Reusable Colorimetric Biosensors on Sustainable Silk-Based Platforms.

In biosensor development, silk fibroin is advantageous for providing transparent, flexible, chemically/mechanically stable, biocompatible, and sustainable substrates, where the biorecognition element remains functional for long time periods. These properties are employed here in the production of point-of-care biosensors for resource-limited regions, which are able to display glucose levels without the need for external instrumentation. These biosensors are produced by photopatterning silk films doped with the enzymes glucose oxidase and peroxidase and photoelectrochromic molecules from the dithienylethene family acting as colorimetric mediators of the enzymatic reaction. The photopatterning results from the photoisomerization of dithienylethene molecules in the silk film from its initial uncolored opened form to its pink closed one. The photoisomerization is dose-dependent, and colored patterns with increasing color intensities are obtained by increasing either the irradiation time or the light intensity. In the presence of glucose, the enzymatic cascade reaction is activated, and peroxidase selectively returns closed dithienylethene molecules to their initial uncolored state. Color disappearance in the silk film is proportional to glucose concentration and used to distinguish between hypoglycemic (below 4 mM), normoglycemic (4-6 mM), and hyperglycemic levels (above 6 mM) by visual inspection. After the measurement, the biosensor can be regenerated by irradiation with UV light, enabling up to five measurement cycles. The coupling of peroxidase activity to other oxidoreductases opens the possibility to produce long-life reusable smart biosensors for other analytes such as lactate, cholesterol, or ethanol.

3D Graphene/silk fibroin scaffolds enhance dental pulp stem cell osteo/odontogenic differentiation.

OBJECTIVES: The current in vitro study aims to evaluate silk fibroin with and without the addition of graphene as a potential scaffold material for regenerative endodontics. MATERIAL AND METHODS: Silk fibroin (SF), Silk fibroin/graphene oxide (SF/GO) and silk fibroin coated with reduced graphene oxide (SF/rGO) scaffolds were prepared (n = 30). The microarchitectures and mechanical properties of scaffolds were evaluated using field emission scanning electron microscopy (FESEM), pore size and water uptake, attenuated total reflectance fourier transformed infrared spectroscopy (ATR-FTIR), Raman spectroscopy and mechanical compression tests. Next, the study analyzed the influence of these scaffolds on human dental pulp stem cell (hDPSC) viability, apoptosis or necrosis, cell adhesion, odontogenic differentiation marker expression and mineralized matrix deposition. The data were analyzed with ANOVA complemented with the Tukey post-hoc test (p < 0.005). RESULTS: SEM analysis revealed abundant pores with a size greater than 50 nm on the surface of tested scaffolds, primarily between 50 nm and 600 µm. The average value of water uptake obtained in pure fibroin scaffolds was statistically higher than that of those containing GO or rGO (p < 0.05). ATR-FTIR evidenced that the secondary structures did not present differences between pure fibroin and fibroin coated with graphene oxide, with a similar infrared spectrum in all tested scaffolds. Raman spectroscopy showed a greater number of defects in the links in SF/rGO scaffolds due to the reduction of graphene. In addition, adequate mechanical properties were exhibited by the tested scaffolds. Regarding biological properties, hDPSCs attached to scaffolds were capable of proliferating at a rate similar to the control, without affecting their viability over time. A significant upregulation of ALP, ON and DSPP markers was observed with SF/rGO and SF/GO groups. Finally, SF/GO and SF/rGO promoted a significantly higher mineralization than the control at 21 days. SIGNIFICANCE: Data obtained suggested that SF/GO and SF/rGO scaffolds promote hDPSC differentiation at a genetic level, increasing the expression of key osteo/odontogenic markers, and supports the mineralization of the extracellular matrix. However, results from this study are to be interpreted with caution, requiring further in vivo studies to confirm the potential of these scaffolds.

Animal model assessment of a new design for a coated mitomycin-eluting biodegradable ureteral stent for intracavitary instillation as an adjuvant therapy in upper urothelial carcinoma.

