Synthesis of in-situ formable hydrogels with collagen and hyaluronan through facile Michael addition

Challenges in Application: Gelation Strategies of DAT-Based Hydrogel Scaffolds

Decellularized adipose tissue (DAT) has great clinical applicability, owing to its abundant source material, natural extracellular matrix microenvironment, and nonimmunogenic attributes, rendering it a versatile resource in the realm of tissue engineering. However, practical implementations are confronted with multifarious limitations. Among these, the selection of an appropriate gelation strategy serves as the foundation for adapting to diverse clinical contexts. The cross-linking strategies under varying physical or chemical conditions exert profound influences on the ultimate morphology and therapeutic efficacy of DAT. This review sums up the processes of DAT decellularization and subsequent gelation, with a specific emphasis on the diverse gelation strategies employed in recent experimental applications of DAT. The review expounds upon methodologies, underlying principles, and clinical implications of different gelation strategies, aiming to offer insights and inspiration for the application of DAT in tissue engineering and advance research for tissue engineering scaffold development.

Progress in injectable hydrogels for hard tissue regeneration in the last decade

Bone disorders have increased with increasing the human lifespan, and despite the tissue's ability to self-regeneration, in many congenital problems and hard fractures, bone grafting such as autograft, allograft, and biomaterials implantation through surgery is traditionally used. Because of the adverse effects of these methods, the emergence of injectable hydrogels without the need for surgery and causing more pain for the patient is stunning to develop a new pattern for hard tissue engineering. These materials are formed with various natural and synthetic polymers with a crosslinked network through various chemical methods such as click chemistry, Michael enhancement, Schiff's base and enzymatic reaction and physical interactions with high water absorption which can mimic the environment of cells. The purpose of this research is to review the capabilities of this class of materials in hard tissue regeneration in the last decade through adaptable physical and chemical properties, the ability to fill defect sites with an irregular shape, and the ability to grow hormones or release drugs, in response to external stimuli.

The bioengineering application of hyaluronic acid in tissue regeneration and repair

The multifaceted role of hyaluronic acid (HA) across diverse biomedical disciplines underscores its versatility in tissue regeneration and repair. HA hydrogels employ different crosslinking including chemical (chitosan, collagen), photo- initiation (riboflavin, LAP), enzymatic (HRP/H2O2), and physical interactions (hydrogen bonds, metal coordination). In biophysics and biochemistry, HA's signaling pathways, primarily through CD44 and RHAMM receptors, modulate cell behavior (cell migration; internalization of HA), inflammation, and wound healing. Particularly, smaller HA fragments stimulate inflammatory responses through toll-like receptors, impacting macrophages and cytokine expression. HA's implications in oncology highlight its involvement in tumor progression, metastasis, and treatment. Elevated HA in tumor stroma impacts apoptosis resistance and promotes tumor growth, presenting potential therapeutic targets to halt tumor progression. In orthopedics, HA's presence in synovial fluid aids in osteoarthritis management, as its supplementation alleviates pain, enhances synovial fluid's viscoelastic properties, and promotes cartilage integrity. In ophthalmology, HA's application in dry eye syndrome addresses symptoms by moisturizing the eyes, replenishing tear film deficiencies, and facilitating wound healing. Intravitreal injections and hydrogel-based systems offer versatile approaches for drug delivery and vitreous humor replacement. For skin regeneration and wound healing, HA hydrogel dressings exhibit exceptional properties by promoting moist wound healing and facilitating tissue repair. Integration of advanced regenerative tools like stem cells and solubilized amnion membranes into HA-based systems accelerates wound closure and tissue recovery. Overall, HA's unique properties and interactions render it a promising candidate across diverse biomedical domains, showcasing immense potentials in tissue regeneration and therapeutic interventions. Nevertheless, many detailed cellular and molecular mechanisms of HA and its applications remain unexplored and warrant further investigation.

