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Flexible bioelectronic devices have attracted immense interest in the biomedical field because of their wearability, biocompatibility, diverse functionalities, and ease of personalization. Recently, flexible energy harvesters have been developed, and attempts have been made to integrate them with such devices, enabling them to operate without external batteries or power supply. In this review, the latest advances in flexible energy harvesters and their use in wearable devices are discussed. Energy harvesters for versatile biomedical applications are summarized. Finally, the challenges and future perspectives of self‐powered biomedical systems that enable wearable healthcare monitoring and management are outlined. [ABSTRACT FROM AUTHOR]

Hepatocellular carcinoma (HCC) is a malignant and deadly form of liver cancer with limited treatment options. Transcatheter arterial chemoembolization, a procedure that delivers embolic and chemotherapeutic agents through blood vessels, is a promising cancer treatment strategy. However, it still faces limitations, such as inefficient agent delivery and the inability to address tumor‐induced immunosuppression. Here, a drug‐eluting shear‐thinning hydrogel (DESTH) loaded with chemotherapeutic and immunotherapeutic agents in nanocomposite hydrogels composed of gelatin and nanoclays is presented as a therapeutic strategy for a catheter‐based endovascular anticancer approach. DESTH is manually deliverable using a conventional needle and catheter. In addition, drug release studies show a sustained and pH‐dependent co‐delivery of the chemotherapy doxorubicin (acidic pH) and the immune‐checkpoint inhibitor aPD‐1 (neutral pH). In a mouse liver tumor model, the DESTH‐based chemo/immunotherapy combination has the highest survival rate and smallest residual tumor size. Finally, immunofluorescence analysis confirms that DESTH application enhances cell death and increases intratumoral infiltration of cytotoxic T‐cells. In conclusion, the results show that DESTH, which enables efficient ischemic tumor cell death and effective co‐delivery of chemo‐ and immunotherapeutic agents, may have the potential to be an effective therapeutic modality in the treatment of HCC. [ABSTRACT FROM AUTHOR]

Stimuli-responsive peptide gels are a growing class of functional biomaterials that are involved in many applications in research. Here, we present a novel di-peptide hydrogel from the compound Boc--Phe--Trp--OH in various buffer and pH conditions. We examine the effects of different stimuli, including temperature and pH, on the mechanical strength of the gels through frequency rheology studies. We found that this hydrogelator is highly pH dependent, only forming a gel in a narrow range of pH 6-7. This hydrogelator hold promise for the development of new stimuli-responsive biomaterials for specific applications that require this type of specific stimuli. Key words: hydrogel, peptides, stimuli responsive, pH-dependent gelation, rheology. Les gels peptidiques stimulables constituent une classe grandissante de biomateriaux fonctionnels mis a contribution dans de nombreuses applications en recherche. Dans le present article, nous faisons etat d'un nouvel hydrogel dipeptidique produit a partir du compose Boc--Phe--Trp--OH dans divers tampons et conditions de pH. Nous examinons les effets de differents stimuli, tels que la temperature et le pH, sur la resistance mecanique des gels au moyen d'etudes de rheologie frequentielle. Nos resultats ont montre que ce gelifiant est tres sensible au pH, formant un hydrogel dans un intervalle de pH etroit (pH 6-7). Ce gelifiant constitue une avenue prometteuse pour la mise au point de nouveaux biomateriaux stimulables destines a des applications particulieres necessitant ce type de stimuli tres precis. [Traduit par la Redaction] Mots-cles : hydrogel, peptides, stimulable, gelification sensible au pH, rheologie., Introduction Peptide-based supramolecular gels are functional materials that have been the subject of research due to their versatility and their wide range of applications in many fields. (1) They can [...]

