Synthesis of functionalized triblock copolyesters derived from lactic acid and macrolactones for bone tissue regeneration

Synthetic and functional grafts are a great alternative to conventional grafts. They can provide a physical support and the precise signaling for cells to heal damaged tissues. In this study, a novel RGD peptide end-functionalized poly(ethylene glycol)-b-poly(lactic acid)-b-poly(globalide)-b-poly(lactic acid)-b-poly(ethylene glycol) (RGD-PEG-PLA-PGl-PLA-PEG-RGD) is synthetized and used to prepare functional scaffolds. The PGl inner block is obtained by enzymatic ring-opening polymerization of globalide. The outer PLA blocks are obtained by ring-opening polymerization of both, l-lactide or a racemic mixture, initiated by the α-ω-telechelic polymacrolactone. The presence of PGl inner block enhances the toughness of PLA-based scaffolds, with an increase of the elongation at break up to 300% when the longer block of PGl is used. PLA-PGl-PLA copolymer is coupled with α-ω-telechelic PEG diacids by esterification reaction. PEGylation provides hydrophilic scaffolds as the contact angle is reduced from 114° to 74.8°. That difference improves the contact between the scaffolds and the culture media. Moreover, the scaffolds are functionalized with RGD peptides at the surface significantly enhancing the adhesion and proliferation of bone marrow-derived primary mesenchymal stem cells and MC3T3-E1 cell lines in vitro. These results place this multifunctional polymer as a great candidate for the preparation of temporary grafts

Dielectric relaxations in poly(glycidyl phenyl ether): Effects of microstructure and cyclic topology

Cyclic and linear, isoregic and aregic, and isotactic and atactic poly(glycidyl phenyl ether) (PGPE) with molecular weights up to Mw = 5.5 kg/mol are synthesized by ring-opening polymerization of glycidyl phenyl ether. Initiation with tetrabutylammonium fluoride leads to isoregic linear polymers with ~95% regular linkages, and initiation with B(C6F5)3 and B(C6F5)3/water leads to aregic cyclic and linear polymers, respectively, with ~50% regular linkages as quantified by 13C NMR. Local, segmental, and chain dynamics in PGPE is investigated by broadband dielectric spectroscopy (10–2–106 Hz). The ß-relaxation for linear PGPE is separated into two contributions arising from the motions of side groups and end groups with activation energies of 35.4 and 23.8 kJ/mol, respectively. The ß-relaxation process for cyclic PGPE shows the same activation energy as that shown by the side-group contribution in linear PGPE, indicating that topology does not play a key role on the side-group local dynamics. Moreover, cyclic PGPE samples show higher calorimetric and dynamic glass transition temperatures as well as lower dynamic fragility compared to linear chains. Unexpectedly from topological considerations, cyclic PGPE shows low frequency dielectric contributions that can be attributed to short wavelength internal ring motions and that are detectable by dielectric relaxation due to the aregic nature of the rings.Peer ReviewedPostprint (author's final draft

A Non-Viral Plasmid DNA Delivery System Consisting on a Lysine-Derived Cationic Lipid Mixed with a Fusogenic Lipid

The insertion of biocompatible amino acid moieties in non-viral gene nanocarriers is an attractive approach that has been recently gaining interest. In this work, a cationic lipid, consisting of a lysine-derived moiety linked to a C12 chain (LYCl) was combined with a common fusogenic helper lipid (DOPE) and evaluated as a potential vehicle to transfect two plasmid DNAs (encoding green fluorescent protein GFP and luciferase) into COS-7 cells. A multidisciplinary approach has been followed: (i) biophysical characterization based on zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and cryo-transmission electronic microscopy (cryo-TEM); (ii) biological studies by fluorescence assisted cell sorting (FACS), luminometry, and cytotoxicity experiments; and (iii) a computational study of the formation of lipid bilayers and their subsequent stabilization with DNA. The results indicate that LYCl/DOPE nanocarriers are capable of compacting the pDNAs and protecting them efficiently against DNase I degradation, by forming Lα lyotropic liquid crystal phases, with an average size of ~200 nm and low polydispersity that facilitate the cellular uptake process. The computational results confirmed that the LYCl/DOPE lipid bilayers are stable and also capable of stabilizing DNA fragments via lipoplex formation, with dimensions consistent with experimental values. The optimum formulations (found at 20% of LYCl content) were able to complete the transfection process efficiently and with high cell viabilities, even improving the outcomes of the positive control Lipo2000*

A gemini cationic lipid with histidine residues as a novel lipid-based gene nanocarrier: a biophysical and biochemical study

