PLGA for Bioresorbable Medical Device Applications

Bioresorbable devices are designed to perform a defined function for a limited period. In a fixation device, that may mean retaining enough strength to support healing tissue. A membrane may need to preserve separation between tissue compartments, while a scaffold may need to maintain its internal architecture long enough for cells and tissue to occupy the structure. In each case, the key question is how long the finished device continues to perform the function for which it was designed.

This affects the way PLGA materials are evaluated. For example, a fixation component may be limited by a change in stiffness, torsional integrity, or pull-out resistance while a membrane may fail through tearing or loss of continuity. In a porous construct, changes at struts or junctions may compromise the architecture before substantial polymer mass is lost. A coating can crack or detach from its substrate even when most of the material is still present.

PLGA is investigated across these device formats, but the polymer name alone does not define how the finished article will behave. The starting material is influenced by its composition, molecular characteristics, chain-end chemistry, residual species, and physical form. Fabrication then creates an additional history through heat, solvent exposure, orientation, cooling, or pore formation. Sterilization and storage can modify that state again before the device is tested or implanted.

Material selection therefore begins with the function the device must retain and the physical mechanism through which that function is expected to decline.

What Is PLGA?

Poly(lactide-co-glycolide), abbreviated PLGA, refers to a family of aliphatic copolyesters produced from lactide and glycolide. Materials sold under the PLGA name can differ substantially in their molecular structure and physical behavior.

A designation such as PLGA 75:25 describes the nominal proportion of lactide and glycolide. It doesn't identify the stereochemical form of the lactide component, nor does it describe molecular weight, molecular-weight distribution, chain-end chemistry, or the concentration of residual low-molecular-weight species.

Monomer sequence introduces another level of variation. In cylindrical matrices and films prepared from the PLGAs examined in one study, sequence and stereochemistry produced substantial differences in swelling, erosion, and molecular-weight loss even when the overall lactide-to-glycolide ratio was comparable.[1] Nominal composition is therefore an important starting descriptor, but it is not a complete description of degradation behavior.

The PLGA backbone contains ester linkages that undergo hydrolytic cleavage in the presence of water. As chain scission proceeds, the average molecular weight declines and shorter oligomers form. Soluble products derived from lactic and glycolic acid appear later in the process. Molecular-weight loss can therefore become measurable well before the article fragments or shows substantial gravimetric mass loss. In electron-beam-irradiated PLGA and PLLA films, spectroscopic changes associated with hydrolysis were observed before the changes associated with measurable mass loss.[2]

The timing and spatial distribution of those changes depend on the polymer state, the geometry of the article, and the environment surrounding it. “PLGA” is best understood as a polymer family rather than a single material with one set of mechanical properties or one characteristic degradation period.

Why PLGA Is Investigated for Temporary Medical Devices

PLGA can be produced over a range of compositions and molecular weights, then converted into several device forms. It has been processed through melt-based methods such as extrusion and injection molding, through solvent-based casting and coating, and through techniques used to create fibers or porous structures. Additive-manufacturing approaches have also been reported.

Each route places different demands on the polymer. Melt processing requires enough flow for fabrication without excessive molecular-weight loss during drying or thermal exposure. Solvent-based processes require the polymer to dissolve at a useful concentration and form a stable structure as the solvent leaves. In a scaffold, the polymer must support the formation of the intended architecture as well as the required mechanical response.

The available variation in PLGA composition and molecular characteristics provides useful development flexibility, although the variables do not act independently. Composition affects water interaction, morphology, and thermal behavior. Molecular weight influences mechanical response and also affects the viscosity encountered during melt or solution processing. Chain-end chemistry may become more significant when residual moisture and heat exposure promote hydrolysis during fabrication.

For that reason, a PLGA grade can't be evaluated separately from the process used to form the device or the function the finished structure must retain.

PLGA Applications in Bioresorbable Device Research

Fixation components

PLGA and related lactide-glycolide copolymers have been investigated for temporary fixation structures, including plates, screws, pins, and anchors.

