Biocompatible Hydrogels Based on Food Gums with Tunable Physicochemical Properties as Scaffolds for Cell Culture

Biomaterial-based strategies for primary human corneal endothelial cells for therapeutic applications: from cell expansion to transplantable carrier

The treatment of corneal blindness due to corneal diseases and injuries often requires the transplantation of healthy cadaveric corneal endothelial graft tissue to restore corneal clarity and visual function. However, the limited availability of donor corneas poses a significant challenge in meeting the demand for corneal transplantation. As a result, there is a growing interest in developing strategies alleviate this unmet need, and one of the postulated approaches is to isolate and expand primary human corneal endothelial cells (HCECs) in vitro for use in cell therapy. This review summarizes the recent advancements in the expansion of HCECs using biomaterials. Two principal biomaterial-based approaches, including extracellular matrix (ECM) coating and functionalized synthetic polymers, have been investigated to create an optimal microenvironment for the expansion and maintenance of corneal endothelial cells (CECs). This review highlights the challenges and opportunities in expanding primary HCECs using biomaterials. It emphasizes the importance of optimizing biomaterial properties, cell culture conditions, and the roles of biophysical cues to achieve efficient expansion and functional maintenance of CECs. Biomaterial-based strategies hold significant promise for expanding primary HCECs and improving the outcomes of CEC transplantation. The integration of biomaterials as cell culture substrates and transplantable carriers offers a comprehensive approach to address the limitations associated with current corneal tissue engineering techniques.

Regulating natural galactomannan into composite hydrogels for improved adhesion, anti-swelling capability and efficient dye pollution removal

Constructing bio-based composite hydrogel materials are receiving much interest, while regulating the interactions of the hydrogel components and integrating functions for multi-application meet various challenges. Herein, composite hydrogels were prepared by cross-linking of poly-acrylamide (PAM) and poly-N-[3-(Dimethylamino) propyl] acrylamide (PDMAPAA), assisted by natural galactomannan (GM) regulation. Even distribution and compatibility of GM in the three-dimensional materials were proved by a series of chemical and morphological characterizations, which favored the improvement of mechanical properties (~80 kPa) and flexibility. Besides, the hydrogels were well-connected with double networks of noncovalent intermolecular hydrogen bonding interactions and hydrophobic interactions, in addition to covalent-linked polymers. Due to great amount of inner hydrogen bond linkages, the hydrogels present satisfying anti-swelling capabilities (<15 %), exhibiting high potential for application in water treatment. Meanwhile, abundant surface functional groups provided possibilities to form interactive layer with the various substrates surface, exhibiting highly adhesive properties. Significant dyes adsorption capabilities were revealed on the hydrogels according to the electrostatic attraction with Congo red and hydrogen bond interactions with Brilliant green respectively. Thus, the proposed composite hydrogels integrated multi-functions due to the tuning the surface groups and cross-linking interactions, which provided deeper understanding on bio-based materials on fields of water treatment and environmental protection.

SOX9 functionalized scaffolds as a barrier to against cartilage fibrosis

Hyaline cartilage regeneration will bring evangel to millions of people suffered from cartilage diseases. However, uncontrollable cartilage fibrosis and matrix mineralization are the primary causes of cartilage regeneration failure in many tissue engineering scaffolds. This study presents a new attempt to avoid endochondral ossification or fibrosis in cartilage regeneration therapy by establishing biochemical regulatory area. Here, SOX9 expression plasmids are assembled in cellulose gels by chitosan gene vectors to fabricate SOX9+ functionalized scaffolds. RT-qPCR, western blot and biochemical analysis all show that the SOX9 reinforcement strategy can enhance chondrogenic specific proteins expression and promote GAG production. Notably, the interference from SOX9 has resisted osteogenic inducing significantly, showing an inhibition of COL1, OPN and OC production, and the inhibition efficiency was about 58.4 %, 22.8 % and 76.9 % respectively. In vivo study, implantation of these scaffolds with BMSCs can induce chondrogenic differentiation and resist endochondral ossification effectively. Moreover, specific SOX9+ functionalized area of the gel exhibited the resistance to matrix mineralization, indicating the special biochemical functional area for cartilage regeneration. These results indicate that this strategy is effective for promoting the hyaline cartilage regeneration and avoiding cartilage fibrosis, which provides a new insight to the future development of cartilage regeneration scaffolds.

