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Tyramine and poly(ethylene glycol) grafted poly(l-glutamic acid) was prepared under physiological conditions in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2).⁷
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In situ injectable hydrogels have shown tremendous potential application in the biomedical field due to their significant drug accumulation at lesion sites, sustained release and markedly reduced systemic side effects. Specifically, peptide-based hydrogels, with unique biodegradation, biocompatibility, and bioactivity, are attractive molecular skel...
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Engineering drug delivery systems (DDS) aim to release bioactive cargo to a specific site within the human body safely and efficiently. Hydrogels have been used as delivery matrices in different studies due to their biocompatibility, biodegradability, and versatility in biomedical purposes. Microparticles have also been used as drug delivery system...
![Figure 1. Scheme showing the steps used to produce [PASP/PEDOT]PHMeDOT...](publication/356852302/figure/fig1/AS:1098770280386561@1638978657301/Scheme-showing-the-steps-used-to-produce-PASP-PEDOTPHMeDOT-hydrogels-a-synthesis-of_Q320.jpg)
In the present study, a composite made of conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), and a biodegradable hydrogel of poly(aspartic acid) (PASP) were electrochemically interpenetrated with poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) to prepare a new interpenetrated polymer network (IPN). Different cross-linker and PED...
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... The future direction of hydrogel development involves customizing the structure and functionalities of peptidebased hydrogels to meet diverse needs across various fields. This requires designing rational two-dimensional and 3D peptide structures by controlling their hydrophobic interactions, π-π stacking, and hydrogen bonding [160]. Additionally, peptidebased hydrogels can serve as frameworks for in vivo biomineralization, leading to the creation of biomimetic mineralized tissues such as bone or teeth. ...
Hydrogels are networks of three-dimensional cross-linked polymers, which possess the capacity to absorb and retain water. Hydrogels have proven to be adaptable and versatile, making them useful in various biomedical applications such as tissue engineering and regenerative medicine. Among the various types of hydrogels, peptide-based hydrogels are most suited for biological applications due to their special features, which include biodegradability, mechanical stability, biocompatibility, capacity to retain more water, injectability, and elasticity like that of tissues. In this review, we will present the recent advancements that have occurred in the field of peptide-based hydrogels concerning its biomedical applications especially delivery of targeted delivery, wound healing, tissue engineering, stem cell therapy, etc.
... Hydrogels are formed through physical or chemical crosslinking of 3D fibre networks [6]. Physical crosslinking connects fibres through hydrogen bonding, electrostatic interactions, or hydrophobic interactions to form secondary alpha (α) helical or beta (β) sheet structures [7]. Chemically crosslinked hydrogels contain covalent bonds induced by polymerisation reactions such as enzyme polymerisation and photo-polymerisation [7]. ...
... Physical crosslinking connects fibres through hydrogen bonding, electrostatic interactions, or hydrophobic interactions to form secondary alpha (α) helical or beta (β) sheet structures [7]. Chemically crosslinked hydrogels contain covalent bonds induced by polymerisation reactions such as enzyme polymerisation and photo-polymerisation [7]. Important features of hydrogels include their biocompatibility, biomimetic nature towards the ECM and high water content [8]. ...
To create functional tissue engineering scaffolds, biomaterials should mimic the native extracellular matrix of the tissue to be regenerated. Simultaneously, the survival and functionality of stem cells should also be enhanced to promote tissue organisation and repair. Hydrogels, but in particular, peptide hydrogels, are an emerging class of biocompatible scaffolds which act as promising self-assembling biomaterials for tissue engineering and regenerative therapies, ranging from articular cartilage regeneration at joint defects, to regenerative spinal cord injury following trauma. To enhance hydrogel biocompatibility, it has become imperative to consider the native microenvironment of the site for regeneration, where the use of functionalised hydrogels with extracellular matrix adhesion motifs has become a novel, emerging theme. In this review, we will introduce hydrogels in the context of tissue engineering, provide insight into the complexity of the extracellular matrix, investigate specific adhesion motifs that have been used to generate functionalised hydrogels and outline their potential applications in a regenerative medicine setting. It is anticipated that by conducting this review, we will provide greater insight into functionalised hydrogels, which may help translate their use towards therapeutic roles.
