An information-theoretic approach to basis-set fitting of electron densities and other non-negative functions.

The numerical ill-conditioning associated with approximating an electron density with a convex sum of Gaussian or Slater-type functions is overcome by using the (extended) Kullback-Leibler divergence to measure the deviation between the target and approximate density. The optimized densities are non-negative and normalized, and they are accurate enough to be used in applications related to molecular similarity, the topology of the electron density, and numerical molecular integration. This robust, efficient, and general approach can be used to fit any non-negative normalized functions (e.g., the kinetic energy density and molecular electron density) to a convex sum of non-negative basis functions. We present a fixed-point iteration method for optimizing the Kullback-Leibler divergence and compare it to conventional gradient-based optimization methods. These algorithms are released through the free and open-source BFit package, which also includes a L2-norm squared optimization routine applicable to any square-integrable scalar function.

Micropatterned functional interfaces on elastic substrates fabricated by fixing out of plane deformations.

We report on the preparation of micropatterned functional surfaces produced by inducing an out-of-plane deformation on elastic substrates and fixing these by creating a rigid oxidized top layer. Specifically, the elastic substrate used was Polydimethylsiloxane (PDMS) and the rigid layer on top was created by ozonation of this material. We evidenced that the surface pattern formed is directly dependent on the pressure applied, the mechanical properties of the elastic substrate and on the dimensions and shape of the mask employed to define the exposed and non-exposed areas. In addition to the pattern formed, another interesting aspect is related to the ozone diffusion within the material. Softer PDMS enables more efficient diffusion and produced a thicker oxidized layer in comparison to rigid PDMS. Finally, a simulation was carried out using the distribution of Von Misses stresses of a solid plate to understand the conditions in which the applied force resulted in the rupture of the rigid oxidized layer under a permanent deformation.

Weak polyelectrolyte brushes: re-entrant swelling and self-organization.

We have studied the combined influence of pH and ionic strength on the properties of brushes of a weak polyion, poly(acrylic acid), in conditions of grafting density close to the mushroom-brush crossover. By combining atomic force microscopy AFM and quartz crystal microbalance, we show that at low ionic strengths the conformational change of grafted polyions is non-monotonic with increasing pH due to the counterintuitive variation of the ionization degree. Thus, reentrant swelling of the polymer chains is observed with increasing pH. This effect is more important at low polymer grafting densities, when it is accompanied by in-plane heterogeneous distribution at intermediate pH values. In addition, we observed self-assembly on the polymer brush (formation of holes and islands) at pH values below pKa, due to the short-range attractive interaction between uncharged grafted chains. The sensitivity of the ionization of grafted chains to the physicochemical environment was also studied by measuring the interaction force between a silica tip and polymer brushes by atomic force microscopy. The dependence of the ionization of polyions on the presence of the tip points toward important charge regulation effects, in particular at pH values corresponding to partial ionization of the polyion.

Cardiovascular risk factors and arterial thrombotic events in congenital heart disease patients.

INTRODUCTION: As congenital patients get older, it can be hypothesised that cardiovascular risk factors increase. METHODS: Retrospective study of congenital heart disease (CHD) patients attended between January 2008 and September 2018. Cardiovascular risk factors, myocardial infarction, stroke, peripheral vascular disease, and analytical data such as serum glucose and lipid profile were determined. RESULTS: Eight hundred and eighteen CHD patients and 1955 control patients matched for age and sex were studied. CHD patients were distributed in simple (462 patients), moderate (228 patients) and great (128 patients) complexity. Median age in CHD patients was 33 (25-41) years old and 56% were male. CHD patients were significantly more hypertensive and diabetic but less dyslipidemic and smokers than patients in the control group. Twenty-seven (3.3%) CHD patients had an arterial thrombotic event: 3 coronary, 22 neurological and 2 peripheral vascular disease. No significant differences were seen in the incidence of myocardial infarction between the control and the CHD groups. However CHD patients had a significant higher incidence of arterial thrombotic events (coronary, neurological and peripheral vascular events) at the expense of strokes and transient ischaemic attacks (22 vs 2 events in CHD and control patients, respectively). Also, no significant differences were seen in age, sex, BMI, arterial hypertension, diabetes mellitus, dyslipidemia, smoking habit, serum glucose, total and LDL cholesterol, statin treatment, myocardial infarction and arterial thrombotic events according to CHD complexity. Being older and having arterial hypertension, diabetes mellitus, dyslipidemia and smoking habit were more frequent among CHD patients with arterial thrombosis. CONCLUSIONS: Congenital heart diseases are more hypertensive and diabetic but less dyslipemic and smokers than patients in the control group. CHD patients have a higher incidence of neurological events but not of myocardial infarction in relation to the control population.