BACKGROUND: A major limitation in the treatment of upper urinary tract urothelial carcinoma is the limited use of adjuvant therapy due to the drawbacks of current techniques for intracavitary instillation. The aim was to assess, in a large animal model, a biodegradable ureteral stent coated with silk fibroin for mitomycin release, i.e. BraidStent-SF-MMC. METHODS: A total of 14 female pigs with a solitary kidney underwent initial urinalysis, blood chemistry, nephrosonographic, and contrast fluoroscopy assessment of the urinary tract. Later, the BraidStent-SF-MMC was placed retrogradely to assess the mitomycin urine concentration from 0-48 hours. Follow-up was performed weekly until complete stent degradation to assess the macroscopic and microscopic changes in the urinary tract, stent complications. RESULTS: The drug eluting stent released mitomycin for the first 12 h. The main complication was the release of obstructive ureteral coating fragments during the first to third week in 28.5 and 7.1% of animals, respectively, related to urinary pH<7.0, which destabilized the stent coating. Another complication was ureteral strictures between the fourth and sixth week in 21%. The stents were completely degraded by 6-7 weeks. There were no stent-related systemic toxic effects. The success rate was 67.5% and the complication rate was 25.7%. CONCLUSIONS: For the first time, we have shown that a biodegradable anti-cancer drug eluting stent, BraidStent-SF-MMC, provides controlled and well-tolerated release of mitomycin into the upper urinary tract in an animal model. Mitomycin release from a silk fibroin coating could be a compelling approach for adjuvant chemotherapy instillation in upper tract urothelial carcinoma management.

Cytotoxicity Assessment of a New Design for a Biodegradable Ureteral Mitomycin Drug-Eluting Stent in Urothelial Carcinoma Cell Culture.

Urothelial tumour of the upper urinary tract is a rare neoplasm, but unfortunately, it has a high recurrence rate. The reduction of these tumour recurrences could be achieved by the intracavitary instillation of adjuvant chemotherapy after nephron-sparing treatment in selected patients, but current instillation methods are ineffective. Therefore, the aim of this in vitro study is to evaluate the cytotoxic capacity of a new instillation technology through a biodegradable ureteral stent/scaffold coated with a silk fibroin matrix for the controlled release of mitomycin C as an anti-cancer drug. Through a comparative study, we assessed, in urothelial carcinoma cells in a human cancer T24 cell culture for 3 and 6 h, the cytotoxic capacity of mitomycin C by viability assay using the CCK-8 test (Cell counting Kit-8). Cell viability studies in the urothelial carcinoma cell line confirm that mitomycin C embedded in the polymeric matrix does not alter its cytotoxic properties and causes a significant decrease in cell viability at 6 h versus in the control groups. These findings have a clear biomedical application and could be of great use to decrease the recurrence rate in patients with upper tract urothelial carcinomas by increasing the dwell time of anti-cancer drugs.

Unexpected high toughness of Samia cynthia ricini silk gut.

Silk gut fibers were produced from the silkworm Samia cynthia ricini silk glands by the usual procedure of immersion in a mildly acidic solution and subsequent stretching. The morphology of the silk guts was assessed by scanning electron microscopy, and their microstructure was assessed by infrared spectroscopy and X-ray diffraction. It was found that both naturally spun and Samia silk guts share a common semicrystalline microstructure. The mechanical characterization of the silk guts revealed that these fibers show an elastomeric behavior when tested in water, and exhibit a genuine ground state to which the fiber may revert independently of its previous loading history. In spite of its large cross-sectional area compared with naturally spun silk fibers, Samia silk guts show values of work to fracture up to 160 MJ m-3, much larger than those of most of their natural counterparts, and establish a new record value for this parameter in silk guts.

Silkworm Gut Fibres from Silk Glands of Samia cynthia ricini-Potential Use as a Scaffold in Tissue Engineering.

