Hyaluronan delivery by polymer demixing in polysaccharide-based hydrogels and membranes for biomedical applications

Alginate-based membranes containing hyaluronic acid (HA) were manufactured by freeze-drying calcium-reticulated hydrogels. The study of the distribution of the two macromolecules within the hydrogel enabled to highlight a polymer demixing mechanism that tends to segregate HA in the external parts of the constructs. Resistance and pliability of the membranes were tuned, while release and degradation studies enabled to quantify the diffusion of both polysaccharides in physiological solution and to measure the viable lifetime of the membranes. Biological studies in vitro proved that the liquid extracts from the HA-containing membranes stimulate wound healing and that fibroblasts are able to colonize the membranes. Overall, such novel alginate-HA membranes represent a promising solution for several medical needs, in particular for wound treatment, giving the possibility to provide an in situ administration of HA from a resorbable device

Rheology of mixed alginate-hyaluronan aqueous solutions

The present manuscript addresses the description of binary systems of hyaluronan (HA) and alginate (Alg) in semi-concentrated solution. The two polysaccharides were completely miscible in the entire range of relative weight fraction explored at a total polymer concentration of up to 3 % (w/V). The rheological study encompassed steady flow and mechanical spectra for HA/Alg systems at different weight fractions with hyaluronan at different molecular weights. These extensive analyses allowed us to propose a model for the molecular arrangement in solution that envisages a mutual exclusion between the two polysaccharides even though a clear phase separation does not occur. This result may have profound implications when biomaterials based on the combination of alginate and hyaluronan are proposed in the field of biomedical materials

Antibacterial-Nanocomposite Bone Filler Based on Silver Nanoparticles and Polysaccharides

Injectable bone fillers represent an attractive strategy for the treatment of bone defects. These injectable materials should be biocompatible, capable of supporting cell growth and possibly able to exert antibacterial effects. In this work, nanocomposite microbeads based on alginate, chitlac, hydroxyapatite and silver nanoparticles were prepared and characterized. The dried microbeads displayed a rapid swelling in contact with simulated body fluid and maintained their integrity for more than 30\ua0days. The evaluation of silver leakage from the microbeads showed that the antibacterial metal is slowly released in saline solution, with less than 6% of silver released after 1\ua0week. Antibacterial tests proved that the microbeads displayed bactericidal effects toward S. aureus, P. aeruginosa and S. epidermidis and were also able to damage pre-formed bacterial biofilms. On the other hand, the microbeads did not exert any cytotoxic effect towards osteoblast-like cells. After characterization of the bioactive microbeads, a possible means to embed them in a fluid medium was explored in order to obtain an injectable paste. Upon suspension of the particles in alginate solution or alginate/hyaluronic acid mixtures, a homogenous and time-stable paste was obtained. Mechanical tests enabled to quantify the extrusion forces from surgical syringes, pointing out the proper injectability of the material. This novel antibacterial bone-filler appears as a promising material for the treatment of bone defects, in particular when possible infections could compromise the bone-healing process

A silver complex of hyaluronan-lipoate (SHLS12): Synthesis, characterization and biological properties

In this study we present a novel silver complex of hyaluronan-lipoate (SHLS12) in a gel-state form. NMR analysis, conductometry and elemental analysis demonstrated stable non-covalent interactions between silver ions and the polysaccharide-lipoate backbone, whereas rheological investigations confirmed its gel-like physical-chemical behavior. Biological studies showed the ability of SHLS12 to exert a straightforward activity against different bacterial strains grown in sessile/planktonic state. The biocompatibility was also proved toward two eukaryotic cell lines. By considering both its ability to preserve antibacterial properties when exposed to the serum protein BSA and its low susceptibility to be degraded by hyaluronidase enzyme, this novel complex may be considered as a promising biomaterial for future in vivo applications

Central and peripheral corneal thickness measurement with Orbscan II and topographical ultrasound pachymetry

