Biomedical subjects

Xian-rong Qi

Publications and source records attributed to Xian-rong Qi.

10 recordsLinked to original sources

PubMed2006

Preparation and characterization of superparamagnetic iron oxide nanoparticles stabilized by alginate.

SPION with appropriate surface chemistry have been widely used experimentally for numerous in vivo applications. In this study, SPION stabilized by alginate (SPION-alginate) were prepared by a modified coprecipitation method. The structure, size, morphology, magnetic property and relaxivity of the SPION-alginate were characterized systematically by means of XRD, TEM, ESEM, AFM, DLS, SQUID magnetometer and MRI, respectively, and the interaction between alginate and iron oxide (Fe(3)O(4)) was characterized by FT-IR and AFM. The results revealed that typical iron oxide nanoparticles were Fe(3)O(4) with a core diameter of 5-10 nm and SPION-alginate had a hydrodynamic diameter of 193.8-483.2 nm. From the magnetization curve, the Ms of a suspension of SPION-alginate was 40 emu/g, corresponding to 73% of that of solid SPION-alginate. This high Ms may be due to the binding of Fe(3)O(4) nanoparticles to alginate macromolecule strands as visually confirmed by AFM. SPION-alginate of several hundred nanometers was stable in size for 12 months at 4 degrees C. Moreover, T1 relaxivity and T2 relaxivity of SPION-alginate in saline (1.5 T, 20 degrees C) were 7.86+/-0.20 s(-1) mM(-1) and 281.2+/-26.4 s(-1) mM(-1), respectively.

Alginates↗

PubMed2006

[Immunogenicity of single-dose HBsAg-PLGA controlled release microspheres in mice].

AIM: To investigate the level of immune response and the immune mechanism of the single-dose hepatitis B surface antigen (HBsAg)-poly (d, l)-lactide-co-glicolide acid (PLGA) microspheres in BALB/c mice. METHODS: Three kind of HBsAg-PLGA microspheres, HBsAg-PLGA50/50-COOH microspheres, HBsAg-PLGA75/25 microspheres and HBsAg-PLGA50/50 microspheres, were prepared by double emulsion microencapsulation technique used three kinds of PLGA with different L/G ratio. The single-dose of HBsAg-PLGA microspheres was subcutaneously injected into BALB/c mice at the dose of 7.5 microg HBsAg per mouse. The conventional aluminum-adjuvant vaccine was subcutaneously injected at 0, 1 and 2 month as positive control. In certain time interval, the induced immune level of total antibody was detected by enzyme linked immunosorbent assay (ELISA). For subclass of IgG antibody and cytokines studies, the dose of HBsAg was 2.5 microg per mouse. RESULTS: The HBsAg-PLGA microspheres could successfully induce a humoral immune response in BALB/c mice. Compared with the conventional aluminum-adjuvant vaccine, the antibody response of the HBsAg-PLGA50/50-COOH microspheres was significantly lower than the group received three injections of aluminum-adjuvant vaccine (P < 0.01) except for a higher priming response during the early 6 weeks. The results were ascribed to the relatively rapid degradation charactics of PLGA50/50-COOH polymer. The immune response for the HBsAg-PLGA50/50 microspheres and HBsAg-PLGA75/25 microspheres were comparable to the group administered with aluminum-adjuvant vaccine (P > 0.05) which was due to the sustained degradation of PLGA50/50 and PLGA75/25 polymer. CONCLUSION: The HBsAg-PLGA microsphere is a promising candidate for the controlled delivery of a vaccine which does not require multiple injections.

Animals↗

PubMed2006

[Pharmacokinetics of doxorubicin alginate microspheres and evaluation of its hepatic arterial embolization in vivo].

AIM: To investigate the pharmacokinetics of doxorubicin alginate microspheres (DOX-AM) in vivo after hepatic arterial embolization. METHODS: China miniature pigs were chosen as the experimental animals. Transcatheter hepatic arterial chemoembolization (TACE) with DOX-AM (experimental group), lipiodol and DOX (DOX-lipiodol, control group 1), and infusion with DOX (control group 2) were performed after angiography and superselection of an intrahepatic branch of hepatic artery. After chemoembolization or infusion, the blood was collected at different time intervals. Drug concentration in plasma was measured by HLPC and the parameters of pharmacokinetics were calculated. RESULTS: The values of T1/2, AUC, Cmax, and MRT of the DOX-AM were significantly different from those of control group 1 and control group 2. After embolization, the DOX-AM embolized in the vessel and still retained there at 8 weeks. The digital subtraction arteriography (DSA) and computerized tomography (CT) showed the reliable embolization results. The histological examination indicated that the liver damnifications were changed transitorily in all groups (P < 0.05) and were recovered within two weeks. The liver damnifications increased in following order: DOX < DOX-AM < DOX-lipiodol. CONCLUSION: DOX-AM showed definite property of delayed release of drug in liver, and increased the retention time and concentration of DOX after embolization in vivo.

