Addition Of Genipin Research Articles

Structural manipulation of the gelatin/genipin network to inform the molecular transport of caffeine

Low-solid gelatin hydrogels crosslinked with varied levels of genipin were examined to determine the effect of morphological properties on swelling and bioactive diffusion phenomena. FTIR analysis paired with WAXD showed the successful entrapment of caffeine and, when combined with the ninhydrin assay, confirmed the crosslinking of gelatin with genipin. Further investigation of the system with rheological profiling yielded a picture of the overall gel strength increasing with crosslinking and a change in the conformation of the gelatin chains with genipin addition. SEM micrographs were utilised to confirm the microstructural evaluation given by the Flory-Rehner theory from swelling studies. Further quantitative estimations of the gel crosslinking were also developed using this theory with increasing genipin concentration markedly changing the network density and mesh properties. Diffusive transport of caffeine was analysed for different proportions of genipin crosslinking with the denser crosslinked structures evidently hindering the free movement of bioactive molecules. The coupling parameter (ξ) between polymeric network and bioactive cargo, and the critical molecular weight between two crosslinks (M*c) were also determined to relate structural property to molecular diffusion.

Genipin as a Cross-linker in a Ciprofloxacin Delivery System Containing a Bovine Hydroxyapatite-Collagen Composite for Bone Infections

The purpose of this research was to design an implant for a ciprofloxacin-based drug delivery system by combining bovine hydroxyapatite and collagen with genipin as the crosslinking agent. The production of ciprofloxacin implants using bovine hydroxyapatite:collagen blend (70:30). In addition, this synthetic preparation was made using three various concentrations of genipin (0.6, 0.8, and 1.0%). The pellets were created by compressing the implants. The tablets are cylindrical with a diameter of 4.0 mm and a weight of 100.0 mg. Ciprofloxacin cultures were characterized for swelling rate, porosity, density, compressive strength, morphology (SEM), dose, and drug release in vitro. The addition of genipin as a crosslinking agent may maintain ciprofloxacin release consistent with in vitro therapeutic levels of ciprofloxacin. These results are supported by compressive strength data, where the addition of genipin concentrations induces higher implant stiffness and scanning electron microscopy photomicrographs reveal small pore sizes and BHA adhere to collagen fibers so that ciprofloxacin is completely dispersed in the implant after cross-linking with genipin. As a drug delivery system for osteomyelitis, it can be concluded that the use of genipin as a cross-linking agent can sustain ciprofloxacin release commensurate with in vitro therapeutic levels of ciprofloxacin for 30 days.

Microstructure and Mechanical Strength Properties of Chitosan Sponges Obtained from Polymer Solutions in Carbonic Acid

Polymer sponges based on chitosan are first obtained from chitosan solutions in carbonic acid and gels based on these solutions crosslinked by a noncytotoxic agent of natural origin, genipin. A comparative analysis of the structure and mechanical strength properties of sponges prepared from chitosan solutions in carbonic and acetic acids is carried out. It is shown that the addition of genipin in an amount of ~2 wt % to a chitosan solution in carbonic acid leads to a decrease in the average pore size by ~2.5 times and a significant increase in the strength characteristics of the material in comparison with the sponge prepared without genipin.

Genipin guides and sustains the polarization of macrophages to the pro-regenerative M2 subtype via activation of the pSTAT6-PPAR-gamma pathway