... Additionally, this work showed that having AzAla residues in the peptide sequence improves the antimicrobial properties of hydrogels. What makes our hydrogel system unique is a synergistic combination of stimuli responsiveness and antimicrobial peptides in a self-healing hydrogel, properties that are useful for wound healing applications [8,12,[23][24][25][26][27][28][29]. Wounds from pressure ulcers [30], diabetic ulcers [31], surgery, or burns are serious global health issues that affect millions of patients worldwide [32], and our hydrogel material is suitable for the healing of wounds. ...
A short peptide, FHHF-11, was designed to change stiffness as a function of pH due to changing degree of protonation of histidines. As pH changes in the physiologically relevant range, G′ was measured at 0 Pa (pH 6) and 50,000 Pa (pH 8). This peptide-based hydrogel is antimicrobial and cytocompatible with skin cells (fibroblasts). It was demonstrated that the incorporation of unnatural AzAla tryptophan analog residue improves the antimicrobial properties of the hydrogel. The material developed can have a practical application and be a paradigm shift in the approach to wound treatment, and it will improve healing outcomes for millions of patients each year.
... An interesting class of hydrogels consists of those based on peptides [3]. Self-assembling peptides are a particular class of molecules characterized by the ability to spontaneously organize themselves into ordered and stable structures in conditions of thermodynamic equilibrium, thanks to the formation of non-covalent bonds (hydrogen bonds, ionic, hydrophobic, and Van der Waals interactions) among the side chains of the amino acids of which they are made [25][26][27]. These intra-and inter-molecular interactions allow the peptide to organize into ordered secondary (α-helix and β-sheet) and tertiary (fibers and fibrils) structures. ...
The recognized antibacterial properties of silver nanoparticles (AgNPs) characterize them as attractive nanomaterials for developing new bioactive materials less prone to the development of antibiotic resistance. In this work, we developed new composites based on self-assembling Fmoc-Phe3 peptide hydrogels impregnated with in situ prepared AgNPs. Different methodologies, from traditional to innovative and eco-sustainable, were compared. The obtained composites were characterized from a hydrodynamic, structural, and morphological point of view, using different techniques such as DLS, SEM, and rheological measurements to evaluate how the choice of the reducing agent determines the characteristics of AgNPs and how their presence within the hydrogel affects their structure and properties. Moreover, the antibacterial properties of these composites were tested against S. aureus, a major human pathogen responsible for a wide range of clinical infections. Results demonstrated that the hydrogel composites containing AgNPs (hgel@AgNPs) could represent promising biomaterials for treating S. aureus-related infections.
... This class of hydrogels responds to small variations in environmental conditions, such as light, ionic strength, magnetic fields, pH, and temperature. Among these, the most commonly studied hydrogels are responsive either to pH or temperature [18][19][20]. Until now, a wide variety of stimuli-responsive hydrogels has been reported; among them is the hydrogel of poly(N-isopropylacrylamide) (PNIPAM), the gold standard polymer in the field of thermoresponsive hydrogels (TRH) [21]. PNIPAM has a lower critical solution temperature of 32−34 °C [22,23]. ...