These devices must retain specific mechanical properties during tissue healing. The relevant property depends on the way the part is loaded. A plate may be limited by flexural stiffness or strength, while a screw must tolerate insertion and remain adequately fixed after placement. An anchor depends on the interaction between its geometry and the surrounding tissue or substrate.

The finished component reflects more than the initial resin properties. Melt history can alter molecular weight, and flow during molding can introduce orientation or residual stress. Sterilization and final dimensions then influence the condition of the article entering mechanical or degradation testing.

In one study of injection-molded PLGA craniofacial plates, specimens produced at different melt temperatures showed differences in physicochemical and mechanical behavior during a 16-week in vitro degradation period. The findings were specific to the material and processing conditions examined, but they show how fabrication history can remain detectable during later degradation.[3]

For a fixation device, the functional requirement is more usefully defined by a device-relevant mechanical measurement than by a generalized statement about degradation time.

Membranes and tissue-separation devices

PLGA membranes have been studied for guided tissue and guided bone regeneration, where the device is intended to preserve separation between tissue populations during healing.

The barrier function depends on the structure of the complete membrane. Thickness affects handling and transport. Pore architecture and permeability influence the movement of cells and fluids. Tensile and tear behavior determine whether the membrane remains continuous during placement and use.

Surface architecture can also be designed to influence biological interaction. One membrane developed for periodontal regeneration used PLGA 85:15 blended with MePEG and incorporated different surface topographies on its opposing sides. Under the reported in vitro conditions, one topography inhibited epithelial-cell migration, while grooves on the other surface promoted directional osteoblast migration. The study illustrates how membrane function may depend on deliberately engineered surface features rather than polymer composition alone.[4]

A membrane can remain visibly present after its barrier properties have deteriorated. Development testing therefore needs an endpoint that reflects the intended function. Depending on the design, that endpoint may involve tearing, perforation, dimensional contraction, or a change in permeability.

Porous scaffolds

PLGA scaffolds have been produced through several pore-forming and fiber-forming methods. The resulting structures differ in pore connectivity, strut dimensions, accessible surface area, and mechanical response.

In a study of gas-foamed and salt-leached PLGA scaffolds, changing the PLGA composition altered relative density and open-cell porosity, while the effect on scaffold modulus was minor.[5] The findings show that polymer composition can influence the architecture produced by a pore-forming process, although a corresponding change in scaffold modulus should not be assumed.

Electrospun constructs introduce another structural scale. Fiber diameter and orientation affect the behavior of the network, while bonding between layers or individual fibers influences how the construct responds under load. In one small-diameter vascular-graft study, tubular scaffolds were assembled by rolling electrospun PLGA films into layered structures bonded with fibrin glue. The researchers evaluated device-relevant mechanical properties and assessed cell viability, proliferation, and migration in cell-containing constructs.[6]

Scaffold performance can change before substantial polymer mass is lost. Hydrolysis may weaken individual struts, fibers, or junctions, allowing the pore network to deform or lose connectivity. Gravimetric mass loss alone may not detect those changes.

Fibers, meshes, and soft-tissue structures

PLGA can also be processed into fibers, nonwoven mats, and mesh-like structures for experimental tissue-repair applications.

Their load-bearing behavior emerges from the structure rather than from the bulk polymer alone. Molecular orientation created during drawing influences individual fibers. At the device level, interfiber bonding and network arrangement determine how those fibers share load.

Degradation can alter the structure through several pathways. Individual fibers may rupture, junctions may weaken, or the network may rearrange as local stiffness declines. A single-fiber tensile test therefore describes a different level of behavior from a strip test performed on the complete mesh.

The appropriate measurement depends on the intended use and loading mode. The device architecture determines how a local change in polymer state becomes a change in system-level performance.