M2 macrophages are associated with deposition of interstitial collagen and other extracellular matrix proteins during the course wound healing and also inflammatory response to biomaterials. Developing advanced biomaterials to promote the M2 subtype may be an effective way to improve tissue reinforcement surgery outcomes. In this study, the effect of genipin, a naturally derived crosslinking agent, on M0 → M2-polarization was investigated. Genipin was introduced either indirectly by seeding cells on aligned collagen biotextiles that are crosslinked by the agent or in soluble form by direct addition to the culture medium. Cellular elongation effects on macrophage polarization induced by the collagen biotextile were also investigated as a potential inducer of macrophage polarization. M0 and M2 macrophages demonstrated significant elongation on the surface of aligned collagen threads, while cells of the M1 subtype-maintained a round phenotype. M0 → M2 polarization, as reflected by arginase and Ym-1 production, was observed on collagen threads only when the threads were crosslinked by genipin, implicating genipin as a more potent inducer of the regenerative phenotype compared to cytoskeletal elongation. The addition of genipin to the culture medium directly also drove the emergence of pro-regenerative phenotype as measured by the markers (arginase and Ym-1) and through the activation of the pSTAT6-PPAR-gamma pathway. This study indicates that genipin-crosslinked collagen biotextiles can be used as a delivery platform to promote regenerative response after biomaterial implantation. Statement of significanceThe immune response is one of the key determinants of tissue repair and regeneration rate, and outcome. The M2 macrophage subtype is known to resolve the inflammatory response and support tissue repair by producing pro-regenerative factors. Therefore, a biomaterial that promotes M2 sub-type can be a viable strategy to enhance tissue regeneration. In this study, we investigated genipin-crosslinked electrochemically aligned collagen biotextiles for their capacity to induce pro-regenerative polarization of M0 macrophages. The results demonstrated that genipin, rather than matrix-induced cellular elongation, was responsible for M0 → M2 polarization in the absence of other bioinductive factors and maintaining the M2 polarized status of macrophages. Furthermore, we identified that genipin polarizes the M2 macrophage phenotype via activation of the pSTAT6-PPAR-gamma pathway.

Fabrication of multifunctional mucoadhesive buccal patch for drug delivery applications

Mucoadhesive buccal patch is a promising dosage form for a successful oral drug delivery, which provides unique advantages for various applications such as treatment of periodontal disease and postdental surgery disorders. The aim of this study is to synthesize a novel multifunctional mucoadhesive buccal patch in a multilayer reservoir design for therapeutic applications. The patches were fabricated through simultaneous electrospinning of chitosan/poly(vinylalcohol) (PVA)/ibuprofen and electrospraying of phenylalanine amino acid nanotubes (PhNTs) containing metronidazole into the electrospun mats through a layer-by-layer process. An electrospun poly(caprolactone) (PCL) was used as an impermeable backing layer to protect the mucoadhesive component from tongue movement and drug loss. Buccal patches were characterized using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) and also evaluated in terms of physicomechanical parameters such as pH, weight, thickness, tensile strength, folding endurance, and mucoadhesive properties. The swelling index of the patches was examined with respect to the PVA/chitosan ratio. The effect of genipin addition to the electrospinning solution was also studied on mucoadhesive and swelling properties. The cell viability of buccal patches was assessed by methylthiazolydiphenyl-tetrazolium bromide test on L929 fibroblast cell line. The patch with an optimal amount of mucoadhesive polymers (PVA/chitosan 80:20) and crosslinking agent (0.05 g) indicated an ideal hemostatic activity along with antibacterial properties against Streptococcus mutans bacteria. The synthesized multifunctional mucoadhesive patch with a novel composition and design has a great potential for oral therapeutic applications.

Polyhexanide and chlorhexidine loaded chitosan wound dressings

Introduction Wounds may be caused by surgery, trauma, or as a result of diseases such as diabetes. The disruption of the skin/internal tissues and the contact with the external environment may lead to microbial infection. Wound dressings are capable of providing a protective barrier and accelerate the wound healing process [1]. Chitosan is one of the most promising materials for wound dressings, due to its good biocompatibility, low toxicity, haemostatic properties, antibacterial activity and biodegradability [2]. The main goal of this work is to produce chitosan-based hydrogels to be used as efficient and safe drug delivery platforms. Materials and methods Two different chitosan-based materials were produced starting from Bioceramed formulations, AbsorKi (suitable for absorbing exudate from the wound) and HemoKi (enhancing haemostasis). The latter was modified by the addition of genipin, a cross-linking agent. The dressings were individually loaded with two different drugs, polyhexamethylene biguanide (PHMB, also called polyhexanide) and chlorhexidine diacetate (CHX), by soaking in solutions containing each drug (24 h, 5 mL, 36 °C, 180 rpm, 0.5 mg/mL for PHMB and 5 mg/mL for CHX). The physical properties (swelling, tensile strength) of the materials were studied prior and upon sterilisation by high hydrostatic pressure (HHP, 600 MPa, 10 min, 70 °C). Surface morphology was analysed by scanning electron microscopy (SEM). In vitro drug release studies were performed with a Franz diffusion cell system, combined with UV–Vis absorption spectroscopy for drug quantification. The efficiency of HHP was evaluated by sterility tests. Chorioallantoic membrane (HET-CAM) tests were done to study potential irritation of the skin. Results Both dressings present a porous structure and an extremely high swelling capacity (>1700%) before sterilisation. HPP affected the materials in different ways: it increased the swelling capacity of AbsorKi but decreased it for HemoKi. The drug release profiles indicated that the concentrations of PHMB and CHX increased in a sustained way on the first day. HHP increases the amount of drug released, except for AbsorKi with PHMB. Regarding the mechanical properties, sterilisation improved the resistance of both dressings. HET-CAM tests suggest that the produced materials do not lead to irritation. Discussion and conclusions HHP revealed an efficient method to ensure the materials sterilisation making the drug loaded wound dressings potentially efficient devices for the absorption of exudate from the wound bed. The combination of chitosan, a natural antibacterial agent, with the studied disinfectant and antiseptic drugs may lead to promising materials to be used as drug delivery platforms. Further studies in animal models are needed to conclude about the safety and clinical usefulness of the developed dressings.

