Developing scaffolds for tissue engineering using the Ca2+-induced cold gelation by an experimental design approach

The Ca2+-induced cold gelation technique was found suitable to prepare highly porous biodegradable scaffolds based on bovine serum albumin (BSA) and alpha-casein from bovine milk for tissue engineering. A 23 full factorial design was used to study the influence and impact of each factor on the several responses of the scaffolds. In vitro degradation (ID), swelling ratio (SR), porosity (PO), and pore size (PS) as well cytotoxicity (CT) were evaluated and shown to be dependent on the pH of sample preparation and on the amount of BSA and casein present, making these scaffolds tunable structures. Under optimized working conditions (4.19% of BSA, 0.69% of Casein, pH 7.07), the ID attained was 37.97%, the SR observed was 11.87, the PO was 82.11%, the PS measured was 180.63 μm at surface, and 175.91 μm at fracture, whereas maximum cell viability was 84% in comparison to controls. Moreover, the scaffold supported cell adhesion and proliferation. These results, consistent with the prediction by the experimental design approach, support the use of this methodology to develop tunable scaffolds for tissue engineering using the Ca2+-induced cold gelation.Contract grant sponsor: FEDER through POFC-COMPETE and by national funds from FCT; contract grant number: PEst-C/BIA/UI4050/201

Tuning iris recognition for noisy images

The use of iris recognition for human authentication has been spreading in the past years. Daugman has proposed a method for iris recognition, composed by four stages: segmentation, normalization, feature extraction, and matching. In this paper we propose some modifications and extensions to Daugman's method to cope with noisy images. These modifications are proposed after a study of images of CASIA and UBIRIS databases. The major modification is on the computationally demanding segmentation stage, for which we propose a faster and equally accurate template matching approach. The extensions on the algorithm address the important issue of pre-processing that depends on the image database, being mandatory when we have a non infra-red camera, like a typical WebCam. For this scenario, we propose methods for reflection removal and pupil enhancement and isolation. The tests, carried out by our C# application on grayscale CASIA and UBIRIS images show that the template matching segmentation method is more accurate and faster than the previous one, for noisy images. The proposed algorithms are found to be efficient and necessary when we deal with non infra-red images and non uniform illumination

Improved Poly (D,L-lactide) nanoparticles-based formulation for hair follicle targeting