Exploring the Progress of Hyaluronic Acid Hydrogels: Synthesis, Characteristics, and Wide-Ranging Applications

This comprehensive review delves into the world of hyaluronic acid (HA) hydrogels, exploring their creation, characteristics, research methodologies, and uses. HA hydrogels stand out among natural polysaccharides due to their distinct features. Their exceptional biocompatibility makes them a top choice for diverse biomedical purposes, with a great ability to coexist harmoniously with living cells and tissues. Furthermore, their biodegradability permits their gradual breakdown by bodily enzymes, enabling the creation of temporary frameworks for tissue engineering endeavors. Additionally, since HA is a vital component of the extracellular matrix (ECM) in numerous tissues, HA hydrogels can replicate the ECM's structure and functions. This mimicry is pivotal in tissue engineering applications by providing an ideal setting for cellular growth and maturation. Various cross-linking techniques like chemical, physical, enzymatic, and hybrid methods impact the mechanical strength, swelling capacity, and degradation speed of the hydrogels. Assessment tools such as rheological analysis, electron microscopy, spectroscopy, swelling tests, and degradation studies are employed to examine their attributes. HA-based hydrogels feature prominently in tissue engineering, drug distribution, wound recovery, ophthalmology, and cartilage mending. Crafting HA hydrogels enables the production of biomaterials with sought-after qualities, offering avenues for advancements in the realm of biomedicine.

Synthesis and Properties of Injectable Hydrogel for Tissue Filling

Hydrogels with injectability have emerged as the focal point in tissue filling, owing to their unique properties, such as minimal adverse effects, faster recovery, good results, and negligible disruption to daily activities. These hydrogels could attain their injectability through chemical covalent crosslinking, physical crosslinking, or biological crosslinking. These reactions allow for the formation of reversible bonds or delayed gelatinization, ensuring a minimally invasive approach for tissue filling. Injectable hydrogels facilitate tissue augmentation and tissue regeneration by offering slow degradation, mechanical support, and the modulation of biological functions in host cells. This review summarizes the recent advancements in synthetic strategies for injectable hydrogels and introduces their application in tissue filling. Ultimately, we discuss the prospects and prevailing challenges in developing optimal injectable hydrogels for tissue augmentation, aiming to chart a course for future investigations.

From crosslinking strategies to biomedical applications of hyaluronic acid-based hydrogels: A review

Hyaluronic acid (HA) is not only a natural anionic polysaccharide with excellent biocompatibility, biodegradability, and moisturizing effect, but also an essential factor that can affect angiogenesis, inflammation, cell behavior, which has a wide range of applications in the biomedical field. Among them, HA-based hydrogels formed by various physical or chemical crosslinking strategies are particularly striking. They not only retain the physiological function of HA, but also have the skeleton function of hydrogel, which further expands the application of HA. However, HA-based natural hydrogels generally have problems such as insufficient mechanical strength and susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. To solve such problems, researchers have prepared a variety of HA-based multifunctional hydrogels with remarkable properties in recent years by adopting various structural modification methods or novel crosslinking strategies, as well as introducing functionally reactive molecules or moieties, which have extended the application scope. This manuscript systematically introduced common crosslinking strategies of HA-based hydrogels and highlighted the development of novel HA-based hydrogels in anticancer drug delivery, cartilage repair, three-dimensional cell culture, skin dressing and other fields. We hope to provide some references for the subsequent development of HA-based hydrogels in the biomedical field.

The incorporated hydrogel of chitosan-oligoconjugated linoleic acid vesicles and the protective sustained release for curcumin in the gel

Assemblies of as called "chitosan hydrogel-liposome" are expected for overcoming the burst effect in drug release from chitosan (CS) hydrogels. Herein, a hydrogel delivery system made of chitosan incorporated fatty acid vesicles was constructed for protective sustained release of curcumin (Cur). The curcumin was encapsulated in the prepared oligo-conjugated linoleic acid vesicles (OCLAVs), and then the drug-embedded vesicles were constructed to Cur-OCLAVs-CS hydrogels with CS solution. The fabricated Cur-OCLAVs-CS hydrogel was fluidic at room temperature and could be rapidly gelled at 37 °C. Morphology study proves that the OCLAVs stayed as nano-vesicles in the gel. The Cur-OCLAVs-CS hydrogels effectively declined the burst effect with enhanced antioxidant activity. The Cur (400 μM)-OCLAVs-CS gel presented a cumulative release rate of 51.23 % of curcumin in 96 h, comparing to 93.37 % of that from the Cur-CS gel. Moreover, the corporation of OCLAVs and CS made the gel exhibited strong synergistic effect on the antioxidant activity, with an enhancement of up to 148.1 % on the ferric reducing power. Therefore, the hydrogel carrier made of incorporated fatty acid vesicles-chitosan can be served as an injectable or 3D printable drug delivery system, which may provide a hint to overcome the burst effect that existed in chitosan and other polysaccharide-based gels.

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.