Study of chondrogenesis of umbilical cord mesenchymal stem cells in curdlan- poly(vinyl alcohol) composite hydrogels and its mechanical properties of freezing-thawing treatments

The curdlan gel is a natural material produced by bacteria. It utilizes chemical cross-linking reactions to form a 3D porous composite hydrogel, increasing its porosity and water content, and improving its mechanical properties. It can be used in tissue repair and regenerative medicine. Curdlan-Poly(vinyl alcohol) (PVA) composite hydrogel can rapidly swell within 1 min due to its porous structure. Compression tests confirmed that it still maintains its original mechanical strength, even after five repeated freeze-thaw (FT) processes, making it suitable for long-term cryopreservation. The purpose of this study is to transplant umbilical cord mesenchymal stem cells (UC-MSCs) on Curdlan-PVA composite hydrogel and observe the chondrocytes on the material. The results of using 4',6-diamidino-2-phenylindole (DAPI), hematoxylin and eosin (H&E), calcein-acetoxymethyl ester (calcein AM), and Collagen type II-Fluorescein isothiocyanate (FITC) staining, confirmed that UC-MSCs can attach and differentiate into chondrocytes on 3D Curdlan-PVA composite hydrogel.

Strong, tough, high-release, and antibacterial nanocellulose hydrogel for refrigerated chicken preservation

Enormous amounts of food resources are annually wasted because of microbial contamination, highlighting the critical role of effective food packaging in preventing such losses. However, traditional food packaging faces several limitations, such as low mechanical strength, poor fatigue resistance, and low water retention. In this study, we aimed to prepare nanocellulose hydrogels with enhanced stretchability, fatigue resistance, high water retention, and antibacterial properties using soy hull nanocellulose (SHNC), polyvinyl alcohol (PVA), sodium alginate (SA), and tannic acid (TA) as raw materials. These hydrogels were applied in food packaging to extend the shelf life of refrigerated chicken. The structure and properties (e.g., mechanical, antibacterial, and barrier properties) of these hydrogels were characterized using different techniques. Fourier-transform infrared spectroscopy revealed the presence of hydrogen and ester bonds in the hydrogels, whereas scanning electron microscopy revealed the three-dimensional network structure of the hydrogels. Mechanical testing demonstrated that the SHNC/PVA/SA/TA-2 hydrogel exhibited excellent tensile properties (elongation = 160 %), viscoelasticity (storage modulus of 1000 Pa), and mechanical strength (compressive strength = 10 kPa; tensile strength = 0.35 MPa). Moreover, under weak acidic and alkaline conditions, the ester bonds of the hydrogel broke down with an increase in pH, improving its swelling and release properties. The SHNC/PVA/SA/TA-2 hydrogel displayed an equilibrium swelling ratio exceeding 300 %, with a release rate of >80 % for the bioactive substance TA. Notably, antibacterial testing showed that the SHNC/PVA/SA/TA-2 hydrogel effectively deactivated Staphylococcus aureus and Escherichia coli, prolonging the shelf life of refrigerated chicken to 10 d. Therefore, the SHNC/PVA/SA/TA hydrogels can be used in food packaging to extend the shelf life of refrigerated meat products. Their cost-effectiveness and simple preparation make them suitable for various applications in the food industry.