PURPOSE: To compare thickness measurements of the central 6.0 mm of the cornea obtained with the Orbscan(R) II topography system and topographical ultrasound pachymetry. SETTING: School of Optometry, University of Santiago de Compostela, Galicia, Spain. METHODS: In 24 right eyes, pachymetric measurements were taken at the center and 1.2 mm and 3.0 mm on the superior and inferior hemimeridians. A 1-sample t test was applied to assess the significance of the relationship between Orbscan II and ultrasound methods. The relationship between the 2 was assessed by analyzing regression and plotting the differences against the mean corneal thickness. Orbscan II data were analyzed in 3 ways: (1) without the application of an acoustic equivalent correction factor; (2) with a correction factor of 0.92, as recommended by the manufacturer; (3) with correction using the equations derived in this study. The data were systematically compared with those of ultrasound pachymetry. RESULTS: Before the correction factor was applied, the Orbscan II overestimated the corneal thickness at all locations, with the mean difference (48.15 microm +/- 33.74 [SD]) significantly different from zero (P .05). CONCLUSIONS: The acoustic equivalent correction factor proposed by the manufacturer to obtain corneal thickness measurements with the Orbscan II compared to those from ultrasound pachymetry was not valid for all corneal topography positions. Orbscan II measurements agreed better with those of ultrasound pachymetry when equations for the central and each peripheral location across the topography were applied

Commercial Common Sense in Contract Interpretation: Observations on the Court of Appeal in Technix v Fitzroy and The Malthouse v Rangatira

The contemporary principles of contract interpretation require courts to have regard to a number of factors to determine the meaning of a contract, including the plain meaning of the express contractual language, the contract's context, and commercial common sense. These principles superseded the narrower plain meaning rule, which directed courts to interpret contracts in a manner largely consistent with the plain and ordinary meaning of their express words. Since their manifestation some 20 years ago, these principles have undergone change, development and elaboration to the extent that some commentators now claim the approach to contract interpretation more closely resembles the former plain meaning rule, with courts giving "primacy" to the words of the contract in order to deliver "commercial certainty". This article argues that while courts must give primacy to the express contractual language, that does not mean courts should maintain an unwavering loyalty to the plain meaning of those words, even if their meaning is clear. Courts that adopt this approach, referred to by some as the "conservative approach", risk obscuring the true meaning of a contract that can only be obtained through the careful balancing of a contract's internal and external factors, including commercial common sense. This article demonstrates the problem with the "conservative approach" through the analysis of two Court of Appeal decisions, and argues that courts should not overstate the circumstances in which departure from the plain meaning of a contract should occur

Adhesion of human gingival fibroblasts/Streptococcus mitis co-culture on the nanocomposite system Chitlac-nAg

10noComposite materials are increasingly used as dental restoration. In the field of biomaterials, infections remain the main reason of dental devices failure. Silver, in the form of nanoparticles (AgNPs), ions and salt, well known for its antimicrobial properties, is used in several medical applications in order to avoid bacterial infection. To reduce both bacterial adhesion to dental devices and cytotoxicity against eukaryotic cells, we coated BisGMA/TEGDMA methacrylic thermosets with a new material, Chitlac-nAg, formed by stabilized AgNPs with a polyelectrolyte solution containing Chitlac. Here we analyzed the proliferative and adhesive ability of human gingival fibroblasts (HGFs) on BisGMA/TEGDMA thermosets uncoated and coated with AgNPs in a coculture model system with Streptococcus mitis. After 48 h, HGFs well adhered onto both surfaces, while S. mitis cytotoxic response was higher in the presence of AgNPs coated thermosets. After 24 h thermosets coated with Chitlac as well as those coated with Chitlac-nAg exerted a minimal cytotoxic effect on HGFs, while after 48 h LDH release raised up to 20 %. Moreover the presence of S. mitis reduced this release mainly when HGFs adhered to Chitlac-nAg coated thermosets. The reduced secretion of collagen type I was significant in the presence of both surfaces with the co-culture system even more when saliva is added. Integrin β1 localized closely to cell membranes onto Chitlac-nAg thermosets and PKCα translocated into nuclei. These data confirm that Chitlac-nAg have a promising utilization in the field of restorative dentistry exerting their antimicrobial activity due to AgNPs without cytotoxicity for eukaryotic cells.openopenCataldi, Amelia; Gallorini, Marialucia; Di Giulio, Mara; Guarnieri, Simone; Mariggiò, Maria Addolorata; Traini, Tonino; Di Pietro, Roberta; Cellini, Luigina; Marsich, Eleonora; Sancilio, SilviaCataldi, Amelia; Gallorini, Marialucia; Di Giulio, Mara; Guarnieri, Simone; Mariggiò, Maria Addolorata; Traini, Tonino; Di Pietro, Roberta; Cellini, Luigina; Marsich, Eleonora; Sancilio, Silvi

