Poly(α-hydroxyacids) in biomedical applications: synthesis and properties of lactic acid polymers

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Rodica Lipsa ◽  
Nita Tudorachi ◽  
Cornelia Vasile
Keyword(s):  
Lactic Acid ◽  
Ring Opening ◽  
Biomedical Applications ◽  
Glycolic Acid ◽  
Recent Literature ◽  
Poly Lactic Acid ◽  
Biodegradation Rate ◽  
Degradation Behaviour ◽  
Food Applications ◽  
Us Fda

AbstractPoly( -hydroxy acids), especially poly(glycolic acid) (PGA), poly(lactic acid) (PLA) and their copolymers poly(lactic-co-glycolic acid) (PLGA) are novel class of commodity polymers, also used in biomedical applications. They can be synthesized with a controlled biodegradation rate and are biocompatible, bioresorbable and approved by US Food and Drug Administration (US FDA) for clinical use. Lactic acid polymers are developed in medicine (sutures, implants, orthopaedics, tissue engineering), pharmacy (controlled drug delivery systems) as well as in packaging, agriculture (mulch films, seed preservation), food applications, etc. The paper reviews recent literature data concerning lactic acid polymers synthesis (polycondensation, ring opening polymerization), physical (thermophysical, solubility, miscibility), mechanical properties, degradation behaviour, emphasizing on the poly(α -hydroxyacids) and lactic acid polymers applications in medicine and pharmacy.

Engineering microenvironment of biodegradable polyester systems for drug stability and release control

2021 ◽  
Author(s):  
Nisar Ul Khaliq ◽  
Dhawal Chobisa ◽  
Coralie A Richard ◽  
Monica R Swinney ◽  
Yoon Yeo
Keyword(s):  
Lactic Acid ◽  
Glycolic Acid ◽  
Release Kinetics ◽  
Drug Stability ◽  
Poly Lactic Acid ◽  
Polymeric Systems ◽  
Us Fda ◽  
History Of Use ◽  
Release Control

Polymeric systems made of poly(lactic acid) or poly(lactic-co-glycolic acid) are widely used for long-term delivery of small and large molecules. The advantages of poly(lactic acid)/poly(lactic-co-glycolic acid) systems include biodegradability, safety and a long history of use in US FDA-approved products. However, as drugs delivered by the polymeric systems and their applications become more diverse, the significance of microenvironment change of degrading systems on long-term drug stability and release kinetics has gained renewed attention. In this review, we discuss various issues experienced with acidifying microenvironment of biodegradable polymer systems and approaches to overcome the detrimental effects of polymer degradation on drug stability and release control.

scholarly journals Synthesis of Poly(Lactic Acid-co-Glycolic Acid) Copolymers with High Glycolide Ratio by Ring-Opening Polymerisation

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2458
Author(s):  
Alastair Little ◽  
Alan M. Wemyss ◽  
David M. Haddleton ◽  
Bowen Tan ◽  
Zhaoyang Sun ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Ring Opening ◽  
Glycolic Acid ◽  
Catalyst Concentration ◽  
Reaction Times ◽  
Monomer Conversion ◽  
Barrier Properties ◽  
Poly Lactic Acid ◽  
Reaction Conditions ◽  
Time Required

The rise in demand for biodegradable plastic packaging with high barrier properties has spurred interest in poly(lactic acid-co-glycolic acid) (PLGA) copolymers with a relatively high glycolide content. In this work, we examined how reaction conditions affect the synthesis of PLGA25 (L:G 25:75) through the ring-opening polymerisation of d-l-lactide (L) and glycolide (G), using tin 2-ethylhexanoate (Sn(Oct)2) as the catalyst and 1-dodecanol as the initiator. The effects of varying the initiator concentration, catalyst concentration, reaction time, and temperature on the molecular weight, monomer conversion, and thermal properties of PLGA25 were investigated. Increasing the reaction temperature from 130 to 205 °C significantly reduced the time required for high monomer conversions but caused greater polymer discolouration. Whilst increasing the [M]:[C] from 6500:1 to 50,000:1 reduced polymer discolouration, it also resulted in longer reaction times and higher reaction temperatures being required to achieve high conversions. High Mn and Mw values of 136,000 and 399,000 g mol−1 were achieved when polymerisations were performed in the solid state at 150 °C using low initiator concentrations. These copolymers were analysed using high temperature SEC at 80 °C, employing DMSO instead of HFIP as the eluent.

scholarly journals Mechanical Properties and Bioactivity of Poly(Lactic Acid) Composites Containing Poly(Glycolic Acid) Fiber and Hydroxyapatite Particles

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 249
Author(s):  
Han-Seung Ko ◽  
Sangwoon Lee ◽  
Doyoung Lee ◽  
Jae Young Jho
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Flexural Strength ◽  
Interfacial Adhesion ◽  
Glycolic Acid ◽  
Compact Bone ◽  
Poly Lactic Acid ◽  
Coupling Reactions ◽  
The Poor ◽  
Human Compact Bone

To enhance the mechanical strength and bioactivity of poly(lactic acid) (PLA) to the level that can be used as a material for spinal implants, poly(glycolic acid) (PGA) fibers and hydroxyapatite (HA) were introduced as fillers to PLA composites. To improve the poor interface between HA and PLA, HA was grafted by PLA to form HA-g-PLA through coupling reactions, and mixed with PLA. The size of the HA particles in the PLA matrix was observed to be reduced from several micrometers to sub-micrometer by grafting PLA onto HA. The tensile and flexural strength of PLA/HA-g-PLA composites were increased compared with those of PLA/HA, apparently due to the better dispersion of HA and stronger interfacial adhesion between the HA and PLA matrix. We also examined the effects of the length and frequency of grafted PLA chains on the tensile strength of the composites. By the addition of unidirectionally aligned PGA fibers, the flexural strength of the composites was greatly improved to a level comparable with human compact bone. In the bioactivity tests, the growth of apatite on the surface was fastest and most uniform in the PLA/PGA fiber/HA-g-PLA composite.

scholarly journals Synthesis and Characterization of Polyphosphazenes Modified with Hydroxyethyl Methacrylate and Lactic Acid

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Evelyn Carolina Martínez Ceballos ◽  
Ricardo Vera Graziano ◽  
Gonzalo Martínez Barrera ◽  
Oscar Olea Mejía
Keyword(s):  
Lactic Acid ◽  
Ring Opening ◽  
Room Temperature ◽  
Block Structure ◽  
Ring Opening Polymerization ◽  
Synthesis And Characterization ◽  
Poly Lactic Acid ◽  
Hydroxyethyl Methacrylate ◽  
H Nmr

Poly(dichlorophosphazene) was prepared by melt ring-opening polymerization of the hexachlorocyclotriphosphazene. Poly[bis(2-hydroxyethyl-methacrylate)-phosphazene] and poly[(2-hydroxyethyl-methacrylate)-graft-poly(lactic-acid)-phosphazene] were obtained by nucleophilic condensation reactions at different concentrations of the substituents. The properties of the synthesized copolymers were assessed by FTIR,1H-NMR and31P-NMR, thermal analysis (DSC-TGA), and electron microscopy (SEM). The copolymers have a block structure and show twoTg's below room temperature. They are stable up to a temperature of 100°C. The type of the substituents attached to the PZ backbone determines the morphology of the polymers.

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