Incorporation of NGR1 promotes bone regeneration of injectable HA/nHAp hydrogels by anti-inflammation regulation via a MAPK/ERK signaling pathway

Suitable bone grafts are commonly required to achieve successful bone regeneration, wherein much effort has been spent to optimize their osteogenesis. Increasing evidence has demonstrated that reducing the levels of TNF-α can enhance bone regeneration at the injury site. Notoginsenoside R1 (NGR1) has been extensively studied in the field of anti-inflammation and regenerative medicine. Nanosized hydroxyapatite (nHAp) possesses excellent biocompatibility and osteoconductivity. In this study, we fabricated a thermoresponsive, injectable hyaluronic acid/nHAp (HA/nHAp) composite hydrogel incorporated with NGR1 to promote bone regeneration. Furthermore, NGR1-HA/nHAp hydrogel could enhance bone regeneration than those of HA and HA/nHAp hydrogels, profited by the underlying osteoblastic mechanism that NGR1 could facilitate activation of the MAPK/ERK signaling pathway and down-regulate the expression of TNF-α, ultimately upregulated expression of osteogenic genes. In summary, the NGR1-HA/nHAp composite hydrogel with controlled inflammation, and excellent osteogenic effect, will have great potential for use in bone regeneration applications.

Enzymatic synthesis of sodium caseinate-EGCG-carboxymethyl chitosan ternary film: Structure, physical properties, antioxidant and antibacterial properties

Proteins and polysaccharides have been frequently used in recent years to prepare environment-friendly packaging materials. However, films based on proteins or polysaccharides alone often have poor performance as packaging, so they need to be combined to improve properties. In this work, we applied enzyme technology to prepare sodium caseinate (SC)-carboxymethyl chitosan (CMC) films, incorporating epigallocatechin gallate (EGCG) as bridging molecules and antibacterial agents. SC-EGCG-CMC ternary conjugate was firstly synthesized by tyrosinase (Tyr), and the composite films were then prepared with the aid of glycerol. Under tyrosinase catalytic conditions, EGCG could cross-link with SC and CMC covalently. The effects of different concentrations of EGCG and tyrosinase on mechanical properties, water vapor permeability, antibacterial properties and free radical scavenging ability were studied. The crosslinking degree and mechanical properties were improved with the increase of EGCG and tyrosinase content. The film showed good antibacterial activity against Gram-positive bacteria. In addition, the antibacterial activity and free radical scavenging ability increased with the increase of EGCG concentration. This work provides an efficient enzymatic method to prepare films with good strength and antibacterial properties, which can be used to improve the storage quality of foods.

Expanding the Repertoire of Electrospinning: New and Emerging Biopolymers, Techniques, and Applications

Electrospinning has emerged as a versatile and accessible technology for fabricating polymer fibers, particularly for biological applications. Natural polymers or biopolymers (including synthetically derivatized natural polymers) represent a promising alternative to synthetic polymers, as materials for electrospinning. Many biopolymers are obtained from abundant renewable sources, are biodegradable, and possess inherent biological functions. This review surveys recent literature reporting new fibers produced from emerging biopolymers, highlighting recent developments in the use of sulfated polymers (including carrageenans and glycosaminoglycans), tannin derivatives (condensed and hydrolyzed tannins, tannic acid), modified collagen, and extracellular matrix extracts. The proposed advantages of these biopolymer-based fibers, focusing on their biomedical applications, are also discussed to highlight the use of new and emerging biopolymers (or new modifications to well-established ones) to enhance or achieve new properties for electrospun fiber materials.

