Effects of PLGA coating on biological and mechanical behaviors of tissue engineering scaffolds

Scaffolds have a key role in the clinical success of tissue engineering for the regeneration of damaged tissues. Their bio-performance is often described as the extent to which they can provide an extracellular matrix-like environment for cells embedded where their function and growth can effectively continue. For this purpose, tissue engineering scaffolds should exhibit biodegradability, biocompatibility, bioactivity, delivery, and mechanical performance. The use of polymer coatings, especially poly(lactic-co-glycolic acid) (PLGA), on tissue engineering scaffolds has been found to be one of the most effective methods to improve the scaffold properties. This paper reviews the techniques used to coat tissue engineering scaffolds with PLGA and its effects on the mechanical characteristics, biodegradability, biocompatibility, Molecular delivery, and osteointegration of the scaffolds. It is concluded that apart from apatite-formation ability, all bio-functionalities can be tuned through PLGA coatings. This reflects the great potential of this modification approach to be used in tissue regeneration and therapeutic delivery applications.

💡 Research Summary

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This review article provides a comprehensive overview of poly(lactic‑co‑glycolic acid) (PLGA) coating as a versatile strategy to enhance the performance of tissue‑engineering scaffolds. The authors first discuss the intrinsic properties of PLGA, emphasizing that the lactide/glycolide (LA/GL) ratio can be tuned to modulate hydrophilicity, glass‑transition temperature, degradation rate, and pH‑buffering capacity. Such tunability allows the scaffold’s dissolution kinetics to be matched with the timeline of new tissue formation, while mitigating the acidic micro‑environment that can arise from polymer hydrolysis.

The paper then categorizes the substrate materials that have been successfully coated with PLGA: (i) bioceramics (hydroxyapatite, tricalcium phosphate, 58S bio‑active glass, etc.), which possess excellent osteoconductivity but suffer from brittleness; (ii) metallic implants (titanium and its alloys), which offer high strength yet are prone to corrosion and adverse ion release; and (iii) polymeric scaffolds (poly‑ε‑caprolactone, silk fibroin, etc.), which already provide a favorable biological interface but often lack sufficient mechanical robustness. In each case, PLGA forms a conformal polymeric layer that improves toughness, reduces crack propagation, and creates a more cell‑friendly surface. For metals, PLGA additionally acts as a corrosion barrier, while for ceramics it bridges the gap between brittleness and flexibility.

Two principal coating techniques are compared: dip‑coating and electrospinning. Dip‑coating is straightforward, inexpensive, and allows precise control of coating thickness by adjusting polymer concentration, immersion time, and drying conditions. However, achieving uniform penetration into highly porous scaffolds often requires auxiliary steps such as vacuum impregnation or centrifugation to remove excess solution. Electrospinning, by contrast, produces nanometer‑scale fibrous mats with exceptionally high specific surface area and porosity, which can dramatically increase cell attachment and nutrient diffusion. The method is more complex, demands careful control of solution viscosity, voltage, tip‑to‑collector distance, and flow rate, and is currently less explored for PLGA on three‑dimensional scaffolds. The authors note the lack of direct comparative data on mechanical and biological outcomes between the two methods, highlighting an area for future research.

The impact of PLGA coating on scaffold functionality is examined in five domains:

1. Mechanical Properties – PLGA‑coated ceramic and metal scaffolds exhibit 30–200 % increases in compressive and flexural strength, attributed to the polymer’s ability to fill micro‑cracks and distribute loads more evenly.

2. Biodegradability – By varying the LA/GL ratio, degradation times can be tuned from a few weeks (high GL content) to several months (high LA content). This flexibility enables designers to synchronize scaffold resorption with tissue regeneration rates.

3. Biocompatibility – PLGA enhances surface hydrophilicity, leading to 1.5–2‑fold higher cell adhesion and proliferation in vitro. Its mild buffering effect reduces local acidity, thereby lowering inflammatory responses in vivo.

4. Molecular Delivery – PLGA matrices can encapsulate growth factors (e.g., BMP‑2, VEGF), antibiotics, or chemotherapeutics. Release profiles typically show an initial burst followed by sustained release over 2–4 weeks, supporting both early osteoinduction and long‑term infection control.

5. Osteointegration and Osteogenesis – While PLGA itself does not nucleate apatite, its coating on bio‑active ceramics promotes calcium‑phosphate deposition and improves bone‑implant contact in animal models, often achieving >80 % bone integration.

The authors acknowledge several gaps: (a) achieving uniform, reproducible coatings on complex, highly porous architectures; (b) developing multilayer or patterned PLGA coatings for sequential or spatially controlled drug release; (c) conducting long‑term in‑vivo safety, immunogenicity, and metabolic fate studies of PLGA degradation products; and (d) scaling the coating processes to GMP‑grade production and navigating regulatory pathways for clinical translation.

In conclusion, PLGA coating emerges as a powerful tool to simultaneously address mechanical, degradative, biological, and therapeutic demands of tissue‑engineering scaffolds. Its ability to be fine‑tuned through monomer composition and applied via relatively simple coating methods positions it for broader adoption. Future work focusing on coating uniformity, advanced drug‑delivery architectures, and rigorous preclinical validation will be essential to move PLGA‑coated scaffolds from the laboratory to the clinic.