Effects of short-duration treatment of cartilage with punicalagin and genipin and the implications for treatment of osteoarthritis.

Punicalagin (PA) not only binds type II collagen, but also blocks its MMP-13-mediated degradation, and genipin (GNP) is a collagen cross-linking agent. We hypothesized that these drugs could mitigate the loss of cartilage if administered in the early phase of osteoarthritis, and experiments were designed to provide proof-of-concept. Porcine cartilage was exposed to both drugs in a manner designed to simulate intra-articular (IA) injection. Based on penetration of PA into cartilage, the rate of drug diffusion was conservatively estimated at 2 μm per minute. GNP caused a measurable degree of cross-linking, increased compressive resistance and coefficient of friction, and substantially inhibited degradation by collagenase, but not by hyaluronidase. Pre-incubation of GNP with collagenase had no effect on enzymatic activity. PA did not cross-link collagen nor affect the mechanical properties of cartilage. It did, however, increase resistance to degradation by collagenase and hyaluronidase. Furthermore, it reacted with collagenase in solution and inhibited its subsequent enzymatic activity. Effects of PA and GNP were not additive. The chondroprotective effect of semi-weekly IA injections was investigated in the monoiodoacetate-induced model of OA in rats. Quantitative histology suggested that injection of PA decreased the amount of cartilage lost compared to saline-injected controls, and the addition of GNP made no difference. This study supports the notion that IA delivery of PA could mitigate OA-induced cartilage erosion.

Development and in vitro evaluation of mucoadhesive gelatin films for the vaginal delivery of econazole.

Several strategies have been explored to obtain effective econazole nitrate (ECN) concentrations at the site of application for a prolonged time. In this paper, different gelatin-based film formulations for vaginal application were investigated, containing ECN (10% w/w with respect to gelatin) as pure drug or as drug-solid dispersions (SD). For the production of SD, different polymers were evaluated: polyvinylpyrrolidone (PVP), Soluplus® (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer) and Gelucire® 50/13 (mixture of mono-, di- and triglycerides of fatty acids, esters of PEG 1500 and free PEG). Gelucire®-SD showed the best solubility enhancement, increasing 9.2 times the ECN solubility in pH 4.5 solution respect to pure drug; DSC and XRD analysis confirmed the crystalline form of the drug. XRD results evidenced that all gelatin-based films, containing either the drug or the SD, underwent the topotactic transformation of ECN into crystalline econazole (EC), owing to a strong interaction between the drug and the gelatin. Films containing Gelucire®-based SD displayed lower brittleness and rigidity with respect to the other samples; moreover they demonstrated good structural integrity after 24h of incubation in the acidic solution (swelling degree of about 350%). Then, Gelucire®-SD based films were compared with the corresponding formulations cross-linked by genipin (2% w/w). The addition of genipin did not interfere with the drug-gelatin interaction. Gelucire®-SD based films showed similar release profiles to neat gelatin films, enhancing the drug release in the first 5h and controlling the EC release over time, avoiding the use of a crosslinking additive. Finally, gelatin films containing Gelucire® solid dispersion displayed good adhesiveness and anti-Candida activity. Overall, results support the potential use of this film formulation as noncytotoxic EC delivery system for the treatment of vaginal candidiasis.