Antimicrobial Polymers for Additive Manufacturing.

Three-dimensional (3D) printing technologies can be widely used for producing detailed geometries based on individual and particular demands. Some applications are related to the production of personalized devices, implants (orthopedic and dental), drug dosage forms (antibacterial, immunosuppressive, anti-inflammatory, etc.), or 3D implants that contain active pharmaceutical treatments, which favor cellular proliferation and tissue regeneration. This review is focused on the generation of 3D printed polymer-based objects that present antibacterial properties. Two main different alternatives of obtaining these 3D printed objects are fully described, which employ different polymer sources. The first one uses natural polymers that, in some cases, already exhibit intrinsic antibacterial capacities. The second alternative involves the use of synthetic polymers, and thus takes advantage of polymers with antimicrobial functional groups, as well as alternative strategies based on the modification of the surface of polymers or the elaboration of composite materials through adding certain antibacterial agents or incorporating different drugs into the polymeric matrix.

Micrometric Wrinkled Patterns Spontaneously Formed on Hydrogel Thin Films via Argon Plasma Exposure.

The generation of microstructured patterns on the surface of a specific polymeric material could radically improve their performance in a particular application. Most of the interactions with the environment occur at the material interface; therefore, increasing the exposed active surface considerably improves their range of application. In this article, a simple and reliable protocol to form spontaneous wrinkled patterns using a hydrogel layer is reported. For this purpose, we took advantage of the doctor blade technique in order to generate homogenous films over solid substrates with controlled thickness and large coverage. The hydrogel wrinkle formation involves a prepolymerization step which produces oligomers leading to a solution with increased viscosity, enough for doctor blade deposition. Subsequently, the material was exposed to vacuum and plasma to trigger wrinkled pattern formation. Finally, a UV-polymerization treatment was applied to fix the undulations on top. Interestingly, the experimental parameters allowed us to finely tune the wrinkle characteristics (period, amplitude, and orientation). For this study, two main aspects were explored. The first one is related to the role of the substrate functionalization on the wrinkle formation. The second study correlates the deswelling time and its relationship with the dimensions and distribution of the wrinkle pattern. In the first batch, four different 3-(trimethoxysilyl)propyl methacrylate (TSM) concentrations were used to functionalize the substrate in order to enhance the adhesion between hydrogel film and the substrate. The wrinkles formed were characterized in terms of wrinkle amplitude, wavelength, pattern roughness, and surface Young modulus, by using AFM in imaging and force spectroscopy modes. Moreover, the chemical composition of the hydrogel film cross-section and the effect of the plasma treatment were analyzed with confocal Raman spectroscopy. These results demonstrated that an oxidized layer was formed on top of the hydrogel films due to the exposure to an argon plasma.

Anemia in Adolescents and Young Adult Patients With Congenital Heart Disease.

INTRODUCTION: Despite anemia in acquired heart disease being a common problem, little is known in patients with congenital heart disease (CHD). METHODS: In total, 544 consecutive stable noncyanotic CHD patients were studied to determine demographic, clinical, and analytic parameters. Anemia was defined as a condition in which hemoglobin concentration was <13 g/dL in male individuals and <12 g/dL in female individuals. RESULTS: In total, 49 (9%) CHD patients had anemia. Patients with complex anatomy had the highest prevalence of anemia (33%). The median hemoglobin concentration was 14.4 (13.5 to 15.6) mg/dL. Of the total anemic CHD patients, 21 of 49 (43%) were microcytic (mean corpuscular volume <84 fL) and 46 of 49 (94%) had a mean corpuscular volume under 95 fL. Oral anticoagulation, oral antiaggregation, diuretic treatment, and having valve prostheses or cardiovascular risk factors, such as arterial hypertension or diabetes mellitus, did not reach statistical significance between anemic and nonanemic CHD patients. Multivariate analyses determined as risk factors for anemia a worse New York Heart Association functional class (patients in class >II/IV) (odds ratio [OR], 8.37; 95% confidence interval [CI], 1.69-41.35), N-terminal proB-type natriuretic peptide levels >125 pg/mL (OR, 7.90; 95% CI, 2.88-21.69), and apoferritn levels below 15 ng/mL (OR, 0.21; 95% CI, 0.09-0.50). The Kaplan-Meier survival analysis showed no significant differences in mortality between anemic and nonanemic CHD patients (P=0.143). CONCLUSIONS: The incidence of anemia in CHD patients is similar to that of the normal population and iron deficiency anemia accounts for most of the cases. There were no significant differences in mortality between CHD patients with and without anemia.