High-performance fibroin fibres are ideal candidates for the manufacture of scaffolds with applications in tissue engineering due to the excellent mechanical properties and optimal biocompatibility of this protein. In this work, the manufacture of high-strength fibres made from the silk glands of Samia cynthia ricini is explored. The glands were subjected to soaking in aqueous dissolutions of acetic acid and stretched to manufacture the fibres. The materials produced were widely characterized, in terms of morphology, mechanical properties, crystallinity and content of secondary structures, comparing them with those produced by the standard procedure published for Bombyx mori. In addition, mechanical properties and biocompatibility of a braided scaffold produced from these fibres was evaluated. The results obtained show that the fibres from B. mori present a higher degree of crystallinity than those from S. c. ricini, which is reflected in higher values of elastic modulus and lower values of strain at break. Moreover, a decrease in the elongation values of the fibres from S. c. ricini was observed as the concentration of acetic acid was increased during the manufacture. On the other hand, the study of the braided scaffolds showed higher values of tensile strength and strain at break in the case of S. c. ricini materials and similar values of elastic modulus, compared to those of B. mori, displaying both scaffolds optimal biocompatibility using a fibroblast cell line.

Products of Sericulture and Their Hypoglycemic Action Evaluated by Using the Silkworm, Bombyx mori (Lepidoptera: Bombycidae), as a Model.

Sericulture generates different natural products with potential medical applications. Silk peptides, worms, or even pupae are commonly employed in traditional Asian medicine with a wide variety of purposes, and some scientific work has been focused on their antidiabetic properties. This work evaluates the postprandial antihyperglycemic activity of fibroin, sericin, and powder made from either larvae or pupae of silkworms, and Bombyx mori L. (Lepidoptera: Bombycidae), employing the silkworm itself as an animal model. The results indicate a reduction in the glucose levels in hemolymph after sucrose or glucose-induced hyperglycemia when these products are included in the diet of the worms.

Nanoporous silk films with capillary action and size-exclusion capacity for sensitive glucose determination in whole blood.

In optical biosensing, silk fibroin (SF) appears as a promising alternative where other materials, such as paper, find limitations. Besides its excellent optical properties and unmet capacity to stabilize biomacromolecules, SF in test strips exhibits additional functions, i.e. capillary pumping activity of 1.5 mm s-1, capacity to filter blood cells thanks to its small, but tuneable, porosity and enhanced biosensing sensitivity. The bulk functionalization of SF with the enzymes glucose oxidase and peroxidase and the mediator ABTS produces colourless and transparent SF films that respond to blood glucose increasing 2.5 times the sensitivity of conventional ABTS-based assays. This enhanced sensitivity results from the formation of SF-ABTS complexes, where SF becomes part of the bioassay. Additionally, SF films triple the durability of most stable cellulose-based sensors. Although demonstrated for glucose, SF microfluidic test strips may incorporate other optical bioassays, e.g. immunoassays, with the aim of transferring them from central laboratories to the place of patient's care.

Prevalence and severity of early childhood caries in malnourished children in Mendoza, Argentina / Prevalencia y severidad de caries de la infancia temprana en niños con desnutrición infantil de Mendoza, Argentina

ABSTRACT The aim of this correlational, descriptive, cross-sectional study was to describe the pathological profile of Early Childhood Caries (ECC) in malnourished children who attended two centers for prevention and treatment of child malnutrition in Mendoza, Argentina. The study included 145 children aged 12 to 71 months, with prior parental consent, and recorded dmft and dmfs according to ICDASII2 to 6 and 4 to 6 active caries categories, age and severity of caries experience. Parametric and non-parametric statistics were applied with p=0.05. Caries prevalence for enamel and dentin lesions was 48.2%, declining to 35.2% when only dentin lesions were considered (dmft 4-6). The following means were found for dmft and dmfs: dmft 2-6 2.10 ± 3.31, with "d" 2.03 ± 3.24; dmfs 3.07 ± 6.1 with "d" 2.91 ± 6.1; dmft 4-6 1.21 ± 2.46 with "d" 1.14 ± 2.37; dmfs 4-6 1.98 ± 5.14 and "d" 1.86 ± 5.06. There were statistically significant differences between dmft 2-6 and dmft 4-6. Active enamel lesions (ICDAS II active categories 2 and 3) accounted for 37% of total lesions. Active lesions type 5 were the most frequent. The indicators for dental status and severity of caries experience increased with age, both with moderate positive correlations. Conclusions: Malnourished children under six years old studied in Mendoza presented comorbidity with ECC. Dental status worsened with age. The values for caries indicators demonstrated the weight of caries diagnoses in early stages and the importance of providing preventive measures and systematic monitoring during these children's early years of life.