In situ Tissue Regeneration in the Cornea from Bench to Bedside

Corneal blindness accounts for 5.1% of visual deficiency and is the fourth leading cause of blindness globally. An additional 1.5-2 million people develop corneal blindness each year, including many children born with or who later develop corneal infections. Over 90% of corneal blind people globally live in low- and middle-income regions (LMIRs), where corneal ulcers are approximately 10-fold higher compared to high-income countries. While corneal transplantation is an effective option for patients in high-income countries, there is a considerable global shortage of corneal graft tissue and limited corneal transplant programs in many LMIRs. In situ tissue regeneration aims to restore diseases or damaged tissues by inducing organ regeneration. This can be achieved in the cornea using biomaterials based on extracellular matrix (ECM) components like collagen, hyaluronic acid, and silk. Solid corneal implants based on recombinant human collagen type III were successfully implanted into patients resulting in regeneration of the corneal epithelium, stroma, and sub-basal nerve plexus. As ECM crosslinking and manufacturing methods improve, the focus of biomaterial development has shifted to injectable, in situ gelling formulations. Collagen, collagen-mimetic, and gelatin-based in situ gelling formulas have shown the ability to repair corneal wounds, surgical incisions, and perforations in in-vivo models. Biomaterial approaches may not be sufficient to treat inflammatory conditions, so other cell-free therapies such as treatment with tolerogenic exosomes and extracellular vesicles may improve treatment outcomes. Overall, many of the technologies described here show promise as future medical devices or combination products with cell or drug-based therapies. In situ tissue regeneration, particularly with liquid formulas, offers the ability to triage and treat corneal injuries and disease with a single regenerative solution, providing alternatives to organ transplantation and improving patient outcomes.

Fabrication of a multi-level drug release platform with liposomes, chitooligosaccharides, phospholipids and injectable chitosan hydrogel to enhance anti-tumor effectiveness

Some anti-cancer drugs have poor solubility and availability, and are easily eliminated by rapid metabolism in vivo. To fix the drugs at the administration site and delay their release, a release platform with multi-level and multi-function was designed. The results showed that the curcumin (Cur) loaded liposomes (Cur@Lip) were coated sequentially with positive Chitooligosaccharides (Cur@Lip-Cos) and negative phospholipids (Cur@Lip-Cos-PC), to enhance water solubility, encapsulation efficiency, and delayed the release of the Cur, stability and cell intake of the liposomes, and the bioactivity of the system. The Cur@Lip-Cos could significantly enhance the inhibitory effect of MCF-7, better than the Cur@Lip-Cos-PC. The Lips were then fixed in an injectable thiolated chitosan hydrogel for local immobilization and sustained release which can effectively delay the release of Cur to inhibit MCF-7 growth. In summary, the innovative and biomimetic liposomal hydrogels are expected to provide more ideas for the design of drug carriers.

Facile Synthesis of In Situ Formable Alginate Composite Hydrogels with Ca2+-Induced Healing Ability

Dental caries have plagued humans for many years. At present, photocrosslinking resin is commonly used in clinics to repair narrow tooth defects, but the ultraviolet light used in this process has unavoidable cytotoxicity. In situ hydrogels with a similar structure to that of the natural extracellular matrix have gradually attracted attention in the field of hard tissue repair engineering. The injectable molding properties of hydrogel also give it the potential to fill irregularly shaped or fine tissue defects. Through a rapid and facile Michael addition reaction, we prepared maleic chitosan (CS-maleic anhydride [MA]) and thiolated alginate (sodium alginate [SA]-SH) to form a CS-MA/SA-SH hydrogel. To endue its mineralize ability, β-glycerophosphate calcium phosphate and calcium carbonate as the precursor of hydroxyapatite (HAp) were premixed in the hydrogel at certain ratios. This kind of hydrogel can quickly form into different shapes within 10 min. It is worth noting that external Ca²⁺ can react with the residual carboxyl groups of SA and provide the hydrogel with a self-healing ability. At the same time, we creatively propose a method that uses alkaline phosphatase to promote the mineralization of HAp in hydrogels, to achieve the purpose of regenerating hard tissue in situ. By examining the properties of hydrogels at different concentrations of calcium and phosphorus salts, we find that the CS-MA/SA-SH hydrogel with 50% (wt.%) inorganic matter presented the best self-healing properties, excellent mineralization of highly crystallized Hap, and has ideal cell compatibility. The potential application of the CS-MA/SA-SH hydrogel in repairing exposed dentin tubules in decayed teeth was explored through preliminary in vitro dental restoration experiments. Obviously, the penetration depth through dentin tubules was better than that of commercial dental sensitizers. In addition, the HAp morphology was affected by the local environment. We believe that this hydrogel can utilize tissues for dental regeneration and mineralization, and the healing ability provides the hydrogel flexibility for further application in hard tissue regeneration.

