.3 %. Therefore, the developed immunochromatographic strip is specific, sensitive, stable, fast and simple, and it is suitable for on-site detection of antibodies against PEDV.

Abstract: Objective To evaluate the effectiveness of prokaryotic expression of fusion proteins pp150-pp65 of human cytomegalovirus (hCMV) for its application as antigen, the fusion protein of pp150-pp65 were expressed in prokaryotic expression system and purified by Ni-NTA affinity chromatography column for preparing the colloidal gold kit. Methods Using DNA from HCMV strain as template, the genes encoding pp150 and pp65 protein fragment were amplified by PCR technique, respectively. After confirmed by DNA sequence analysis, the recombinant plasmid pET28a-pp150-pp65 was transformed into E.Coil.BL21(DE3) and induced to express with IPTG. The expressed fusion protein was characterized by SDS-PAGE and western blot after purified, then we used the purified fusion protein to develop combined detection kit of IgM/IgG antibody against HCMV (colloidal gold method) with Beijing Innovita Bio-tech Co., Ltd for detecting the samples, compared with the imported kits (ELISA). Results The gene of fusion fragment pp150-pp65 was correctly amplified and the recombinant vector was successfully constructed. The purified protein with the molecular weight of 45KD had good antigenicity by western blot. The protein was subjected to assay with an ELI SA capture kit in its specific and sensitive assay based on colloidal gold nanoparticles, testing of 600 serum samples indicated that this kit had a sensitivity of 92.7%;, specificity of 83.1%, crude consistency o f 90.2%, compared to the imported HCMV-IgG kit; the sensitivity of the kit was 88.1%, specificity was 89.2%, coarse consistency was 88.5%, compared to the imported HCMV-IgM kit; Conclusion In this experiment, the HCMV antigen with high purity and specificity (pp150-pp65 recombinant protein) was prepared effectively through genetic engineering technology. Compared to imported reagents, the colloidal gold kit consisting of fusion protein in a capture assay had high sensitivity and specificity. Preliminary clinical use warrants further development and use of this kit. Furthermore, it provides a technological basis for detection of HCMV in different stages of clinical infection.

Abstract: Colloidal gold immunochromatographic strip is a simple and convenient method for detecting harmful substances, such as Morphine and CLB. For the purpose of reducing sterically hinder and enhancing the measurement sensitivity, 20nm colloidal gold was choosed. Therefor, in this paper, the microwave heating method was improved to synthesize the 20nm collidal gold, the addtion of reductantan and the heating time were explored. We use transmission electron microscope and UV-vis spectroscope to character the size of series particles. The result showed that when 1ml reduces was added and the heating time was more than 2min, the gold particles were close to 20nm and much more uniform. In conclusion, the improved microwave method was more suitable for preparation of small diameter gold particles.

Abstract: A new catalyst of gold supported on nanometal oxide for oxidation of SO2 was developed. Deposition-precipitation method was used to prepare gold-based catalysts. The catalytic activity of the catalysts was evaluated by determining the concentration of SO2 with gas chromatography under reaction temperature from 100 to 700°C. The results showed that there was an enhancement of catalytic activity when gold nanoparticles were dispersed on the surface of nano-metal oxides, furthermore, γ-Fe2O3 showed the highest activity as the support of the colloidal gold supported catalysts among the nanometal oxides including γ-Fe2O3, Fe2O3, ZnO, and Al2O3. It was also found that water vapour in the reaction enhanced the catalytic activity of Au/γ-Fe2O3. The Au/γ-Fe2O3 was characterized by XRD and FTIR methods, which indicated that the gold nanoparticles were dispersed on the γ-Fe2O3 support and sulfate species were formed on the surface of catalysts.

Abstract: The catalytic activities of various nanometer metal oxides (ZnO, CeO2, ZrO2, Al2O3, Co3O4, MgO) supported colloidal gold catalysts with self-designed equipment were evaluated and compared for benzene catalytic oxidation. The results showed that ZnO was the most activive support of the colloidal gold among these nanometer metal oxides. The effects of Au/ZnO on the activity for benzene oxidation were investigated at 50- 300°C. The optimal gold loading was 2 wt%. The Au/ZnO was characterized using BET, XRD, and TEM methods. The XRD patterns and TEM image showed that gold nanoparticles were well dispersed on the surface of ZnO, and the mean diameter was 3.1±0.81 nm. The gaseous products of benzene oxidation and the adsorbed species on Au/ZnO catalyst surface were characterized with FTIR and GC-MS. It was proved that benzene was completely oxidized into CO2 and H2O over the Au/ZnO catalyst at low temperature.