Objective Hair follicles are widely recognized as the preferential target and site of accumulation for nanoparticles after topical application. This feature is of particular importance for hair cosmetics, having the potential to refine the treatment of several hair follicle-related disorders. The aim of this work was to improve the preparation of Poly (D,L-lactide) (PLA) nanoparticles for in vivo follicular target and drug delivery. Methods Envisaging a future industrial scale-up of the process, nanoprecipitation method was used to prepare PLA nanoparticles: the effect of several processing parameters on their properties was examined and the yield of nanoparticles formation determined. Encapsulation efficiencies and in vitro release profiles of lipophilic and hydrophilic model compounds were also assessed. In vitro cytotoxicity and ex vivo penetration studies were performed on a reference skin cell line (NCTC2455, human skin keratinocytes) and porcine skin, respectively. Results Using acetone : ethanol (50 : 50, v/v) as the solvent phase, 0.6% (w/w) of Pluronic® F68 as a surfactant agent and agitation to mix the solvent and non-solvent phases, a monodispersed population of non-cytotoxic spherical nanoparticles of approximately 150 nm was obtained. The yield of nanoparticles for this formulation was roughly 90%. After encapsulation of model compounds, no significant changes were found in the properties of particles and the entrapment efficiencies were above 80%. The release kinetics of dyes from PLA nanoparticles indicate an anomalous transport mechanism (diffusion and polymer degradation) for Nile Red (lipophilic) and a Fickian diffusion of first order for fluorescein 5(6)-isothiocyanate (hydrophilic). Ex vivo skin penetration studies confirmed the presence of nanoparticles along the entire follicular ducts. Conclusions The optimized method allows the preparation of ideal PLA nanoparticles-based formulations for hair follicle targeting. PLA nanoparticles can effectively transport and release lipophilic and hydrophilic compounds into the hair follicles, and the yields obtained are acceptable for industrial purposes.Objectif Les follicules pileux sont largement reconnus comme la cible préférentielle et le site de l'accumulation des nanoparticules après application topique. Cette caractéristique est particulièrement importante pour les produits cosmétiques pour les cheveux, ayant la possibilité d'affiner le traitement de plusieurs troubles des follicules de cheveux. Le but de ce travail était d'améliorer la préparation de nanoparticules poly (D,L-lactide) (PLA) pour une administration folliculaire in vivo ciblée de drogues. Méthodes En envisageant un avenir à l’échelle industrielle du procédé, une méthode de nanoprécipitation a été utilisé pour préparer des nanoparticules de PLA: l'effet de plusieurs paramètres de traitement sur leurs propriétés a été examiné et le rendement de la formation des nanoparticules a été déterminé. Les efficacités d'encapsulation et de profils de libération in vitro de composés modèles lipophiles et hydrophiles ont également été évaluées. La cytotoxicité in vitro et ex vivo des études de pénétration a été effectuée sur une lignée de cellules de peau de référence (NCTC2455, des kératinocytes de peau humaine) et la peau de porc, respectivement. Resultats En utilisant l'acétone : éthanol (50 : 50, v/v) comme phase solvant, 0,6% (p/p) de Pluronic® F68 à titre d'agent tensioactif et l'agitation pour mélanger les phases de solvant et de non-solvant, une population monodispersée des nanoparticules sphériques non cytotoxiques d'environ 150 nm a été obtenue. Le rendement de nanoparticules pour cette formulation était d'environ 90%. Après encapsulation de composés modèles, aucune modification significative n'a été observée dans les propriétés des particules et les efficacités de piégeage ont été supérieures à 80%. La cinétique de libération de colorants de nanoparticules de PLA indique un mécanisme de transport anormal (diffusion et dégradation de polymère) pour le rouge Nil (lipophile) et une diffusion selon Fick de premier ordre pour FITC (hydrophile). Les études de pénétration ex vivo de la peau ont confirmé la présence de nanoparticules sur tous les conduits folliculaires. Conclusions La méthode optimisée permet la préparation de formulations à base de nanoparticules de PLA, idéales pour ciblage du follicule pileux. Les nanoparticules de PLA peuvent effectivement transporter et libérer des composés lipophiles et hydrophiles dans les follicules pileux; les rendements obtenus sont acceptables à des fins industrielles.The authors thank to the FCT Strategic Project PEst-OE/EQB/LA0023/2013 and to the Project “BioHealth – Biotechnology and Bioengineering approaches to improve health quality”, Ref. NORTE- 07-0124-FEDER-000027, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER. This work was partly supported by FEDER through POFC–582 COMPETE and by Portuguese funds from FCT– Fundacão Para a Ciência e a Tecnologia through the project PEst-OE/BIA/UI4050/2014. The authors thank C. Botelho for technical assistance

Cutinase promotes dry esterification of cotton cellulose

Cutinase from Thermobifida fusca was used to esterify the hydroxyl groups of cellulose with the fatty acids from triolein. Cutinase and triolein were pre-adsorbed on cotton and the reaction proceeded in a dry state during 48 hours at 35ºC. The cutinase-catalyzed esterification of the surface of cotton fabric resulted in the linkage of the oleate groups to the glycoside units of cotton cellulose. The superficial modification was confirmed by performing ATR-FTIR on treated cotton samples and by MALDI-TOF analysis of the liquors from the treatment of the esterified cotton with a crude cellulase mixture. Modified cotton fabric also showed a significant increase of hydrophobicity. This work proposes a novel bio-based approach to obtain hydrophobic cotton. This article is protected by copyright. All rights reserved.This work is supported by Opening Project of National Engineering Laboratory for Modern Silk (Grant No. KJS1312); the National Natural Science Foundation of China (Grant No. 31201134 and No. 31470509); the Jiangsu Provincial Natural Science Foundation of China (Grant No.BK2012112), the Industry-academic Joint Technological Prospective Fund Project of Jiangsu Province (Grant No.BY2013015-24) and the Graduate Funding Program of Jiangnan University for Overseas Study

Nanostructured thin coatings from chitosan and an elastin-like recombinamer with acute stimuli-responsive behavior