Investigation of Chitosan Film Degradation in Tissue Engineering Applications

In this paper, the biological and physical properties of chitosan, a potential polysaccharide resource, were investigated. The proposed film was synthesised by mixing chitosan (CS) solution and polyvinyl alcohol (PVA) using solvent casting. The modified chitosan/PVA films were then subjected to analysis by Fourier transform infrared spectroscopy (FTIR), in which intermolecular hydrogen bonding between the molecules of CS and PVA was clearly demonstrated. The swelling degree of chitosan along with the contact angle were also examined. After the addition of genipin, which increased chitosan concentration the swelling degree, degradation rate, and contact angle was decreased. The results confirm that the properties of chitosan are such that they can be employed for tissue engineering applications.

Fibrin-Genipin Hydrogel for Cartilage Tissue Engineering in Nasal Reconstruction.

Nasal reconstruction is limited by the availability of autologous cartilage. The aim is to investigate an adhesive biomaterial for tissue engineering of nasal cartilage by evaluating mechanical properties of hydrogels made of fibrin crosslinked with genipin as compared to native tissue. Hydrogels of fibrin, fibrin-genipin, and fibrin-genipin with extracellular matrix (ECM) particles were created and evaluated with mechanical testing to determine compression, tensile, and shear properties. Rabbit nasal septal cartilage was harvested and tested in these modalities for comparison. Transmission electron microscopy characterized hydrogel structure. Fibrin-genipin gels had higher compressive, tensile, and shear moduli compared to fibrin alone or fibrin-genipin with ECM. However, all hydrogel formulations had lower moduli than the rabbit nasal septal cartilage. Electron microscopy showed genipin crosslinking increased structural density of the hydrogel and that cartilage ECM created larger structural features with lower crosslinking density. The addition of genipin significantly improved mechanical properties of fibrin hydrogels by increasing the compressive, tensile, and shear moduli. The addition of cartilage ECM, which can add native structure and composition, resulted in decreased moduli values. Fibrin-genipin is a bioactive and biomechanically stable hydrogel that may offer promise as a scaffold for cartilage tissue engineering in nasal reconstruction, yet further augmentation is required to match material properties of native nasal cartilage.

Diffusion and relaxation contributions in the release of vitamin B6 from a moving boundary of genipin crosslinked gelatin matrices

A fundamental study was carried out to evaluate patterns of vitamin B6 release from genipin crosslinked gelatin in aqueous media at ambient temperature. Up to ninety percent crosslinking was achieved, with FTIR and WAXD data arguing for partial replacement of the triple helix with a covalent pattern of bonding between protein and crosslinker. Formation of a “composite network” yielded increasing compressive stress-at-failure values followed by a decrease as a function of genipin addition, with the yield strain decreasing continuously. Electron microscopy images showed a reduction in the size of the hydrogel pores with a higher degree of crosslinking. Experimental evidence was supported by the Flory-Rehner theory that predicted a lower swelling ratio and reduced molecular weight between adjacent crosslinks with genipin addition. Furthermore, Peppas-Sahlin equation was used to rationalise the interplay between network morphology and diffusion of bioactive compound over prolonged timeframes of release testing.

Study on the preparation and drug release property of soybean selenoprotein/carboxymethyl chitosan composite hydrogel

Abstract Soybean selenoprotein/carboxymethyl chitosan (SSP/CMCS) composite hydrogel obtained by the crosslinking of genipin was evaluated for caffeine release. The gelation process of the hydrogel was investigated by resonance Rayleigh scattering spectra and viscosity methods. The hydrogels presented a compact network structure, which was observed by positive fluorescence microscopy (PFM). The structural properties of the hydrogel were revealed by fluorescence and FT-IR. The swelling characteristic of the hydrogel and its application in the slow release of caffeine were also studied. These results indicate that there is obvious interaction between SSP and CMCS by the addition of genipin, and the CMCS/SSP solution experiences a significant sol-gel phase transition process upon polymerization. The swelling ratio and release of caffeine slow down obviously at pH 1.2. However, larger swelling and more drug release can be observed at pH 7.4. The experimental values of the empiric diffusional exponent show that the release profiles abide by the non-Fickian diffusion process under both investigated pH conditions. The hydrogel, which is pale transparent with light yellow color at room temperature, can be formulated to be a suitable carrier for site-specific drug delivery.

