ABSTRACT
To prepare the mimetic exosomes and co-delivery proteins and nucleic acids, and achieve efficient and safe co-delivery of multi-component drugs, an optimized formulation was designed by modifying a polylactic acid-glycolic acid copolymer (PLGA) matrix with a cationic lipid excipient dioleyl trimethylammonium propane (DOTAP), and a PLGA/DOTAP nanoparticles packaged protein and nucleic acid was prepared by double emulsion method, and the outermost membrane structure prepared by reverse phase evaporation method and consists of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol and membrane proteins. The structure of the mimetic exosomes is formed by ultrasonic dispersion and extrusion, and analyzed its characteristics and nature of the transfer effect. The size of mimetic exosomes was about 156.13 nm, with negative charge (-18.23 ± 0.57 mV), and it could efficiently co-transfer protein and siRNA, and siRNA could effectively inhibit the expression of target gene Trim28. The mimetic exosomes simulate the structure of exosomes and achieve safe and efficient co-delivery of multi-component drugs.
ABSTRACT
Objective: To investigate the preparation process of polylactic acid-glycolic acid copolymer/ hydroxyapatite (PLGA/HA) microcarriers by electrostatic spraying method, and to elucidate the superiority of PLGA/HA microcarriers. Methods: The PLGA/HA microcarriers were prepared by electrostatic spraying method using nano-HA (20 nm, 99.9%) and PLGA (LA/GA = 50/50, Mw30k), and the influence of different concentrations (1%, 3%, 5%) and different voltages (4. 0, 4. 5, > 5. 0 kV) of HA in the morphology of the microcarriers was investigated and the best ball making parameters were obtained. The PLGA microcarriers were used as PLGA group, PLGA+1%HA as 1% PLGA/HA group, PLGA + 3% HA as 3% PLGA/HA group, PLGA+ 5% HA as 5% PLGA/HA group, and the simple cells were used as blank control group. The characteristics of PLGA/HA microcarriers were detected by scanning electron microscope (SEM), cell proliferation test, cell fluorescence staining experiment, and Fourier transform infrared spectroscopy (FTIR). Results: The SEM results showed that the microcarrier particles were uniform, all of them were elliptical or circular, without abnormal shape spheres, with smooth surface, without sharp edges, adhesion between the spheres and aggregation, and there were no significant differences between the different concentrations of microcarriers. The cell proliferation test results showed that the order of adhesion cells was 5% PLGA/HA group > 3% PLGA/HA group > 1% PLGA/HA group > PLGA group > blank control group (P<0. 05); the number of cells was increased with the increasing of HA concentration; the microcarriers in 5% PLGA/HA group had the best cell affinity and the microcarriers had no cytotoxity. The cell fluorescence staining experiment showed that the MC3T3-E1 cells adhered well on the microcarriers. The FTIR analysis results showed that HA characteristic absorption peak was observed, indicating that the composite microcarrier contained PLGA and HA. Conclusion: The preparation process of PLGA/ HA microcarriers is successfully established by electrostatic spraying method. The method is simple and convenient to operate, and has excellent ball-making effect. It has broadly application prospects in bone tissue engineering.
ABSTRACT
Objective To prepare the biodegradable polylactic acid glycolic acid (PLGA) copolymer.encapsulated vascular endothelial growth factor(VEGF) loaded fluorescent controlled release sub-microspheres,to understand the efficiency of microspheres loading and releasing VEGF and to observe in vitro microspheres degradation.Methods VEGF-loading PLGA sub-microspheres were prepared by the two-phase solvent evaporation method,the in vitro degradation of fluorescent microspheres was observed by the laser confocal scanning electron microscopy.The drug loading efficiency and drug release curve were observed by ELISA.Results The VEGF loading PLGA fluorescent microspheres were successfully prepared by using the two-phase solvent evaporation method.The microspheres morphology was normal by using the scanning electron microscope and laser confocal microscope.The particle size was 0.5-1.0 μm with the laser particle size analyzer.The distribution was homogeneous.The VEGF loading rate and encapsulation rate detected by the quantitative ELISA were 3.91％ and 51.42 ％ respectively.The fluorescent microscope observed their slow degradation.The VEGF gentle release was detected by the quantitative ELISA,which showing linear zero order release trend.Conclusion The drug loading efficiency of VEGF-loading PLGA microspheres with 0.5-1.0 μm diameter is higher with linear zero order release,which can be directly observed by fluorescent light.
ABSTRACT
BACKGROUND: During conventional treatment for bone tuberculosis, there is a low effective concentration of anti-tuberculosis drugs, and the therapeutic effect is poor. OBJECTIVE:To develop a new biomaterial as a slow-release artificial carrier that can be directly implanted into the surrounding tissue of bone tuberculosis, maintain a certain anti-tuberculosis drug concentration for a long time, thereby playing an effective therapeutic action. METHODS:Rifampicin/polylactic acid/glycolic acid microspheres and isoniazid/polylactic acid/glycolic acid microspheres were prepared using the emulsion-solvent evaporation method. Usingα-cyanoacrylate, a biological adhesive, two kinds of microspheres were processed into a long-term slow-release bicomponent drug carrier. Then, in vitro release characteristics of the dual-drug sustained-release carrier were observed. After that, the dual-drug sustained-release carrier was implanted into rabbit intertrochanteric femur bone defects for observing drug release concentrations, histocompatibility and bone defect healing at different time points after drug delivery carrier implantation. RESULTS AND CONCLUSION:For rifampicin/polylactic acid/glycolic acid microspheres, the mean particle size was (240±13)μm, and the drug loading load rate was (26±1.5)%. For isoniazid/polylactic acid/glycolic acid microspheres, the mean particle size was (250±10)μm, and drug loading rate was (28±1.8)%. The in vitro cumulative release rate could reach 80%for rifampicin and 90%for isoniazid at day 90. The in vivo released concentration of rifampicin and isoniazid within 90 days was (0.5±0.4) and (0.6±0.3)μg/g, respectively. There were a smal amount of infiltrated neutrophils between the fascia and muscle fibers after the drug delivery carrier was implanted, and the amount of neutrophils in the muscle were reduced significantly at day 59. X-ray plain film showed that bone defects decreased obviously in size. These findings indicate that this dual-drug sustained-release carrier can maintain a certain anti-tuberculosis drug concentration in the surrounding tissues of bone tuberculosis, which is expected to provide a new type of dual-drug delivery carrier in the surgical treatment of bone tuberculosis.