The aim of this work is to evaluate the effects of different extraction and material processing protocols on the collagen structure and hierarchical organization of equine tendons. Wide and Small ...Angle X-ray Scattering investigations on raw powders and thin films revealed that not only the extraction and purification treatments, but also the processing conditions may affect the extent of the protein crystalline domain and induce a nanoscale “shield effect.” This is due to the supramolecular fiber organization, which protects the atomic scale structure from the modifications that occur during fabrication protocols. Moreover, X-ray analyses and Fourier Transform Infrared spectroscopy performed on the biomaterial sheds light on the relationship between processing conditions, triple helical content and the organization in atomic and nanoscale domains. It was found that the mechanical homogenization of the slurry in acidic solution is a treatment that ensures a high content of super-organization of collagen into triple helices and a lower crystalline domain in the material. Finally, mechanical tensile tests were carried out, proving that the acidic solution is the condition which most enhances both mechanical stiffness and supramolecular fiber organization of the films.
Study on the degradation of chitosan slurries Martini, Benjamin; Dimida, Simona; De Benedetto, Egidio ...
Results in physics,
2016, 2016-00-00, 2016-01-01, Letnik:
6
Journal Article
Recenzirano
Odprti dostop
In the present work, we measured the degradation rate of different chitosan slurries. Several parameters were monitored such as temperature (25°C, 37°C, 50°C); chitosan concentration (1% and 2% ...(w/V)); and polymer molecular weight. The samples were tested in dynamic sweep test mode. This test is able to provide a reliable estimation of viscosity variations of the slurries; in turn, these variations could be related to degradation rate of the system in the considered conditions. The resulting information is particularly important especially in applications in which there is a close relationship between physical properties and molecular structure.
The goal of the work was the manufacturing of hydroxyapatite microsphere/polylactic acid (PLA) scaffolds by means of fused deposition modelling (FDM). Micrometer-sized hydroxyapatite spheres ...synthesized by spray drying (sdHA), were dispersed in PLA by extrusion compounding. Composite filaments were obtained from extrusion which were used in FDM 3D printing for the production of macroporous scaffolds. The sdHA microspheres were used in the composite in order to improve the biomimicry and the bioactivity of the 3D printed scaffold to increase the bone regeneration capacity. Morphological, thermal, physical and mechanical characterizations were performed on the 3D printed composites. Pure PLA scaffolds were 3D printed and used as a reference.
Thermal analyses, TGA and DSC evidenced that the glass transition temperature and the degree of crystallinity of PLA were not influenced by the presence of sdHA. Morphological analysis showed a smooth surface of the printed samples when pure PLA was used. A rough surface was found on the PLA/sdHA composites, confirming, the homogeneous dispersion of the ceramic phase in the polymeric matrix. The higher porosity of the composite samples compared to PLA ones, most likely caused a decrease of the mechanical performances of the PLA/sdHA scaffolds. Composite scaffolds displayed stiffness values compatible with that of bone tissue.
Polymeric biomaterials represent an essential tool in the biomedical field. Their high biocompatibility and ability to provide adequate regenerative support are fundamental for the development of new ...therapeutic devices. In particular, biomaterials derived from living organisms can exhibit not only structural roles but also several non-structural functions implicated in cellular growth, migration, and differentiation. Among them, type I collagen, a ubiquitous structural protein present in the mammalian body, plays a dominant role in maintaining the biological and structural integrity of various tissues. In recent years, with the goal of developing multi-functional collagen-based devices able to better promote the functional recovery of damaged tissues, numerous studies have focused on novel techniques and methods for the development and characterization of innovative and advanced high-performance formulations. The ability to control, modify, and tune collagen-based biomaterials performance by optimizing their architecture, besides modifying their chemistry, blending with other materials/therapeutics, or developing stimuli-responsive formulations, is an extremely important knowledge to acquire when specific multi-functionalities are sought.The present Special Issue collected 12 peer-reviewed interdisciplinary contributions on the broad topic of multi-functional collagen-based biomaterials.
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•Global hyaluronic acid (HA) market expected to reach USD 15.4 billion by 2025.•HA involved in many biological pathways in physiological and pathological states.•Chemical ...modifications to prolong HA half-life in vivo may challenge the safety.•Cancer therapy and tissue regeneration as advanced HA applications.•Need to improve HA production to face increasing demand at sustainable costs.
Hyaluronic acid (HA), also termed hyaluronan, is a key extracellular matrix glycosaminoglycan that not only provides tissue hydration, but also shows intrinsic bioactivity towards cellular proliferation, differentiation and inflammatory response. These properties make HA attractive both as a potential target for the treatment of several diseases and as an effective biomaterial to control cell behavior. This concise review aims at emphasizing the increasing role of HA as a promising biomaterial for advanced medical applications that include, among others, the development of targeted therapies for cancer treatment and the development of scaffolds for regenerative medicine. Although the bioactive mechanisms of HA are not fully understood, its molecular weight and purity are well known to affect the cellular and immunological responses to HA-based products. Furthermore, in spite of the complex translation of novel HA-based medical devices from the lab bench to the clinic, a rapid growth of the HA market is foreseen in the next future, also due to the growing aging of the population and the increasing demand for anti-aging products. In this perspective, the industrial HA production is briefly addressed, with reference to the technological issues that are currently undergoing extensive research to improve the HA yield and quality, in an attempt to meet the quickly rising HA demand.
