Crosslinking effect of dialdehyde starch (DAS) on decellularized porcine aortas for tissue engineering

In vitro and in silico approach towards antimicrobial and antioxidant behaviour of water-soluble chitosan dialdehyde biopolymers

Chitosan dialdehyde (ChDA) was prepared from a three-step process initiated by thermal organic acid hydrolysis, periodate oxidization, and precipitation from native chitosan (NCh). The developed ChDA resulted in an aldehydic content of about 82 % with increased solubility (89 %) and maximum yield (97 %). The functional alteration of the aldehydic (-CHO) group in ChDA was established using vibrational stretching at 1744 cm-1. The increase in the zone of inhibition of ChDA compared to NCh has confirmed the inherent antimicrobial effect against bacterial and fungal species. ChDA showed better antioxidant activity of about 97.4 % (DPPH) and 31.1 % (ABTS) compared to NCh, measuring 45.3 % (DPPH) and 15.9 % (ABTS), respectively. The novel insilico predictions of the ChDA's biocidal activity were confirmed through molecular docking studies. The amino acid moiety such as ARG 110 (A), ASN 206 (A), SER 208 (A), THR 117 (B), ASN 118 (B), and LYS 198 (B) residues of 7B53 peptide from E. coli represents the binding pockets responsible for interaction with aldehyde group of ChDA. Whereas PHE 115 (E), ALA 127 (H), TYR 119 (C), GLN 125 (H), ASN 175 (E), ARG 116 (E), LYS 101 (H), and LYS 129 (H) of 1IYL A peptide from Candida albicans makes possible for binding with ChDA. Hence, the synergistic effect of ChDA as a biocidal compound is found to be plausible in the drug delivery system for therapeutic applications.

Dialdehyde Starch as a Cross-Linking Agent Modifying Fish Collagen Film Properties

The aim of this research was the modification of fish collagen films with various amounts of dialdehyde starch (DAS). Film properties were examined before and after the cross-linking process by DAS. Prepared biopolymer materials were characterized by Fourier Transform Infrared Spectroscopy and Atomic Force Microscopy. Moreover, the mechanical, thermal and swelling properties of the films were evaluated and the contact angle was measured. Research has shown that dialdehyde starch applied as a cross-linking agent influences collagen film properties. Mechanical testing indicated a decrease in Young's Modulus and an increase in breaking force, elongation at break, and tensile strength parameters. Results for contact angle were significantly higher for collagen films cross-linked with DAS; thus, the hydrophilicity of samples decreased. Modified samples presented a lower swelling degree in PBS than native collagen films. However, the highest values for the degree of swelling among the modified specimens were obtained from the 1% DAS samples, which were 717% and 702% for 1% and 2% collagen, respectively. Based on AFM images and roughness values, it was noticed that DAS influenced collagen film surface morphology. The lowest value of Rq was observed for 2%Coll_2%DAS and was approximately 10 nm. Analyzing thermograms for collagen samples, it was observed that pure collagen samples were less thermally stable than cross-linked ones. Dialdehyde starch is a promising cross-linking agent for collagen extracted from fish skin and may increase its applicability.

Recent advances on the preparation conditions, structural characteristics, physicochemical properties, functional properties and potential applications of dialdehyde starch: A review

Starch, a natural storage polysaccharide of plant kingdom, has many industrial applications. However, native starch has some inherent shortages, which can be overcome by structural modification. Dialdehyde starch, one kind of oxidized starch produced by periodate oxidation, has good physical properties and bioactivities with wide applications in different fields. Dialdehyde starch is typically achieved by oxidizing native starch slurry through periodate oxidation under controlled reaction conditions. Several factors including the source of starch, the type of oxidant, the molar ratio of oxidant to starch, reaction temperature, reaction time and solution pH value can influence the synthesis of dialdehyde starch. Dialdehyde starch shows different spectroscopic/chromatographic characters and physicochemical properties from native starch. Moreover, dialdehyde starch exhibits good antioxidant activity, antimicrobial activity and cross-linking property. Based on these functional properties, dialdehyde starch has shown application potentials in food packaging, thermoplastic production, enzyme immobilization, heavy metal ion adsorption, drug delivery, wood adhesion and leather tanning. In this review, the preparation conditions, structural characteristics, physicochemical properties, functional properties and potential applications of dialdehyde starch are summarized for the first time. The future research and development prospects of dialdehyde starch are also discussed.

