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Materials used for the manufacture of implants may suffer alterations in their surface properties as a result of continuous contact with physiological fluids. Moreover, in biodegradable and bioabsorbable materials, such as polylactic acid (PLA), these changes may be more accentuated, and their biological response may be affected by the presence of proteins, enzymes or other compounds of an oxidizing character. This research proposes to study the degradation of PLA in a close-to-reality environment by supplementing the physiological buffer m- SBF with concentrations of glucose and ketone bodies of healthy individuals. To this end, parameters such as hydrophobicity, surface tension, topography and surface chemical composition of PLA films and PLA films doped with magnesium particles after degradation were evaluated to determine how these components influence these properties compared to degradation in standard buffer. The presence of glucose and/or ketone bodies in the degradation medium of PLA doped with magnesium particles altered the composition of the salt layers absorbed on the surface of the material due to the action of gluconate and/or hydroxybutyrate anions, which were able to coordinate with ions from the solution as well as Mg2+ cations from polymer degradation. The salt accumulation on polymeric films changes the surface mechanical response increasing the Young's modulus after degradation. • Composition of physiological medium affects the biodegradability of polylactic acid. • Glucose promotes CaP layer formation on Mg-containing polylactic acid films. • Ketone bodies increase hydrophilicity of Mg-containing polylactic acid films. • Both compounds have to be considered in in vitro degradation models of biomaterials. [ABSTRACT FROM AUTHOR]

Plasma treatment is one of the methods currently used to obtain polymeric materials with surface properties appropriate to the functionality for which they were designed. However, the effects achieved after surface modification are not always long lasting and involve chemical and physical changes in the outermost layer. In this context, the effects of both argon and oxygen plasma on polylactic acid (PLA) films deposited on titanium were studied to determine which physical and chemical processes occur at the surface, and their duration. Regarding physical surface changes, there were scarcely any differences between both plasmas: roughness was very similar after treatments, root mean square height (Sq) being 10 times higher than the control, without plasma. Water contact angle (WCA) showed that the surface became more hydrophilic after application of the plasma, although hydrophilization was longer lasting in the case of argon treatment. With regard to chemical changes, it was observed that the argon plasma treatment caused greater fragmentation of the polymer chains, and increased crosslinking between them. ToF-SIMS analysis made it possible to propose mechanisms to explain the formation of the fragments observed. • Oxygen and argon treatment make the PLA surface more hydrophilic. • Ar plasma induces more long lasting hydrophilization than O 2 plasma. • O 2 plasma leads to new oxygen-rich, higher molecular weight species. • Ar plasma favors cross-linking and fragmentation of the polymer chains. [ABSTRACT FROM AUTHOR]