RESUMEN El presente estudio descriptivo transversal correlacional tuvo como objetivo describir el perfil de patología de la Caries de Infancia Temprana (CIT) en niños con desnutrición infantil asistentes a dos centros de prevención y tratamiento de la desnutrición infantil, en Mendoza, Rep. Argentina. Sobre un total de 145 niños entre 12 y 71 meses de edad, previo consentimiento parental, se registraron dmft y dmfs según categorías de caries activas ICDAS II2 a 6y 4 a 6; edad, y severidad de experiencia de caries. Se aplicó estadística paramétrica y no paramétrica con nivel de p=0,05. La prevalencia de caries para lesiones de esmalte y dentina fue del 48,2% disminuyendo a un 35,2% cuando se consideraron solo lesiones en dentina (dmft 4-6). Se hallaron las siguientes medias para dmft y dmfs: dmft 2-6 2,10 ± 3,31, con "c" de de 2,03 ± 3,24; dmfs de 3,07 ± 6,1 con "c" de 2,91 ± 6,1; dmft 4-6 de 1.21 ± 2,46 con "c" de 1,14 ± 2,37; dmfs 4-6 de 1,98 ± 5,14y "c" de 1,86 ± 5,06. Las diferencias observadas entre dmft 2-6 y dmft 4-6 fueron estadísticamente significativas. Las lesiones activas de esmalte (categorías 2 y 3 activas de ICDAS II) constituyeron 37% del total de lesiones. Las lesiones activas tipo 5 fueron las más frecuentes. Los indicadores de estado dental y de severidad de experiencia de caries aumentaron con la edad, hallándose correlaciones positivas moderadas para ambas variables. Conclusiones: Los niños menores de seis años con desnutrición infantil estudiados en Mendoza, presentaron co- morbilidad con CIT. El estado dental empeoró con la edad. Los valores encontrados de los indicadores de caries demostraron el peso del diagnóstico de caries en sus estadíos iniciales y la importancia de arribar con medidas preventivas y seguimiento sistemático en los primeros años de vida de estos niños.

Gallstone ileus caused by a gallstone impacted at a cecum neoplasm - A case report.

BACKGROUND: Gallstone ileus is an infrequent complication of biliary disease that produces a mechanical intestinal obstruction. It is caused by a gallstone passing through a bilio-digestive communication, usually a cholecystoduodenal fistula. The presence of neoplasms can decrease the bowel lumen size and may cause the gallstone to impact at the narrowing site. CASE SUMMARY: In this report, we present a unique case of gallstone ileus due to a gallstone impacted in a cecum tumor, causing obstruction at the level of the ileocecal valve. The patient needed an urgent right hemicolectomy to solve both his problems. The gallbladder and the enterobiliary fistula remained in situ. DISCUSSION: The clinical presentation is not always straightforward and sometimes the diagnosis is only made by imaging, mostly resorting to an abdominal CT. The mainstay of management is surgical relief of the gastrointestinal obstruction, with the surgical method being based on what is found intra-operatively and according to the patient general condition. CONCLUSION: Although a rare disease, gallstone ileus should be suspected in elderly patients with intestinal obstruction and a previous history of biliary problems, keeping in mind that other conditions may be present and can alter the surgical treatment of choice.

First steps for the development of silk fibroin-based 3D biohybrid retina for age-related macular degeneration (AMD).