Publicado em: Materials Science Forum, vols. 730-732; Online available since 2012/Nov/12In the present work, chitosan (CHI) and elastin-like recombinamers (ELRs) were used to conceive nanostructured thin films driven by sequential electrostatic layer-by-layer (LbL), a simple and versatile technique that discards the use of harmful reagents. Two similar ELRs were engineered to contain negatively charged aminoacids and organized and a single monoblock or a triblock. The buildup of the films was monitored in real time using a quartz-crystal microbalance with dissipation monitoring (QCM-D). Wettability transitions were observed from a moderate hydrophobic surface to an extremely wettable upon increasing the temperature to 50 ºC, accompanied by topography changes at the nanoscale as assessed by atomic force microscopy (AFM). Furthermore, the dependence on time for the surface molecular rearrangement was studied for the films with each ELR. The potential of this technology may stimulate the development of devices and biomaterials for biomedical applications in the near future, such as surfaces with tunable and patterned cell adhesion, while the use of ELRs will allow developing polypeptides with biological significance.The authors acknowledge the financial support through Fundação para a Ciência e Tecnologia (FCT, PhD grant SFRH/BD/61126/2009, ‘‘Junta de Castilla y Leon’’ (VA034A09), the MICINN (MAT 2009-14195-C03-03, ACI2009-0890, IT2009-0089, MAT2010-15310, and MAT2010- 15982), the CIBER-BBN and the ‘‘Network Center of Regenerative Medicine and Cellular Therapy of Castilla y León’’.MICINNFundação para a Ciência e a Tecnologia (FCT)Junta de Castilla y LeónCIBER-BBNNetwork Center of Regenerative Medicine and Cellular Therapy of Castilla y Leó

Characterization of edible beeswax-based oleogels aiming at food incorporation

São Paulo School of Advanced Sciences on Reverse Engineering of Processed Foods[Excerpt] Uprising concern and consciousness of consumers, regarding saturated fat consumption, and the consequent demand for healthier food products are well visible in today’s society. Such continuous challenges question the food industry to quickly present solutions. Replace saturated fats in the food processing chain can be accomplished with the incorporation of edible oilbased gels or oleogels, which try to reproduce common fat structural and sensorial characteristics. Oil gelation effectiveness is managed by the gelators’ crystallization behaviour, where beeswax rises as a good candidate. [...]info:eu-repo/semantics/publishedVersio

Study of sardine oil antioxidant properties for the development of topical therapeutic formulations

Sardine is one of the most common fish of the Portuguese coast with important nutritional features. Sardine oil is also a natural source of nutrients with proven benefits for human health, being rich in omega-3 fatty acids, particularly EPA and DHA (polyunsaturated fatty acids-PUFAs) [1]. Several studies show that there is a direct link between a diet enriched in omega-3 and the prevention of diseases such as cardiovascular disease, inflammatory conditions, mental disorders and prevention of various types of cancer [2]. The aim of this work was to characterize the antioxidant role of sardine oil for the development of topical applications. To evaluate the antioxidant effect of sardine oil on skin, human fibroblasts (BJ-5ta), human melanocytes (A375) and human keratinocytes (NCTC2544) were used. Concentrations of oil higher than 8 mg/ml affected significantly the cell viability while for lower concentrations the effect was reduced. The lowest concentrations, 0.5 and 4 mg/ml, were tested to evaluate the protective role of sardine oil in situation of induced oxidative stress. These two concentrations were able to protect cells from damage with a higher effect measured for the fibroblasts. Moreover the incubation of cells with the sardine oil was able to activate a transcription factor Nuclear factor-erythroid-2-related factor 2 (Nrf2) which plays a crucial role in the coordinated induction of genes encoding many stress-responsive and cytoprotective enzymes and related proteins [3]. These results open the opportunity to develop new therapeutic and cosmetic applications based on sardine-derived compounds. Their incorporation in topical creams may contribute to a better treatment of inflammation and in the prevention of skin aging

Photodynamic therapy review: principles, photosensitizers, applications, and future directions