This work reports the synthesis of a novel gemini cationic lipid that incorporates two histidine-type head groups (C3(C16His)2). Mixed with a helper lipid 1,2-dioleoyl-sn-glycero3-phosphatidyl ethanol amine (DOPE), it was used to transfect three different types of plasmid DNA: one encoding the green fluorescence protein (pEGFP-C3), one encoding a luciferase (pCMV-Luc), and a therapeutic anti-tumoral agent encoding interleukin-12 (pCMV-IL12). Complementary biophysical experiments (zeta potential, gel electrophoresis, small-angle X-ray scattering (SAXS), and fluorescence anisotropy) and biological studies (FACS, luminometry, and cytotoxicity) of these C3(C16His)2/DOPE-pDNA lipoplexes provided vast insight into their outcomes as gene carriers. They were found to efficiently compact and protect pDNA against DNase I degradation by forming nanoaggregates of 120–290 nm in size, which were further characterized as very fluidic lamellar structures based in a sandwich-type phase, with alternating layers of mixed lipids and an aqueous monolayer where the pDNA and counterions are located. The optimum formulations of these nanoaggregates were able to transfect the pDNAs into COS-7 and HeLa cells with high cell viability, comparable or superior to that of the standard Lipo2000*. The vast amount of information collected from the in vitro studies points to this histidine-based lipid nanocarrier as a potentially interesting candidate for future in vivo studies investigating specific gene therapies

Carbohydrate-based PBT copolyesters from a cyclic diol derived from naturally occurring tartaric acid: a comparative study regarding melt polycondensation and solid-state modification

2,3-O-Methylene-L-threitol (Thx) is a cyclic carbohydrate-based diol prepared by acetalization and subsequent reduction of the naturally occurring tartaric acid. The structure of Thx consists of a 1,3-dioxolane ring with two attached primary hydroxyl groups. Two series of partially bio-based poly(butylene terephthalate) (PBT) copolyesters were prepared using Thx as a comonomer by melt polycondensation (MP) and solid-state modification (SSM). Fully random copolyesters were obtained after MP using mixtures of Thx and 1,4-butanediol in combination with dimethyl terephthalate. Copolyesters with a unique block-like chemical microstructure were prepared by the incorporation of Thx into the amorphous phase of PBT by SSM. The partial replacement of the 1,4-butanediol units by Thx resulted in satisfactory thermal stabilities and gave rise to an increase of the Tg values, this effect was comparable for copolyesters prepared by MP and SSM. The partially bio-based materials prepared by SSM displayed higher melting points and easier crystallization from the melt, due to the presence of long PBT sequences in the backbone of the copolyester. The incorporation of Thx in the copolyester backbone enhanced the hydrolytic degradation of the materials with respect to the degradation of pure PBT.Peer ReviewedPostprint (published version

Effectiveness of an mHealth intervention combining a smartphone app and smart band on body composition in an overweight and obese population: Randomized controlled trial (EVIDENT 3 study)

Background: Mobile health (mHealth) is currently among the supporting elements that may contribute to an improvement in health markers by helping people adopt healthier lifestyles. mHealth interventions have been widely reported to achieve greater weight loss than other approaches, but their effect on body composition remains unclear. Objective: This study aimed to assess the short-term (3 months) effectiveness of a mobile app and a smart band for losing weight and changing body composition in sedentary Spanish adults who are overweight or obese. Methods: A randomized controlled, multicenter clinical trial was conducted involving the participation of 440 subjects from primary care centers, with 231 subjects in the intervention group (IG; counselling with smartphone app and smart band) and 209 in the control group (CG; counselling only). Both groups were counselled about healthy diet and physical activity. For the 3-month intervention period, the IG was trained to use a smartphone app that involved self-monitoring and tailored feedback, as well as a smart band that recorded daily physical activity (Mi Band 2, Xiaomi). Body composition was measured using the InBody 230 bioimpedance device (InBody Co., Ltd), and physical activity was measured using the International Physical Activity Questionnaire. Results: The mHealth intervention produced a greater loss of body weight (–1.97 kg, 95% CI –2.39 to –1.54) relative to standard counselling at 3 months (–1.13 kg, 95% CI –1.56 to –0.69). Comparing groups, the IG achieved a weight loss of 0.84 kg more than the CG at 3 months. The IG showed a decrease in body fat mass (BFM; –1.84 kg, 95% CI –2.48 to –1.20), percentage of body fat (PBF; –1.22%, 95% CI –1.82% to 0.62%), and BMI (–0.77 kg/m2, 95% CI –0.96 to 0.57). No significant changes were observed in any of these parameters in men; among women, there was a significant decrease in BMI in the IG compared with the CG. When subjects were grouped according to baseline BMI, the overweight group experienced a change in BFM of –1.18 kg (95% CI –2.30 to –0.06) and BMI of –0.47 kg/m2 (95% CI –0.80 to –0.13), whereas the obese group only experienced a change in BMI of –0.53 kg/m2 (95% CI –0.86 to –0.19). When the data were analyzed according to physical activity, the moderate-vigorous physical activity group showed significant changes in BFM of –1.03 kg (95% CI –1.74 to –0.33), PBF of –0.76% (95% CI –1.32% to –0.20%), and BMI of –0.5 kg/m2 (95% CI –0.83 to –0.19). Conclusions: The results from this multicenter, randomized controlled clinical trial study show that compared with standard counselling alone, adding a self-reported app and a smart band obtained beneficial results in terms of weight loss and a reduction in BFM and PBF in female subjects with a BMI less than 30 kg/m2 and a moderate-vigorous physical activity level. Nevertheless, further studies are needed to ensure that this profile benefits more than others from this intervention and to investigate modifications of this intervention to achieve a global effect