‐stimulated crosslinking of catechol‐conjugated hydroxyethyl chitosan as a tissue adhesive

Catechol-functionalized polymers are of particular interest because of their strong water-resistant adhesive properties. Hydroxymethyl chitosan (HECTS) has been used as an implantable biomaterial having good water solubility, biodegradability and biocompatibility. Here, hydrocaffeic acid (HCA) grafted HECTS (HCA-g-HECTS) was prepared through carbodiimide coupling and the tethered catechol underwent periodate ( )-stimulated mono and double cross-linking with genipin. The gelation time of these cross-linked HCA-g-HECTS hydrogels decreased with increasing molar ratio of cross-linker to grafted catechol group, increasing temperature, or the addition of genipin. Under the same molar ratio of cross-linker to catechol, -induced cross-linked HCA-g-HECTS hydrogels exhibited much stronger storage modulus and temperature stability than hydrogels made by Fe3+ -triggered cross-linking. The -stimulated HCA-g-HECTS hydrogels were biocompatible on a cellular level when the molar ratio of to catechol group was less than 0.5:1. The hydrogels prepared with a 0.125:1 molar ratio of to catechol group exhibited high adhesion strength of 73.56 kPa against wet rat skin, and a higher adhesion strength than sutures in a rat wound closure model. This biocompatible -stimulated HCA-g-HECTS hydrogel may represent a promising new tissue adhesive. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 582-593, 2019.

Genipin Reverses HFD-Induced Liver Damage and Inhibits UCP2-Mediated Pyroptosis in Mice

Background/Aims: Liver damage is a typical manifestation of nonalcoholic fatty liver disease (NAFLD). It originates from excessive fat accumulation, leading to hepatocyte death, inflammation, and fibrosis. Nonalcoholic steatohepatitis (NASH) is a type of NAFLD with a prevalence of 49% in morbidly obese patients. Pyroptosis plays an important role in the development of NASH; thus, it is important to elucidate the effect of lipid accumulation on pyroptosis. Genipin (GNP), a natural water-soluble cross-linking agent, has hepatoprotective effects and decreases lipid accumulation in the liver; however, the mechanisms underlying these effects are unknown. Methods: In this study, qPCR and Western blot were used to examine pyroptotic gene expression in high-fat diet (HFD) induced obese mice and free fatty acids (FFAs) treated hepatocytes. At the same time, relative lactate dehydrogenase (LDH) release and Hoechst & propidium iodide (PI) staining were done to verify cell death. To explore the molecular mechanism, cell transfection were constructed with siRNA or plasmid to obtain knockdown or overexpression hepatocytes. Results: We found that HFD-fed mice and FFAs-treated hepatocytes had obvious pyroptosis, and addition of GNP reversed liver damage and inhibited pyroptosis both in vitro and in vivo. Besides, UCP2 knockdown cells showed suppressed FFAs-mediated pyroptosis, as determined by decreased pyroptotic gene expression, reduced lactate dehydrogenase (LDH) release, and reduced cell death. Consistent with this, cells transfected with UCP2 had upregulated pyroptotic gene expression, increased LDH release, and increased cell death. Conclusion: GNP reverses HFD-induced liver damage and inhibits UCP2-mediated pyroptosis. Thus, GNP may serve as a potential therapeutic candidate for NAFLD.

A mussel-inspired double-crosslinked tissue adhesive intended for internal medical use

