Investigating the Structure-Related Properties of Cellulose-Based Superabsorbent Hydrogels

Superabsorbent hydrogels are macromolecular networks able to absorb and retain large amounts of water solutions within their fine mesh-like structure. More importantly, they are capable of multiple swelling/shrinking transitions in response to specific environmental cues (e.g., pH, ionic strength, temperature, presence of given electrolytes), thus exhibiting a stimuli-sensitive behavior, which makes them appealing for the design of smart devices in a number of technological fields. In particular, in the last two decades, cellulose-based superabsorbent hydrogels have proven to be an environmentally friendly and cost-effective alternative to acrylamide-based products. This chapter reviews the relationship between the molecular structure of cellulose-based hydrogels and their physicochemical properties. First, the network formation through the use of different cellulose derivatives and chemical or physical crosslinking agents is presented. Successively, the smart swelling capability of the hydrogels as a function of composition and structure is thoroughly discussed. Finally, several approaches to the hydrogel characterization are reviewed, with focus on the assessment of key mechanical, thermal and morphological properties

Study on the degradation of chitosan slurries

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. Keywords: Chitosan, Degradation, Molecular weight, Viscosit

Current Trends in Gelatin-Based Drug Delivery Systems

Gelatin is a highly versatile natural polymer, which is widely used in healthcare-related sectors due to its advantageous properties, such as biocompatibility, biodegradability, low-cost, and the availability of exposed chemical groups. In the biomedical field, gelatin is used also as a biomaterial for the development of drug delivery systems (DDSs) due to its applicability to several synthesis techniques. In this review, after a brief overview of its chemical and physical properties, the focus is placed on the commonly used techniques for the development of gelatin-based micro- or nano-sized DDSs. We highlight the potential of gelatin as a carrier of many types of bioactive compounds and its ability to tune and control select drugs' release kinetics. The desolvation, nanoprecipitation, coacervation, emulsion, electrospray, and spray drying techniques are described from a methodological and mechanistic point of view, with a careful analysis of the effects of the main variable parameters on the DDSs' properties. Lastly, the outcomes of preclinical and clinical studies involving gelatin-based DDSs are thoroughly discussed

Mimicking the Hierarchical Organization of Natural Collagen: Toward the Development of Ideal Scaffolding Material for Tissue Regeneration

Biological materials found in living organisms, many of which are proteins, feature a complex hierarchical organization. Type I collagen, a fibrous structural protein ubiquitous in the mammalian body, provides a striking example of such a hierarchical material, with peculiar architectural features ranging from the amino acid sequence at the nanoscale (primary structure) up to the assembly of fibrils (quaternary structure) and fibers, with lengths of the order of microns. Collagen plays a dominant role in maintaining the biological and structural integrity of various tissues and organs, such as bone, skin, tendons, blood vessels, and cartilage. Thus, "artificial" collagen-based fibrous assemblies, endowed with appropriate structural properties, represent ideal substrates for the development of devices for tissue engineering applications. In recent years, with the ultimate goal of developing three-dimensional scaffolds with optimal bioactivity able to promote both regeneration and functional recovery of a damaged tissue, numerous studies focused on the capability to finely modulate the scaffold architecture at the microscale and the nanoscale in order to closely mimic the hierarchical features of the extracellular matrix and, in particular, the natural patterning of collagen. All of these studies clearly show that the accurate characterization of the collagen structure at the submolecular and supramolecular levels is pivotal to the understanding of the relationships between the nanostructural/microstructural properties of the fabricated scaffold and its macroscopic performance. Several studies also demonstrate that the selected processing, including any crosslinking and/or sterilization treatments, can strongly affect the architecture of collagen at various length scales. The aim of this review is to highlight the most recent findings on the development of collagen-based scaffolds with optimized properties for tissue engineering. The optimization of the scaffolds is particularly related to the modulation of the collagen architecture, which, in turn, impacts on the achieved bioactivity

Cellulose Acetate and Cardanol Based Seed Coating for Intraspecific Weeding Coupled with Natural Herbicide Spraying

