Surface modification of biomaterials is a strategy used to improve cellular and in vivo outcomes. However, most studies do not evaluate the lifetime of the introduced surface layer, which is an important aspect affecting how a biomaterial will interact with a cellular environment both in the short and in the long term. This study evaluated the surface layer stability in vitro in buffer solution of materials produced from poly(lactic-co-glycolic acid) (50:50) and polycaprolactone modified by hydrolysis and/or grafting of hydrophilic polymers using grafting from approaches. The data presented in this study highlight the shortcomings of using model substrates (e.g., spun-coated films) rather than disks, particles, and scaffolds. It also illustrates how similar surface modification strategies in some cases result in very different lifetimes of the surface layer, thus emphasizing the need for these studies as analogies cannot always be drawn.

The design of current implants produced from biodegradable polyesters is based on strength and rate of degradation and tailored by the choice of polyester used. However, detailed knowledge about the degradation mechanism of surface modified materials with applications in biomaterials science and tissue engineering is currently lacking. This perspective aims to outline the need for a greater focus on analyzing the degradation of modified polyesters to ensure they can fulfil their intended function and that degradation products can effectively be cleared from the body. The status of the literature regarding surface modified polyesters is summarized to illustrate the main aspects investigated in recent studies and specifically the number of studies investigating the fate of the materials upon degradation.

Sialorrhea is a disorder which causes an increase in salivation. Scopolamine butylbromide (SBB) can be administrated to treat sialorrhea and its transdermal application minimizes the occurrence of side effects. This work compared SBB adsorption and release from two polymer matrices, polycaprolactone and natural rubber latex, as well as the matrices modified by gamma irradiation-induced graft copolymerization of acrylic acid (AAc). Grafting with AAc-introduced carboxylate groups onto the surface of the matrices evident from chemical analysis and resulted in increased hydrophilicity evident from contact angle measurements. SBB adsorbed to the matrices without changing its structure and for the AAc-grafted matrices this was governed by electrostatic interactions. Higher SBB loading was observed for the AAc-grafted matrices while SBB release was slower for the nongrafted matrices than the grafted matrices. The four different matrices produced are candidates for the development of a transdermal drug delivery system.

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