It has been a great challenge to develop aldehyde-free tissue adhesives that can function rapidly and controllably on wet internal tissues with fine adhesion strength, sound biocompatibility and degradability. To this end, we have devised a mussel-inspired easy-to-use double-crosslink tissue adhesive (DCTA) comprising a dopamine-conjugated gelatin macromer, a rapid crosslinker (namely, Fe3+), and a long-term acting crosslinker (namely, genipin). As a mussel-inspired gluing macromer, dopamine is grafted onto gelatin backbone via an one-step reaction, the catechol groups of which are capable of performing strong wet adhesion on tissue surfaces. By addition of genipin and Fe3+, the formation of catechol–Fe3+ complexation and accompanying spontaneous curing of genipin-primed covalent crosslinking of gluing macromers in one pot endows DCTA with the double-crosslink adhesion mechanism. Namely, the reversible catechol–Fe3+ crosslinking executes an controllable and instant adhesive curing; while genipin-induced stable covalent crosslinking promises it with long-term effectiveness. This novel DCTA exhibits significantly higher wet tissue adhesion capability than the commercially available fibrin glue when applied on wet porcine skin and cartilage. In addition, this DCTA also demonstrates fine elasticity, sound biodegradability, and biocompatibility when contacting in vitro cultured cells and blood. In vivo biocompatibility and biodegradability are checked and confirmed via trials of subcutaneous implantation in nude mice model. This newly developed DCTA may be a highly promising product as a biological glue for internal medical use including internal tissue adhesion, sealing, and hemostasis. Statement of SignificanceThere is a great demand for ideal tissue adhesives that can be widely used in gluing wet internal tissues. Here, we have devised a mussel-inspired easy-to-use double-crosslink tissue adhesive (DCTA) that meets the conditions as an ideal tissue adhesive. It is composed of gelatin–dopamine conjugates – a gluing macromer, Fe3+ – a rapid crosslinker, and genipin – a long-term acting crosslinker. This DCTA is constructed with a novel complexation-covalent double-crosslinking principle in one pot, in which the catechol–Fe3+ crosslinking executes a controllable and instant adhesive curing, at the same time, genipin-induced covalent crosslinking promises it with long-term effectiveness in physiology conditions. This novel DCTA, with excellent wet tissue adhesion capability, fine elasticity, sound biodegradability, and biocompatibility, is a promising biological glue for internal medical use in surgical operations.

Highly Porous Gelatin Reinforced 3D Scaffolds for Articular Cartilage Regeneration.

3D highly porous (93% total porosity) gelatin scaffolds were prepared according to a novel, simple method, which implies gelatin foaming, gelification, soaking into ethanol and successive freeze-drying. Reinforcement of the as-prepared scaffolds (GEL) was performed through immersion in aqueous solutions at different gelatin concentrations. Reinforcement solutions with and without genipin addition allowed to prepare two series of samples:cross-linked and uncross-linked samples, respectively. The amount of gelatin adsorbed onto the reinforced samples increases as a function of gelatin concentration in solution and provokes a drastic improvement of the compressive modulus and collapse strength up to values of about 30 and 4 MPa, respectively. The open and interconnected porosity, although slightly reduced, is still of the order of 80% in the samples reinforced with the highest concentration of gelatin. Water uptake ability evaluated after immersion in PBS for 20 s decreases with gelatin reinforcement. The presence of genipin in cross-linked samples reduces gelatin release and stabilizes the scaffolds in solution. Chondrocytes from human articular cartilage adhere, proliferate, and penetrate into the scaffolds. The evaluation of differentiation markers both on the supernatants of cell culture and by means of quantitative polymerase chain reaction (qPCR) indicates a dose-dependent promotion of cell differentiation.

Development and characterization of novel agar and gelatin injectable hydrogel as filler for peripheral nerve guidance channels

Injectable hydrogels are becoming of increasing interest in the field of tissue engineering thanks to their versatile properties and to the possibility of being injected into tissues or devices during surgery. In peripheral nerve tissue engineering, injectable hydrogels having shear-thinning properties are advantageous as filler of nerve guidance channels (NGCs) to improve the regeneration process. In the present work, gelatin-based hydrogels were developed and specifically designed for the insertion into the lumen of hollow NGCs through a syringe during surgery. Injectable hydrogels were obtained using an agar-gelatin 20:80 weight ratio, (wt/wt) blend crosslinked by the addition of genipin (A/GL_GP). The physicochemical properties of the A/GL_GP hydrogels were analysed, including their injectability, rheological, swelling and dissolution behaviour, and their mechanical properties under compression. The hydrogel developed showed shear-thinning properties and was applied as filler of NGCs. The A/GL_GP hydrogel was tested in vitro using different cell lines, among them Schwann cells which have been used because they have an important role in peripheral nerve regeneration. Viability assays demonstrated the lack of cytotoxicity. In vitro experiments showed that the hydrogel is able to promote cell adhesion and proliferation. Two- and three-dimensional migration assays confirmed the capability of the cells to migrate both on the surface and within the internal framework of the hydrogel. These data show that A/GL_GP hydrogel has characteristics that make it a promising scaffold material for tissue engineering and nerve regeneration. Copyright © 2014 John Wiley & Sons, Ltd.

