102,620 research outputs found
Silk fibroin/gelatin blend films crosslinked with enzymes for biomedical applications
No full textMicrobial transglutaminase (mTG) and mushroom tyrosinase (MT) are used to crosslink B. mori silk fibroin/gelatin (SF/G) films. Crosslinked and uncrosslinked SF/G films show no phase separation. The thermal behavior and the conformational structure of SF/G films are strongly affected by blending and enzymatic treatment. Formation of high thermally stable crosslinked macromolecular species is observed, suggesting the occurrence of strong intermolecular interactions between the two polymers as confirmed by FT-Raman spectroscopy. Preliminary in vitro tests show that MT-crosslinked blends with G amounts ≥40% and mTG-crosslinked SF/G 60/40 films support C2C12 cardiomyocyte adhesion and proliferation. In this study, microbial transglutaminase (mTG) and mushroom tyrosinase (MT) are used as crosslinking agents for pure and blend B. mori silk fibroin (SF)/gelatin (G) films. In the light of their morphological, mechanical, physical, structural, and biological properties, SF/G blends appear promising candidate substrates in the field of soft tissue engineering
Preparation and biodegradation of clay composites of PLA
No full text[EN] Purpose: Perspective applications of nanocomposites in biomedical applications are investigated in this work by producing intercalated dispersions of clays into a biodegradable polymer matrix. Poly(lactic acid) (PLA) was selected being produced from renewable resources and approved by the Food and Drug Administration for medical use.
In order to improve PLA mechanical properties and to accelerate its degradation, different layered silicate nanoclays are added: montmorillonites and fluorohectorites, without or with organic modifiers. Preparation, characterization, mechanical properties and biodegradation in blood plasma are evaluated. Results: New biodegradable materials were obtained, with improved mechanical properties (Young modulus, Peak stress and Strain at break) and with increased degradation rate (weight loss and lactic acid release).Nieddu, E.; Mazzucco, L.; Gentile, P.; Benko, T.; Balbo, V.; Mandrile, R.; Ciardelli, G. (2009). Preparation and biodegradation of clay composites of PLA. Reactive and Functional Polymers. 69(6):371-379. https://doi.org/10.1016/j.reactfunctpolym.2009.03.002S37137969
Coherence in inquisitive first-order logic
No full textInquisitive first-order logic, InqBQ, is a conservative extension of classical first-order logic with questions. Formulas of InqBQ are interpreted with respect to information states---essentially, sets of relational structures over a common domain. It is unknown whether entailment in InqBQ is compact, and whether validities are recursively enumerable. In this paper, we study the semantic property of finite coherence: a formula of InqBQ is finitely coherent if in order to determine whether it is satisfied by a state, it suffices to check substates of a fixed finite size. We show that finite coherence has interesting implications. Most strikingly, entailment towards finitely coherent conclusions is compact. We identify a broad syntactic fragment of the language, the rex fragment, where all formulas are finitely coherent. We give a natural deduction system which is complete for InqBQ- entailments with rex conclusions, showing in particular that rex validities are recursively enumerable. On the way to this result, we study approximations of InqBQ obtained by restricting to information states of a fixed cardinality. We axiomatize the finite approximations and show that, in contrast to the situation in the propositional setting, InqBQ does not coincide with the limit of its finite approximations, settling a question posed by Sano
Games and cardinalities in inquisitive first-order logic