Age-related macular degeneration is an incurable chronic neurodegenerative disease, causing progressive loss of the central vision and even blindness. Up-to-date therapeutic approaches can only slow down he progression of the disease. OBJECTIVE: Feasibility study for a multilayered, silk fibroin-based, 3D biohybrid retina. APPROACH: Fabrication of silk fibroin-based biofilms; culture of different types of cells: retinal pigment epithelium, retinal neurons, Müller and mesenchymal stem cells ; creation of a layered structure glued with silk fibroin hydrogel. MAIN RESULTS: In vitro evidence for the feasibility of layered 3D biohybrid retinas; primary culture neurons grow and develop neurites on silk fibroin biofilms, either alone or in presence of other cells cultivated on the same biomaterial; cell organization and cellular phenotypes are maintained in vitro for the seven days of the experiment. SIGNIFICANCE: 3D biohybrid retina can be built using silk silkworm fibroin films and hydrogels to be used in cell replacement therapy for AMD and similar retinal neurodegenerative diseases.

Prevalência da obesidade e risco cardiovascular associado numa zona de saúde rural / Prevalence of obesity and associated cardiovascular risk in a rural health area

Existem dados sobre uma evolução crescente da prevalência da obesidade na população espanhola desde 1987. Este trabalho analisa a prevalência da obesidade numa população rural pertencente à Zona Básica de Saúde de Talavera la Real, na província de Badajoz tendo sido incluídos no estudo 132 dos 664 doentes pertencentes à população. Nos resultados obtidos, no estudo, quase 80% da população estudada tem problemas de excesso de peso e obesidade e foram encontradas diferenças significativas (P<0.001) em função da idade, do estado civil e do nível sociocultural da população. No decorrer do Mestrado de Enfermagem Comunitária, e em consonância com a Estratégia para a Abordagem da Cronicidade no Sistema Nacional de Saúde Español, foi decidido realizar um projeto de intervenção comunitária sobre esta comunidade utilizando a Metodologia do Planeamento em Saúde como ponto chave da sua estruturação, e através do qual, poderemos observar se as intervenções desenhadas foram eficazes. Este relatório pretende descrever todo o percurso desde o diagnóstico até à intervenção efetuada e respectiva avaliação.

There are data on an increasing evolution of the prevalence of obesity in the Spanish population since 1987. This work analyses the prevalence of obesity in a rural population belonging to the Basic Health Zone of Talavera la Real, in the province of Badajoz, included in the study,132 out of the 664 patients belonging to the population. As for the results obtained in the study, 80% of the population studied has problems of overweight and obesity, finding significant differences (P<0.001) depending on the age, marital status and sociocultural level of the population. In the Master's course in Community Nursing, and in accordance with the Strategy for the approach of the Chronoty of the National System of Spanish Sude, it was decided to carry out a community intervention project on this community using the Health Planning Methodology as a key point of its structuring, and through which, we will be able to observe if the interventions designed were effective. This document aims to describe all the work carried out, from the diagnosis to the intervention carried out and its respective evaluation.

Chemoprevention of Experimental Periodontitis in Diabetic Rats with Silk Fibroin Nanoparticles Loaded with Resveratrol.

OBJECTIVE: the objective of the present work is to study the effectiveness of treatment with silk fibroin nanoparticles loaded with resveratrol in experimental periodontitis in a diabetic rat model. INTRODUCTION: Periodontitis is an inflammatory pathology highly related to other diseases, such as type II diabetes. Both diseases have a specific inflammatory condition, with Interleukin (IL)-6, IL-1ß and Transforming Grow Factor (TGF)-1ß being the most relevant proinflammatory factors. Silk fibroin (SF) nanoparticles loaded with resveratrol (Res-SFN) are a new alternative as a treatment. METHODS: 40 diabetic Sprague Dawley male rats were used and periodontitis was induced by ligation. The animals were divided into 5 treatment groups, and 1 mL of treatment was administered once a day for 4 weeks. The groups were: I: Carboxymethyl cellulose (CMC) 0.8%, II: CMC 0.8% + SF 1%, III: CMC 0.8% + RES-SFN 3 mg/mL, IV: CMC 0.8% + SF 1% + RES-SFN 3 mg/mL, V: Water. A peripheral blood sample was taken every week to quantify the inflammatory profile by ELISA (IL-6, IL-1ß and TGF-1ß). After 4 weeks the sacrifice was carried out and biopsies of the gum were taken. RESULTS: Treatment with SF and RES-SFN reduced the amount of chemical inflammation mediators (with the exception of IL-1ß in comparisons I-IV and II-IV (p > 0.05)), as well as the anatomopathological variables linked to it, in a significant way (p < 0.05). CONCLUSION: treatment with RES-SFN has reduced local inflammation in this experimental periodontitis model.