Modification and swelling kinetic study of kappa-carrageenan-based hydrogel for controlled release study

In this article, the physical stability of carrageenan hydrogels was improved for in vitro controlled drug delivery in different pH mediums. Physical property changes were studied using various characterization tests. The effect of modification on swelling behavior of hydrogels as well as swelling kinetics of hydrogels was also investigated. It was found that the addition of genipin to the hydrogels can increase the physical properties of carrageenan hydrogels. An optimum genipin concentration in which molecular structure of hydrogel can be in its most stable form is also determined. The study of swelling kinetics revealed that the modification has resulted in the relaxation of carageenan molecules and the swelling mechanism from a diffusion-controlled mechanism is changed to a polymer relaxation-controlled mechanism. Release study shows that by changing the genipin concentration in the hydrogel drug release can be controlled.

Novel naturally crosslinked electrospun nanofibrous chitosan mats for guided bone regeneration membranes: material characterization and cytocompatibility

Guided bone regeneration (GBR) barrier membranes are used to prevent soft tissue infiltration into the graft space during dental procedures that involve bone grafting. Chitosan materials have shown promise as GBR barrier membranes, due to their biocompatibility and predictable biodegradability, but degradation rates may still be too high for clinical applications. In this study, chitosan GBR membranes were electrospun using chitosan (70% deacetylated, 312 kDa, 5.5 w/v%), with or without the addition of 5 or 10 mm genipin, a natural crosslinking agent, in order to extend the degradation to meet the clinical target time frame of 4-6 months. Membranes were evaluated for fibre diameter, tensile strength, biodegradation rate, bond structure and cytocompatibility. Genipin addition, at 5 or 10 mm, resulted in median fibre diameters 184, 144 and 154 nm for uncrosslinked, 5 mm and 10 mm crosslinked, respectively. Crosslinking, examined by Fourier transform infrared spectroscopy, showed a decrease in N-H stretch as genipin levels were increased. Genipin-crosslinked mats exhibited only 22% degradation based on mass loss, as compared to 34% for uncrosslinked mats at 16 weeks in vitro. The ultimate tensile strength of the mats was increased by 165% to 32 MPa with 10 mm crosslinking as compared to the uncrosslinked mats. Finally, genipin-crosslinked mats supported the proliferation of SAOS-2 cells in a 5 day growth study, similar to uncrosslinked mats. These results suggest that electrospun chitosan mats may benefit from genipin crosslinking and have the potential to meet clinical degradation time frames for GBR applications.

Injectable Collagen–Genipin Gel for the Treatment of Spinal Cord Injury: In Vitro Studies

AbstractSpinal cord injury (SCI) often results in a cavitary lesion, contained within the dura, which involves only a portion of the cord. Injectable biopolymers are an attractive treatment option for SCI to re‐establish cell migratory pathways within the lesion while minimizing the collateral damage attendant to an open surgical procedure. In this study we evaluate a thermoresponsive soluble collagen gel incorporating genipin, an amine reactive covalent cross‐linker with low cytotoxicity and fluorogenic attributes. Unlike previous studies, genipin is being investigated as an in situ covalent cross‐linker that will continue to act on the gel after injection. Physical characterization studies show that the addition of genipin provides control over the mechanical and degradative behavior of the gel, to meet design specifications of an injectable material for neural tissues. Additionally, an improved in situ assay to predict the extent of cross‐linking reaction is investigated. Encapsulation of mesenchymal stem cells (MSCs) in collagen–genipin gels show the gels support cell viability and proliferation, and thus serve as a cell delivery vehicle. Neural stem cells are found to be more sensitive to genipin, with respect to toxicity, as compared to MSCs. From our studies, 0.25‐0.5 mM is an appropriate genipin concentration to use for an in situ forming scaffold capable of delivering cells and therapeutic agents.