On the biodegradation of micropatterned polymeric films

Polymeric implants for local drug delivery offer significant advantages for treating various medical conditions by enabling the temporal and spatial control of drug release, improving efficacy, and reducing systemic side effects. In this context, µMESH, a 20 μm thin, dual-compartmentalized film comprising a poly(lactic-co-glycolic acid) (PLGA) micronetwork intercalated with a polyvinyl alcohol (PVA) microlayer, represents an interesting opportunity as its geometry can be systematically and accurately micropatterned during the fabrication process, enabling the systematic analysis of the effect of geometry on biodegradation rates mechanisms. In this study, four different µMESH films were realized with different surface area-to-volume ratios ( S _a / V ), ranging from 0.67 to 1.7 µm ⁻¹ . After characterizing the µMESH geometry via fluorescent and scanning electron microscopy, biodegradations studies were performed up to 60 days in different media to assess the mass loss of PLGA, the reduction in PLGA molecular weight, and the formation of macroscopic defects – pores, holes and crack – within the PLGA micronetwork. By comparing the four µMESH films among themselves and to a flat, continuous PLGA slab (FLAT), it was confirmed the importance of the surface-to-volume ratio and demonstrated that µMESH with higher S _a / V ratios exhibited slower degradation rates compared to FLAT. Scanning electron microscopy images of the PLGA micronetworks revealed morphological changes indicative of bulk erosion, including surface roughening and pore formation, in FLAT and µMESH configurations with low S _a / V ratios. These findings confirm that film micropatterning significantly influences degradation kinetics.