•Tunable PEGDA cryogels produced via fast UV irradiation (up to 60 s).•Gelation yield affected by polymer concentration and UV time.•Cryogel swelling, porosity and stiffness controlled by polymer ...concentration.•Porosity and swelling of 10% w/v PEGDA cryogels affected by UV time.
Poly(ethylene glycol) diacrylate (PEGDA) cryogels, particularly useful for biotechnological applications, are currently fabricated exploiting crosslinking systems that require long freezing/crosslinking times (20 h or longer). The aim of this work was to assess whether fast UV irradiation (up to 60 s) of frozen PEGDA solutions could be an advantageous alternative for cryogel production. By using different polymer concentrations and UV times, cryogels with highly interconnected macropores (about 50–90 μm) were produced. A gelation yield in the range 60–80% was recorded, with higher values obtained for low PEGDA concentrations (5 and 10% w/v). Interestingly, while decreasing the swelling and increasing the stiffness of the cryogels, a higher polymer concentration was also found to reduce the pore size. Furthermore, increasing the UV time resulted in significantly higher swelling and larger pores for 10% PEGDA samples, while having negligible effect on other cryogel types and/or features. Although deserving further exploration, fast UV irradiation is an effective method to produce PEGDA cryogels with tunable properties.
A porous collagen-based hydrogel scaffold was prepared in the presence of iron oxide nanoparticles (NPs) and was characterized by means of infrared spectroscopy and scanning electron microscopy. The ...hybrid scaffold was then loaded with fluorescein sodium salt as a model compound. The release of the hydrosoluble species was triggered and accurately controlled by the application of an external magnetic field, as monitored by fluorescence spectroscopy. The biocompatibility of the proposed matrix was also tested by the MTT assay performed on 3T3 cells. Cell viability was only slightly reduced when the cells were incubated in the presence of the collagen–NP hydrogel, compared to controls. The economicity of the chemical protocol used to obtain the paramagnetic scaffolds as well as their biocompatibility and the safety of the external trigger needed to induce the drug release suggest the proposed collagen paramagnetic matrices for a number of applications including tissue engeneering and drug delivery.
•Incorporation of an active agent via green-based technology.•Correlation between composition and mechanical properties.•Demonstration of the effectiveness of the material against the proliferation ...of a selected mould line.
Bioactive food-preserving materials are based on the use of a natural antimicrobial compound loaded in a carrier material, which is able to trigger its release when requested and to modulate the rate of release, thus using either toxic or inhibitory properties against pathogens or bacteria due to food decomposition. In this study, the Schiff base formation for chitosan functionalization was achieved by the reaction of chitosan with cinnamaldehyde at different concentrations. Cinnamaldehyde is an aromatic α,β-unsaturated aldehyde, and the major component in essential oils from some cinnamon species. It has been shown to exert antimicrobial action against a large number of microorganisms including bacteria, yeasts, and mould. The formation of the Schiff base is reversible under suitable conditions, and this might allow the release of the active cinnamaldehyde from chitosan, used as the carrier. The reaction kinetics was investigated by means of rheological measurements, while infrared spectroscopy was used to assess the efficacy of the functionalization. The addition of nanometric graphene stacks to the cinnamaldehyde-functionalized chitosan films was evaluated with the aim to increase the mechanical properties of the film. Finally, the films were tested for antifungal properties with bread slices against a selected mould line.
In this work, an innovative cellulose-based superabsorbent polymer (SAP) was experimentally assessed as an environmentally friendly alternative to acrylate-based SAPs, for the optimization of water ...consumption in agriculture. The cellulose-based SAP was synthesized and tested for its swelling capability in different aqueous media. The effectiveness of the SAP in agricultural applications was then evaluated by analyzing its performance after several absorption/desorption cycles, over a period of approximately 80 days, upon addition to different types of soil, i.e., white and red soil, for the cultivation of two varieties of plants typical of the Mediterranean area (tomatoes and chicory). The results confirmed that SAP-amended soil can store a considerable amount of water and can release it gradually to the plant roots when needed. The adoption of the proposed SAP in cultivations could thus represent a promising solution for the rationalization of water resources, especially in desert areas.
This narrative review aims to study the accuracy of different intra-oral scanner (IOS) devices already available on the market. The accuracy emerged during in vitro, in vivo and ex vivo studies made ...with IOS devices during the scan of a full arch implant rehabilitation that have been analysed to evaluate which device may be the most suitable in this clinical situation. The literature review was performed by searching topics and keywords using the PubMed and Medline databases, for example, 'digital workflow', 'full arch', 'full arch implant rehabilitation' and 'accuracy of IOS'. Inclusion and exclusion criteria for studies were: correct IMRAD (introduction, methods, results and discussion) structure; article with clear and detailed objectives; consistency of the articles with the purpose of the review; two-year range from the year of publication of the article; reproducible materials and methods; and correct follow-up. Most of the intra-oral scanners employed in vitro provided acceptable accuracy (below a threshold of 150 μm). The main parameters identified for their influence on precision were interim plant distance, body scan design, scanning pattern and operator experience. Even though literature is limited, significant differences emerged between the different models of intra-oral scanners evaluated in the studies considered within this review.
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