Prevalence and severity of early childhood caries in malnourished children in Mendoza, Argentina.

The aim of this correlational, descriptive, cross-sectional study was to describe the pathological profile of Early Childhood Caries (ECC) in malnourished children who attended two centers for prevention and treatment of child malnutrition in Mendoza, Argentina. The study included 145 children aged 12 to 71 months, with prior parental consent, and recorded dmft and dmfs according to ICDAS II 2 to 6 and 4 to 6 active caries categories, age and severity of caries experience. Parametric and non-parametric statistics were applied with p=0.05. Caries prevalence for enamel and dentin lesions was 48.2%, declining to 35.2% when only dentin lesions were considered (dmft 4-6). The following means were found for dmft and dmfs: dmft 2-6 2.10 ± 3.31, with "d" 2.03 ± 3.24; dmfs 3.07 ± 6.1 with "d" 2.91 ± 6.1; dmft 4-6 1.21 ± 2.46 with "d" 1.14 ± 2.37; dmfs 4-6 1.98 ± 5.14 and "d" 1.86 ± 5.06. There were statistically significant differences between dmft 2-6 and dmft 4-6. Active enamel lesions (ICDAS II active categories 2 and 3) accounted for 37% of total lesions. Active lesions type 5 were the most frequent. The indicators for dental status and severity of caries experience increased with age, both with moderate positive correlations. Conclusions: Malnourished children under six years old studied in Mendoza presented comorbidity with ECC. Dental status worsened with age. The values for caries indicators demonstrated the weight of caries diagnoses in early stages and the importance of providing preventive measures and systematic monitoring during these children's early years of life.

El presente estudio descriptivo transversal correlacional tuvo como objetivo describir el perfil de patología de la Caries de Infancia Temprana (CIT) en niños con desnutrición infantil asistentes a dos centros de prevención y tratamiento de la desnutrición infantil, en Mendoza, Rep. Argentina. Sobre un total de 145 niños entre 12 y 71 meses de edad, previo consentimiento parental, se registraron dmft y dmfs según categorías de caries activas ICDAS II 2 a 6 y 4 a 6; edad, y severidad de experiencia de caries. Se aplicó estadística paramétrica y no paramétrica con nivel de p=0,05. La prevalencia de caries para lesiones de esmalte y dentina fue del 48,2% disminuyendo a un 35,2% cuando se consideraron solo lesiones en dentina (dmft 4-6). Se hallaron las siguientes medias para dmft y dmfs: dmft 2-6 2,10 ± 3,31, con "c" de de 2,03 ± 3,24; dmfs de 3,07 ± 6,1 con "c" de 2,91 ± 6,1; dmft 4-6 de 1.21 ± 2,46 con "c" de 1,14 ± 2,37; dmfs 4-6 de 1,98 ± 5,14 y "c" de 1,86 ± 5,06. Las diferencias observadas entre dmft 2-6 y dmft 4-6 fueron estadísticamente significativas. Las lesiones activas de esmalte (categorías 2 y 3 activas de ICDAS II) constituyeron 37% del total de lesiones. Las lesiones activas tipo 5 fueron las más frecuentes. Los indicadores de estado dental y de severidad de experiencia de caries aumentaron con la edad, hallándose correlaciones positivas moderadas para ambas variables. Conclusiones: Los niños menores de seis años con desnutrición infantil estudiados en Mendoza, presentaron co- morbilidad con CIT. El estado dental empeoró con la edad. Los valores encontrados de los indicadores de caries demostraron el peso del diagnóstico de caries en sus estadíos iniciales y la importancia de arribar con medidas preventivas y seguimiento sistemático en los primeros años de vida de estos niños.