In situ forming of PEG-NH2/dialdehyde starch Schiff-base hydrogels and their application in slow-release urea

In this study, a biodegradable Schiff-base hydrogel urea, possessing substantial water retention and certain slow-release ability was designed and synthesized. Firstly, dialdehyde starch (DAS) and amine-terminated polyethylene glycol (PEG-(NH2)2) were synthesized using potato starch and polyethylene glycol. Then, a novel Schiff-base hydrogel (SH) was prepared through the in-situ reaction between the aldehyde group of DAS and the amino group of PEG-(NH2)2. Three SH based slow-release urea, designated as SHU1, SHU2, and SHU3 and distinguished by varying urea content, were obtained using SH as the substrate. Several characterizations and tests were conducted to determine the structure, thermal properties, morphology, swelling properties, sustainable use, water retention, and biodegradation properties of SH. Additionally, the slow-release behavior of SHU was studied. SEM results revealed that SH possessed a porous three-dimensional network structure, with a maximum water absorption capacity of 4440 % ± 6.23 %. Compared to pure urea, SHU exhibited better slow-release performance after 30 days of release in soil, with SHU1 having a residual nitrogen content of specifically 36.01 ± 0.57 % of the initial nitrogen content. A pot experiment with pakchoi substantiated the water retention and plant growth promotion properties of SHU. This study demonstrated a straightforward method for the preparation of starch-based Schiff-base hydrogels as fertilizer carriers.

Are Natural Compounds a Promising Alternative to Synthetic Cross-Linking Agents in the Preparation of Hydrogels?

The main aim of this review is to assess the potential use of natural cross-linking agents, such as genipin, citric acid, tannic acid, epigallocatechin gallate, and vanillin in preparing chemically cross-linked hydrogels for the biomedical, pharmaceutical, and cosmetic industries. Chemical cross-linking is one of the most important methods that is commonly used to form mechanically strong hydrogels based on biopolymers, such as alginates, chitosan, hyaluronic acid, collagen, gelatin, and fibroin. Moreover, the properties of natural cross-linking agents and their advantages and disadvantages are compared relative to their commonly known synthetic cross-linking counterparts. Nowadays, advanced technologies can facilitate the acquisition of high-purity biomaterials from unreacted components with no additional purification steps. However, while planning and designing a chemical process, energy and water consumption should be limited in order to reduce the risks associated with global warming. However, many synthetic cross-linking agents, such as N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate, poly (ethylene glycol) diacrylates, epichlorohydrin, and glutaraldehyde, are harmful to both humans and the environment. One solution to this problem could be the use of bio-cross-linking agents obtained from natural resources, which would eliminate their toxic effects and ensure the safety for humans and the environment.

The combined effect of thermal-acid hydrolysis, periodate oxidation, and iodine species removal on the properties of native tapioca (Manihot esculenta Crantz) starch