Structurally Modified Polysaccharides: Physicochemical Properties, Biological Activities, Structure-Activity Relationship, and Applications

Polysaccharides are an important class of biomolecules derived from several sources. However, the inherent structure of polysaccharides prevents them from exhibiting favorable physicochemical properties, which restricts their development in agriculture, industry, food, and biomedicine. This paper systematically summarizes the changes in the primary and advanced structures of modified polysaccharides, and focuses on the effects of various modification methods on the hydrophobicity, rheological properties, emulsifying properties, antioxidant activity, hypoglycemic, and hypolipidemic activities of polysaccharides. Then there is a list the applications of modified polysaccharides in treating heavy metal pollutants, purifying water resources, improving beverage stability and bread quality, and precisely delivering the drug. When summarized and reviewed, the information above can shed further light on the relationship between polysaccharide structure and function. Determining the structure-activity relationship provides a scientific basis for the direction of molecular modifications of polysaccharides.

Construction and properties of a carbon dots-decorated gelatin-dialdehyde starch hydrogel with pH response release and antibacterial activity

An antibacterial carbon dot hydrogel (GDSS-PCD) was constructed based on gelatin, dialdehyde starch (DS) and carbon dots (S-PCDs). The formation mechanism of GDSS-PCD hydrogels was attributed to the synergistic cross-linking of hydrogen bonds and dynamic covalent bonds. With increasing S-PCD content, the mechanical and rheological properties of GDSS-PCD hydrogels can be improved, and the micropore size becomes denser. GDSS-PCD hydrogels had pH-dependent swelling and degradation behavior, with a high swelling rate under acidic conditions and relatively low swelling under neutral and alkaline conditions. The cumulative release of S-PCDs from the same hydrogel in an acidic environment was higher than that in an alkaline environment, indicating that the GDSS-PCD hydrogel had a pH-dependent controlled release ability. The release behavior of S-PCDs conformed to the first-order kinetic release model (R2 > 0.95), and the release mechanism was related to Fickian diffusion. The synergistic antibacterial mechanism of GDSS-PCD hydrogels against Staphylococcus aureus suggested that bacterial metabolism leads to an acidic culture environment, which releases S-PCDs and destroys the bacterial cell membrane for antibacterial purposes. In GDSS-PCD hydrogels, S-PCDs play the main antibacterial role, and the hydrogel plays a synergistic role in trapping bacteria. Carbon dot hydrogels are promising materials to fulfil the functions of antibacterial and controlled release in the food and biomedical fields.

Characterization of structural and functional properties of soy protein isolate and sodium alginate interpenetrating polymer network hydrogels

BACKGROUND

This study used enzymatic and Ca2+ cross-linking methods to prepare edible soy protein isolate (SPI) and sodium alginate (SA) interpenetrating polymer network hydrogels to overcome the disadvantages of traditional interpenetrating polymer network (IPN) hydrogels, such as poor performance, high toxicity, and inedibility. The influence of changes in SPI and SA mass ratio on the performance of SPI-SA IPN hydrogels was investigated.

RESULTS

Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the structure of the hydrogels. Texture profile analysis (TPA), rheological properties, swelling rate, and Cell Counting Kit-8 (CCK-8) were used to evaluate physical and chemical properties and safety. The results showed that, compared with SPI hydrogel, IPN hydrogels had better gel properties and structural stability. As the mass ratio of SPI-SA IPN changed from 1:0.2 to 1:1, the gel network structure of hydrogels also tended to be dense and uniform. The water retention and mechanical properties of these hydrogels, such as storage modulus (G'), loss modulus (G"), and gel hardness increased significantly and were greater than those of the SPI hydrogel. Cytotoxicity tests were also performed. The biocompatibility of these hydrogels was good.

CONCLUSIONS

This study proposes a new method to prepare food-grade IPN hydrogels with mechanical properties of SPI and SA, which may have strong potential for the development of new foods. © 2023 Society of Chemical Industry.