Revealing the Influence of the Degumming Process in the Properties of Silk Fibroin Nanoparticles.

Several studies have stated that the process used for sericin removal, or degumming, from silk cocoons has a strong impact in the silk fibroin integrity and consequently in their mechanical or biochemical properties after processing it into several biomaterials (e.g. fibers, films or scaffolds) but still, there is a lack of information of the impact on the features of silk nanoparticles. In this work, silk cocoons were degummed following four standard methods: autoclaving, short alkaline (Na2CO3) boiling, long alkaline (Na2CO3) boiling and ultrasounds. The resultant silk fibroin fibers were dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate and used for nanoparticle synthesis by rapid desolvation in polar organic solvents. The relative efficiencies of the degumming processes and the integrity of the resulting fibroin fibers obtained were analyzed by mass loss, optical microscopy, thermogravimetric analysis, infrared spectroscopy and SDS-PAGE. Particle sizes and morphology were analyzed by Dynamic Light Scattering and Field Emission Scanning Electronic Microscopy. The results showed that the different treatments had a remarkable impact on the integrity of the silk fibroin chains, as confirmed by gel electrophoresis, which can be correlated with particle mean size and size distribution changes. The smallest nanoparticles (156 ± 3 nm) and the most negative Z potential (-30.2 ± 1.8 mV) were obtained with the combination of long treatment (2 h) of boiling in alkaline solution (Na2CO3 0.02 eq/L). The study confirms that parameters of the process, such as composition of the solution and time of the degumming step, must be controlled in order to reach an optimum reproducibility of the nanoparticle production.

Enhancement of the Inelastic Nuclear Interaction Rate in Crystals via Antichanneling.

The interaction rate of a charged particle beam with the atomic nuclei of a target varies significantly if the target has a crystalline structure. In particular, under specific orientations of the target with respect to the incident beam, the probability of inelastic interaction with nuclei can be enhanced with respect to the unaligned case. This effect, which can be named antichanneling, can be advantageously used in the cases where the interaction between beam and target has to be maximized. Here we propose to use antichanneling to increase the radioisotope production yield via cyclotron. A dedicated set of experimental measurements was carried out at the INFN Legnaro Laboratories with the AN2000 and CN accelerators to prove the existence of the antichanneling effect. The variation of the interaction yield at hundreds of keV to MeV energies was observed by means of sapphire and indium phosphide crystals, achieving an enhancement of the interaction rate up to 73% and 25%, respectively. Such a result may pave the way to the development of a novel type of nozzle for the existing cyclotrons, which can exploit crystalline materials as targets for radioisotope production, especially to enhance the production rate for expensive prime materials with minor upgrades of the current instrumentation.

Effect of different cocoon stifling methods on the properties of silk fibroin biomaterials.

Stifling treatments are applied to silk cocoons in order to kill the pupae, preventing the emergence of moths and allowing to preserve the silk during long periods of time. All of them involve the application of aggressive steps, such as sun exposure, hot steam from boiling water or hot air, during hours or even days. None of the scientific articles related to silk fibroin biomaterials has previously taken into account this fact in its section of materials and methods. In this work, the consequences of the stifling treatments most commonly used by the silk producing countries and companies are explored in depth, using fibroin films as biomaterial model. The protein degradation (visualised by SDS-PAGE) was dramatically increased in all the fibroin dissolutions produced from stifled cocoons; heavy and light chains of fibroin were specially degraded, reducing their presence along the lanes of the gel compared to the negative control (untreated fresh cocoons). Structural changes are also described for annealed silk fibroin films. The ß-sheet content, analysed by means of infrared spectroscopy, was significantly higher when stifling was performed at higher temperature (70 °C and 85 °C). It is also exposed the impact of the stifling on the mechanical properties of the materials. Tensile strength and strain at break values were detected as significantly lower when this procedure was carried out by means of dry heat (85 °C) and sun exposure. On the other hand, and contrary to expectations, the proliferation of fibroblasts growing on the materials was improved by all the different stifling methods, compared to negative control, being this improvement, especially accentuated, on the films produced with fibroin purified from cocoons treated with dry heat.