AbstractAgricultural pesticides can become persistent environmental pollutants and their use is destined to be reduced. Consequently, weed control is shifting to green products and strategies. A combined approach, made of pelargonic acid based herbicide spraying and interspecific competition (i.e. seeding of plants species competing for growth against weeds) could boost the weeding effect. In case of the contemporary seeding and spraying, needed to reduce costs, seed coating is necessary as barrier to herbicide toxic effects but, at the same time, the coating has to be endowed with the right features to allow germination. This work aims to verify the feasibility of using cellulose acetate/cardanol (CA/Card) as seed coating polymer–plasticizer blend and to identify possible relationship between material features and germination rate. For these purposes, untreated and pelargonic acid herbicide treated coated seeds coated through solvent evaporation methods (CA/Card ratios from 0/0 to 100/0) were subjected to germination test. Coatings were characterized through SEM, EDX, media uptake, DSC and mechanical analysis with and without conditioning in seeding conditions. Germination test showed that 70/30 seeds, treated and untreated with herbicide, presented the best germination rate. Germination assays showed that coating presence reduced and slowed (without stopping) seeds germination equally with and without herbicide treatment. Consequently, was possible to conclude that CA/Card coatings allowed germination and presented a barrier effect against herbicide. Thus coating resulted suitable for seed coating in herbicide spraying/interspecific combined applications. No strong correlations were found between material features and germination, but it is plausible to hypothesize that both water absorption and mechanical properties of the coating play an important role and have to be optimized to improve germination rate avoiding difficulty in sprouting. Finally, the study opened a new perspective in the use of cellulose acetate for seed coating from waste sources such as cigarette filters.Graphic Abstrac

Biocompatible Collagen Paramagnetic Scaffold for Controlled Drug Release

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

Design of Antibody-Functionalized Polymeric Membranes for the Immunoisolation of Pancreatic Islets

none8noAn immunoencapsulation strategy for pancreatic islets aimed to reduce the risk of rejection in transplanted patients due to the immune response of the host organism is proposed. In this sense, a polyethylene glycol (PEG) hydrogel functionalized with an immunosuppressive antibody (Ab), such as Cytotoxic T-lymphocyte antigen-4 Ig (CTLA4-Ig), would act as both passive and active barrier to the host immune response. To demonstrate the feasibility of this approach, a photopolymerizable-PEG was conjugated to the selected antibody and the PEG-Ab complex was used to coat the islets. Moreover, to preserve the antigen-recognition site of the antibody during the conjugation process, a controlled immobilization method was setup through the attachment of the His-tagged antigen to a solid support. In detail, a gold-coated silicon wafer functionalized with 11-Mercaptoundecanoic acid was used as a substrate for further modification, leading to a nickel(II)-terminated ligand surface. Then, the immobilized antigen was recognized by the corresponding antibody that was conjugated to the PEG. The antibody-PEG complex was detached from the support prior to be photopolymerized around the islets. First, this immobilization method has been demonstrated for the green fluorescent protein (GFP)–anti-green fluorescent protein (Anti-GFP) antigen-antibody pair, as proof of principle. Then, the approach was extended to the immunorelevant B7-1 CTLA-4-Ig antigen-antibody pair, followed by the binding of Acryl-PEG to the immobilized constant region of the antibody. In both cases, after using an elution protocol, only a partial recovery of the antibody-PEG complex was obtained. Nevertheless, the viability and the functional activity of the encapsulated islets, as determined by the glucose-stimulated insulin secretion (GSIS) assay, showed the good compatibility of this approach.openAnna Cavallo; Ugo Masullo; Alessandra Quarta; Alessandro Sannino; Amilcare Barca; Tiziano Verri; Marta Madaghiele; Laura BlasiCavallo, Anna; Masullo, Ugo; Quarta, Alessandra; Sannino, Alessandro; Barca, Amilcare; Verri, Tiziano; Madaghiele, Marta; Blasi, Laur

