Poly (lactic acid) (PLA) is a polymer synthesized from lactic acid with good biocompatibility and biodegradability. At present, PLA manufactured on industrial scale is mainly synthesized from L-lactic acid. The obtained products have good transparency but poor heat resistance. Adding nucleating agents could increase the crystallinity of PLA, to improve heat resistance. We reviewed the progress of research on organic and inorganic nucleating agents that can be used for PLA synthesis.
Chemical Industry ; Lactic Acid ; Polyesters ; chemistry ; Polymers

Polylactic acid is synthesized indirectly by the polymerization method, according to the standard GB/T 16886.18-2011, the evaluation parameters and methods about chemical characterization of polylactic acid have been established. By using rigorous and comprehensive comparative analysis, the chemical equivalency of domestic and imported polylactic acid materials has been proved, along with the "Medical Device Biology Evaluation and Review Guide", paving the way of using domestic polylactic acid in implantable medical devices.
Equipment and Supplies ; Lactic Acid ; Polyesters ; chemistry ; Polymers

Optimization of a process for extracting astaxanthin from Phaffia rhodozyma by acidic method was investigated, regarding several extraction factors such as acids, organic solvents, temperature and time. Fractional factorial design, central composite design and response surface methodology were used to derive a statistically optimal model, which corresponded to the following optimal condition: concentration of lactic acid at 5.55 mol/L, ratio of ethanol to yeast dry weight at 20.25 ml/g, temperature for cell-disruption at 30 degrees C, and extraction time for 3 min. Under this condition, astaxanthin and the total carotenoids could be extracted in amounts of 1294.7 microg/g and 1516.0 microg/g, respectively. This acidic method has advantages such as high extraction efficiency, low chemical toxicity and no special requirement of instruments. Therefore, it might be a more feasible and practical method for industrial practice.
Basidiomycota ; chemistry ; Hydrochloric Acid ; Lactic Acid ; Xanthophylls ; isolation & purification

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

Poly lactic acid (PLA) fibers a biodegradable fiber produced from PLA resin by melt spinning, solvent spinning or electrostatic spinning. Based on the excellent safety, comfortability, environmental protection and good mechanical properties, PLA can be widely applied in textile fabric, nonwoven, filler fabric and many downstream health products application, such as sanitary napkins, baby diapers, facial masks, and wipes.
Biotechnology ; Chemical Industry ; Lactic Acid ; Polyesters ; chemistry ; Polymers

Biorefinery of chemicals from straw is an effective approach to alleviate the environmental pollution caused by straw burning. In this paper, we prepared gellan gum immobilized Lactobacillus bulgaricus T15 gel beads (LA-GAGR-T15 gel beads), characterized their properties, and established a continuous cell recycle fermentation process for D-lactate (D-LA) production using the LA-GAGR-T15 gel beads. The fracture stress of LA-GAGR-T15 gel beads was (91.68±0.11) kPa, which was 125.12% higher than that of the calcium alginate immobilized T15 gel beads (calcium alginate-T15 gel beads). This indicated that the strength of LA-GAGR-T15 gel beads was stronger, and the strain was less likely to leak out. The average D-LA production was (72.90±2.79) g/L after fermentation for ten recycles (720 h) using LA-GAGR-T15 gel beads as the starting strain and glucose as the substrate, which was 33.85% higher than that of calcium alginate-T15 gel beads and 37.70% higher than that of free T15. Subsequently, glucose was replaced by enzymatically hydrolyzed corn straw and fermented for ten recycles (240 h) using LA-GAGR-T15 gel beads. The yield of D-LA reached (1.74±0.79) g/(L·h), which was much higher than that of using free bacteria. The wear rate of gel beads was less than 5% after ten recycles, which indicated that LA-GAGR is a good carrier for cell immobilization and can be widely used in industrial fermentation. This study provides basic data for the industrial production of D-LA using cell-recycled fermentation, and provides a new way for the biorefinery of D-LA from corn straw.
Fermentation ; Lactobacillus delbrueckii ; Zea mays ; Lactic Acid ; Alginates/chemistry* ; Glucose

In this study, we prepared various matrices of hydrogel patches and studied their cross-linking mechanism by observing their rheological properties, which could provide theoretical basis and deep technical support for further industrial development of hydrogel patch. Rheology method was used to do the amplitude scanning and single-frequency scanning for various hydrogel matrix, under the condition of oscillation mode of the rheometer. Then the linear viscoelastic region, composite modulus value, as well as changes in slope with time of the composite modulus and phase angle of various hydrogel matrix were analyzed in detail. The results showed that the stability of matrix was mainly determined by hydrogel frame; only in acidic environment, the cross-linking reaction between cross-linker and hydrogel frame can occur; elasticity of matrix can be decreased by organic acid and the effect level was related to the ratio of the number of carboxyl and hydroxyl (-COO(-)/-OH) in adjusters: if the ratio was not equal, the higher -COO(-)/-OH in adjusters would be the less elasticity of matrix decreased; the cross-linking speed of matrix was determined by adjuster, the cross-linking speed of matrix contain different adjusters was ranged in following order: matrix containing tartaric acid > matrix containing lactic acid > matrix containing malic acid > matrix containing citric acid; the cross-linking speed of matrix was not uniform in the whole cross-linking process.
Citric Acid ; chemistry ; Cross-Linking Reagents ; chemistry ; Hydrogels ; chemistry ; Lactic Acid ; chemistry ; Malates ; chemistry ; Rheology ; Tartrates ; chemistry ; Viscosity

OBJECTIVETo prepare polylactic acid microspheres containing total alkaloid extracts of Caulis sinomenii and study their release characteristics in vitro.

