Smart hydrogels based on semi-interpenetrating polymeric networks of collagen-polyurethane-alginate for soft/hard tissue healing, drug delivery devices, and anticancer therapies.

In this work, hydrogels based on semi-interpenetrating polymeric networks (semi-IPN) based on collagen-polyurethane-alginate were studied physicochemically and from different approaches for biomedical application. It was determined that the matrices in the hydrogel state are crosslinked by the formation of urea and amide bonds between the biopolymer chains and the polyurethane crosslinker. The increment in alginate content (0-40 wt%) significantly increases the swelling capacity, generating semi-crystalline granular structures with improved storage modulus and resistance to thermal, hydrolytic, and proteolytic degradation. The in vitro bioactivity results indicated that the composition of these novel hydrogels stimulates the metabolic activity of monocytes and fibroblasts, benefiting their proliferation; while in cancer cell lines, it was determined that the composition of these biomaterials decreases the metabolic activity of breast cancer cells after 48 h of stimulation, and for colon cancer cells their metabolic activity decreases after 72 h of contact for the hydrogel with 40 wt% alginate. The matrices show a behavior of multidose release of ketorolac, and a higher concentration of analgesic is released in the semi-IPN matrix. The inhibition capacity of Escherichia coli is higher if the polysaccharide concentration is low (10 wt%). The in vitro wound closure test (scratch test) results indicate that the hydrogel with 20 wt% alginate shows an improvement in wound closure at 15 days of contact. Finally, the bioactivity of mineralization was evaluated to demonstrate that these hydrogels can induce the formation of carbonated apatite on their surface. The engineered hydrogels show biomedical multifunctionality and they could be applied in soft and hard tissue healing strategies, anticancer therapies, and drug release devices.

Smart collagen/xanthan gum-based hydrogels with antibacterial effect, drug release capacity and excellent performancein vitrobioactivity for wound healing application.

The design of hydrogels based on natural polymers that have modulation of antibacterial capacity, ideal performance in release capacity of encapsulated drugs, and desired bioactivity for applications in wound healing represents a modern trend in biomaterials. In this work, novel hydrogels of semi-interpenetrating polymeric networks based on collagen and xanthan gum (XG) were investigated. The linear chains of XG can semi-interpenetrate inside to matrix of crosslinked collagen with polyurethane under physiological conditions, generating amorphous surfaces with fibrillar-granular reliefs that have accelerated gelation time (about 15 min), super water absorption (up to 3100%) and high inhibition capacity of pathogenic bacteria such asEscherichia coli(up to 100% compared to amoxicillin at 20 ppm). The increment of XG in the hydrogel (up to 20 wt.%) allows for improvement in the storage module, resistance to thermal degradation, slow the rate of hydrolytic and proteolytic degradation, allowing to encapsulate and controlled release of molecules such as ketorolac and methylene blue; besides, it shows to keep the metabolic activity of fibroblasts and monocytes at 48 h of evaluation, without observing cytotoxic effects. The bioactivity of these hydrogels is improved since they have excellent hemocompatibility and enhanced cell proliferation. Specifically, the hydrogel with 20 wt.% of XG shows to decrease the production of tumor necrosis factor-αand CCL-2 cytokines, increasing the production of transforming growth factor-ßin human monocytes, which could be used to modulate inflammation and regenerative capacity in wound healing strategies.

Semi-IPN hydrogels of collagen and gum arabic with antibacterial capacity and controlled release of drugs for potential application in wound healing.

The preparation of hydrogels based on biopolymers like collagen and gum arabic gives a chance to provide novel options that can be used in biomedical field. Through a polymeric semi-interpenetration technique, collagen-based polymeric matrices can be associated with gum arabic while controlling its physicochemical and biological properties. To create novel hydrogels with their potential use in the treatment of wounds, the semi-interpenetration process, altering the concentration (0-40% by wt) of gum arabic in a collagen matrix is explored. The ability of gum arabic to create intermolecular hydrogen bonds in the collagen matrix enables the development of semi-interpenetrating polymeric networks (semi-IPN)-based hydrogels with a faster gelation time and higher crosslinking. Amorphous granular surfaces with linked porosity are present in matrices with 30% (by wt) of gum arabic, enhancing the storage modulus and thermal degradation resistance. The hydrogels swell to very high extent in hydrolytic and proteolytic environments, good hemocompatibility, and suppression of growth of pathogens like E. coli, and all it is enhanced by gum arabic included them, in addition to enabling the controlled release of ketorolac. The chemical composition of theses semi-IPN matrices have no deleterious effects on monocytes or fibroblasts, promoting their proliferation, and lowering alpha tumor necrosis factor (α-TNF) secretion in human monocytes.

