Surface Modification Techniques for Polylactic Acid Applications

Surface modification of polylactic acid (PLA) encompasses a range of physical and chemical approaches designed to tailor interfacial properties such as wettability, roughness, functional group density and mechanical stability. Physical methods include ultrafast laser structuring, plasma treatments and UV-assisted grafting, which can generate micro- and nanoscale topographies or introduce polar functionalities without bulk alteration. Chemical strategies feature alkali or enzymatic hydrolysis, which cleave surface ester bonds to yield carboxyl and hydroxyl moieties, and wet-chemical etching to adjust porosity and surface free energy. Combined protocols often enhance cell adhesion, controlled drug release, bioresorbable stent endothelialisation and adhesive bonding in wood composites. Crucially, the interplay between crystallinity and modification technique governs durability, degradation rate and mechanical behaviour. Advances in spatially resolved patterning and green chemistries have expanded the scope of PLA in tissue engineering, medical devices, packaging and environmental applications, underlining its global relevance as a sustainable polymer platform.

Research from Nature Portfolio

Recent studies have demonstrated that femtosecond laser pulses can serve as a highly precise tool for spatially distributed surface and subsurface modification of PLLA. Ultrafast irradiation at near-infrared wavelengths produces filamentation-induced microchannels of micrometre diameter, enabling controlled stress fields that promote crystallisation at reduced temperatures. Characterisation by X-ray diffraction, calorimetry and spectroscopies confirms that laser-induced defects accelerate crystallite formation and can be tuned to modify hydrolytic degradation profiles. This approach offers a non-contact, maskless route to engineer PLA crystallinity and surface architecture for implantable devices and scaffolds, where local mechanical and degradation properties must be precisely controlled.

Research from all publishers

An alkali hydrolysis technique has been developed to enhance surface hydrophilicity by selectively cleaving ester bonds in PLLA films. The process generates polar terminal groups and increases surface roughness, with the extent of hydrophilicity improvement shown to depend strongly on the underlying crystallinity. High-crystallinity specimens exhibit a synergistic effect between newly formed hydrophilic moieties and micro-valley networks, leading to markedly enhanced water uptake and degradation resistance.

Dielectric barrier discharge plasma applied to PLA scaffolds obtained by phase inversion has been shown to increase surface porosity and free energy without compromising membrane integrity. Optimising the gas composition and power leads to significant reductions in water contact angle and elevated polar surface energy components, fostering improved nutrient transport and cell–material interactions for tissue engineering membranes.

Solvent-cast PLLA films functionalised for bioresorbable stents have been treated by oxygen plasma, sodium hydroxide etching or cutinase enzyme hydrolysis. These methods introduce carboxyl and hydroxyl groups in varying densities, with plasma and enzymatic hydrolysis yielding the highest functional group loading. Enhanced endothelial cell adhesion and spreading correlate with increased surface polarity, while mechanical properties and degradation rates remain within target ranges. Fabrication of 3D-printed stents from treated PLLA demonstrates the feasibility of combining surface functionalisation with additive manufacturing for personalised vascular implants.

Surface Modification Techniques for Polylactic Acid Applications publication trend

The graph below shows the total number of articles in surface modification techniques for polylactic acid applications across all publications each year (not limited to Nature Index journals).

Technical terms

Polylactic acid (PLA): A biodegradable polyester derived from lactic acid, widely used in biomedical and packaging applications.

Femtosecond laser ablation: A high-precision surface structuring technique using ultrashort laser pulses to create micro- and nanofeatures.

Dielectric barrier discharge plasma: A low-temperature plasma generated between electrodes separated by a dielectric, used for surface activation without heat damage.

Alkali hydrolysis: A chemical process that cleaves ester bonds in PLA using a base to generate polar hydroxyl and carboxyl groups.

Crystallinity: The degree of ordered molecular arrangement within PLA, affecting mechanical properties and degradation behaviour.

Hydrolytic degradation: The breakdown of PLA through reaction with water, influenced by surface chemistry and crystallinity.

References

1. Plasma Modification Techniques for Natural Polymer-Based Drug Delivery Systems. Pharmaceutics (2023).
2. Diverse nature of femtosecond laser ablation of poly(L-lactide) and the influence of filamentation on the polymer crystallization behaviour. Scientific Reports (2019).
3. Crystallinity Dependence of PLLA Hydrophilic Modification during Alkali Hydrolysis. Polymers (2022).
4. Discharge Plasma Treatment as an Efficient Tool for Improved Poly(lactide) Adhesive–Wood Interactions. Materials (2021).
5. Functionalization Strategies and Fabrication of Solvent-Cast PLLA for Bioresorbable Stents. Applied Sciences (2021).
6. Modification of PLA Scaffold Surface for Medical Applications. Applied Sciences (2021).
7. Development and Characterization of Photoinduced Acrylamide‐Grafted Polylactide Films for Biomedical Applications. International Journal of Polymer Science (2017).