Electrowetting of Weak Polyelectrolyte-Coated Surfaces.

Polymer coatings are commonly used to modify interfacial properties like wettability, lubrication, or biocompatibility. These properties are determined by the conformation of polymer molecules at the interface. Polyelectrolytes are convenient elementary bricks to build smart materials, given that polyion chain conformation is very sensitive to different environmental variables. Here we discuss the effect of an applied electric field on the properties of surfaces coated with poly(acrylic acid) brushes. By combining atomic force microscopy, quartz crystal microbalance, and contact angle experiments, we show that it is possible to precisely tune polyion chain conformation, surface adhesion, and surface wettability using very low applied voltages if the polymer grafting density and environmental conditions (pH and ionic strength) are properly formulated. Our results indicate that the effective ionization degree of the grafted weak polyacid can be finely controlled with the externally applied field, with important consequences for the macroscopic surface properties.

Chemical and Topographical Modification of Polycarbonate Surfaces through Diffusion/Photocuring Processes of Hydrogel Precursors Based on Vinylpyrrolidone.

Facile procedures capable of simultaneously conferring hydrophilicity and tailored topography to surfaces of hydrophobic supports, such as polycarbonate (PC), are very attractive but rare. In this work, we describe a simple methodology to wrinkle PC surfaces after a process of (a) contacting with a photopolymerizable vinylic solution, (b) UV curing of such solutions, and (c) detachment of the formed polymer network, upon swelling in ethanol. The influence of different parameters such as contact lag time between the PC surface and the polymerizable solution, the monomer concentration and type of solvents, as well as the cross-linking degree on the formation of wrinkles, has been studied. The dimensions of the wrinkles can be tailored to some extent by altering the different parameters. Surface chemistry has been analyzed by contact angle measurements and by confocal Raman microscopy. The results are consistent with a chemical alteration of the surface and the formation of an outer hydrogel layer, which is interpenetrated into the PC structure. A mechanism of monomer diffusion and PC swelling that produces surface instabilities and wrinkling is proposed.

Hydrogels with Modulated Ionic Load for Mammalian Cell Harvesting with Reduced Bacterial Adhesion.

In this manuscript, we describe the fabrication of hydrogel supports for mammalian cell handling that can simultaneously prevent materials from microbial contamination and therefore allow storage in aqueous media. For that purpose, hydrogels based on the antifouling polymer polyvinylpyrrolidone (PVP) were functionalized with different ionic groups (anionic, cationic, or two types of zwitterions). In order to prevent bacterial adhesion in the long-term, we took advantage of the synergistic effect of inherently antifouling PVP and additional antifouling moieties incorporated within the hydrogel structure. We evaluated, in a separated series of experiments, both the capability of the materials to act as supports for the growth of mammalian cell monolayers for transplantation (using C-166-GFP endothelial cell line), as well their antifouling properties against Staphylococcus aureus, were studied. All of the hydrogels are structurally pseudodouble networks with high swelling (around 90%) and similar mechanical properties (in the low range for hydrogel materials with Young modulus below 1250 kPa). With some differences, all the charged hydrogels were capable of hosting mouse endothelial cell line C166-GFP to confluence, as well as a monolayer detachment and transplantation through simple mechanical agitation. On the contrary, the uncharged hydrogel was not capable to detach a full monolayer for transplantation. Bacterial adhesion and proliferation was highly sensitive to the functionality (type of charge and density). In particular, we evidenced that monomers bearing zwitterionic sulfobetaine groups, those negatively charged as well as "electro neutral" hydrogels fabricated from stoichiometric amounts of positive and negative units, exhibit excellent antifouling properties both at initial adhesion times and during longer periods up to 72 h.

Tuning the pore composition by two simultaneous interfacial self-assembly processes: breath figures and coffee stain.