Photo-degradable salecan/xanthan gum ionic gel induced by iron (III) coordination for organic dye decontamination

As dye adsorbents with great potential, polysaccharide-based hydrogels are significantly hampered in practical application owing to intricate preparation methods, low absorption, and bad degradability. Salecan is a water-soluble extracellular polysaccharide with excellent physicochemical and biological properties. Here, salecan and xanthan gum were first used as a dual-precursors system, their mixed solution was crosslinked by Fe³⁺ to assemble a photo-degradable ionic gel for malachite green (MG) adsorption. Photo-degradation was done using visible light under very mild conditions, which gave rise to gel network dissolution and homogeneous solution formation. Extensive dynamic coordinate interactions between Fe³⁺ and polysaccharides maintained gel matrix stability and were systematically investigated. The control of water uptake, micro-structure, and rheology can be facilely implemented by tuning salecan/xanthan gum ratios. Furthermore, various parameters such as polysaccharide ratios, pHs, MG concentrations, and contact time affecting adsorption were optimized using batch experiments. Adsorption process accurately adhered to pseudo-second-order kinetic and Langmuir isotherm model, with the maximum adsorption capacity of 463.0 mg/g. Such mechanism implied monolayer chemisorptive characteristics. The gel exhibited satisfactory reusability and was recycled five times without apparent decrease in adsorption capacity. From these results, the photo-degradable Fe³⁺-induced salecan/xanthan gum ionic gel is an alternative and sustainable absorbent for MG removal.

Modified gellan gum-based hydrogel with enhanced mechanical properties for application as a cell carrier for cornea endothelial cells

Recently, the number of people suffering from visual loss due to eye diseases is increasing rapidly around the world. However, due to the severe donor shortage and the immune response, corneal replacement is needed. Gellan gum (GG) is biocompatible and widely used for cell delivery or drug delivery, but its strength is not suitable for the corneal substitute. In this study, a GM hydrogel was prepared by blending methacrylated gellan gum with GG (GM) to give suitable mechanical properties to the corneal tissue. In addition, lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP), a crosslinking initiator, was added to the GM hydrogel. After the photo-crosslinking treatment, it was named GM/LAP hydrogel. GM and GM/LAP hydrogels were analyzed for physicochemical properties, mechanical characterization, and transparency tests to confirm their applicability as carriers for corneal endothelial cells (CEnCs). Also, in vitro studies were performed with cell viability tests, cell proliferation tests, cell morphology, cell-matrix remodeling analysis, and gene expression evaluation. The compressive strength of the GM/LAP hydrogel was improved compared to the GM hydrogel. The GM/LAP hydrogel showed excellent cell viability, proliferation, and cornea-specific gene expression than the GM hydrogel. Crosslinking-improved GM/LAP hydrogel can be applied as a promising cell carrier in corneal tissue engineering.

Injectable hybrid hydrogels physically crosslinked based on carrageenan and green graphene for tissue repair

Injectable and biocompatible novel hybrid hydrogels based on physically crosslinked natural biopolymers and green graphene for potential use in tissue engineering are reported. Kappa and iota carrageenan, locust bean gum and gelatin are used as biopolymeric matrix. The effect of green graphene content on the swelling behavior, mechanical properties and biocompatibility of the hybrid hydrogels is investigated. The hybrid hydrogels present a porous network with three-dimensionally interconnected microstructures, with lower pore size than that of the hydrogel without graphene. The addition of graphene into the biopolymeric network improves the stability and the mechanical properties of the hydrogels in phosphate buffer saline solution at 37 °C without noticeable change in the injectability. The mechanical properties of the hybrid hydrogels were enhanced by varying the dosage of graphene between 0.025 and 0.075 w/v%. In this range, the hybrid hydrogels preserve their integrity during mechanical test and recover the initial shape after removing the applied stress. Meanwhile, hybrid hydrogels with graphene content of up to 0.05 w/v% exhibit good biocompatibility for 3T3-L1 fibroblasts; the cells proliferate inside the gel structure and show higher spreading after 48 h. These injectable hybrid hydrogels with graphene have promising future as materials for tissue repair.