Tailoring biocompatibility of composite scaffolds of collagen/guar gum with metal-organic frameworks.

Metal-organic frameworks (MOFs) are microporous materials with high potential for biomedical applications. They are useful as drug delivery systems, antibacterials, and biosensors. Recently, composite materials comprised of polymer matrixes and MOFs have gained relevance in the biomedical field due to their high potential as materials to accelerate wound healing. In this work, we studied the potential applications of composite hydrogels containing MgMOF74, CaMOF74, and Zn(Atz)(Py). The composite hydrogels are biodegradable, being completely degraded after 15 days by the action of collagenase and papain. The composites showed high biocompatibility reaching cell viabilities up to 165.3 ± 8.6% and 112.3 ± 12.8% for porcine fibroblasts and human monocytes, respectively. The composites did not show hemolytic character and they showed antibacterial activity against Escherichia coli reaching up to 84 ± 5% of inhibition compared with amoxicillin (20 ppm). Further, the immunological assays revealed that the composites produce a favorable cell signaling stimulating the secretion of the TGF-ß and MCP-1 cytokines and maintaining the secretion of TNF-α in normal levels. Finally, the composites showed potential to be used as controlled drug delivery systems reaching a release efficiency of 30.5 ± 2.5% for ketorolac. Finally, results revealed that ColGG-Zn(Atz)(Py) was the best formulation evaluated.

Highly absorbent hydrogels comprised from interpenetrated networks of alginate-polyurethane for biomedical applications.

Developing new approaches to improve the swelling, degradation rate, and mechanical properties of alginate hydrogels without compromising their biocompatibility for biomedical applications represents a potential area of research. In this work, the generation of interpenetrated networks (IPN) comprised from alginate-polyurethane in an aqueous medium is proposed to design hydrogels with tailored properties for biomedical applications. Aqueous polyurethane (PU) dispersions can crosslink and interpenetrate alginate chains, forming amide bonds that allow the structure and water absorption capacity of these novel hydrogels to be regulated. In this sense, this work focuses on studying the relation of the PU concentration on the properties of these hydrogels. The results indicate that the crosslinking of the alginate with PU generates IPN hydrogels with a crystalline structure characterized by a homogeneous smooth surface with high capacity to absorb water, tailoring the degradation rate, thermal decomposition, and storage module, not altering the native biocompatibility of alginate, providing character to inhibit the growth of E. coli and increasing also its hemocompatibility. The IPN hydrogels that include 20 wt.% of PU exhibit a reticulation index of 46 ± 4%, swelling capacity of 545 ± 13% at 7 days of incubation at physiological pH, resistance to both acidic and neutral hydrolytic degradation, mechanical improvement of 91 ± 1%, and no cytotoxicity for monocytes and fibroblasts growing for up to 72 h of incubation. These results indicate that these novel hydrogels can be used for successful biomedical applications in the design of wound healing dressings.

Study of the polyacrylate interpenetration in a collagen-polyurethane matrix to prepare novel hydrogels for biomedical applications.

Currently, the control of the properties of collagen based hydrogels represents a promising area of research to develop novel materials for biomedical applications. The crosslinking of the collagen with trifunctional polyurethane (PU) allows a hybrid matrix to be formed by improving the coupling with exogenous polymeric chains to generate innovative semi-interpenetrated network (semi-IPN) hydrogels. The incorporation of polyacrylate (PA) within a hybrid matrix of collagen-PU allows to regulate the structure and physicochemical properties such as polymerization rate, physicochemical crosslinking, thermal stability, storage module and swelling/degradation behavior of the 3D matrices in the hydrogel state, also exhibiting modulation of their in vitro biocompatibility properties. This work contemplates the study of the effect of PA concentration on the physicochemical properties and the in vitro biological response of these novel semi-IPN hydrogels based on collagen-PU-PA. The results indicate that semi-IPN hydrogels that include 20 wt% of PA exhibit improved swelling with respect to the collagen-PU hydrogel, controlling the degradation rate in acidic, alkaline and proteolytic media; showing E. coli inhibition capacity, high hemocompatibility and not altering the metabolism of monocytes and fibroblasts growing on them. Therefore, these novel hydrogels represent biomaterials with potential application in biomedical strategies such as wound healing dressings.