In light of the growing bacterial resistance to antibiotics and in the absence of the development of new antimicrobial agents, numerous antimicrobial delivery systems over the past decades have been developed with the aim to provide new alternatives to the antimicrobial treatment of infections. However, there are few studies that focus on the development of a rational design that is accurate based on a set of theoretical-computational methods that permit the prediction and the understanding of hydrogels regarding their interaction with cationic antimicrobial peptides (cAMPs) as potential sustained and localized delivery nanoplatforms of cAMP. To this aim, we employed docking and Molecular Dynamics simulations (MDs) that allowed us to propose a rational selection of hydrogel candidates based on the propensity to form intermolecular interactions with two types of cAMPs (MP-L and NCP-3a). For the design of the hydrogels, specific building blocks were considered, named monomers (MN), co-monomers (CM), and cross-linkers (CL). These building blocks were ranked by considering the interaction with two peptides (MP-L and NCP-3a) as receptors. The better proposed hydrogel candidates were composed of MN3-CM7-CL1 and MN4-CM5-CL1 termed HG1 and HG2, respectively. The results obtained by MDs show that the biggest differences between the hydrogels are in the CM, where HG2 has two carboxylic acids that allow the forming of greater amounts of hydrogen bonds (HBs) and salt bridges (SBs) with both cAMPs. Therefore, using theoretical-computational methods allowed for the obtaining of the best virtual hydrogel candidates according to affinity with the specific cAMP. In conclusion, this study showed that HG2 is the better candidate for future in vitro or in vivo experiments due to its possible capacity as a depot system and its potential sustained and localized delivery system of cAMP.
... At present, due to the soft texture, high water content, good mechanical properties, good histocompatibility, and versatility of hydrogel, it is believed that hydrogel materials have broad application prospects in tissue engineering (cell culture, tissue regeneration, tissue repair, etc.), intelligent devices, drug delivery, hemostatic agents, antibacterial materials, and other fields (Zhao et al. 2017;Huang et al. 2017;Norouzi et al. 2016;Sharma and Tiwari 2020). Among them, much attention has been paid to amino acid-based hydrogels because of their low cost, high biocompatibility, low or no immunogenicity, ability to adapt, and possible use as biomedical materials (Liu et al. 2019;Marchesan et al. 2014). Among the 20 natural amino acids, phenylalanine, cystine, and tyrosine were found to self-assemble to form elongated and fibrillar structures at the nanoscale (Adler-Abramovich et al. 2012;Shaham-Niv et al. 2015). ...
During trauma and surgery, bleeding is a major concern. One of the crucial strategies for hemostasis is the use of biological hemostatic material. Herein, we reported an amino acid-based hydrogel FmocF-ADP hydrogel, which consisted of N-[(9H-fluoren-9-ylmethoxy) carbonyl]-3-phenyl-L-alanine (FmocF) and adenosine diphosphate (ADP) sodium solution. The hydrogel was created by FmocF self-assembling to nanofiber in ADP sodium solution and then cross-linking to hydrogel. FmocF-ADP hydrogel showed good in vitro coagulation activity as measured by whole blood clotting assays, platelet clotting assays, platelet activation assays, and platelet adhesion assays. Further, it was noted to reveal an exceptional in vivo hemostatic effect in a mouse liver bleeding model. Together with the previous report of the good biocompatibility and antimicrobial activity of FmocF hydrogel, our study would extend the biomedical application of FmocF hydrogel. In conclusion, the present study would provide a constructive strategy for the development of new antimicrobial and hemostatic materials or develop a potential hemostatic material.
... This allows for the preservation of biological product characteristics and long-term drug release, as well as a decrease in early burst release and unwanted pharmaceutical effects. 72 Thermosensitive hydrogels are particularly intriguing as specific injectable biomaterials since they form gels spontaneously when exposed to body temperature and do not require extra chemical treatment. The demand for regulated medication or cell delivery is growing in tandem with the fast advancement of regenerative medicine. ...