High-Release, Residue-Free Polysaccharide Hydrogel for Refrigerated Food Preservation

Hundreds of millions of tons of food resources are wasted annually due to microbial contamination. Effective food packaging can prevent food contamination and wastage. However, traditional food packaging has the problem of low release of bioactive substances. This study aimed to prepare a pH-responsive polysaccharide hydrogel (GDPP) by double cross-linking of ester and hydrogen bonds that could result in a high release of bioactive substances and no residual peeling. The infrared results showed the existence of ester bonds in the hydrogel, and the scanning electron microscopy results showed the porous network structure of the hydrogel. The results of texture profile analysis and self-healing tests showed that GDPP-1 has good mechanical and self-healing properties. Moreover, the ester bond of the hydrogel broke in response to the pH in the environment, improving the swelling and release properties of the hydrogel. The equilibrium swelling ratio of GDPP-1 was greater than 1000%, and the release rate of bioactive substances was more than 80%. Notably, the results of peeling experiments showed that only 0.1 N external force was needed to separate the hydrogel from the salmon, and no residue was observed on the salmon surface. The final freshness test results showed that the hydrogel effectively prolonged the shelf life of refrigerated salmon for 3-6 days. These findings indicated that hydrogels could be used in food packaging to extend the shelf life of refrigerated food. Furthermore, their advantages of low cost and simple preparation can better meet the needs of food industry applications.

Synthesis and Rheological Characterization of a Novel Salecan Hydrogel

Salecan (Sal) is a novel microbial polysaccharide. In the present research, thermal treatment was performed to fabricate Sal hydrogel. The effect of Sal concentration on water holding capacity, swelling properties, texture properties, and microstructure of the hydrogels was discussed. It was found that the equilibrium degree of swelling (EDS) of Sal hydrogels was above 1500%, inferred Sal was a highly hydrophilic polysaccharide. As Sal concentration increased from 3.5 to 8.0 wt%, the hardness increased from 0.88 to 2.07 N and the water hold capability (WHC) increased from 91.3% to 98.2%. Furthermore, the internal network structure of Sal hydrogel also became denser and more uniform. Rheological studies suggested that elastic hydrogel formed under the gelation process. All these results demonstrated that Sal hydrogel prepared by thermal treatment had good gelling properties, which opened up a new safe way for the preparation of Sal hydrogel and broadened the application range of Sal.

Casein micelles embedded composite organohydrogel as potential wound dressing

Excellent mechanical and tissue adhesive properties, long-lasting environmental suitability and reliable biocompatibility are essential factors for the hydrogels to be applied as wound dressing in the clinical fields. Based on the self-assembly micelle structures, a new type of casein micelles (CEs)/polyvinyl alcohol (PVA) GW (glycerol-water) organohydrogel was designed and synthesized by a simple one-pot method. Through a unique "load sharing" effect, the CEs which own suitable adhesion abilities and drug loading capacities simultaneously were embedded into the PVA networks by rich hydrogen bonds, so that to obtain the composite organ hydrogel with not only excellent adhesive abilities, but also enhanced mechanical properties. Benefited from the unique GW binary solvent system, the organohydrogel showed long-lasting moisture lock-in capacity and extreme temperature tolerance (in the range of --20 °C ~ 60 °C). Particularly, after loading the model antibacterial drugs (allicin) within the CEs, the as-developed CEs/PVA GW gel exhibited a prominent long-lasting (>100 h) antibacterial properties (>90%). Furthermore, the organohydrogel was confirmed with prominent biocompatibility to support fibroblast cell proliferation and migration. This work proposed a new strategy to build CEs-based gel system, which have a great potential application in terms of prevent bacterial infection, accelerate tissue proliferation and wound healing.