In the current paper, we prepared microstructured porous films by the breath figures approach using polymer blends consisting of polystyrene as the major component and an amphiphilic additive, either a synthetic block copolymer {two different polystyrene-b-poly[poly(ethylene glycol) methyl ether methacrylate] copolymers} or a series of commercial surfactants. Tetrahydrofuran was employed as the solvent. Confocal micro-Raman spectroscopy demonstrated the preferential location of the amphiphilic additives in the cavities of the film as a consequence of the breath figures mechanism. However, the distribution of the copolymer within the cavities varies depending upon the structure and, more precisely, the surface properties of the additives, leading to three different situations. First of all, the copolymer with a larger polystyrene segment, insoluble in the condensed water droplets, is homogeneously distributed along the whole surface of the cavities. On the contrary, when the copolymer is soluble in water (shorter polystyrene segment), it migrates inside the droplet and a coffee-stain phenomenon takes place during the water droplet evaporation, conducting to a ring-like deposition on the top edge of the cavities. Finally, when a water-soluble surfactant with high surface activity is used, the surfactant is solubilized inside the water droplets, which provokes a decrease on the surface tension and the coffee-ring effect is modified. In this situation, the copolymer covers the bottom of the pore.

Versatile approach for the fabrication of functional wrinkled polymer surfaces.

A simple and versatile approach to obtaining patterned surfaces via wrinkle formation with variable dimensions and functionality is described. The method consists of the simultaneous heating and irradiation with UV light of a photosensitive monomer solution confined between two substrates with variable spacer thicknesses. Under these conditions, the system is photo-cross-linked, producing a rapid volume contraction while capillary forces attempt to maintain the contact between the monomer mixture and the cover. As a result of these two interacting forces, surface wrinkles were formed. Several parameters play a key role in the formation and final characteristics (amplitude and period) of the wrinkles generated, including the formulation of the photosensitive solution (e.g., the composition of the monomer mixture) and preparation conditions (e.g., temperature employed, irradiation time, and film thickness). Finally, in addition, the possibility of modifying the surface chemical composition of these wrinkled surfaces was investigated. For this purpose, either hydrophilic or hydrophobic comonomers were included in the photosensitive mixture. The resulting surface chemical composition could be finely tuned as was demonstrated by significant variations in the wettability of the structured surfaces, between 56° and 104°, when hydrophilic and hydrophobic monomers were incorporated, respectively.

Formation of multigradient porous surfaces for selective bacterial entrapment.

Herein we describe the preparation of multigradient porous platforms by using the breath figures approach. In a single and straightforward step, we prepared porous surfaces in which three different parameters vary gradually from the edge of the sample to the center in a radial manner. Thus, we evidenced the gradual variation of the pore size and the shape of the pores that can be varied, depending on the sample concentration, but also depending on their radial position within the same sample. In addition, we succeeded in the control over the chemical composition inside and outside the pores as well as the variation of the concentration of block copolymer inside the pores as a function of their radial position. Moreover, the chemical composition and the variable cavity size of porous surfaces have been evaluated to analyze the influence of these variables on the selective bacterial immobilization. To the best of our knowledge this is the first example in which, by using a simple one-step strategy, a multigradient surface can be obtained. These initial results can be the base to construct platforms for selective immobilization and isolation of bacteria.

Osteoblastic Cell Sheet Engineering Using P(VCL-HEMA)-Based Thermosensitive Hydrogels Doped with pVCL@Icariin Nanoparticles Obtained with Supercritical CO2-SAS.

New clinical strategies for treating severe bone and cartilage injuries are required, especially for use in combination with implant procedures. For this purpose, p(VCL-co-HEMA) thermosensitive hydrogels have been activated with icariin-loaded nanoparticles to be used as bone-cell-harvesting platforms. Supercritical CO2-SAS technology has been applied to encapsulate icariin, a small molecule that is involved in osteoblastic differentiation. Thus, physical-chemical analysis, including swelling and transmittance, showed the impact of HEMA groups in hydrogel composition. Moreover, icariin (ICA) release from p(VCL-co-HEMA) platforms, including pVCL@ICA nanoparticles, has been studied to evaluate their efficacy in relevant conditions. Finally, the thermosensitive hydrogels' cell compatibility, transplant efficiency, and bone differentiation capacity were tested. This study identifies the optimal formulations for icariin-activated hydrogels for both control and HEMA formulations. Using this technique, osteoblastic sheets that were rich in collagen type I were successfully transplanted and recultivated, maintaining an optimal extracellular matrix (ECM) composition. These findings suggest a new cell-sheet-based therapy for bone regeneration purposes using customized and NP-activated pVCL-based cell platforms.