Alginates↗

PubMed2005

[Preparation, release and immunogenicity evaluation of HBsAg-PLGA microspheres].

OBJECTIVE: To investigate microencapsulation technique, release of HBsAg-PLGA microspheres and degradation of the polymer in vitro, and the level of immune response after the single-dose HBsAg-PLGA microspheres subcutaneously injected (sc) to BALB/c mice. METHODS: HBsAg-PLGA microspheres were prepared by double emulsion microencapsulation technique with orthogonal experiments. The pharmaceutical characteristics of size and surface morphology, antigen loading efficiency, release of HBsAg-PLGA microspheres and degradation of the polymer in vitro, and the level of immune response after single sc of PLGA microspheres in BALB/c mice were investigated. RESULTS: The concentration of PVA was the significant factor affecting the particle size (P<0.05). The release of protein from the microspheres was controlled mainly by the bulk erosion of polymer matrix. When single sc of HBsAg-PLGA microspheres mixed with different formulations, the immunogenicity effect was comparable to that of the aluminium adjuvant vaccine. CONCLUSION: The single-dose HBsAg-PLGA microspheres mixture with different release behavior is a promising candidate for controlled delivery vaccine.

Animals↗

PubMed2005

[Preparation of 8-chloro-adenosine long circulation liposomes and its pharmacokinetics in rats].

AIM: To prepare 8-chloro-adenosine (8-Cl-A) long circulation liposomes with high entrapped efficiency and prolonged action-time of 8-Cl-A in vivo. METHODS: To prepare 8-Cl-A long circulation liposomes of nanometer size by improved multiple emulsion. The entrapped efficiency, size and size distribution of 8-Cl-A long circulation liposomes were determined, and its pharmacokinetics in rats was evaluated. RESULTS: The entrapped efficiency of 8-Cl-A long circulation liposomes was 62.70% and mean diameter of the liposomes was 79.9 nm. The pharmacokinetics studies indicated that 8-Cl-A long circulation liposomes showed higher drug concentration and larger AUC values than that of 8-Cl-A after iv to rats. CONCLUSION: 8-Cl-A long circulation liposomes could prolong the action-time of 8-Cl-A in vivo.

2-Chloroadenosine↗

PubMed2003

[Preparation of cisplatin multivesicular liposomes and release of cisplatin from the liposomes in vitro].

AIM: To prepare cisplatin multivesicular liposomes with high encapsulation efficiency and sustained-release character, and compare the release characteristics with conventional liposomes prepared by reverse-phase evaporation method. METHODS: Cisplatin multivesicular liposomes were prepared using multiple emulsion method. The concentrations of cisplatin and lipids in the liposomes were measured by flameless atomic absorbance spectroscopy (FAAS) and phosphalipid enzyme reagent method, respectively. The encapsulation efficiency, size and release of the cisplatin from the liposomes were studied in vitro. RESULTS: The mean diameter of cisplatin multivesicular liposomes was (16.6 +/- 1.0) micron. The encapsulation efficiency of cisplatin was more than 80%. The release profile in vitro fitted with a first-order equation. The releasing t1/2 of cisplatin multivesicular liposomes is 37.7 h, which is 8.4 that of conventional liposomes. Co-membrane stabilizer has remarkable stabilizing effect on the multivesicular liposomal membrane confirmed by differential scattering calorimetry (DSC). CONCLUSION: The cisplatin multivesicular liposomes showed high encapsulation efficiency and sustained-release character.

Antineoplastic Agents↗

PubMed2003

[Cationic lipid and polyethylene glycol enhance liposomes-mediated cell transfection and increase the fluidity of liposomes membranes].

