PLGA Polymer: Ultimate Buying Guide

by | Oct 26, 2020

Do you know PLGA(Poly(lactic-co-glycolic acid) are widely used in medical devices?  Yes, there are many types of plga polymer in the market. They have different ratios, viscosity, end group,s, and shapes.

In this PLGA buying guide, I am going to explain the advantages, structure, cost, application, synthesis, and FAQ about this polymer.

What is PLGA Polymer?

It is an Abbreviation, the full name is Poly(lactic-co-glycolic acid). It is polymerized from lactic acid and glycolic acid monomers, By changing the polymer monomer ratio and molecular weight, the degradation rate of the copolymer in the body, DNA encapsulation rate, and gene release rate can be adjusted.

This is the appearance we can see.

PLGA polymer
Maybe you will know PLA material, it is a type of degradable plastic and mainly used in 3d printing and package. Actually PLGA is based on PLA. PLGA Polymerized from lactide and glycolide, Lactide is the monomer of PLA.

Now you will know what is the plga polymer, let me know tell why do you need this material.

PLGA Structure

PLGA is light yellow or colorless substance, Because lactide has three different structures, PLGA also has three structures, PLLGA,PDLGA and PDLLGA. PLLGA and PDLGA are is semi-crystalline, PDLLGA is amorphous.

How to synthesis PLGA?

PLGA is mostly manufactured by ring-opening polymerization. It is the dehydration and cyclization of glycolic acid and lactic acid to synthesize two monomers of glycolide and lactide, and then ring-opening polymerization to obtain PLGA random copolymer.

Another route is to make two polymer monomers of lactic acid and glycolic acid into six-membered cyclic lactide-glycolide, and then ring-opening polymerization to obtain an alternating copolymer of PLGA. The polymer has regular structure, fixed composition and stable degradation performance.

PLGA route

The reaction formula of ring-opening polymerization to synthesize PLGA

Benefits of PLGA polymer(here’s why you need it)

As the types of biomedical polymer materials, PLGA combines the advantages of two materials: polylactic acid and polyglycolic acid. It has good biocompatibility and degradability, which is widely used in the field of biomedicine.

  1. Controllable degradation rate

As we have said, PLGA has different structure, viscosity and ratio(LA: GA).By modifying the component ratio of LA and GA and molecular weight, it can effectively adjust the degradation rate of the copolymer. It is used in Controllable drug/protein delivery systems, tissue engineering scaffolds and other fields.

  1. Easy to Manufacture

PLGA can be processed in many ways, such as extrude, spinning and biaxial stretching. Meanwhile, PLGA can exist in various forms such as microspheres, microcapsules, nanospheres and nanofibers.

  1. cell adsorption and proliferation

PLGA also has the effect of promoting cell adsorption and proliferation.This property makes it a potential tissue engineering application. Many studies have prepared micro-nano-scale PLGA three-dimensional scaffolds.

Limited of PLGA Polymer

The main disadvantage of PLGA polymer is the solubility. PLGA is formed by random copolymerization of lactide and glycolide. If the GA content is too high during the copolymerization process, it will easily form a peg segment with local GA interlinking too long, thereby partially showing the performance of PGA. It makes PLGA difficult to dissolve.

If the GA content in the plga ratio exceeds 50%, the general solvent cannot dissolve it, and the molecular weight cannot be too high in the 50:50 ratio. Generally, the molecular weight is less than 100,000 to ensure methylene chloride It can be dissolved in chloroform, and the molecular weight of 1 million in the ratio of 75:25 can also be dissolved in dichloromethane and chloroform

PLGA mechanical properties

The initial strength of polylactic acid and its copolymers is poor, it is far from meeting the strength requirements of bone materials. PLGA composite prepared by self-reinforcement technology, this can significantly improve mechanical properties.

Self-reinforced PLGA(PGA/PLLA) has high strength and moderate degradation rate, it meets the requirements for internal fixation materials for composite fractures.

LA:GACrystallinityElongationShear modulusTensile strength
100:0High1.5%130-150 Mpa2.10 Mpa
75:25Medium2.7%105-110 Mpa1.36 Mpa
50:50No2.5%85-91 Mpa1.04 Mpa
25:75Medium2.5%79-85 Mpa1.02 Mpa
0:100High2.8%65-72 Mpa1.02 Mpa

PLGA Degradation process

The biodegradation of polymers is a very complicated process. Degradation time mainly depends on the size and structure of polymer molecules. Types of microorganisms, temperature, enzymes, and other factors.

From a chemical point of view, there are three types of polymer degradation:

  1. Hydrophobic polymers become a low relative molecular weight, water-soluble molecules through the hydrolysis of unstable bonds on the main chain
  2. Water-insoluble polymer becomes water-soluble polymer through hydrolysis, ionization, or protonation of side-chain groups
  3. The water-insoluble polymer is hydrolyzed and the unstable cross-linked chain becomes a water-soluble linear polymer

The degradation of PLGA is mainly carried out by the hydrolysis of ester bonds. The hydrolytic cleavage of the ester bond on the molecular chain is irregular. Each ester bond may be hydrolyzed, The longer the molecular chain, the more parts will be hydrolyzed.

In biological media, first, small molecules of water move to the surface of the polymer material and diffuse into the surrounding ester bonds or hydrophilic groups. Under the action of acid-base or enzyme in the medium, the ester bond is broken by acid-base hydrolysis or degraded by enzymatic hydrolysis.

Application of PLGA

PLGA is currently restricted by its price and other factors, it mainly used in engineering fields such as biomedicine

1. Drug release control system

Release control is to contact the drug or other biologically active substances with the substrate so that the drug can be released into the environment at a certain rate within a certain period of time through diffusion and other means.

Controllable drug release with biodegradable materials as a carrier can gradually release drugs through slow degradation in the body to exert the best effect in the body. PLGA is widely used in drug microspheres due to its good processing and drug release properties

2. Tissue engineering and bone fixation materials

PLGA is non-toxic in the body and has good biocompatibility, it also can participate in the carbohydrate metabolism cycle in the human body without residue. Therefore, his application in tissue engineering is extremely wide.

It can be used as a cell growth carrier in bone tissue regeneration, cartilage tissue regeneration, artificial skin, peripheral nerve repair, etc.

medical suture

3. Medical suture

PLGA can be used as a surgical suture. Due to its biodegradability, it will automatically degrade and absorb after the wound has healed, without the need for a second operation.

This also requires the polymer to have a strong initial tensile strength and be stable for a period of time, while being able to effectively control the degradation rate of the polymer. As the wound heals, the suture slowly degrades.