Recent Advances in Polysaccharide-Based Physical Hydrogels and Their Potential Applications for Biomedical and Wastewater Treatment

Polysaccharides have been widely employed to fabricate hydrogels owing to their intrinsic properties including biocompatibility, biodegradability, sustainability, and easy modification. However, a considerable amount of polysaccharide-based hydrogels are prepared by chemical crosslinking method using organic solvents or toxic crosslinkers. The presence of reaction by-products and residual toxic substances in the obtained materials cause a potential secondary pollution risk and thus severely limited their practical applications. In contrast, polysaccharide-based physical hydrogels are preferred over chemically derived hydrogels and can be used to address existing drawbacks of chemical hydrogels. The polysaccharide chains of such hydrogel are typically crosslinked by dynamic non-covalent bonds, and the co-existence of multiple physical interactions stabilize the hydrogel network. This review focuses on providing a detailed outlook for the design strategies and formation mechanisms of polysaccharide-based physical hydrogels as well as their specific applications in tissue engineering, drug delivery, wound healing, and wastewater treatment. The main preparation principles, future challenges, and potential improvements are also outlined. The authors hope that this review could provide valuable information for the rational fabrication of polysaccharide-based physical hydrogel. The specific research works listed in the review will provide a systematic and solid research basis for the reliable development of polysaccharide-based physical hydrogel. This article is protected by copyright. All rights reserved.

Harnessing the potential of dialdehyde alginate-xanthan gum hydrogels as niche bioscaffolds for tissue engineering

Biomimetic hydrogels composed of natural polysaccharides have invariably blossomed as niche biomaterials in tissue engineering applications. The prospects of creating an extracellular matrix (ECM)-like milieu from such hydrogels has garnered considerable importance. In this study, we have fabricated bioscaffolds comprising dialdehyde alginate and xanthan gum and explored their potential use in tissue regeneration. The fabricated scaffolds displayed an interconnected porous network structure that is highly desirable for the aforesaid application. The scaffolds were endowed with good mechanical properties, thermostability, protein adsorption efficacy and degradability. Curcumin-loaded hydrogels exhibited appreciable antibacterial activity against E. coli. In vitro cytocompatibility studies revealed that the scaffolds promoted adhesion and proliferation of 3T3 fibroblast cells. The Western blot analysis of p53 gene indicated no growth arrest or apoptosis in 3T3 cells thus, signifying the non-toxic nature of the scaffolds. Furthermore, the ECM formation was confirmed via SDS-PAGE analysis. The overall results clearly validated these scaffolds as effectual biomaterials for tissue engineering applications.

A biocompatible hydrogel as a template for oxidative decomposition reactions: a chemodosimetric analysis and in vitro imaging of hypochlorite

The self-assembly properties of new biocompatible, thermoreversible fluorescent hydrogels, composed of amino acid residues have been reported. A unique gel-to-sol transition is triggered by chemodosimetric interaction in the presence of hypochlorite.

A Bio-Based Hydrogel Derived from Moldy Steamed Bread as Urea-Formaldehyde Loading for Slow-Release and Water-Retention Fertilizers

In this work, a novel slow-release and water-retention nitrogen (N) fertilizer (SRWRNF) was prepared using moldy steamed bread-based starch-g-poly(acrylic acid-co-acrylic amide) (SBS-g-P(AA/AM)) as the skeleton and urea-formaldehyde oligomers (UF) incorporated as the slow-release N source by semi-interpenetrating methods. Various analysis technologies including scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry were used to characterize the structure and properties of SRWRNFs. Swelling measurements indicated that the maximum water absorbency of SBS-g-P(AA/AM)-UF samples was 104.2 g/g in distilled water. The water-retention study showed that the SBS-g-P(AA/AM)-UF improved the maximum soil water content by 15.3-17.6% while improving soil water-retention capacity. N release experiments confirmed that SBS-g-P(AA/AM)-UF enabling offered a gradual N supply in soil. In comparison to conventional urea and UF fertilizers, the maize yield of SBS-g-P(AA/AM)-UF was increased by 20.3 and 9.7%, respectively. This study implies that the SRWRNFs provide a promising feasibility for large-scale applications in agriculture.