AIM: To prepare fluorescein sodium (FS) cationic liposomes and investigate the influence of cationic lipid (DC-chol) and polyethylene glycol (PEG) with different molecule weight (MW) on cationic liposome incorporation efficiency, cellular delivery and fluidity of liposome membrane. METHODS: Using FS as a model material for encapsulation, the liposomes were prepared and separated (by sephadex G-50 1 cm x 20 cm column), and the liposome incorporation efficiencies was measured. The interaction between the FS and cationic liposomes was investigated by measuring the change of fluorescent spectrum. The cellular uptake of different liposome forms by choosing HepG2 2.2.15 as an in vitro cell culture assay model, and the influence of PEG on the fluidity of liposome membrane with the technique of fluorescence polarization were investigated. RESULTS: Cationic lipid and different PEGs showed great effects on increasing liposome incorporation efficiency (from 0.64% to 86.57%), cellular uptake (from 2.18% to 48.46%) and fluidity of liposome membrane. The effect of PEG was MW dependent, and with the increase of MW, the incorporation efficiency and transfection was improved, and the fluidity of liposome membrane increased. CONCLUSION: Addition of cationic lipid and high MW PEG into cationic liposomes can enhance the cellular delivery and fluidity of cationic liposomes. Also, they can improve the incorporation efficiency of cationic liposomes.

Cholesterol↗

PubMed2003

[Secondary structure of insulin encapsulated within liposomes].

AIM: To determine the secondary structure of insulin encapsulated within liposomes. METHODS: The secondary structure of insulin, mixture of insulin with liposomes (I) and insulin liposomes (II) were determined by Fourier transform infrared (FTIR) spectroscopy. RESULTS: The figures of secondary structure of insulin, sample I and II were similar. The results showed that the amount of alpha-helix and beta-sheet of insulin, sample I and II had little difference, from 36.09% (insulin) to 31.68% (sample I) and 31.45% (sample II), and from 47.83% (insulin) to 53.29% (I) and 51.36% (II), respectively. The results showed that the insulin of sample I and II did not insert in liposomes membrane, only adsorbed or extendedon the surface of the liposomes. CONCLUSION: The secondary structure of insulin encapsulated within liposomes has not been destroyed and still remain the original state.

Drug Carriers↗

PubMed2002

[Study on pharmaceutical characterization and pharmacokinetics of daunorubicin long-circulating liposomes in rat].

AIM: To study the pharmaceutical characterization and pharmacokinetics of long-circulating liposomes containing daunorubicin. METHODS: The morphology of daunorubicin long-circulating liposome was surveyed under the transmission electron microscope. The size of daunorubicin long-circulating liposomes was determined by laser scatter method. The entrapment efficiency and accelerative experiment stability of the daunorubicin long-circulating liposomes were examined. Visible spectrophotometry and the HPLC method were established for determination of the daunorubicin in the long-circulating liposomes. The percent release of daunorubicin from long-circulating liposomes in HBS (pH 7.5) and rat serum at 37 degrees C were examined. The pharmacokinetics in rats were studied. RESULTS: The high entrapment efficiency (> 85%) and stabilized long-circulating liposomes could be achieved. The drug was slowly released from the daunorubicin long-circulating liposomes. The drug released from liposomes was less than 10% in 24 h. The T1/2 alpha and AUC of long-circulating liposome were higher than those in injections. CONCLUSION: The long-circulating liposomes prepared by us have high encapsulation efficiency and the pharmaceutical characterization showed good stability, they can be used for clinical purpose.

Animals↗

PubMed2002

[Interaction between insulin with liposome].

AIM: To study the characteristics of the interaction between insulin and liposome. METHODS: The interaction between insulin and liposome was studied by fluorescence spectra and microcalorimetry methods. The sample of insulin liposome interaction after separation by supper-centrifugalization or gel filtration was determined by fluorescence and HPLC. RESULTS: The results indicate that there was only little increase in fluorescence intensity and no blue shift of peak in fluorescence spectrum. Fluorescence quenching experiments with NaI and acrylamide as quenchers showed that the KSVs (the slope of Strm-Volmer equation) of insulin were more similar to that with added liposome, indicating low interaction between insulin with liposome. The microcalorimetric results indicate that the heat released during the mixture of liposome with insulin, was 1.98 kcal.mol-1, suggesting that the reaction belongs to weak reaction. The quantity of insulin in the insulin-liposome mixture sample after separation by ultracentrifuge or by Sephadex G-75 determined by HPLC, the combination percent was only 0.2%, indicating low interaction between insulin and liposome. CONCLUSION: The interaction between insulin and liposome was weak.

Chemistry, Pharmaceutical↗