Coatings and combination devices

PLGA coatings have been investigated as temporary surface layers and as matrices for local delivery from implantable structures. One study used a combined dip-coating and drop-casting process to form ibuprofen-loaded PLGA coatings, then evaluated coating degradation, swelling, drug release, and cell responses under the reported test conditions.[7]

A coating introduces interfaces that are absent from a bulk polymer specimen. Adhesion to the underlying substrate becomes part of the device response, and the layer can retain stress as solvent leaves or as the polymer changes during storage. Local variation in thickness or the presence of defects can also influence transport and mechanical integrity.

The coating may therefore lose function through cracking, delamination, or a change in permeability before substantial mass loss occurs.

Adding a drug or another dispersed constituent creates a formulation with properties that differ from neat PLGA. The additive may alter chain mobility, water uptake, local acidity, or the morphology formed during processing. It can also change the route through which fluid enters the matrix or soluble products leave it.

Performance data from the unfilled polymer cannot be assumed to represent the final combination device.

Device Function and Complete Resorption Follow Different Timelines

PLGA degradation is often summarized in weeks or months, but that description has limited meaning unless the endpoint and test conditions are defined.

Hydrolytic chain scission first reduces molecular weight. As the chains become shorter, the polymer may enter a range where its mechanical, thermal, or barrier properties begin to change. Fragmentation and measurable mass loss can occur later. The device may therefore remain physically present after it no longer performs its original function.

Studies of PLGA have reported different relationships among molecular-weight loss, dimensional change, mechanical retention, and mass loss. In oriented, melt-processed PLGA 85:15, residual lactide-monomer content affected the hydrolytic degradation rate and the retention of mechanical properties. The study also reported differences in mass loss, crystallinity, and dimensional stability.[8] The observed thresholds were specific to the material and process studied and should not be applied to other PLGA grades as universal values.

The relevant endpoint depends on the device. In a fixation component, functional loss may correspond to a defined decline in strength or stiffness. In a membrane, it may be the point at which continuity or barrier performance is no longer maintained. A scaffold may reach its functional endpoint when its internal architecture collapses, even though polymer remains in the test system. A coating may fail when it delaminates from the substrate.

Complete resorption is therefore not necessarily the same event as the end of useful device function.

Material and Device Variables That Require Separate Evaluation

Polymer composition and molecular characteristics

Lactide ratio, stereochemistry, molecular weight, molecular-weight distribution, and chain ends influence how a PLGA grade processes and degrades. The nominal monomer ratio remains useful as an initial descriptor, but it cannot independently predict device lifetime.

Fabrication history

The certificate of analysis describes the polymer before device manufacturing. Fabrication may change that material through drying, melting, dissolution, solvent removal, cooling, or orientation. These steps can affect molecular weight and morphology before device testing begins. They may also introduce residual stress or spatial differences within the article.

Device geometry

Geometry affects transport through the device. Thickness changes the distance over which water and soluble degradation products must move. Porous structures introduce accessible pathways as well as dense regions where products may be retained. The same geometry also determines how the remaining material carries load as degradation proceeds.

Sterilization, packaging, and storage

The implanted device has usually undergone sterilization and storage after fabrication. Those stages can introduce additional changes in polymer state or device structure. Their significance depends on the sterilization method, the barrier properties of the package, and the environmental conditions experienced during storage.

Where these stages can influence the final device output, they need to be represented in development testing.

Defining the Functional Requirement Before Selecting a Grade

A useful material requirement starts with the device and its expected mode of failure.

The development team first needs to define which property must be retained and how long it must remain above an acceptable limit. That property should be measured under conditions that represent the intended geometry and loading mode. A mechanically loaded component may require a defined level of strength or stiffness. A membrane may need to retain continuity and resistance to tearing. In a scaffold, the relevant requirement may involve compression behavior or preservation of the pore network.

The fabrication route belongs in the same discussion. A polymer may have suitable initial mechanical properties and still require processing conditions that cause excessive molecular-weight loss. A lower-viscosity material may fill a complex mold more readily, yet provide less molecular-weight margin before the device begins to lose function. Sterilization and aging may narrow that margin further.

