Fundamental properties of smart hydrogels for tissue engineering applications: A review (original) (raw)
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Materials Today Bio, 2021
Recently, biomedicine and tissue regeneration have emerged as great advances that impacted the spectrum of healthcare. This left the door open for further improvement of their applications to revitalize the impaired tissues. Hence, restoring their functions. The implementation of therapeutic protocols that merge biomimetic scaffolds, bioactive molecules, and cells plays a pivotal role in this track. Smart/stimuli-responsive hydrogels are remarkable three-dimensional (3D) bioscaffolds intended for tissue engineering and other biomedical purposes. They can simulate the physicochemical, mechanical, and biological characters of the innate tissues. Also, they provide the aqueous conditions for cell growth, support 3D conformation, provide mechanical stability for the cells, and serve as potent delivery matrices for bioactive molecules. Many natural and artificial polymers were broadly utilized to design these intelligent platforms with novel advanced characteristics and tailored functionalities that fit such applications. In the present review, we highlighted the different types of smart/stimuli-responsive hydrogels with emphasis on their synthesis scheme. Besides, the mechanisms of their responsiveness to different stimuli were elaborated. Their potential for tissue engineering applications was discussed. Furthermore, their exploitation in other biomedical applications as targeted drug delivery, smart biosensors, actuators, 3D and 4D printing, and 3D cell culture were outlined. In addition, we threw light on smart self-healing hydrogels and their applications in biomedicine. Eventually, we presented their future perceptions in biomedical and tissue regeneration applications. Conclusively, current progress in the design of smart/stimuli-responsive hydrogels enhances their prospective to function as intelligent, and sophisticated systems in different biomedical applications.
Arabian Journal of Chemistry , 2024
Hydrogels are three-dimensional structures that serve as substitutes for the extracellular matrix (ECM) and possess outstanding physicochemical and biochemical characteristics. They are gaining importance in regenerative medicine because of their similarity to the natural extracellular matrix in terms of moisture content and wound and tissue healing permeability. Tissue engineering advancements have resulted in the development of flexible hydrogels that mimic the dynamic characteristics of the ECM. Several approaches have been applied to produce hydrogels from biopolymers with enhanced functional and structural characteristics for different applications in tissue engineering and regenerative medicine (TERM). This review provides a comprehensive overview of hydrogel in wound healing, tissue engineering, and drug delivery systems. We outline different types of hydrogels based on the physical and chemical crosslinking, fundamental properties, and their applications in TERM. This review article provided the recent literature on hydrogels for tissue engineering and regenerative medicine within five years. Recent developments in biopolymer-based hydrogels for state-of-the-art tissue engineering and regenerative medicine have been discussed, emphasizing their significant challenges and future perspectives.
25th Anniversary Article: Rational Design and Applications of Hydrogels in Regenerative Medicine
Advanced Materials, 2014
Hydrogels are three-dimensional (3D) networks consisting of hydrophilic polymer chains, which are crosslinked to form matrices with high water content (up to thousand of times their dry weight). [ 1 ] Due to their remarkable characteristics, including tunable physical, chemical, and biological properties, high biocompatibility, versatility in fabrication, and similarity to native extracellular matrix (ECM), hydrogels have emerged as promising materials in the biomedical fi eld. [ 1-3 ] Signifi cant progress has been made in the synthesis and fabrication of hydrogels from both natural and synthetic sources for various applications; these include regenerative medicine, drug/gene delivery, stem cell and cancer research, and cell therapy. [ 4-6 ] Naturally-derived hydrogels, such as collagen, chitosan, hyaluronic acid (HA), alginate, gelatin, elastin, chondroitin sulfate, and heparin, are appealing for biological applications due to their cell signaling and cell-interactive properties, and biodegradability. [ 7 ] However, their limitations include low mechanical properties, inability to control their degradation and structure, and potential immunogenicity. On the other hand, synthetic hydrogels, such as poly(ethylene glycol) (PEG), poly(vinyl alcohol)(PVA), poly(2-hydroxyethyl methacrylate) (PHEMA), and polyacrylamide (PAM), possess controllable degradation and microstructure, generally show high mechanical properties, but lack biological moieties. [ 3,7 ] Due to the distinct properties of each of these hydrogel classes, gels that are based on the combination of natural and synthetic polymers have attracted signifi cant attention for biological and biomedical applications. [ 8 ] Various crosslinking approaches, including chemical and physical, have been employed to create polymer networks and preserve their 3D structures in aqueous environments. In physically crosslinked gels, physical interactions between polymer chains prevent dissociation of the hydrogel, while in chemically crosslinked gels, covalent bonds between polymer chains create stable hydrogels. Physically crosslinked hydrogels are formed through changes in environmental conditions (e.g., pH, temperature, and ionic interactions), hydrogen bonds, Hydrogels are hydrophilic polymer-based materials with high water content and physical characteristics that resemble the native extracellular matrix. Because of their remarkable properties, hydrogel systems are used for a wide range of biomedical applications, such as three-dimensional (3D) matrices for tissue engineering, drug-delivery vehicles, composite biomaterials, and as injectable fi llers in minimally invasive surgeries. In addition, the rational design of hydrogels with controlled physical and biological properties can be used to modulate cellular functionality and tissue morphogenesis. Here, the development of advanced hydrogels with tunable physiochemical properties is highlighted, with particular emphasis on elastomeric, light-sensitive, composite, and shape-memory hydrogels. Emerging technologies developed over the past decade to control hydrogel architecture are also discussed and a number of potential applications and challenges in the utilization of hydrogels in regenerative medicine are reviewed. It is anticipated that the continued development of sophisticated hydrogels will result in clinical applications that will improve patient care and quality of life.