Silk fibroin scaffolds seeded with Wharton's jelly mesenchymal stem cells enhance re-epithelialization and reduce formation of scar tissue after cutaneous wound healing.

BACKGROUND: The treatment of extensive and/or chronic skin wounds is a widespread and costly public health problem. Mesenchymal stem cells (MSCs) have been proposed as a potential cell therapy for inducing wound healing in different clinical settings, alone or in combination with biosynthetic scaffolds. Among them, silk fibroin (SF) seeded with MSCs has been shown to have increased efficacy in skin wound healing experimental models. METHODS: In this report, we investigated the wound healing effects of electrospun SF scaffolds cellularized with human Wharton's jelly MSCs (Wj-MSCs-SF) using a murine excisional wound splinting model. RESULTS: Immunohistopathological examination after transplant confirmed the presence of infiltrated human fibroblast-like CD90-positive cells in the dermis of the Wj-MSCs-SF-treated group, yielding neoangiogenesis, decreased inflammatory infiltrate and myofibroblast proliferation, less collagen matrix production, and complete epidermal regeneration. CONCLUSIONS: These findings indicate that Wj-MSCs transplanted in the wound bed on a silk fibroin scaffold contribute to the generation of a well-organized and vascularized granulation tissue, enhance reepithelization of the wound, and reduce the formation of fibrotic scar tissue, highlighting the potential therapeutic effects of Wj-MSC-based tissue engineering approaches to non-healing wound treatment.

Preparation and characterization of Nephila clavipes tubuliform silk gut.

Tubuliform silk glands were dissected from Nephila clavipes spiders, and silk gut fibers were produced by immersing the glands in a mild acid solution and subsequent stretching. The tensile properties of the as produced fibers were obtained through tensile tests, and the stress-strain curves were compared with those of naturally spun tubuliform silk fibers. The influence on the mechanical properties of the fibers after immersion in water and drying was also discerned. The microstructure of the silk guts was obtained by X-ray diffraction (XRD) and infrared spectroscopy (FTIR). It was found that the stress-strain curves of the stretched tubuliform silk guts concur with those of their natural counterparts (tubuliform silk fibers).

Potential use of silkworm gut fiber braids as scaffolds for tendon and ligament tissue engineering.

Tendon and ligament tissue engineering require scaffolds for the treatment of various conditions in the medical field. These must meet requirements such as high tensile strength, biocompatibility, fast and stable repair and a rate of degradation that allows the repair of the damaged tissue. In this work, we propose the use of silkworm gut fiber braids as materials to temporarily replace and repair this type of tissues. The mechanical characterization of the braids made with different number of silk gut fibers is provided, as well as a descriptive analysis of the proliferation and adhesion of cultures of adult human mesenchymal stem cells from bone marrow and fibroblasts (L929) on the braids. As expected, the breaking force increases linearly in the scaffold with the number of fibers, thus being a parameter adaptable to the specific requirements of the tissue to repair and the animal model of study. On the other hand, in all of the cases studied, the values obtained for the elastic modulus of the hydrated fibers were in the range of the ones reported for various human tendons and ligaments. Moreover, the scaffold demonstrated excellent biocompatibility in vitro, allowing the adhesion and proliferation, in the same culture conditions, of the two cell types studied, therefore posing as an ideal candidate to be employed in future in vivo studies that allow elucidating its behavior in the articular environment or extra-articular tendinous areas. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res B Part B: 2019. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2209-2215, 2019.