Recent Advances in Injectable Hydrogels for Controlled and Local Drug Delivery

Injectable hydrogels have received considerable interest in the biomedical field due to their potential applications in minimally invasive local drug delivery, more precise implantation, and site-specific drug delivery into poorly reachable tissue sites and into interface tissues, where wound healing takes a long time. Injectable hydrogels, such as in situ forming and/or shear-thinning hydrogels, can be generated using chemically and/or physically crosslinked hydrogels. Yet, for controlled and local drug delivery applications, the ideal injectable hydrogel should be able to provide controlled and sustained release of drug molecules to the target site when needed and should limit nonspecific drug molecule distribution in healthy tissues. Thus, such hydrogels should sense the environmental changes that arise in disease states and be able to release the optimal amount of drug over the necessary time period to the target region. To address this, researchers have designed stimuli-responsive injectable hydrogels. Stimuli-responsive hydrogels change their shape or volume when they sense environmental stimuli, e.g., pH, temperature, light, electrical signals, or enzymatic changes, and deliver an optimal concentration of drugs to the target site without affecting healthy tissues.

Injectable and In Situ-Formable Thiolated Chitosan-Coated Liposomal Hydrogels as Curcumin Carriers for Prevention of In Vivo Breast Cancer Recurrence

To improve water solubility and bioavailability, curcumin (Cur) was encapsulated by liposomes (Cur-Lip), which was further coated with thiolated chitosan (CSSH) to form liposomal hydrogels (CSSH/Cur-Lip gel). The hydrogels were thermosensitive with in situ injectable performance, which were fluidic at room temperature and gelled quickly at 37 °C. The cumulative release ratio of the 200 μM CSSH/Cur-Lip gel was 31.57 ± 1.34% at 12 h, which could effectively delay the release of curcumin. Worthily, the resilient hydrogels were compressive even after five cycles of compression. The cytotoxicity test indicated that the liposomal hydrogels had good cytocompatibility, but after encapsulation of curcumin, MCF-7 cells were suppressed and killed dramatically after 72 h. The in vivo breast cancer recurrence experiment showed that the CSSH/Cur-Lip gel inhibited breast cancer recurrence after tumors were resected, and the tissue of defect in the CSSH/Cur-Lip gel group was repaired. The results showed that the drug-loaded liposomal hydrogels can deliver curcumin continuously and exerted an excellent tumoricidal effect in vitro and in vivo. The injectable, in situ-formable, and thermosensitive CSSH/Cur-Lip gel can be designed as a promising novel drug delivery vehicle to be used as carriers for local accurate and sustained drug delivery to minimize burst release and as tissue engineering scaffolds for tissue regeneration after tumor resection.

Extracellular matrix-mimetic composite hydrogels of cross-linked hyaluronan and fibrillar collagen with tunable properties and ultrastructure

A platform of enzymatically-crosslinked Collagen/Tyramine hyaluronan derivative (Col/HA-Tyr) hydrogels with tunable compositions and gelation conditions was developed to evaluate the impact of the preparation conditions on their physical, chemical and biological properties. At low HA-Tyr content, hydrogels exhibited a fibrillar structure, with lower mechanical properties compared to pure Col hydrogels. At high HA-Tyr and Horse Radish Peroxydase (HRP) content, a microfibrillar network was formed beside the banded Col fibrils and a synergistic effect of the hybrid structure on mechanical properties was observed. These hydrogels were highly resistant against enzymatic degradation while keeping a high degree of hydration. Unlike HA-Tyr hydrogels, encapsulation of human dermal fibroblasts within Col/HA-Tyr hydrogels allowed for high cell viability. These results showed that high HA-Tyr and HRP concentrations are required to positively impact the physical properties of hydrogels while preserving collagen fibrils. Those Col/HA-Tyr hydrogels appear promising for novel tissue engineering applications following a biomimetic approach.

Review of polysaccharide particle-based functional drug delivery

This review investigates the significant role polysaccharide particles play in functional drug delivery. The importance of these systems is due to the wide variety of polysaccharides and their natural source meaning that they can provide biocompatible and biodegradable systems with a range of both biological and chemical functionality valuable for drug delivery. This functionality includes protection and presentation of working therapeutics through avoidance of the reticuloendothelial system, stabilization of biomacromolecules and increasing the bioavailability of incorporated small molecule drugs. Transport of the therapeutic is also key to the utility of polysaccharide particles, moving drugs from the site of administration through mucosal binding and transport and using chemistry, size and receptor mediated drug targeting to specific tissues. This review also scrutinizes the methods of synthesizing and constructing functional polysaccharide particle drug delivery systems that maintain and extend the functionality of the natural polysaccharides.