Antibacterial polyvinyl alcohol/bacterial cellulose/nano-silver hydrogels that effectively promote wound healing

The lack of antibacterial properties limits the application of bacterial cellulose hydrogels in wound dressings. To overcome this deficiency, silver nanoparticles (AgNPs) were introduced as antibacterial agents into a polyvinyl alcohol (PVA)/bacterial cellulose (BC) solution. A freeze-thaw method promoted formation of PVA/BC/Ag hydrogels and improved their mechanical properties. The physicochemical and biological properties of this hydrogel were systematically characterized. Those results showed the hydrogels contained a porous three-dimensional reticulum structure and had high mechanical properties. Also, the hydrogels possessed outstanding antibacterial properties and good biocompatibilities. More importantly, it effectively repaired wound defects in mice models and wound healing reached 97.89% within 15 days, and far exceeded other groups and indicated its potential for use in wound treatment applications.

Physically cross-linked chitosan/dextrin cryogels entrapping Thymus vulgaris essential oil with enhanced mechanical, antioxidant and antifungal properties

Herein, we entrapped Thymus vulgaris essential oil (EO) within the physically cross-linked sponge-like architecture of cryogels by ice template-assisted freeze-drying. Their 3D cryogenically-structured network was built through hydrogen bonding formed by blending two naturally-derived polysaccharides, chitosan and dextrin. The embedment of EOs within the cryogel matrix generates porous films with an increased elasticity that allows their fast shape recovery after full compression. Thus, the swollen EOs-loaded cryogel films exhibited an elastic modulus of 3.00 MPa, which is more than 40 times higher than that of polysaccharide films without EOs (an elastic modulus of only 0.07 MPa). In addition, the encapsulation of bioactive compounds endows the bio-based films with both antioxidant and antifungal properties, showing a radical scavenging activity of 65% and a zone inhibition diameter of 40 mm for Candida parapsilosis fungi. Our results recommend the entrapment of EOs into bio-based cryogel carriers as a straightforward approach to provide 'green' polysaccharide-based films having both improved physicochemical properties and remarkable antifungal activity.

Toward Designing of Anti-infective Hydrogels for Orthopedic Implants: From Lab to Clinic

An alarming increase in implant failure incidence due to microbial colonization on the administered orthopedic implants has become a horrifying threat to replacement surgeries and related health concerns. In essence, microbial adhesion and its subsequent biofilm formation, antibiotic resistance, and the host immune system's deficiency are the main culprits. An advanced class of biomaterials termed anti-infective hydrogel implant coatings are evolving to subdue these complications. On this account, this review provides an insight into the significance of anti-infective hydrogels for preventing orthopedic implant associated infections to improve the bone healing process. We briefly discuss the clinical course of implant failure, with a prime focus on orthopedic implants. We identify the different anti-infective coating strategies and hence several anti-infective agents which could be incorporated in the hydrogel matrix. The fundamental design criteria to be considered while fabricating anti-infective hydrogels for orthopedic implants will be discussed. We highlight the different hydrogel coatings based on the origin of the polymers involved in light of their antimicrobial efficacy. We summarize the relevant patents reported in the prevention of implant infections, including orthopedics. Finally, the challenges concerning the clinical translation of the aforesaid hydrogels are described, and considerable solutions for improved clinical practice and better future prospects are proposed.