New Insights of Scaffolds Based on Hydrogels in Tissue Engineering
Polymers, 2022
In recent years, biomaterials development and characterization for new applications in regenerative medicine or controlled release represent one of the biggest challenges. Tissue engineering is one of the most intensively studied domain where hydrogels are considered optimum applications in the biomedical field. The delicate nature of hydrogels and their low mechanical strength limit their exploitation in tissue engineering. Hence, developing new, stronger, and more stable hydrogels with increased biocompatibility, is essential. However, both natural and synthetic polymers possess many limitations. Hydrogels based on natural polymers offer particularly high biocompatibility and biodegradability, low immunogenicity, excellent cytocompatibility, variable, and controllable solubility. At the same time, they have poor mechanical properties, high production costs, and low reproducibility. Synthetic polymers come to their aid through superior mechanical strength, high reproducibility, red...
2018
This review discusses basic aspects used to control the architecture and functional properties of smart hydrogels. The introduction briefly outlines what has been accomplished regarding smart hydrogels and explores historical aspects and the fundamental understanding of these systems. Then, a short discussion on the chemical interactions and the main variables involved in architectural construction is exhibited. Further analysis provides the basis for optimizing biological responses through system modulation. Finally, we outline perspectives and challenges for building smart hydrogels into functionalized and modulated delivery systems.
Exploiting Advanced Hydrogel Technologies to Address Key Challenges in Regenerative Medicine
Advanced healthcare materials, 2018
Regenerative medicine aims to tackle a panoply of challenges from repairing focal damage to articular cartilage to preventing pathological tissue remodeling after myocardial infarction. Hydrogels are water-swollen networks formed from synthetic or naturally derived polymers and are emerging as important tools to address these challenges. Recent advances in hydrogel chemistries are enabling researchers to create hydrogels that can act as 3D ex vivo tissue models, allowing them to explore fundamental questions in cell biology by replicating tissues' dynamic and nonlinear physical properties. Enabled by cutting edge techniques such as 3D bioprinting, cell-laden hydrogels are also being developed with highly controlled tissue-specific architectures, vasculature, and biological functions that together can direct tissue repair. Moreover, advanced in situ forming and acellular hydrogels are increasingly finding use as delivery vehicles for bioactive compounds and in mediating host cell...
Development of hydrogels for regenerative engineering
The aim of regenerative engineering is to restore complex tissues and biological systems through convergence in the fields of advanced biomaterials, stem cell science, and developmental biology. Hydrogels are one of the most attractive biomaterials for regenerative engineering, since they can be engineered into tissue mimetic 3D scaffolds to support cell growth due to their similarity to native extracellular matrix. Advanced nano-and micro-technologies have dramatically increased the ability to control properties and functionalities of hydrogel materials by facilitating biomi-metic fabrication of more sophisticated compositions and architectures, thus extending our understanding of cell-matrix interactions at the nanoscale. With this perspective, this review discusses the most commonly used hydrogel materials and their fabrication strategies for regenera-tive engineering. We highlight the physical, chemical, and functional modulation of hydrogels to design and engineer biomimetic tissues based on recent achievements in nano-and micro-technologies. In addition, current hydrogel-based regenerative engineering strategies for treating multiple tissues, such as musculoskeletal, nervous and cardiac tissue, are also covered in this review. The interaction of multiple disciplines including materials science, cell biology, and chemistry , will further play an important role in the design of functional hydrogels for the regeneration of complex tissues.
Polymers, 2021
Due to their highly hydrophilic nature and compositional versatility, hydrogels have assumed a protagonic role in the development of physiologically relevant tissues for several biomedical applications, such as in vivo tissue replacement or regeneration and in vitro disease modeling. By forming interconnected polymeric networks, hydrogels can be loaded with therapeutic agents, small molecules, or cells to deliver them locally to specific tissues or act as scaffolds for hosting cellular development. Hydrogels derived from decellularized extracellular matrices (dECMs), in particular, have gained significant attention in the fields of tissue engineering and regenerative medicine due to their inherently high biomimetic capabilities and endowment of a wide variety of bioactive cues capable of directing cellular behavior. However, these hydrogels often exhibit poor mechanical stability, and their biological properties alone are not enough to direct the development of tissue constructs wit...