Through a four-step top-down approach, native tapioca starch (NTS) was thermally acid-hydrolyzed, periodate-oxidized with subsequent removal of iodine species (i.e., IO₄(-), IO₃(-), I(-), and I₂), and dialdehyde tapioca starch (DTS) alcohol-precipitation. The percent yield was ∼91%. Analyses confirmed the presence of aldehydic functionalities (∼71%), effectual iodine species removal (∼98%), and enhanced water-solubility (∼96.57%). Besides, the combined treatment significantly reduced the M_w (∼57.81 kDa) and ameliorated homogeneity as well as thermal stability (T_max ∼ 667.15 °C). Structural-spectral characterization also confirmed the presence of aldehydic functionality, polymorphic transition (C- to A-type), and a higher degree of crystallinity (∼91.77%), the latter further corroborated by thermal analysis. The morphological study revealed that the combined treatment reduced size (∼393.55-nm-diameter and ∼5.22-μm-length) and changed shape into rod-like crystals. DTS showed considerably and significantly low cytotoxicity to HaCaT cells in vitro at the concentrations assayed over the test period (24 h). DTS's conformation was most stable at -289 kcal/mol and -151.7 au heat formation and minimum potential energies, respectively. Overall, these results demonstrated that the combined treatment had no deleterious effects on NTS's properties, thus yielded DTS with ideal properties for multifarious uses.

Highly stable collagen scaffolds crosslinked with an epoxidized natural polysaccharide for wound healing

As a biocompatible and bioactive natural tissue engineering collagen scaffold, porcine acellular dermal matrix (pADM) has limitations for the application in tissue regeneration due to its low strength and rapid biodegradation. Herein, to get a good wound dressing, the epoxy group was added to N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC) to synthesize the epoxidized N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (EHTCC), and the porcine acellular dermal matrix was modified with EHTCC at different dosage of 0, 4, 8, 12, 16 and 20%. The properties of the EHTCC-pADM were evaluated. The results indicated that the thermal stability and mechanical properties of EHTCC-pADM were remarkably improved, and the natural conformation of the matrix was maintained, which was beneficial to natural and excellent biological properties of the pADM. According to the test results of water contact angle, the hydrophilicity of the material was improved, which is conducive to cell adhesion, proliferation and growth. Cytotoxicity experiments showed that the introduction of EHTCC would not adversely affect the biocompatibility of the materials. In vivo experiments showed that EHTCC-pADM could promote wound healing. In conclusion, EHTCC-pADM is a potential collagen-based dressing for wound healing.

Is Dialdehyde Chitosan a Good Substance to Modify Physicochemical Properties of Biopolymeric Materials?

The aim of this work was to compare physicochemical properties of three dimensional scaffolds based on silk fibroin, collagen and chitosan blends, cross-linked with dialdehyde starch (DAS) and dialdehyde chitosan (DAC). DAS was commercially available, while DAC was obtained by one-step synthesis. Structure and physicochemical properties of the materials were characterized using Fourier transfer infrared spectroscopy with attenuated total reflectance device (FTIR-ATR), swelling behavior and water content measurements, porosity and density observations, scanning electron microscopy imaging (SEM), mechanical properties evaluation and thermogravimetric analysis. Metabolic activity with AlamarBlue assay and live/dead fluorescence staining were performed to evaluate the cytocompatibility of the obtained materials with MG-63 osteoblast-like cells. The results showed that the properties of the scaffolds based on silk fibroin, collagen and chitosan can be modified by chemical cross-linking with DAS and DAC. It was found that DAS and DAC have different influence on the properties of biopolymeric scaffolds. Materials cross-linked with DAS were characterized by higher swelling ability (~4000% for DAS cross-linked materials; ~2500% for DAC cross-linked materials), they had lower density (Coll/CTS/30SF scaffold cross-linked with DAS: 21.8 ± 2.4 g/cm3; cross-linked with DAC: 14.6 ± 0.7 g/cm3) and lower mechanical properties (maximum deformation for DAC cross-linked scaffolds was about 69%; for DAS cross-linked scaffolds it was in the range of 12.67 ± 1.51% and 19.83 ± 1.30%) in comparison to materials cross-linked with DAC. Additionally, scaffolds cross-linked with DAS exhibited higher biocompatibility than those cross-linked with DAC. However, the obtained results showed that both types of scaffolds can provide the support required in regenerative medicine and tissue engineering. The scaffolds presented in the present work can be potentially used in bone tissue engineering to facilitate healing of small bone defects.

