This research was aimed to develop the technique and formula for the preparation of stable and effective microbubbles containing hydrophilic drugs. We prepared EB-PLGA microbubbles and evaluated its drug loading and burst release to choose the best technique and formula. The result of optimizing formula was W1/O (1:15), EB-PLGA (0.04), PVA (5%). The burst release decreased after the addition of supplemental agent and the change of method for preparation. We concluded that the optimizing formula could elevate drug loading and decrease burst release obviously.
Drug Carriers ; chemistry ; Lactic Acid ; chemical synthesis ; chemistry ; Microbubbles ; Polyglycolic Acid ; chemical synthesis ; chemistry ; Quality Control

OBJECTIVEThe aim of the present study was to prepare uniform-sized silybin loaded poly (lactic-co-glycolic acid) (PLGA) microspheres in study of silybin with stainless steel membrane.

METHODSilybin PLGA microspheres were prepared by stainless steel membrane emulsification. The preparation conditions were optimized by single-factor test and orthogonal experiment, and evaluating the mean diameters, the particle size distribution, drug loading, entrapment efficiency and morphology of microsphere.

RESULTPrepared microspheres were round and surface was smooth. The mean diameter was (4.961 +/- 0.56) microm. The span was (1.75 +/- 0.18). The entrapment efficiency was (54.997 +/- 4.05)% and the average drug loading was (23.6 +/- 1.70)%.

CONCLUSIONThe stainless steel membrane emulsification can be used to prepare the silybin PLGA microspheres. The mean diameters of the silybin PLGA microspheres can be controlled in certain level. Stainless steel membrane emulsification has great potentiality exploitation and utilization.

Drug Compounding ; methods ; Emulsions ; chemistry ; Lactic Acid ; chemistry ; Microspheres ; Particle Size ; Polyglycolic Acid ; chemistry ; Silymarin ; chemistry ; Stainless Steel ; chemistry

OBJECTIVETo prepare the poly(lactic-co-glycolic acid) (PLGA) microspheres and composite alginate-chitosan-PLGA microspheres containing superoxide dismutase (SOD) and to evaluate their SOD activities.

METHODSThe SOD-PLGA microspheres were prepared by W/O/W emulsification method, and the composite microspheres were prepared by two steps:alginate-chitosan microcapsules were first prepared by a modified emulsification and ion crosslinking method, and then they were further dispersed in PLGA to form the composite microspheres. The SOD concentration was determined by Coomassie method, its activity was measured by xanthine oxidase system.

RESULTSThe SOD activity was less sensitive to temperature and sensitive to pH, organic solvents, ultrasound and vigorous stir without iced bath. The entrapment efficiencies of SOD in PLGA (50:50) microspheres, PLGA (70:30) microspheres, alginate-chitosan microcapsules, the composite PLGA (50:50) microspheres and the composite PLGA (70:30) microspheres were 36.42%±1.81%, 66.18%±0.05%, 91.08%±1.28%, 87.30%±3.89% and 83.19%±3.48%, respectively. In vitro release tests demonstrated that the SOD activities in 50:50 composite microspheres were higher than that in the PLGA ones at 1 h, 8 h and 1 w.

CONCLUSIONThe composite alginate-chitosan-PLGA microspheres for SOD sustained release can significantly improve the protein entrapment efficiency and maintain its protein activity.

Alginates ; chemistry ; Chitosan ; chemistry ; Delayed-Action Preparations ; chemistry ; Glucuronic Acid ; chemistry ; Hexuronic Acids ; chemistry ; Lactic Acid ; chemistry ; Microspheres ; Polyglycolic Acid ; chemistry ; Superoxide Dismutase ; chemistry