Hydrogels with dual sensitivity to temperature and pH in physiologically relevant ranges as supports for versatile controlled cell detachment.

Thermosensitive hydrogels based on the N-vinyl caprolactam (VCL), capable of allowing for cell adhesion and proliferation, as well as non-aggressive detachment by controlled temperature drop, were functionalized with 23 % or lower molar percentages of the cationizable hydrophobic unit 2-(diisopropylamino) ethyl methacrylate (DPAEMA), to obtain networks with dual sensitivity to temperature and pH. The swelling analysis of the systems has shown a transition pK (pKb) close to physiological values, dependent on the temperature of the medium (pKb of 6.6 and 6.9 when the temperature of the medium is above and below the transition temperature VPTT, respectively) and little dependence on the degree of functionalization of DPAEMA. In addition, at temperatures below the transition temperature (VPTT), the systems have shown large swelling variations as a function of the pH (i.e. below and above the pKb), exhibiting greater absorption capacity at pHs below pKb, where the DPAEMA units are cationized. Cytocompatibility and transplant capacity have been evaluated using the C166-GFP endothelial cell line. None of the thermosensitive hydrogels with variable DPAEMA content showed a delay with respect to the control without DPAEMA neither in terms of adhesion nor in proliferation. However, by increasing the percentage of DPAEMA functionalization -and decreasing thermosensitivity-, a correlative decrease in mitochondrial activity was obtained in the transplant, with significant differences for the hydrogels with DPAEMA molar percentage of 3 % or higher. Taking advantage of the proximity of the pKb to the physiological value, we have evaluated the cellular response and the capacity for transplantation after lowering the pH to 6.5, below pKb. A direct relationship of the DPAEMA functionalization degree on the detachment efficiency was observed, since the hydrogels with the highest molar load of DPAEMA showed higher mitochondrial metabolic activity after cell detachment.

Development of Biocompatible Digital Light Processing Resins for Additive Manufacturing Using Visible Light-Induced RAFT Polymerization.

Patients with bone diseases often experience increased bone fragility. When bone injuries exceed the body's natural healing capacity, they become significant obstacles. The global rise in the aging population and the escalating obesity pandemic are anticipated to lead to a notable increase in acute bone injuries in the coming years. Our research developed a novel DLP resin for 3D printing, utilizing poly(ethylene glycol diacrylate) (PEGDA) and various monomers through the PET-RAFT polymerization method. To enhance the performance of bone scaffolds, triply periodic minimal surfaces (TPMS) were incorporated into the printed structure, promoting porosity and pore interconnectivity without reducing the mechanical resistance of the printed piece. The gyroid TPMS structure was the one that showed the highest mechanical resistance (0.94 ± 0.117 and 1.66 ± 0.240 MPa) for both variants of resin composition. Additionally, bioactive particles were introduced to enhance the material's biocompatibility, showcasing the potential for incorporating active compounds for specific applications. The inclusion of bioceramic particles produces an increase of 13% in bioactivity signal for osteogenic differentiation (alkaline phosphatase essay) compared to that of control resins. Our findings highlight the substantial improvement in printing precision and resolution achieved by including the photoabsorber, Rose Bengal, in the synthesized resin. This enhancement allows for creating intricately detailed and accurately defined 3D-printed parts. Furthermore, the TPMS gyroid structure significantly enhances the material's mechanical resistance, while including bioactive compounds significantly boosts the polymeric resin's biocompatibility and bioactivity (osteogenic differentiation).

Constructing robust and functional micropatterns on polystyrene surfaces by using deep UV irradiation.

