Preparation, characterization and antioxidation activity in vitro of quercetin loaded chitosan nanoparticles / 中国生化药物杂志

Objective To prepare quercetin ( QUE) loaded chitosan nanoparticles ( CS-NPs), evaluate its physicochemical properties and antioxidation activity in vitro.Methods Quercetin chitosan nanoparticles were prepared by ionic crosslinking method and self-assembly method.The preparation method was optimized using entrapment efficiency (EE), drug loading (DL) and size as indexes.The best formulation and preparation conditions were optimized by orthogonal test based on single-factor test, evaluation indicator as particle size and EE.The physicochemical properties of the obtained QUE-CS-NPs were characterized by the following methods: the transmission electron microscope (TEM), dynamic light scattering (DLS) analysis for morphology, size distribution and Zeta potential.In vitro release behavior in 0.5% SDS solution was evaluated by dialysis tube method.In vitro antioxidant activity assays were performed by evaluating the abilities of the microspheres for hydroxide radicals and superoxide anions .Results TEM results revealed QUE-CS-NPs with round and uniform.Particle-size analysis showed that the diameters and Zeta potential of the QUE-CS-NPs were (282.9 ±20) nm and (30.5 ±2) mV, with uniform distribution (polydispersity below 0.185).DL and EE of QUE-CS-NPs were (8.81 ±0.65) %and (80.02 ±1.04) %, respectively.QUE-CS-NPs showed extended administration times with 66.2% cumulative release within 72 h.QUE-CS-NPs showed pronounced antioxidant activity and a concentration dependent, even more substantial than that of pure QUE.Conclusion QUE-CS-NPs show a good size, sustain release effect and pronounce antioxidant activity.

Preparation of fusion protein between ZZ affinity peptide and alkaline phosphatase and its primary application / 中国免疫学杂志

Objective:To construct and express the fusion protein between ZZ affinity peptide and alkaline phosphatase and examine its biological activities.Methods:The alkaline phosphatase gene was cloned into pEZZ 18 vector containing ZZ peptide gene resulted in the pEZZ-AP recombinant vector.Then the vector was transformed and expressed in E.coli DH5α.And HisTrap affinity chromatography was employed to separate and purify the target protein.After analyzed by Western blot , ZZ-AP fusion protein was applied to immunocytochemistry as an alterative second antibody.Results:The result of SDS-PAGE showed that the fusion protein with a relative molecular weight was consistent with the theoretical values (62 kD).The fusion protein has rabbit IgG-binding ability and en-zymatic activity of alkaline phosphatase ,those were validated in Western blot;and it produced a good signal that was comparable in its staining pattern to that generated with goat anti-rabbit IgG-AP in immunocytochemistry.Conclusion: The ZZ-AP fusion protein was constructed successfully ,it has rabbit IgG-binding ability and enzymatic activity of alkaline phosphatase.We anticipate that the ZZ-AP fusion protein has a potential application in immunoassay field.

Site-specific biotinylation of EGFP with double biotin molecules based on Avi-tag technology / 中国免疫学杂志

Objective:To prepare the site-specific biotinylation of enhanced green fluorescence protein with double biotin molecules using Avi-tag technology.Methods:The EGFP gene was prepared by PCR and cloned into pdi-Avitag resulting the vector pEGFP-( Avitag) 2.The fusion protein EGFP-( Avitag ) 2 was expressed in E.coli DH5αand purified by employing IMAC.The site-specific biotinylation was implemented by BirA enzyme in vitro, and then was identified by competitive ELISA and Western blot.Results:The recombinant prokaryotic expression vector pEGFP-(Avitag)2 was correctly constructed,and EGFP-(Avitag)2 fusion was successfully expressed in E.coli DH5α.The results of competitive ELISA and Western blot showed that the EGFP-( Avitag) 2 could be site-specific biotinylation with double biotin molecules based on Avi-tag technology.Conclusion: The site-specific biotinylation of EGFP with double biotin molecules is successfully prepared,and we anticipate that can be used for BAS to improve the sensitivity and specificity of immunosensors.

Construction and identification of a screening vector using enhanced green fluorescent protein(EGFP) as an indicator / 中国海洋药物

Objective To construct and identify the screening vector pUC18-EGFP,using EGFP as an indicator. Methods The EGFP gene was prepared by PCR and cloned into pUC18 resulting the vector pUC18-EGFP. Then DNA fragment was inserted into the MCS of pUC18-EGFP to test its practicability based on green fluorescence. Results The pUC18-EGFP was confirmed correctly by restriction enzyme analyses. The pUC18-EGFP was used to select recombinants. The green strains on the plate were confirmed by restriction enzyme and DNA analyses,which were E.coli harboring recombinants. Conclusion The screening vector PUCl8-EGFP was constructed successfully. Thus,we can select the positive clones on plates based on the green fluorescence of EGFP.