In the present study, a risperidone loaded microsphere/sucrose acetate isobutyrate (SAIB) in situ forming complex depot was designed to reduce the burst release of SAIB in situ forming depot and to continuously release risperidone for a long-term period without lagime. The model drug risperidone (Ris) was first encapsulated into microspheres and then the Ris-microspheres were embedded into SAIB depot to reduce the amount of dissolved drug in the depot. The effects of different types of microsphere matrix, including chitosan and poly(lactide-coglycolide) (PLGA), matrix/Ris ratios in microspheres and morphology of microspheres on the drug release behavior of complex depot were investigated. In comparison with the Ris-loaded SAIB depot (Ris-SAIB), the complex depot containing chitosan microspheres (in which chitosan/Ris = 1 : 1, w/w) (Ris-Cm-SAIB) decreased the burst release from 12.16% to 5.80%. However, increased drug release rate after 4 days was observed in Ris-Cm-SAIB, which was caused by the high penetration of the medium to Ris-Cm-SAIB due to the hydrophilie of chitosan. By encapsulation of risperidone in PLGA microspheres, most drugs can be prevented from dissolving in the depot and meanwhile the hydrophobic PLGA can reduce the media penetration effect on the depot. The complex depot containing PLGA microspheres (in which PLGA/ drug=4 : 2, w/w) (Ris-Pm-SAIB) showed a significant effectiveness on reducing the burst release both in vitro and in vivo whereby only 0.64% drug was released on the first day in vitro and a low AUC0-4d value [(105.2± 24.4) ng.mL-1.d] was detected over the first 4 days in vivo. In addition, drug release from Ris-Pm-SAIB can be modified by varying the morphology of microspheres. The porous PLGA microspheres could be prepared by adding medium chain triglyceride (MCT) in the organic phase which served as pore agents during the preparation of PLGA microspheres. The complex depot containing porous PLGA microspheres (which were prepared by co-encapsulation of 20% MCT) (Ris-PPm-SAIB) exhibited a slightly increased AUC0-4d of (194.6±15.8) ng.mL-1d and high plasma concentration levels from 4 to 78 days [Cs(4-78d)=(7.8±1.2) ng.mL-1]. The plasma concentration on 78 day C78d was (9.0 2.5) ng.mL-1 which was higher than that of Ris-Pm-SAIB [C78d= (1.6 ± 0.6) ng.mL-1]. In comparison with Ris-Pm-SAIB, the AUC4-78d of Ris-PPm-SAIB increased from (379.0±114.3) ng.mL-1.d to (465.0 ±149.2) ng.mL-1.d, indicating sufficient drug release from the Ris-PPm-SAIB. These results demonstrate that the risperidone loaded porous PLGA microsphere/SAIB in situ forming complex depot could not only efficiently reduce the burst release of SAIB depot both in vitro and in vivo, but also release the drug sufficiently in vivo, and be capable to continuously release the drug for 78 days.
Chitosan ; Drug Carriers ; Lactic Acid ; Microspheres ; Polyglycolic Acid ; Risperidone ; chemistry ; Sucrose ; analogs & derivatives ; Technology, Pharmaceutical

This newly-emerging field uses tissue-specific cells in a three-dimensional organization, provided by a scaffolding material, to return functionality of the organ. For these applications, the choice of scaffolding material is crucial to the success of the technique. In addition to the chemical properties of the material, physical properties such as surface area for cell attachment are essential. Various methods of creating pores in these materials to increase surface area are reviewed here. Scaffolds formed using the different techniques, which include fiber bonding, solvent casting/particulate leaching, gas foaming and phase separation, are compared on the basis of porosity, pore size, and promotion of tissue growth.
Absorbable Implants ; Biocompatible Materials ; Lactic Acid ; chemistry ; Polyesters ; Polyglycolic Acid ; chemistry ; Polymers ; chemistry ; Surface Properties ; Tissue Engineering

Gene therapy has shown great potentials in the treatment of a number of human key diseases, such as genetic diseases, cancer and so on, yet there are still some big challenges to face. One of these challenges is how to develop efficient, safe, targeting and controlled release gene delivery systems. With the progress of nanobiotechnologies, some nanobiomaterials such as liposome, poly (D,L lactic-co-glycolic acid) and poly (L-lactide) have great potencies in developing the ideal gene transfer vector, just because of their properties of biocompatibility, bio-degradation, controllable release, easy modification for targeting and so on. In this review is presented a summary of the excellent properties of the nanobiotechnological gene delivery systems and their recent encouraging advances.
Biocompatible Materials ; Gene Transfer Techniques ; Genetic Therapy ; Genetic Vectors ; Humans ; Lactic Acid ; chemistry ; Liposomes ; chemistry ; Nanotechnology ; Polyglycolic Acid ; chemistry