METHODPolylactic acid microspheres containing total alkaloid extracts of C. sinomenii were prepared by O/W emulsification solvent-evaporation process. The microspheres were characterized in terms of morphology, encapsulation efficiency, and particle size distribution. The effect of different conditions on release property of microspheres was studied.

RESULTThe formed microspheres were spherical with smooth surfaces. The encapsulation efficiency and rate of drug loading were (83.4 +/- 5.63)% and (8.7-0.35)%, respectively. The distribution of particle size was uniform and the average size was (21.5 +/- 1.22) microm. In vitro release study revealed that the 32-hour accumulative release percentage reached 80%.

CONCLUSIONPolylactic acid microspheres containing total alkaloid extracts of C. sinomenii were prepared successfully. Microspheres with good sustained-release characteristics can be produced by controlling different process parameters.

Drugs, Chinese Herbal ; administration & dosage ; chemistry ; Lactic Acid ; chemistry ; Microspheres ; Polyesters ; Polymers ; chemistry ; Sinomenium ; chemistry

BACKGROUNDIn-stent restenosis caused by airway granulation poses a challenge due to the high incidence of recurrence after treatment. Weekly applications of anti-proliferative drugs have potential value in delaying the recurrence of airway obstruction. However, it is not practical to subject patients to repeated bronchoscopy and topical drug applications. We fabricated novel pacilitaxel-eluting tracheal stents with sustained and slow pacilitaxel release, which could inhibit the formation of granulation tissue. And we assessed the quality and drug release behaviors of drug-eluting stents (DESs) in vitro.

METHODSStents were dipped vertically into a coating solution prepared by dissolving 0.5 g (2% w/v) of poly lactic acid-coglycolic acid (PLGA) and 0.025 g (0.1% w/v) of pacilitaxel in 25 ml of dichloromethane. DES morphology was examined by scanning electron microscopy (SEM). Pacilitaxel release kinetics from these DESs was investigated in vitro by shaking in PBS buffer followed by high performance liquid chromatography (HPLC).

RESULTSUsing an orthogonal experimental design, we fabricated numerous pacilitaxel/PLGA eluting tracheal stents to assess optimum coating proportions. The optimum coating proportion was 0.1% (w/v) pacilitaxel and 2% (w/v) PLGA, which resulted in total pacilitaxel loading of (16.380 6 ± 0.002 1) mg/stent. By SEM the coating was very smooth and uniform. Pacilitaxel released from DES was at (0.376 3 ± 0.003 8) mg/d, which is a therapeutic level. There was a prolonged, sustained release of pacilitaxel of >40 days.

CONCLUSIONSPaclitaxel-loaded PLGA coating tracheal stents were successfully developed and evaluated. Quality assessments demonstrated favorable surface morphology as well as sustained and effective drug release behavior, which provides an experimental reference for clinical practitioners.

Drug-Eluting Stents ; Glycolates ; chemistry ; Humans ; Lactic Acid ; chemistry ; Paclitaxel ; chemistry ; Polyesters ; Polymers ; chemistry

This study aims to investigate the preparation process and in vitro release behavior of artesunate polylactic acid microspheres, in order to prepare an artesunate polylactic acid (PLA) administration method suitable for hepatic arterial embolization. With PLA as the material and polyvinyl alcohol (PVA) as the emulsifier, O/W emulsion/solvent evaporation method was adopted to prepare artesunate polylactic acid microspheres, and optimize the preparation process. With drug loading capacity, encapsulation efficiency and particle size as indexes, a single factor analysis was made on PLA concentration, PVA concentration, drug loading ratio and stirring velocity. Through an orthogonal experiment, the optimal processing conditions were determined as follows: PLA concentration was 9. 0% , PVA concentration was 0. 9% , drug loading ratio was 1:2 and stirring velocity was 1 000 r x min(-1). According to the verification of the optimal process, microsphere size, drug loading and entrapment rate of artesunate polylactic acid microspheres were (101.7 +/- 0.37) microm, (30.8 +/- 0.84)%, (53.6 +/- 0.62)%, respectively. The results showed that the optimal process was so reasonable and stable that it could lay foundation for further studies.
Artemisinins ; chemistry ; Calibration ; Drug Compounding ; methods ; Lactic Acid ; chemistry ; Microspheres ; Polyesters ; Polymers ; chemistry ; Polyvinyl Alcohol ; chemistry