Structure validation of oxidized poly (2-hydroxyethyl acrylate) with multiple aldehyde groups and its application for collagen modification

The structural characteristic of oxidized poly (2-hydroxyethyl acrylate) (OP) was confirmed by high-performance liquid chromatography, gel permeation chromatography and hydroxylamine hydrochloride titration. The results demonstrated that OP prepared through 2,2,6,6-tetramethylpiperidine-1-oxyl-mediated oxidation of poly (2-hydroxyethyl acrylate) was featured by multiple aldehyde groups on its side chain, with no free formaldehyde produced during the oxidation process. The computational simulation for the electrophilic reactivity of OP molecule showed that the reactivity of the aldehyde groups in OP with the amino groups of collagen was comparable to that of glutaraldehyde. In this study, OP was chosen as a collagen modifier to investigate the modification effects on the secondary structure, aggregation behaviour and thermal stability of collagen. The covalent cross-linking occurred between the aldehyde groups of OP and the amino groups of collagen under alkaline condition. The covalent binding between OP and collagen was strengthened with the increasing reaction pH and OP dosage, and the triple helix of collagen was altered to some degree. Furthermore, OP promoted the intense aggregation of collagen and enhanced the thermal stability of collagen. This work provides guidance for preparing novel collagen modifier with multiple aldehyde groups.

Development of Contact Lens-Shaped Crosslinked Amniotic Membranes for Sutureless Fixation in the Treatment of Ocular Surface Diseases

Purpose

To develop a new method of manufacturing contact lens-shaped crosslinked amniotic membranes (AMs) using glutaraldehyde (GA) and dialdehyde starch (DAS) as crosslinking agents.

Methods

Amniotic membranes were placed on a curved plastic mold and crosslinked with either 4.5% DAS or 1% GA, after which their physical properties and biological safety were evaluated.

Results

The tensile strength of the GA- and DAS-crosslinked samples was much increased compared with that of normal AMs. Neither crosslinking process affected AM transparency. Although the GA-crosslinked AM showed better enzymatic resistance, its physiological structure was severely damaged after the crosslinking process. On the other hand, compared with the GA-crosslinked AM, the DAS-crosslinked AM showed higher growth factor concentrations and better biocompatibility, similar to normal AMs. In addition, the DAS-crosslinked AM was effective in the recovery of corneal epithelial wounds and was well maintained over 3 days without decentration or degradation on the ocular surface in human subjects.

Conclusions

Contact lens-shaped AMs were successfully prepared with crosslinking agents. Crosslinking with DAS did not affect the structural properties or biological activity of the AMs, and the improved mechanical properties helped the AM to maintain its curved shape. This crosslinking method allowed us to transplant AMs into patients’ eyes without sutures.

Translational Relevance

Sutureless fixation of contact lens-shaped AMs would be very convenient and safe for the treatment of corneal surface disease.

Crosslinking of Chitosan with Dialdehyde Chitosan as a New Approach for Biomedical Applications

Materials based on natural high molecular compounds are particularly interesting for biomedical applications. It is known that the cross-linking agent used for preparation of biomacromolecule-based materials is as important as used biopolymer. Therefore, natural cross-linkers containing reactive carbonyl groups are of great interest especially for modifying properties of natural polysaccharides. One of the most popular cross-linking agents is glutaraldehyde. Nevertheless, the unreacted particles can be released from the cross-linked material and cause cytotoxic effects. This can be eliminated when using a cross-linker based e.g., on polysaccharides. This article describes quick and efficient synthesis of dialdehyde chitosan (DACS) and its application for the preparation of chitosan films. Materials obtained with different amount of DACS were fully characterized in terms of structure and surface morphology. Thermal and mechanical properties as well as hydrophilic character were also examined. The results obtained were compared with the materials obtained by cross-linking chitosan with low molecular weight glutaraldehyde and high molecular weight cross-linking agent based on polysaccharide-dialdehyde starch. Toxicity of all obtained materials was tested using the Microtox® test. It has been shown that due to better mechanical, thermal and surface properties as well as lower toxicity, dialdehyde chitosan is a very promising crosslinking agent.