We report the preparation of different surface patterns based on the photo-cross-linking/degradation kinetics of polystyrene (PS) by using UV light. Upon exposure to UV light, PS can be initially cross-linked, whereas an excess of the exposure time or intensity provokes the degradation of the material. Typically photolithography employs either positive or negative photoresist layers that upon removal of either the exposed or the nonexposed areas transfer the pattern of the mask. Herein, we present a system that can be both negative and positive depending on several aspects, including the irradiation time, intensity, or presence of absorbing active species (photoinitiators) using a general setup. As a result of the optimization of the time of exposure and the use of an appropriate cover or the incorporation of an appropriate amount of photoinitiator (in this particular case IRG 651), different tailor-made surface patterns can be obtained. Moreover, changes of the chemical composition of the polystyrene using, for instance, block copolymers can lead to surface patterns with variable functional groups. In this study we describe the formation of surface patterns using polystyrene-block-poly(2,3,4,5,6-pentafluorostyrene) block copolymers. The introduction of fluorinated moieties clearly modifies the wettability of the films when compared with that of the same structures obtained with PS. As a consequence we present herein a patterning methodology that can simultaneously vary not only the morphology but also the surface chemical composition.

Boundary lubricant polymer films: effect of cross-linking.

We have studied the adsorption and lubricant properties of a multifunctional triblock copolymer poly(L-lysine)-b-poly(acrylic acid)-b-poly(L-lysine). In particular, we investigated the nature of the layer adsorbed under different conditions of polymer and salt concentration and the lubricant properties of the polymer layer before and after its chemical cross-linking by bridging the poly(acrylic acid) blocks. We found that the amount of polymer adsorbed is controlled by the ionic strength and the polymer concentration in the solution. In all cases, the self-assembled polymer layer is a poor lubricant before cross-linking, but the cohesion and load-carrying ability of the layer are substantially improved by this reaction. However, the chemically cross-linked coating has a limited deformation capacity as a consequence of its permanent network nature, and irreversible damage is observed after excessive strain of the film.

Versatile functional microstructured polystyrene-based platforms for protein patterning and recognition.

We report the preparation of different functional surface patterns based on the optimization of the photo-cross-linking/degradation kinetics of polystyrene (PS) upon exposure to UV-light. We employed a PS-b-PGA (polystyrene-block-poly(l-glutamic acid)) block copolymer that will, in addition to the surface pattern, provide functionality. By using short irradiation times, PS can be initially cross-linked, whereas an excess of the exposure time provokes the degradation of the material. As a result of the optimization of time of exposure, the use of an appropriate cover, or the incorporation of an appropriate amount of absorbing active species (photoinitiator), different tailor-made surface patterns can be obtained, from boxes to needles. Moreover, in addition to the surface pattern, we introduced changes on the chemical composition of the polystyrene using an amphiphilic block copolymer (for instance, we employ PS-b-PGA) that will provide functional surfaces with major advantages. In particular, the presence of carboxylic functional groups provides a unique opportunity to anchor, for instance polypeptide sequences. We describe the immobilization of polypeptide sequences in precise surface positions that allows the use of the surfaces for protein recognition purposes. The immobilization of the proteins evidence the success of the recognition and opens a new alternative for protein patterning on surfaces for many biotechnological and biomedical applications.

Hierarchical Hybrid Coatings with Drug-Eluting Capacity for Mg Alloy Biomaterials.

A hierarchical hybrid coating (HHC) comprising a ceramic oxide layer and two biodegradable polymeric (polycaprolactone, PCL) layers has been developed on Mg3Zn0.4Ca cast alloy in order to provide a controlled degradation rate and functionality by creating a favorable porous surface topography for cell adhesion. The inner, ceramic layer formed by plasma electrolytic oxidation (PEO) has been enriched in bioactive elements (Ca, P, Si). The intermediate PCL layer sealed the defect in the PEO layer and the outer microporous PCL layer loaded with the appropriate active molecule, thus providing drug-eluting capacity. Morphological, chemical, and biological characterizations of the manufactured coatings loaded with ciprofloxacin (CIP) and paracetamol (PAR) have been carried out. In vitro assays with cell lines relevant for cardiovascular implants and bone prosthesis (endothelial cells and premyoblasts) showed that the drug-loaded coating allows for cell proliferation and viability. The study of CIP and PAR cytotoxicity and release rate indicated that the porous PCL layer does not release concentrations detrimental to the cells. However, complete system assays revealed that corrosion behavior and increase of the pH negatively affects cell viability. H2 evolution during corrosion of Mg alloy substrate generates blisters in PCL layer that accelerate the corrosion locally in crevice microenvironment. A detailed mechanism of the system degradation is disclosed. The accelerated degradation of the developed system may present interest for its further adaptation to new cancer therapy strategies.