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The use of active components in biomaterials improves the properties of existing ones and makes it possible to obtain new devices with antibacterial properties that prevent infections after implantation, thus guaranteeing the success of the implant. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles were incorporated into polylactic acid (PLA) films to assess the extent to which progressive aging of the new surfaces resists bacterial colonization processes. For this purpose, the films' surface was characterized by contact angle measurements, ToF-SIMS and AFM, and adhesion, viability and biofilm growth of Staphylococcus epidermidis bacteria on these films were also evaluated. The results show that the inclusion of Mg and CTAB in PLA films changes their surface properties both before and after aging and also modifies bacterial adhesion on the polymer. Complete bactericidal activity is exhibited on non-degraded films and films with CTAB. This antibacterial behavior is maintained after degradation for three months in the case of films containing a higher amount of CTAB. [ABSTRACT FROM AUTHOR]

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]

[Display omitted] • It is possible to spontaneously create ordered micro-structures on PLA surface. • The patterns obtained are hole type. • Doping the PLA with Mg and/or CTAB, sizes between 0.5 and 20 μm can be achieved. • New surfaces could favour cell adhesion and not bacterial adhesion. The fabrication of biomaterials with structured surfaces for medical purposes is a topic of great interest. Producing topographies with certain characteristics can benefit tissue formation and/or reduce the probability of developing an infection due to the hindrance shown by certain micro-structures to microbial adhesion. This work presents a new, economically attractive way to fabricate micro-structured patterns on the surface of one of the currently most interesting bioabsorbable polymeric materials, polylactic acid (PLA). Formation of homogeneously distributed holes is presented as a function of three factors: the concentration of cetyltrimethylammonium bromide (CTAB), the presence or not of the dispersant magnesium, and the hydrophobicity of the support used in the PLA-film fabrication, silicone or glass. The size of the holes increases with the CTAB concentration: from 1 to 5 µm on silicone and 2 to 20 µm on glass. Magnesium particles make CTAB to disperse better inside the PLA matrix, provoking the irregular holes observed on glass become regular with sizes between 0.5 and 2 µm. The topographies obtained on silicone are highly stable over time, while on glass they degrade after 28 days. Consequently, it is possible to design a wide spectrum of micro-structured topographies, covering both antimicrobial and tissue integration targets. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is a good candidate for the manufacture of polymeric biodegradable biomaterials. The inclusion of metallic particles and surfactants solves its mechanical limitations and improves its wettability, respectively. In this work, cetyltrimethylammonium bromide (CTAB) and magnesium particles have been incorporated into PLA films to evaluate the changes produced in the polymeric matrix cast on glass and silicone substrates. For this purpose, the surface of the films has been characterized by means of contact angle measurements and ToF-SIMS. Depth profiles and SEM images of the cross sections of the films have also been obtained to study their morphology. The results show that the CTAB in the polymer matrix with and without magnesium improves the wettability of the films, making them more suitable for cell adhesion. The higher the hydrophilicity, the higher the surfactant concentration. The depth profiles show, for the first time, that, depending on the surfactant concentration and the presence of Mg, there is a layer-like distribution near the surface where, in addition to the CTAB + PLA mixture, a surfactant exclusion zone can be seen. This new structure could be relevant in in vitro/in vivo situations when the degradation processes remove the film components in a sequential form. [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]

[Display omitted] • When facing UV exposure, doping PLA with Qr and Mg guarantees the chemical stability of the polymer matrix. • In addition, Qr and Mg reinforces the PLA mechanical properties of the matrix. • Polymer crystallinity rules the dopants distribution inside the PLA matrix and its response to the UV irradiation. The use of biopolymers like poly(lactic acid) (PLA) doped with natural and harmless active agents in industrial, medical and food packaging applications is of great interest due to the multitude of property enhancements included. External factors, such as UV exposure, can accelerate the degradation process of these biomaterials and cause changes in structural and mechanical properties of medical or industrial devices. In this research, PLA-based composites with different degrees of crystallinity are fabricated using magnesium (Mg) particles and quercetin (Qr) as doping agents, providing new biomaterials with different responses against an UV-C radiation source. Physical surface changes are studied by atomic force microscopy (AFM), goniometry and scanning electron microscopy (SEM). Chemical modifications are evaluated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Thermal response is studied by differential scanning calorimetry (DSC). PLA crystallinity is crucial in the polymer response to UV radiation. Under irradiation Mg particles cause a catalytic effect that enhances the degradation by hydrolysis of PLA chains. However, when Qr is present this effect is inhibited, making the Qr/Mg combination an ideal enrichment to protect the polymer from chemical photooxidation, while improving the surface mechanical properties of the new biocomposite. [ABSTRACT FROM AUTHOR]