Owing to their properties such as biocompatibility, tunable mechanical properties, permeability toward oxygen, nutrients, and the ability to hold a significant amount of water, hydrogels have wide applications in biomedical research. They have been engaged in drug delivery systems, 3D cell culture, imaging, and extracellular matrix (ECM) mimetics. Injectable hydrogels represent a major subset of hydrogels possessing advantages of site-specific conformation with minimal invasive techniques. It preserves the inherent properties of drug/biomolecules and is devoid of any side effects associated with surgery. Various polymeric materials utilized in developing injectable hydrogels are associated with the limitations of toxicity, immunogenicity, tedious manufacturing processes, and lack of easy synthetic tunability. Peptides are an important class of biomaterials that have interesting properties such as biocompatibility, stimuli responsiveness, shear thinning, self-healing, and biosignaling. They lack immunogenicity and toxicity. Therefore, numerous peptide-based injectable hydrogels have been explored in the past, and a few of them have reached the market. In recent years, minimalistic dipeptides have shown their ability to form stable hydrogels through cooperative noncovalent interactions. In addition to inherent properties of lengthy peptide-based injectable hydrogels, dipeptides have the unique advantages of low production cost, high synthetic accessibility, and higher stability. Given the instances of expanding significance of injectable peptide hydrogels in biomedical research and an emerging recent trend of dipeptide-based injectable hydrogels, a timely review on dipeptide-based injectable hydrogels shall highlight various aspects of this interesting class of biomaterials. This concise review that focuses on the dipeptide injectable hydrogel may stimulate the current trends of research on this class of biomaterial to translate its significance as interesting products for biomedical applications.
... such as poly(ethylene glycol) (PEG), poly(vinyl alcohol) (PVA), and poly(acrylamide) (PAA)-based formulations, are known to be characterized by strong and tunable mechanical properties and prolonged stability in aqueous media [7][8][9]. Conversely, systems of natural origin, such as gelatin, chitosan, hyaluronic acid, alginate, and peptide-based formulations, generally show enhanced bioactive features, such as biocompatibility, higher mimesis of the extracellular matrix structure, and capability to promote tissue regeneration and angiogenesis [10][11][12][13][14]. However, both synthetic and natural polymers show some drawbacks, e.g., reduced biocompatibility and weak mechanical properties and high batchto-batch variability, respectively. ...
Bioartificial hydrogels are hydrophilic systems extensively studied for regenerative medicine due to the synergic combination of features of synthetic and natural polymers. Injectability is another crucial property for hydrogel mini-invasive administration. This work aimed at engineering injectable bioartificial in situ cross-linkable hydrogels by implementing green and eco-friendly approaches. Specifically, the versatile poly(ether urethane) (PEU) chemistry was exploited for the development of an amphiphilic PEU, while hyaluronic acid was selected as natural component. Both polymers were functionalized to expose thiol and catechol groups through green water-based carbodiimide-mediated grafting reactions. Functionalization was optimized to maximize grafting yield while preserving group functionality. Then, polymer miscibility was studied at the macro-, micro-, and nano-scale, suggesting the formation of hydrogen bonds among polymeric chains. All hydrogels could be injected through G21 and G18 needles in a wide temperature range (4–25 °C) and underwent sol-to-gel transition at 37 °C. The addition of an oxidizing agent to polymer solutions did not improve the gelation kinetics, while it negatively affected hydrogel stability in an aqueous environment, suggesting the occurrence of oxidation-triggered polymer degradation. In the future, the bioartificial hydrogels developed herein could find application in the biomedical and aesthetic medicine fields as injectable formulations for therapeutic agent delivery.
... In contrast to proteins, which commonly integrate into biomaterials via non-specific amine carboxylic acid couplings, peptides may be added with a high level of chemical selectivity. The unique properties of protein-based hydrogels made by supramolecular approaches include their biocompatibility, biodegradability, safety, and bioactivity by mimicking natural proteins [70,71]. As a result of non-covalent interactions (e.g., hydrogen bonding, electrostatic interactions, hydrophobic interactions, and p-p interactions), they can self-assemble into fibers, followed by fiber entanglement leading to the formation of the final hydrogel network. ...