Photodynamic therapy (PDT) is a minimally invasive therapeutic modality that has gained great attention in the past years as a new therapy for cancer treatment. PDT uses photosensitizers that, after being excited by light at a specific wavelength, react with the molecular oxygen to create reactive oxygen species in the target tissue, resulting in cell death. Compared to conventional therapeutic modalities, PDT presents greater selectivity against tumor cells, due to the use of photosensitizers that are preferably localized in tumor lesions, and the precise light irradiation of these lesions. This paper presents a review of the principles, mechanisms, photosensitizers, and current applications of PDT. Moreover, the future path on the research of new photosensitizers with enhanced tumor selectivity, featuring the improvement of PDT effectiveness, has also been addressed. Finally, new applications of PDT have been covered.This work was supported by FCT with project OpticalBrain reference PTDC/CTMREF/28406/2017, operation code POCI-01-0145-FEDER-028406, through the COMPETE 2020; CMEMSUMinho Strategic Project UIDB/04436/2020; Infrastructures Micro&NanoFabs@PT, operation code NORTE 01-0145-FEDER-022090, POR Norte, Portugal 2020; and MPhotonBiopsy, PTDC/FIS-OTI/1259/2020. The authors thank Biolitec research GmbH (Jena, Germany) for providing the photosensitizer Foscan®.The APC was funded by Chongqing Technology and Business University (CTBU)

Enzymatic synthesis of poly(catechin)-antibiotic conjugates : an antimicrobial approach for indwelling catheters

Biofilm formation in urinary indwelling catheters is one of the most critical issues that patients face. Catheters were coated with poly(catechin)-antibiotic conjugates with enhanced antimicrobial properties. Catechin was conjugated with two antibiotics, namely trimethoprim (TMP) and sulfamethoxazole (SMZ) via activation with N,N′-disuccinimidyl carbonate (DSC) and subsequent coupling to molecules containing α-amine moieties. Silicone and polyurethane catheters were functionalized in situ through laccase oxidation of catechin-antibiotic conjugates. Four antimicrobial coatings were produced, namely with poly(catechin), poly(catechin)- TMP, poly(catechin)-SMZ and poly(catechin)-TMP-SMZ. The bacterial adhesion reduction was tested on the functionalized devices using gram-negative and gram-positive strains. The most significant reduction in adhesion was observed with poly(catechin)-TMP (gram-negative −85 % and grampositive −87 %) and with poly(catechin)-TMP-SMZ (gramnegative −85 % and gram-positive −91 %). The cytotoxicity to mammalian cells was tested by indirect contact for 5 days and revealed that all the tested coatings supported more than 90 % of viable cells. A promising approach for the increase of the indwelling catheter lifespan was developed aiming to reduce catheter-associated chronic infections.The authors would like to acknowledge Pronefro (Portugal) and Degania (Israel) for supplying polyurethane and silicone catheters, respectively. The author Idalina Goncalves would like to acknowledge the NOVO project (FP7-HEALTH-2011.2.3.1-5) for funding. This work was partly supported by FEDER through POFC-COMPETE and by Portuguese funds from Fundacao para a Ciencia e a Tecnologia (FCT) through the project PEst-OE/BIA/UI4050/2014. The authors Carla Silva and Teresa Matama would like to acknowledge FCT for their scholarships SFRH/BPD/46515/2008 and SFRH/BPD/47555/2008

Ultrasound enhances lipase-catalyzed synthesis of poly (ethylene glutarate)

The present work explores the best conditions for the enzymatic synthesis of poly (ethylene glutarate) for the first time. The start-up materials are the liquids; diethyl glutarate and ethylene glycol diacetate, without the need of addition of extra solvent. The reactions are catalyzed by lipase B from Candida antarctica immobilized on glycidyl methacrylate-ter-divinylbenzene-ter-ethylene glycol dimethacrylate at 40 °C during 18 h in water bath with mechanical stirring or 1 h in ultrasonic bath followed by 6 h in vacuum in both the cases for evaporation of ethyl acetate. The application of ultrasound significantly intensified the polyesterification reaction with reduction of the processing time from 24 to 7 h. The same degree of polymerization was obtained for the same enzyme loading in less time of reaction when using the ultrasound treatment. The degree of polymerization for long-term polyesterification was improved approximately 8-fold due to the presence of sonication during the reaction. The highest degree of polymerization achieved was 31, with a monomer conversion of 96.77%. The ultrasound treatment demonstrated to be an effective green approach to intensify the polyesterification reaction with enhanced initial kinetics and high degree of polymerization.This study was supported by Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684). The work was also supported by Bioprocess and Bionanotechnology Research Group (BBRG) of Minho University and the Post Graduate Funding Program of Jiangnan University for Overseas Study. All authors also acknowledge the funding of Department of Science and Technology and Portuguese Science Foundation under the Indo-Portuguese collaborative program