Preparation and characterization of collagen/hyaluronic acid/chitosan film crosslinked with dialdehyde starch

In this work thin film made from the mixture of collagen, hyaluronic acid and chitosan were obtained during solvent evaporation method. The mixtures of biopolymers were modified by dialdehyde starch, which was used as a crosslinking agent. The influence of crosslinking agent on the physico-chemical properties of polymeric matrices was evaluated. The interactions between functional groups of polymers were evaluated by Fourier transform infrared spectroscopy for both unmodified and modified samples. Mechanical properties of film were tested in dry condition using a mechanical testing machine. Morphology of the surface was studied by Atomic Force Microscopy and the roughness parameters were analyzed. Moreover, surface free energy and its polar and dispersive components were evaluated by contact angle measurements. It was found that the addition of dialdehyde starch modified all tested parameters of the studied films. Samples became less elastic and more resist for rupture. Moreover, samples became less rough after crosslinking process and surface free energy increased. Thin film made from the mixture of collagen, hyaluronic acid and chitosan crosslinked with dialdehyde starch can be applied in medicine and in cosmetics.

Injectable hydrogel based on dialdehyde galactomannan and N-succinyl chitosan: a suitable platform for cell culture

Regenerative medicine proposes to regenerate or even replace human damaged tissues to return to normal functions. Hence, biomaterials have been used to provide appropriate environment for cell development. Among the groups of biodegradable biomaterials, hydrogels, which are characterized by three-dimensional and cross-linked networks of water-soluble polymers, have been highlighted as suitable matrices for such applications. An injectable hydrogel based on oxidized galactomannan (OxGM) from Delonix regia and N-succinyl chitosan (NSC) was developed and characterized according to its physicochemical and biocompatible properties. The hydrogel was formed by Schiff base (-CH = N-) cross-linking between aldehyde groups from OxGM and NH₂ groups from NSC, in few minutes (9.7 min) without any external stimulus. A hydrogel with macroporous structure, interconnected pores, and porosity of 69% was obtained. The biomaterial exhibited excellent injectability. No change in volume or integrity was observed in the hydrogel after its swelling in phosphate buffered saline (PBS) medium. This is an important property because when the hydrogel is injected into the site of interest and it fills the environment, it will not have additional space to occupy. Biocompatibility studies were conducted in vitro, which revealed the non-cytotoxic nature of the material and demonstrated the potential of the hydrogel based on dialdehyde galactomannan and N-succinyl chitosan for cell culture and soft tissue engineering.

Design of biostable scaffold based on collagen crosslinked by dialdehyde chitosan with presence of gallic acid

In this study, we have prepared the biostable collagen scaffold which is crosslinked by dialdehyde chitosan (DAC) with presence of Gallic acid (GA) and characterized its physico-chemical, biostable and biocompatible properties. The digital photographic and scanning electron microscopic (SEM) images of the prepared collagen scaffold is exposed well with properly oriented interconnected porous natured structure. The appearance of diffraction peaks showed slightly crystalline characteristic when compared to others. The differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) measurements indicates well significantly increased denaturation temperature (T_D) and decreased decomposition rate. FT-IR result suggests the structural integrity of collagen which favours the molecular stability. The dialdehyde groups from DAC crosslinked with collagen functional groups that increase the molecular crosslinking owing to the large number of amino groups in its molecular chain. This scaffold exhibited 87% resistance against collagenolytic degradation by collagenase. The results showed that the improved biostability which prevents the free access of the collagenase to binds with the collagen triple helical chains. This scaffold confirm high biocompatibilities; enhanced cell proliferation and adhesions properties. This results gains new insight into the collagen scaffold to improves the biostability. This could be suitable method to preparation of collagenous biomaterials for tissue engineering applications.