... Peptide-based hydrogels have various potential benefits in tissue engineering since they are biocompatible and may offer nutritional conditions conducive to cell development. They can also be used to mimic natural extracellular matrices and may have the potential to encapsulate cells or bioactive substances [70]. Due to various drawbacks of conventional therapies, such as drug resistance, poor biocompatibility, and limited antibacterial effects, peptide-based hydrogels with antibacterial activity have recently gained interest. ...
An immune system responds to pathogens, toxic compounds, or certain physiological conditions which lead to inflammation. However, uncontrolled and excessive inflammation is associated with a variety of severe chronic conditions including intestinal disorders, cancer, diabetes, and myocardial infarction. The development of anti-inflammatory therapies to treat and manage relevant chronic diseases has resulted from a better understanding of inflammation. However, clinical outcomes vary among patients and serious adverse effects are often observed. Furthermore, clinical anti-inflammatory therapeutics have some limitations due to their insolubility in water, low bioavailability, and poor accessibility to subcellular compartments. To address these challenges, the drug delivery system specific to inflammation offers significant potential. A hydrogel is attractive as a drug delivery platform because of its outstanding characteristics, including swellability, biocompatibility, controlled degradation, and sustained drug release. Hydrogels have been widely used in biomedical applications for several reasons, using diverse polymers of synthetic and natural origin. The design of hydrogels relies heavily on proteins and peptides because proteins are the fundamental macromolecules in living organisms for biochemical, mechanical, and structural functions. Therefore, they provide us with a wide range of structural building blocks for the formation of various types of biomaterials, including hydrogels. Since natural proteins and peptides are biocompatible and biodegradable, they have features advantageous for their use as the building blocks of hydrogels for biomedical applications. This review aims to focus on hydrogels derived from protein and peptide-based systems and highlights recent trends in the use of protein and peptide-based hydrogels as drug delivery systems for inflammation.
... In this context, self-assembling amino acids (AA), peptide-based (nature's preferred building blocks) supramolecular hydrogels are at the forefront of advanced biomaterials owing to their fascinating properties such as exclusive biocompatibility, biodegradability, low toxicity, and bioactivity as well as their remarkable applications in biomedicine, including drug delivery, in vivo feedbacks in targeted tissue niches, regenerative medicine, etc. [19][20][21][22][23][24]. Hydrogels are three-dimensional (3D) cross-linked polymeric networks in which a substantial amount of water is entrapped and have been universally accepted biomaterials for tissue engineering applications [24][25][26][27][28][29]. ...
... In this context, self-assembling amino acids (AA), peptide-based (nature's preferred building blocks) supramolecular hydrogels are at the forefront of advanced biomaterials owing to their fascinating properties such as exclusive biocompatibility, biodegradability, low toxicity, and bioactivity as well as their remarkable applications in biomedicine, including drug delivery, in vivo feedbacks in targeted tissue niches, regenerative medicine, etc. [19][20][21][22][23][24]. Hydrogels are three-dimensional (3D) cross-linked polymeric networks in which a substantial amount of water is entrapped and have been universally accepted biomaterials for tissue engineering applications [24][25][26][27][28][29]. The 3D fibrous networks of these hydrogels efficiently mimic the fibrous part of the extracellular matrix (ECM) protein architectures and are capable of sustaining cell differentiation and growth when applied as coatings or 3D matrices [30]. ...
Thixotropy is a fascinating feature present in many gel systems that has garnered a lot of attention in the medical field in recent decades. When shear stress is applied, the gel transforms into sol and immediately returns to its original state when resting. The thixotropic nature of the hydrogel has inspired scientists to entrap and release enzymes, therapeutics, and other substances inside the human body, where the gel acts as a drug reservoir and can sustainably release therapeutics. Furthermore, thixotropic hydrogels have been widely used in various therapeutic applications, including drug delivery, cornea regeneration and osteogenesis, to name a few. Because of their inherent biocompatibility and structural diversity, peptides are at the forefront of cutting-edge research in this context. This review will discuss the rational design and self-assembly of peptide-based thixotropic hydrogels with some representative examples, followed by their biomedical applications.