This is a work aimed to investigate the biodegradability, biocompatibility and mechanical property of the poly-lactide-co-glycolic acid (PLGA) knitted mesh preliminarily and to further explore its applications in tissue engineering and regenerative medicine. The biological property of PLGA mesh was investigated comprehensively with the degradation experiment in vitro, the acute cytotoxicity assay, the intradermal irritation test and the subcutaneous implantation test in vivo utilized. The degradation experiment in vitro demonstrated that the pH value of the removed solution fluctuated between 6.68 and 7.33. The elastic modulus of the PLGA mesh increased at first and then decreased afterwards. The acute toxicity test and the intradermal irritation test indicated that the PLGA mesh was with innocuity safety. The PLGA mesh accelerated degradation and was replaced gradually by the neotissue. The results of immunohistochemical staining demonstrated that the number of ED-1+ cells increased at first and then decreased afterwards. The PLGA mesh with excellent mechanical properties, good biocompatibility and favorable degradation ratio has the potential to be employed as a "skeleton" to reinforce the mechanical property of collagen-based dermal substitutes in tissue engineering.
Absorbable Implants ; Biocompatible Materials ; chemistry ; Humans ; Lactic Acid ; chemistry ; Materials Testing ; Polyglycolic Acid ; chemistry ; Skin, Artificial ; Tissue Engineering ; methods

To modify the surface property of poly lactide-co-glycolide (PLGA) by biomimetic mineralization to construct a new kind of artificial bone. PLGA films and 3-diamensional (3-D) porous scaffolds hydrolyzed in alkaline solution were minerilized in SBF for 14 days. The morphology and composition of the mineral grown on PLGA were analyzed with SEM, FTIR and XRD. The porosity of the scaffolds was detected by using the liquid displacement method. The compressive strength of the scaffolds was detected by using a Shimadzu universal mechanic tester. An obvious mineral coating was detected on the surface of films and scaffolds. The main component of the mineral was carbonated hydroxyapatite (HA) similar to the major mineral component of bone tissues. The porosity of the un-mineralized and mineralized porous scaffolds was (84.86 +/- 8.52) % and (79.70 +/- 7.70) % respectively. The compressive strength was 0.784 +/- 0.156 N/mm2 in un-mineralized 3-D porous PLGA and 0.858 +/- 0.145 N/mm2 in mineralized 3-D porous PLGA. There were no significant differences between the mineralized and un-mineralized scaffolds (P > 0.05) in porosity and biomechanics. Biomimetic mineralization is a suitable method to construct artificial bone.
Biocompatible Materials ; Bone Substitutes ; Calcification, Physiologic ; Durapatite/metabolism ; Lactic Acid/*chemistry ; Polyglycolic Acid/*chemistry ; Polymers/*chemistry ; Porosity ; Tissue Engineering

pH and temperature sensitive biodegradable block copolymers are some macromolecules connected by biodegradable materials and pH sensitive monomers according to a certain sequence, or biodegradable polyesters polymerized themselves. On the basis of pertinent documents, the development of pH and temperature sensitive biodegradable block copolymers was introduced, involving their mechanism of action and potential application. PH and temperature sensitive biodegradable block copolymers could control the drug release rate freely, avoiding burst effect. Besides, the biocompatibility of these biodegradable materials is also excellent. So the use of pH and temperature sensitive biodegradable block copolymers as biodegradable drug delivery devices has attracted considerable interest in the intelligent drug delivery system.
Biocompatible Materials ; chemistry ; Drug Delivery Systems ; Hydrogen-Ion Concentration ; Lactates ; chemistry ; Lactic Acid ; chemistry ; Polyesters ; chemistry ; Polyethylene Glycols ; chemistry ; Polyglactin 910 ; chemistry ; Polyglycolic Acid ; chemistry ; Polymers ; chemistry ; Temperature

A new technique was developed to fabricate PDLLA and PDLLA/PELA composite scaffolds by thermally induced phase separation in combination, with particulate-leaching. Effects of PDLLA/PELA ratio, PEG/PLA ratio and PEG molecular weight on properties of mechanics, degradation behavior and cell toxicity as well as morphological properties were investigated. As the result showed, by thermally induced phase separation/ particulate-leaching, a unique morphology that macropores (100-250 microm) and micropores (5-40 microm)coexisted in the scaffold was obtained. An increase of PEG content or a decrease of PEG molecular weight raised the porosity of the scaffold. A decrease of PDLLA/PELA ratio or an increase of PEG/PLA ratio weakened mechanical properties and accelerated the degradation of the scaffold. PDLLA and PDLLA/PELA scaffolds didn't show cell toxicity. When PDLLA/PELA ratio was 3:1 and PEG5000/PLA ratio was 25:75, the scaffold got a regular, highly interconnected, macro-co-micro porous structure.
Biocompatible Materials ; chemistry ; Lactates ; chemistry ; Lactic Acid ; chemistry ; Polyesters ; Polyethylene Glycols ; chemistry ; Polyglycolic Acid ; chemistry ; Polymers ; chemistry ; Porosity ; Surface Properties ; Tissue Engineering ; methods ; Tissue Scaffolds ; chemistry ; Water ; chemistry