Innovative Thermal and Acoustic Insulation Foams from Recycled Fiberglass Waste

This study examines a lightweight thermal and acoustic insulation material, produced starting from a hydrogel-based mixture composed by renewable biopolymer and fiberglass waste powders. The gel 3D porous network is preserved after water removal by sublimation, resulting in a lightweight thermal and acoustic insulation material with good overall performance. Mechanical, thermal, and acoustic properties can be tuned as a function of biopolymer and additives concentration. This material addresses environmental concerns both in terms of secondary raw sources use and fiberglass waste disposal. Moreover, contrary to mineral wools currently on the market, it can overcome the problem of fiber release, with significant human health benefits. Thanks to its good properties and its fabrication process based on a circular economy approach, it can be appealing for thermal and acoustic insulating applications in building and industrial sectors and also in terms of environmental footprint

Redox control of IL-6-mediated dental pulp stem cell differentiation on alginate/hydroxyapatite biocomposites for bone ingrowth

Composites and porous scaffolds produced with biodegradable natural polymers are very promising constructs which show high biocompatibility and suitable mechanical properties, with the possibility to be functionalized with growth factors involved in bone formation. For this purpose, alginate/hydroxyapatite (Alg/HAp) composite scaffolds using a novel production design were successfully developed and tested for their biocompatibility and osteoconductive properties in vitro. Redox homeostasis is crucial for dental pulp stem cell (DPSC) differentiation and mineralized matrix deposition, and interleukin-6 (IL-6) was found to be involved not only in immunomodulation but also in cell proliferation and differentiation. In the present study, we evaluated molecular pathways underlying the intracellular balance between redox homeostasis and extracellular matrix mineralization of DPSCs in the presence of composite scaffolds made of alginate and nano-hydroxyapatite (Alg/HAp). Prostaglandin-2 (PGE2) and IL-6 secretion was monitored by ELISA assays, and protein expression levels were quantified by Western blotting. This work aims to demonstrate a relationship between DPSC capacity to secrete a mineralized matrix in the presence of Alg/HAp scaffolds and their immunomodulatory properties. The variation of the molecular axis Nrf2 (nuclear factor erythroid 2-related factor 2)/PGE2/IL-6 suggests a tight intracellular balance between oxidative stress responses and DPSC differentiation in the presence of Alg/HAp scaffolds

Qualitative and quantitative contaminants assessment in recycled pellets from post-consumer plastic waste by means of spectroscopic and thermal characterization

The complexity of any plastic recycling initiative lies in the heterogeneous nature of the post-consumer commingled plastic waste stream: recycling treatments are challenging without prior reliable sorting. A suitable identification system should be able to recognize different plastics and blends. Nowadays, the main technique used as quality control in plastic waste sorting centers is differential scanning calorimetry, whose result can be purely qualitative or semi-quantitative, since only the crystalline fraction is evaluated. Moreover, the time required for data acquisition is relatively long. Infrared spectroscopy is an alternative, faster technique extensively used in applied research, but not widely utilized in industry. In this work, the cross-use of infrared spectroscopy and calorimetry is tested in a real, practical case: the quality control of recycled pellets (namely composed of polyolefins only), which represent the output of a commingled plastic recycling plant and are used as secondary raw materials for different applications. Appropriate infrared spectroscopy calibration curves were built to allow the quantitative analysis with respect to the most common polymers found in the commingled plastic waste stream; the composition and contaminants in the recycled pellets were thereby determined and tracked through different production batches through the cross-use of the two techniques outlined above