Electrical losses in multi-MW wind energy conversion systems

Publisher Copyright: © 2012, European Association for the Development of Renewable Energy, Environment and Power Quality (EA4EPQ). All rights reserved.This paper proposes a procedure to assess the electrical losses in Wind Energy Conversion Systems (WECSs) with different electrical topologies. Those losses are evaluated in an annual basis considering the randomness of the wind with a Rayleigh probability distribution function. Due to the lack of specific standards, the analysis is based on standards applicable to low voltage (LV) and medium voltage (MV) installations. After reviewing the WECSs offered in main manufacturers’ portfolio, three electric topologies have been studied with the proposed calculation procedure. The main difference among alternatives is the position of the power transformer and, therefore, the characteristics of the voltage in the wiring going down the tower. Another two alternative topologies with direct current (DC) output have also been studied. The parameters of the base case study are commented in detailed and the results of several sensitivity analyses are also presented.The investigation has been accomplished in the GAMESA Classroom at the Engineering Faculty of Bilbao, University of the Basque Country, with the collaboration of Tecnalia Research & Innovation.Peer reviewe

Comblike Ionic Complexes of Poly(γ-glutamic acid) and Alkanoylcholines Derived from Fatty Acids

A series of ionic complexes with almost stoichiometric composition have been “synthesized” from bacterial poly(γ-glutamic acid) and alkanoylcholines derived from fatty acids with 12, 14, 16, and 18 carbon atoms. The complexes were stable up to temperatures close to 200 °C and were non-water-soluble but readily soluble in organic solvents. In the solid state they adopted the biphasic structure typical of comblike systems with the polypeptide chains arranged in sheets and periodically separated by a paraffinic phase which was partially crystallized for C14, C16, and C18. The window width of the layered structure was estimated by SAXS to be within the 3.6–4.5 nm range, and WAXS showed that the alkyl tails were crystallized in a hexagonally packed lattice with a d100 spacing of 0.41 nm. These complexes displayed reversible melting of the paraffinic phase in the 40–65 °C range at temperatures with values increasing with the length of the alkanoyl group. A slight expansion of the intersheet distance occurred at melting followed by contraction upon heating at higher temperatures but without significant alteration of the layered structure. The 13C CP-MAS NMR analysis revealed the underlying polymethylene anti-to-gauche conformational conversion that takes place at the thermal transition. An energy-based simulation study of the crystallization process afforded a molecular picture of the complex and evidenced the favoring effect of the choline structure on the packing of the alkyl side chains

Poly(gamma-Glutamic Acid) Esters with Reactive Functional Groups Suitable for Orthogonal Conjugation Strategies

We report on a series of novel poly(gamma-glutamic acid) (PGGA) esters, in which the chemical structure and composition, and the molecular weight are systematically changed. Modification of PGGA of microbial origin, used either as the sodium salt or in the free acid form, by means of alkylation with highly reactive bromides under SN2 conditions, affords copolymers with an essentially random microstructure. These reaction conditions are applied iteratively to achieve full esterification, obtaining allyl or propargyl ester functionalities within the polymer backbone, diluted with inert functional groups, such as benzyl, ethyl, or hexyl ester functionalities. The copolymers have been characterized regarding their chemical structure and thermal and bulk properties using nuclear magnetic resonance, thermogravimetry, differential scanning calorimetry, and X-ray diffraction techniques. We demonstrate that allyl and propargyl ester groups can be efficiently transformed using click chemistries, such as thiol-ene or copper(I)-catalyzed azide–alkyne cycloaddition reactions; such efficient conjugation strategies will be required to transformthe native bacterial biopolymer into a material with tailored properties for bulk scale or biomedical applications