Disruption of Phaffia rhodozyma cells and preparation of microencapsulated astaxanthin with high water solubility

A novel process was developed for encapsulation of astaxanthin from Phaffia rhodozyma. The yeast cells were disrupted by glass beads and the high shearing force partially emulsified the astaxanthin in aqueous phase. The enzymolysis method was then adopted to prepare the yeast extract for a full use of the cells. The gelatin and porous starch were used to microencapsulate the emulsified astaxanthin. Under optimized conditions, the recovery of amino nitrogen and solid reached 3.68 ± 0.32% and 49.22 ± 2.34%, respectively. The microencapsulation conditions were optimized through orthogonal experiment and the encapsulation efficiency, loading astaxanthin, and amino-nitrogen reached 88.56%, 1.55 mg/g, and 1.35 ± 0.14%, respectively. The water solubility of microcapsules reached 81.5 ± 0.35%. Color and storage stability analysis showed that microencapsulation of astaxanthin possessed higher thermal stability. The results demonstrated that the established process was effective and practical.

A quantitative comparable study on multi-hierarchy conformation of acid and pepsin-solubilized collagens from the skin of grass carp (Ctenopharyngodon idella)

This work aimed to improve yield of collagen from the grass carp skin by employing different strategies (acid-acid method, pepsin-pepsin method and acid-pepsin method, denoted as A-A, P-P, A-P, respectively). And further to conduct quantitative characterization on structural properties, self-assembly kinetics and gelation properties of these collagens. Herein, a two-step collagen extraction method (pepsin-pepsin) was established with the high yield. Meanwhile, structural measurements of high-yield collagen (pepsin-soluble collagen, PSC) and acid-soluble collagen (ASC) indicated that both collagens maintained the typical triple helical conformation of collagen type I. Moreover, the fibrillogenesis tests of PSC and ASC at the various temperatures confirmed that self-assembly were the entropy-driven process. The gelation time of both ASC and PSC was determined by the dynamic time sweep at the different frequencies combined with Winter's criterion. The self-assembly kinetics results showed that fibrillogenesis rate for ASC solution was faster, and more liable to gelation relative to PSC. Mechanical measurements suggested that ASC showed the more resistance ability to deformation than PSC due to more complicated architecture, confirmed by higher fractal dimension. However, the equivalent typical assemblies of PSC to ASC at the various stages can still be expected via controlling incubation time or temperature under the guidance of Arrhenius equation. This study would provide some strategies for achieving maximum utilization of waste biomass and significant insights into the mechanisms underlying the quantitative differences in multiple hierarchy conformation (molecule, fibrillogenesis and hydrogel) of ASC and PSC, which may benefit for subsequent design, development and optimization of collagen-based hydrogels in biomedical industries.

Protein-Engineered Biomaterials for Cancer Theranostics

Proteins are an important class of biomaterials promising a variety of applications such as drug delivery, and imaging or therapy, owing to their biodegradability, biocompatibility, as well as inherent biological activities acting as enzymes, recognizing molecules, or therapeutics by themselves. Over the few past decades, different types of proteins with desired properties have been widely explored for biomedical applications. Many therapeutic proteins have now entered clinical use. This review therefore summarizes various strategies in the engineering of biomaterials for delivery of therapeutic proteins, as well as the recent development of protein-based biomaterials for cancer theranostics.

Polysaccharide and poly(methacrylic acid) based biodegradable elastomeric biocompatible semi-IPN hydrogel for controlled drug delivery

Nanoparticles embedded semi-interpenetrating (semi-IPNs) polymeric hydrogels with enhanced mechanical toughness and biocompatibility could have splendid biomedical acceptance. Here we propose poly(methacrylic acid) grafted polysaccharide based semi-IPNs filled with nanoclay via in situ Michael type reaction associated with covalent crosslinking with N,N-methylenebisacrylamide (MBA). The effect of nanoclay in the semi-IPN hydrogel has been investigated which showed significant improvement of mechanical robustness. Meanwhile, the hydrogels showed reversible ductility up to 70% in response to cyclic loading-unloading cycle which is an obvious phenomenon of rubber-like elasticity. The synthesized semi-IPN hydrogel show biodegradability and non-cytotoxic nature against human cells. The live-dead assay showed that the prepared hydrogel is a viable platform for cell growth without causing severe cell death. The in vitro drug release study in psychological pH (pH = 7.4) reveals that the controlled drug release phenomena can be tuned by simulating the environment pH. Such features in a single hydrogel assembly can propose this as high performance; biodegradable and non-cytotoxic 3D scaffold based promising biomaterial for tissue engineering.