A useful development plan therefore connects the functional endpoint to the complete device history. It should establish how the selected property will be measured, whether the test article represents the final geometry, and what chemical or structural data will be used to explain changes in function. It should also account for the condition of the device after fabrication, sterilization, and aging.

This produces a device-specific material target. A generalized PLGA degradation chart cannot provide the same information.

Moving from Feasibility Work to Controlled Production

Early PLGA studies often use small quantities to compare materials, establish process feasibility, and determine whether a device concept can be fabricated. At this stage, the goal may be to distinguish broad material or process effects.

As the program advances, the acceptable range of variation usually becomes narrower. The composition and molecular characteristics of the polymer may require more formal control, together with residual species, moisture, supplied form, packaging, and storage. Process conditions also become more important when they affect device behavior. Drying, thermal exposure, solvent removal, cooling, and environmental holds may need to be defined more closely as the manufacturing process scales.

Research-grade material may support early comparative work without providing the controls expected at later clinical or commercial stages. Traceability, analytical documentation, change management, and manufacturing controls should therefore be considered before the grade and process become difficult to change.

Supplier controls, analytical documentation, scale-up, and change notification are addressed separately in What to Look for in a PLGA Supplier.

PLGA Materials and Development Support from Polysciences

Polysciences supplies PLGA polymers for biomaterials research, controlled-release studies, tissue engineering, and medical-device development. The portfolio includes materials with different lactide compositions, inherent-viscosity ranges, chain-end chemistries, and physical forms. The specification and documented manufacturing status of each product should be reviewed in relation to the intended stage of development.

Projects requiring attributes outside the catalog range may involve custom synthesis or additional process development. Analytical characterization, scale-up, and contract manufacturing can also be defined around the needs of a specific program.

Polysciences’ quality system is certified to ISO 13485:2016, and the company maintains active FDA establishment registration. Its service capabilities include custom polymer synthesis, pilot- and commercial-scale manufacturing, analytical-method development, and technology transfer. The scope of testing, validation, documentation, and manufacturing control remains specific to the material and project.

A technical discussion should begin with the function the device must retain and the process used to make it. Polymer attributes, final geometry, sterilization, and the stage of development then provide the context needed to evaluate the material. A general indication that a polymer is used in biomedical research does not establish suitability for a particular regulated device.

Frequently Asked Questions

What does PLGA stand for?

PLGA stands for poly(lactide-co-glycolide), a family of copolyesters produced from lactide and glycolide. The abbreviation includes materials with different compositions, molecular weights, stereochemistries, chain ends, and physical forms.

Why is PLGA used in bioresorbable-device research?

PLGA can be processed into several temporary device formats, including molded components, membranes, fibers, coatings, and porous structures. Its usefulness depends on whether a particular grade and manufacturing process produce the required device properties after fabrication, sterilization, and storage.

Does a PLGA device disappear when it loses mechanical strength?

Usually not at the same time. Molecular-weight loss and mechanical decline can occur before substantial fragmentation or gravimetric mass loss. The device may remain physically present after it no longer provides its original mechanical or barrier function.

Can the same PLGA grade behave differently in two devices?

Yes. Processing history and device geometry affect the condition of the polymer and the transport environment in which it degrades. Sterilization, storage, and the conditions of use can introduce further differences between devices made from the same incoming grade.

Does the PLGA ratio determine how long a device will function?

The ratio contributes to degradation behavior, but it cannot determine device lifetime independently. The observed functional period also depends on molecular characteristics, residual species, processing history, geometry, sterilization, and the endpoint used to define failure.

Discussing a PLGA Device-Development Program

A useful PLGA discussion starts with the function the device must retain and the period over which that function is needed. The fabrication route and final geometry establish how the polymer will be processed and loaded, while sterilization and aging determine the condition of the article that will enter testing or use.

Review the Polysciences PLGA portfolio for research and development materials, or contact the technical team regarding custom polymer attributes, process development, scale-up, analytical requirements, and project-specific manufacturing controls.