Biomimetic cellulose-based superabsorbent hydrogels for treating obesity

In the treatment of obesity, nutritional and behavioral modifications are difficult to implement and maintain. Since vegetable consumption is a fundamental part of many dietary interventions and daily nutrient requirements, we developed a novel cellulose-based superabsorbent hydrogel (CB-SAH) platform, inspired by the composition and mechanical properties of raw vegetables, as a mechanobiological therapy. The CB-SAHs properties were studied in a simulated gastrointestinal environment, while their impact on gut tissue was investigated by an ex vivo organ culture (EVOC) model. Functional fibers and raw vegetables were used as reference. CB-SAHs demonstrated orders of magnitude higher elasticity in comparison to the tested functional fibers, however performed similar to the tested raw vegetables. Notably, the biomimetic CB-SAHs with elasticity levels similar to raw vegetables showed benefits in preserving and regulating the gut tissue in the EVOC model. Non-systemic oral mechanotherapeutics based on this technology were advanced through clinical studies, with a first product cleared as an aid for weight management in the US and Europe

Biomimetic gradient scaffold of collagen–hydroxyapatite for osteochondral regeneration:

Osteochondral defects remain a major clinical challenge mainly due to the combined damage to the articular cartilage and the underlying bone, and the interface between the two tissues having very different properties. Current treatment modalities have several limitations and drawbacks, with limited capacity of restoration; however, tissue engineering shows promise in improving the clinical outcomes of osteochondral defects. In this study, a novel gradient scaffold has been fabricated, implementing a gradient structure in the design to mimic the anatomical, biological and physicochemical properties of bone and cartilage as closely as possible. Compared with the commonly studied multi-layer scaffolds, the gradient scaffold has the potential to induce a smooth transition between cartilage and bone and avoid any instability at the interface, mimicking the natural structure of the osteochondral tissue. The scaffold comprises a collagen matrix with a gradient distribution of low-crystalline hydroxyapatite particles. Physicochemical analyses confirmed phase and chemical compositions of the gradient scaffold and the distribution of the mineral phase along the gradient scaffold. Mechanical tests confirmed the gradient of stiffness throughout the scaffold, according to its mineral content. The gradient scaffold exhibited good biological performances both in vitro and in vivo. Biological evaluation of the scaffold, in combination with human bone-marrow–derived mesenchymal stem cells, demonstrated that the gradient of composition and stiffness preferentially increased cell proliferation in different sub-regions of the scaffold, according to their high chondrogenic or osteogenic characteristics. The in vivo biocompatibility of the gradient scaffold was confirmed by its subcutaneous implantation in rats. The gradient scaffold was significantly colonised by host cells and minimal foreign body reaction was observed. The scaffold's favourable chemical, physical and biological properties demonstrated that it has good potential as an engineered osteochondral analogue for the regeneration of damaged tissue

Comparison of Bioengineered Scaffolds for the Induction of Osteochondrogenic Differentiation of Human Adipose-Derived Stem Cells

osteochondral lesions may be due to trauma or congenital conditions. In both cases, therapy is limited because of the difficulty of tissue repair. tissue engineering is a promising approach that relies on designed scaffolds with variable mechanical attributes to favor cell attachment and differentiation. human adipose-derived stem cells (hASCs) are a very promising cell source in regenerative medicine with osteochondrogenic potential. based on the assumption that stiffness influences cell commitment, we investigated three different scaffolds: a semisynthetic animal-derived GelMA hydrogel, a combined scaffold made of rigid PEGDA coated with a thin GelMA layer and a decellularized plant-based scaffold. we investigated the role of different biomechanical stimulations in the scaffold-induced osteochondral differentiation of hASCs. we demonstrated that all scaffolds support cell viability and spontaneous osteochondral differentiation without any exogenous factors. In particular, we observed mainly osteogenic commitment in higher stiffness microenvironments, as in the plant-based one, whereas in a dense and softer matrix, such as in GelMA hydrogel or GelMA-coated-PEGDA scaffold, chondrogenesis prevailed. we can induce a specific cell commitment by combining hASCs and scaffolds with particular mechanical attributes. however, in vivo studies are needed to fully elucidate the regenerative process and to eventually suggest it as a potential approach for regenerative medicine