Bioinspired Design of Novel Microscaffolds for Fibroblast Guidance toward In Vitro Tissue Building

Porous microscaffolds (μ-scaffs) play a crucial role in modular tissue engineering as they control cell functions and guide hierarchical tissue formation toward building new functional tissue analogues. In the present study, we developed a new route to prepare porous polycaprolactone (PCL) μ-scaffs with a bioinspired trabecular structure that supported in vitro adhesion, growth, and biosynthesis of human dermal fibroblasts (HDFs). The method involved the use of poly(ethylene oxide) (PEO) as a biocompatible porogen and a fluidic emulsion/porogen leaching/particle coagulation process to obtain spherical μ-scaffs with controllable diameter and full pore interconnectivity. To achieve this objective, we investigated the effect of PEO concentration and the temperature of the coagulation bath on the μ-scaff architecture, while we modulated the μ-scaff diameter distribution by varying the PCL-PEO amount in the starting solution and changing the flow rate of the continuous phase (Q_CP). μ-Scaff morphology, pore architecture, and diameter distribution were assessed using scanning electron microscopy (SEM) analysis, microcomputed tomography (microCT), and Image analysis. We reported that the selection of 60 wt % PEO concentration, together with a 4 °C coagulation bath temperature and ultrasound postprocessing, allowed for the design and fabrication of μ-scaff with porosity up to 80% and fully interconnected pores on both the μ-scaff surface and the core. Furthermore, μ-scaff diameter distributions were finely tuned in the 100-600 μm range with the coefficient of variation lower than 5% by selecting the PCL-PEO concentration in the 1-10% w/v range and Q_CP of either 8 or 18 mL/min. Finally, we investigated the capability of the HDF-seeded PCL μ-scaff to form hybrid (biological/synthetic) tissue in vitro. Cell culture tests demonstrated that PCL μ-scaff enabled HDF adhesion, proliferation, colonization, and collagen biosynthesis within inter- and intraparticle spaces and guided the formation of a large (centimeter-sized) viable tissue construct.

A freeze-thawing method applied to the fabrication of 3-d curdlan/polyvinyl alcohol hydrogels as scaffolds for cell culture

In this work, an innovative composite hydrogel composed of curdlan (CD)/polyvinyl alcohol (PVA) hydrogels with a 3-d network structure was successfully prepared by freeze-thaw processing. The presence of interactions, changes in crystallinity, and thermal behaviour were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetry (TGA and DTG), respectively. The morphology of the hydrogels was investigated by scanning electron microscopy (SEM). With the increase of PVA concentration, the composite hydrogel had a greater mechanical strength while remaining remarkably ductile as evinced by tensile test results. PVA content affects the swelling and water retention of CD/PVA hydrogels. The results of CCK-8 assay showed that CD/PVA hydrogels have no cytotoxic effect on the mouse fibroblast L929 cells. The AO/EB double-staining experiment further proved that the cells in the composite hydrogels had good cytocompatibility. The porous biohydrogels developed in the present work can provide an ideal cell growth environment as a scaffold. CD/PVA hydrogels highlight the value of this system for cell adhesion and proliferation, and further soft tissue engineering application.

Construction of functional curdlan hydrogels with bio-inspired polydopamine for synergistic periodontal antibacterial therapeutics

Curdlan, a bacteria-derived polysaccharide resource, possesses substantial potential for periodontal antimicrobial delivery. Here, the facile engineering of a functionalized curdlan/polydopamine (PDA) composite hydrogels was reported. The physiochemical evaluations of composite hydrogels proved their tunable properties associated with concentration of PDA including pore size, rheological property and swelling behavior. We have systematically assessed biocompatibility in vitro and found these hydrogels toxicity-free. Moreover, photothermal performance upon near infrared light (NIR) exposure was conducted and eventually indicated the best matches for antibacterial application. The acetate chlorhexidine (CHX) was chosen as a model antimicrobial and the release profiles demonstrated the entrapped CHX could be triggered and nicely controlled by NIR. The optimized bacteriostatic rate reached 99.9 %. Overall, we aimed to provide new curdlan-based hydrogels for periodontal antibacterial treatment by combining photothermal effect and antimicrobial simultaneously.