Development and characterization of bladder acellular matrix cross-linked by dialdehyde carboxymethyl cellulose for bladder tissue engineering

In order to address the disadvantage of rapid degradation and serious immune response of bladder acellular matrix (BAM) tissues in clinical application, in this study, oxidized carboxymethyl cellulose (DCMC) was developed to replace glutaraldehyde (GA), a most common synthetic crosslinking reagent in clinical practice, to fix BAM tissues for lower cytotoxicity. The aim of this work was to evaluate feasibility of DCMC as a crosslinking reagent for BAM fixation and developing DCMC fixed-BAM (D-BAM) tissues for tissue engineering. For the preparation of DCMC, the results showed that when DCMC was prepared using a specific concentration of sodium periodate solution (the mass ratio of NaIO₄/CMC is 1 : 1) and a specific reaction time (4 hours), its cytotoxicity was the lowest and its fixation effect was better. The critical crosslinking characteristics and cytocompatibility of optimum D-BAM tissues were also investigated. The results demonstrated that DCMC-fixation (especially 30 mg ml⁻¹ DCMC-fixation) not only formed stable cross-linking bonds but also preserved well the original ultrastructure of the BAM tissues, which simultaneously increased the mechanical strength and capacity of the enzymatic hydrolytic resistance. The DCMC-fixation could also reduce the expression of α-Gal in BAM tissues and preserve the useful growth factors such as GAGs, KGF and TGF-β in bladder tissues. In addition, 30 mg ml⁻¹ D-BAM tissues had excellent cytocompatibility. Moreover, it could stimulate the secretion of PDGF and EGF from seeded bladder transitional epithelial cells (BTECs), which is a critical feature for further re-epithelialization. Its anti-calcification ability was also prominent, which is necessary in bladder repair. The present studies demonstrated that DCMC could be a potential biological crosslinking agent for BAM fixation due to its excellent crosslinking effects, and the D-BAM tissues were suitable to be used as a substitute for the bladder due to their resistance to enzymatic degradation, anticalcification and cytocompatibility.

To address the disadvantage of rapid degradation and serious immune response of bladder acellular matrix tissues in clinical application, oxidized carboxymethyl cellulose was developed to replace commonly used glutaraldehyde, to fix BAM tissues for lower cytotoxicity.

Characterization and properties of biodegradable thermoplastic grafted starch films by different contents of methacrylic acid

Due to poor mechanical and thermal properties of native starch (NS) film; in the present work; NS was modified by graft copolymerization. Thermoplastic starch (TPS) grafted by methacrylic acid (MAA) with different percentage of grafting, i.e., 0%, 18.3%, 36.3%, 52.1% and 89.7% were prepared and tested. The result demonstrated that the intensity of IR peak of acrylic group increased with the increasing percentage of grafting. The higher graft copolymerization with MAA also significantly reduced degree of crystallinity. The strain at maximum load of TPS film grafted by MAA increased with the increasing percentage of grafting. However, water uptake of TPS film grafted by MAA reduced with high percentage of grafting (52.1% and 89.7%). In addition, different TPS films grafted by MAA were also examined for morphology, water vapor permeability, thermal property and biodegradable property by soil buried test.

Effect of dual modification on properties of biodegradable crosslinked-oxidized starch and oxidized-crosslinked starch films

Due to poor properties of biodegradable native starch (NS) film; in this work, dual-modified starch films i.e. crosslinked-oxidized starch (C-OS) and oxidized-crosslinked starch (O-CS) films were prepared and compared to single-modified starch i.e. crosslinked starch (CS) and oxidized starch (OS) films. All modified starch films were oxidized and crosslinked using hydrogen peroxide and boric acid by casting technique. Degree of crystallinity and swelling behavior of both dual-modified starch films were found to decrease. Moreover, O-CS film showed smoother fractured morphology than C-OS and NS films. Both C-OS and O-CS films presented not only high stress at maximum load and Young's modulus but also high strain at maximum load, as compared to single-modified film. Furthermore, water vapor permeability, thermal property and biodegradability of all modified films were also studied.