No full textInquisitive first-order logic, InqBQ, is a system which extends classical first-order logic with formulas expressing questions. From a mathematical point of view, formulas in this logic express properties of sets of relational structures. This paper makes two contributions to the study of this logic. First, we describe an Ehrcnfeucht-Frai'ssc game for InqBQ and show that it characterizes the distinguishing power of the logic. Second, we use the game to study cardinality quantifiers in the inquisitive setting. That is, we study what statements and questions can be expressed in InqBQ about the number of individuals satisfying a given predicate. As special cases, we show that several variants of the question how many individuals satisfy a(x) are not expressible in InqBQ, both in the general case and in restriction to finite models
Plga membranes functionalized with gelatin through biomimetic mussel-inspired strategy
No full textElectrospun membranes have been widely used as scaffolds for soft tissue engineering due to their extracellular matrix-like structure. A mussel-inspired coating approach based on 3,4-dihydroxy-DL-phenylalanine (DOPA) polymerization was proposed to graft gelatin (G) onto poly(lactic-co-glycolic) acid (PLGA) electrospun membranes. PolyDOPA coating allowed grafting of gelatin to PLGA fibers without affecting their bulk characteristics, such as molecular weight and thermal properties. PLGA electrospun membranes were dipped in a DOPA solution (2 mg/mL, Tris/HCl 10 mM, pH 8.5) for 7 h and then incubated in G solution (2 mg/mL, Tris/HCl 10 mM, pH 8.5) for 16 h. PLGA fibers had an average diameter of 1.37 ± 0.23 μm. Quartz crystal microbalance with dissipation technique (QCM-D) analysis was performed to monitor DOPA polymerization over time: after 7 h the amount of deposited polyDOPA was 71 ng/cm2. After polyDOPA surface functionalization, which was, also revealed by Raman spectroscopy, PLGA membranes maintained their fibrous morphology, however the fiber size and junction number increased. Successful functionalization with G was demonstrated by FTIR-ATR spectra, which showed the presence of G adsorption bands at 1653 cm−1 (Amide I) and 1544 cm−1 (Amide II) after G grafting, and by the Kaiser Test, which revealed a higher amount of amino groups for G functionalized membranes. Finally, the biocompatibility of the developed substrates and their ability to induce cell growth was assessed using Neonatal Normal Human Dermal Fibroblasts
TENOGENIC DIFFERENTIATION PROTOCOL IN XENOGENIC-FREE MEDIA ENHANCES TENDON-RELATED MARKER EXPRESSION IN ADIPOSE-DERIVED STEM CELLS
No full textTendon injuries are common and current therapies often are unsuccessful. Cell-based therapy using mesenchymal stem cells (MSCs) seems to be the most promising approach to heal tendon. Moreover, providing safe and regulated cell therapy products to patients requires adherence to good manufacturing practices (GMP). Adipose-derived stem cells (n=4) were cultured in 6-well plates coated with type-I collagen in a chemically defined serum-free medium (SF) or a xenogenic-free human pooled platelet lysate medium (hPL). At passage 4, ASCs were induced to tendon lineage for 14 days using 100ng/ml CTGF, 10ng/ml TGFβ3, 50ng/ml BMP12 and 50μg/ml ascorbic acid in the SF (SF-TENO) or in the hPL (hPL-TENO) medium. Cells cultured without any supplements are used as control. Morphological appearance, cell viability and FACS were performed in undifferentiated cells to evaluate the xenogenic-free culture conditions; the gene and protein expression were performed by RT-PCR and immunofluorescence to evaluate to expression of stem cell- and tendon-related markers upon cell differentiation. SF-CTRL and hPL-CTRL showed similar viability and MSC's surface proteins and expressed the stemness markers NANOG, OCT4 and Ki67. Moreover, both SF-TENO and hPL-TENO expressed significant higher levels of SCX, COL1A1, COL3A1, COMP, MMP3 and MMP13 genes already at 3d (p<0.05) respect to CTRLs. Scleraxis and collagen were also detected in both SF-TENO and hPL-TENO at protein level in higher amount than CTRLs. In conclusion, ASCs exposed to CTGF, BMP12, TGFb3 and AA in both serum and xenogenic-free media possess similar tenogenic differentiation ability moving forward the GMP-compliant approaches for the clinical use of ASCs
SOFT-MI: Integration of Soft-Lythography and Molecular Imprinting such as a Novel Microfabrication Technique
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