Application Note | ElastoSens™ Bio
PLGA Polymers: Properties, Applications & Mechanical Behavior
by Maya Salame and Dimitria Camasao
Application Scientists
What is a PLGA?
Poly(lactic-co-glycolic acid) (PLGA) is a synthetic, biodegradable aliphatic polyester obtained by the copolymerization of lactic acid and glycolic acid. It is an industrially produced polymer derived from renewable monomers that are metabolized through natural biochemical pathways. PLGA is synthesized primarily via ring-opening polymerization of lactide and glycolide, allowing precise control over molecular weight, copolymer ratio, and end-group chemistry. By adjusting the lactic-to-glycolic acid ratio, PLGA properties such as hydrophobicity, crystallinity, and degradation rate can be finely tuned, making it a versatile biomaterial for medical and pharmaceutical applications.
Key Properties of PLGA Polymers
Physicochemical Characteristics
PLGA does not undergo gelation in the classical hydrogel sense but forms solid or porous polymeric matrices through solvent casting, particulate leaching, electrospinning, or molding processes. Its physicochemical behavior is governed by ester bond hydrolysis and polymer chain mobility.
Key influencing factors include:
- Copolymer ratio (lactide:glycolide), which dictates crystallinity and degradation speed.
- Molecular weight and polydispersity.
- End-group chemistry (acid- or ester-terminated).
- Processing conditions such as solvent choice, temperature, and moisture exposure.
Crosslinking is not intrinsic to PLGA but can be introduced indirectly through blending or surface modification with other polymers or functional groups.
Mechanical Properties
PLGA exhibits a broad range of mechanical behaviors depending on composition and processing. It typically behaves as a stiff, elastic polymer at early stages, transitioning toward softer, viscoelastic behavior as degradation progresses.
- Elastic modulus and tensile strength decrease over time due to hydrolytic chain scission.
- Higher glycolic acid content generally increases stiffness but accelerates degradation.
- Porosity and scaffold architecture strongly influence compressive and tensile properties.
- Mechanical integrity diminishes progressively as molecular weight decreases during degradation.
This time-dependent mechanical evolution is critical for load-bearing and temporary support applications.
Biological Interactions
PLGA is widely recognized for its biocompatibility and predictable bioresorption. Its degradation products—lactic and glycolic acids—are naturally metabolized, though localized acidity can influence cellular responses.
- Generally supports cell attachment when surface-modified or combined with bioactive components.
- Exhibits low immunogenicity but may induce mild inflammatory responses during rapid degradation.
- Does not inherently present cell-adhesive motifs, often requiring functionalization.
- Degrades primarily through bulk hydrolysis rather than enzymatic processes.
Applications of PLGA
Tissue Engineering
PLGA is extensively used as a scaffold material for tissue engineering due to its tunable mechanics and degradation. It supports the regeneration of bone, cartilage, nerve, cardiac, and vascular tissues by providing temporary structural support while gradually resorbing as new tissue forms.
3D Cell Culture & Disease Models
PLGA-based porous scaffolds and microspheres are employed to create three-dimensional cellular environments that better replicate in vivo conditions. These systems are used to study cell–material interactions, tissue development, and disease progression under controlled mechanical and biochemical conditions.
Drug, Gene & Cell Delivery
PLGA is a benchmark material for controlled delivery systems. It is widely used to fabricate nanoparticles, microspheres, and implants that enable sustained and tunable release of drugs, genes, proteins, and cells, with release kinetics governed by polymer composition and degradation rate.
Why the Viscoelasticity of PLGA Matters
Although PLGA is often considered a solid polymer, its viscoelastic behavior evolves significantly over time due to hydrolytic degradation. Changes in stiffness, damping, and energy dissipation directly affect load transfer, scaffold stability, and cellular mechanotransduction. Understanding this time-dependent viscoelasticity is essential for predicting in vivo performance, optimizing scaffold design, and aligning mechanical support with tissue regeneration timelines.
Methods to Characterize the Viscoelasticity of PLGA
PLGA mechanical characterization typically relies on destructive or endpoint testing methods, including tensile testing, compression testing, dynamic mechanical analysis, and rheological measurements on melts or composites. These approaches often require multiple samples, disrupt structural integrity, and provide limited insight into real-time mechanical evolution during degradation or culture.
ElastoSens™ Bio: A Non-Destructive Tool to Measure Soft PLGA Polymers
The ElastoSens™ Bio enables non-destructive, contactless measurement of viscoelastic properties in soft and degrading polymer systems such as PLGA-based scaffolds and composites. By applying gentle oscillatory excitation, it measures storage and loss moduli in real time without altering sample integrity.
Key advantages include:
- High sensitivity and repeatability for soft and evolving materials.
- Real-time monitoring of stiffness changes during degradation.
- Ability to test the same sample longitudinally under sterile conditions.
- Compatibility with hydrated and biologically relevant environments.
This approach provides unique insight into the dynamic mechanical behavior of PLGA systems throughout their functional lifetime.
Conclusions and perspectives
The mechanical behavior of PLGA—governed by composition, processing, and time-dependent degradation—is critical to its performance in scaffolds, delivery systems, and injectable biomaterials. Because PLGA systems often undergo continuous mechanical evolution, their properties must be monitored without altering structure or sterility. Non-destructive viscoelastic characterization with the ElastoSens™ Bio enables:
Non-destructive viscoelastic characterization with the ElastoSens™ Bio enables:
- Sensitive and repeatable tracking of stiffness evolution during degradation.
- Identification of liquid–solid transition and end stiffness in PLGA-based soft systems and composites.
- Longitudinal testing of the same sample to capture time-dependent mechanical behavior under sterile conditions.
- Real-time monitoring of photocrosslinking kinetics when PLGA is used in photo-reactive or hybrid formulations.
Together, this approach supports improved understanding, reproducibility, and optimization of PLGA-based materials for biomedical and industrial applications.
References
Gentile, P., Chiono, V., Carmagnola, I., & Hatton, P. V. (2014). An overview of poly (lactic-co-glycolic) acid (PLGA)-based biomaterials for bone tissue engineering. International journal of molecular sciences, 15(3), 3640-3659.
Martins, C., Sousa, F., Araújo, F., & Sarmento, B. (2018). Functionalizing PLGA and PLGA derivatives for drug delivery and tissue regeneration applications. Advanced healthcare materials, 7(1), 1701035.
Patel, M., Jha, A., & Patel, R. (2021). Potential application of PLGA microsphere for tissue engineering. Journal of Polymer Research, 28(6), 214.
Discover how our technology non-destructively measures the viscoelastic properties of soft biomaterials and tissues using micro-volumes of samples
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