Preparation and Characterization of Superabsorbent Polymers Based on Starch Aldehydes and Carboxymethyl Cellulose

Superabsorbent polymers (SAPs) are crosslinked hydrophilic polymers that are capable of absorbing large amounts of water. Commercial SAPs are mostly produced with acrylic acid that cannot be easily biodegraded. Therefore, in this study, polysaccharide-based SAPs using carboxymethyl cellulose as a major component were prepared. Starch aldehydes and citric acid were selected due to their environment-friendly, non-toxic, and biodegradable properties compared to conventional crosslinking agents. Starch aldehydes were prepared by periodate oxidation, which forms aldehyde groups by taking the places of C–OH groups at C-2 and C-3. Furthermore, starch aldehydes were analyzed through the change in FT-IR spectra, the aldehyde quantitation, and the morphology in FE-SEM images. In the crosslinking of polysaccharide-based SAPs, the acetal bridges from starch aldehydes led to a large amount of water entering the network structure of the SAPs. However, the ester bridges from citric acid interfered with the water penetration. In addition, the swelling behavior of the SAPs was analyzed by the Fickian diffusion model and the Schott’s pseudo second order kinetics model. The relationship between swelling behavior and morphology of the SAPs was analyzed by FE-SEM images. In conclusion, polysaccharide-based SAPs were well prepared and the highest equilibrium swelling ratio was 87.0 g/g.

Tough and tissue-adhesive polyacrylamide/collagen hydrogel with dopamine-grafted oxidized sodium alginate as crosslinker for cutaneous wound healing

Natural collagen has good biocompatibility and ability to promote tissue regeneration; however, its low flexibility and easy degradation hinder its applications in wound repair. In this study, we synthesized a skin wound-repairing hydrogel with good bioactivity and high toughness and adhesion. Inspired by the good adhesion of natural mussels, dopamine was grafted onto oxidized sodium alginate to synthesize a new crosslinker (COA), which was introduced into the collagen/polyacrylamide (PAM-Col) double network to synthesize hydrogel. The morphological characterization of the hydrogel using scanning electron microscopy confirmed that the hydrogel formed a more chaotic interconnected structure after the introduction of COA. PAM-Col-COA hydrogel had good mechanical properties, skin tissue adhesion, water absorption, and sustained biological activity. In vivo wound healing experiments showed that hydrogel accelerates the wound healing process and has potential applications in wound dressings.

Natural collagen has good biocompatibility and ability to promote tissue regeneration; however, its low flexibility and easy degradation hinder its applications in wound repair.

Preparation and evaluation of decellularized porcine carotid arteries cross-linked by genipin: the preliminary results

Decellularized arteries have been considered as promising scaffolds for small-diameter vascular substitutes. However, weakened mechanical properties, immunological rejection and rapid degradation after transplantation still exist after decellularization. Previous studies indicated that genipin cross-linking can solve these problems. Therefore, genipin was selected as the cross-linking agent for the pre-treatment of decellularized arteries in our study. Histological analysis, scanning electron microscopy, mechanical properties analysis and subcutaneous embedding experiment were adopted to investigate the efficiency of decellularization and the effect of genipin cross-linking on improving mechanical, structural and biological properties of decellularized arteries. Decellularization protocols based on three trypsin concentrations were used to prepare decellularized arteries, after decellularization, arteries were cross-linked with genipin. Results showed that 0.5% trypsin was the most efficient concentration to remove cellular components and preserve ECM. However, mechanical properties of 0.5% trypsin decellularized arteries weakened significantly, while genipin cross-linking improved mechanical properties of decellularized arteries to the same level as fresh arteries. After 4 weeks subcutaneous embedding, cross-linked arteries caused the mildest inflammatory response. In conclusion, genipin could be employed as an ideal cross-linking agent to strengthen mechanical properties, enhance the resistance to degradation and reduce the antigenicity of decellularized arteries for small-diameter blood vessel tissue engineering applications.