Hemorrhage is the leading cause of trauma-related deaths, in hospital and prehospital settings. Hemostasis is a complex mechanism that involves a cascade of clotting factors and proteins that result in the formation of a strong clot. In certain surgical and emergency situations, hemostatic agents are needed to achieve faster blood coagulation to prevent the patient from experiencing a severe hemorrhagic shock. Therefore, it is critical to consider appropriate materials and designs for hemostatic agents. Many materials have been fabricated as hemostatic agents, including synthetic and naturally derived polymers. Compared to synthetic polymers, natural polymers or biopolymers, which include polysaccharides and polypeptides, have greater biocompatibility, biodegradability and processibility. Thus, in this review, we focus on biopolymer-based hemostatic agents of different forms, such as powder, particles, sponges and hydrogels. Finally, we discuss biopolymer-based hemostatic materials currently in clinical trials and offer insight into next-generation hemostats for clinical translation. [ABSTRACT FROM AUTHOR]

Abstract: Supramolecular gels are a fascinating class of soft materials that have attracted significant attention in recent years. They are composed of small molecule gelators that assemble into supramolecular network structures. The resulting space is filled with solvent. Some gel materials are able to respond to various stimuli making them attractive drug delivery vehicles and as matrices for tissue regeneration. Peptide‐based gel materials are particularly attractive as they possess numerous advantages including biocompatibility and biodegradability. Stimuli‐responsive peptides that alter properties as a function of pH, redox, temperature, and enzymes offer the potential to create materials with tunable characteristics. In addition, the ability of metal ions to improve the strength of gelation or act as a scaffold has become an interesting approach to develop dynamic peptide gel materials. In this review, the stimuli‐responsive properties (pH, redox, temperature, and enzyme responsive properties), as well as the biocompatible/‐degradable nature of the peptide gelators are highlighted. In addition, metal ions are discussed as a stimulus to enhance peptide gelation and a number of potential applications of these peptide gelators are provided with an outlook on future directions. [ABSTRACT FROM AUTHOR]

Supramolecular amino acid and peptide hydrogels are functional materials with a wide range of applications, however, their ability to serve as matrices for enzyme entrapment have been rarely explored. Two amino acid conjugates were synthesized and explored for hydrogel formation. These hydrogels were characterized in terms of strength and morphology, and their ability to entrap enzymes while keeping them active and reusable was explored. It was found that the hydrogels were able to successfully entrap two common and significant enzymes—horseradish peroxidase and α-amylase—thus keeping them active and stable, along with inducing recycling capabilities, which has potential to further advance the industrial biotransformation field. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) in vitro tumor models that can capture the pathophysiology of human tumors are essential for cancer biology and drug development. However, simulating the tumor microenvironment is still challenging because it consists of a heterogeneous mixture of various cellular components and biological factors. In this regard, current extracellular matrix (ECM)-mimicking hydrogels used in tumor tissue engineering lack physical interactions that can keep biological factors released by encapsulated cells within the hydrogel and improve paracrine interactions. Here, we developed a nanoengineered ion-covalent cross-linkable bioink to construct 3D bioprinted organotypic tumor models. The bioink was designed to implement the tumor ECM by creating an interpenetrating network composed of gelatin methacryloyl (GelMA), a light cross-linkable polymer, and synthetic nanosilicate (Laponite) that exhibits a unique ionic charge to improve retention of biological factors released by the encapsulated cells and assist in paracrine signals. The physical properties related to printability were evaluated to analyze the effect of Laponite hydrogel on bioink. Low GelMA (5%) with high Laponite (2.5%-3.5%) composite hydrogels and high GelMA (10%) with low Laponite (1.0%-2.0%) composite hydrogels showed acceptable mechanical properties for 3D printing. However, a low GelMA composite hydrogel with a high Laponite content could not provide acceptable cell viability. Fluorescent cell labeling studies showed that as the proportion of Laponite increased, the cells became more aggregated to form larger 3D tumor structures. Reverse transcription-polymerase chain reaction (RT-qPCR) and western blot experiments showed that an increase in the Laponite ratio induces upregulation of growth factor and tissue remodeling-related genes and proteins in tumor cells. In contrast, cell cycle and proliferation-related genes were downregulated. On the other hand, concerning fibroblasts, the increase in the Laponite ratio indicated an overall upregulation of the mesenchymal phenotype-related genes and proteins. Our study may provide a rationale for using Laponite-based hydrogels in 3D cancer modeling., (© 2023 IOP Publishing Ltd.)

Smart antibacterial systems, delivering antimicrobials in a highly controlled manner, are one strategy toward fighting the rise of antibiotic-resistant pathogens. Here, we engineer a laser-responsive antimicrobial nanocomposite hydrogel combining a peptide amphiphile and a photothermally active polydopamine nanoparticle (PDNP) to entrap the hydrophobic rifampicin within the hydrophilic hydrogel matrix. We show that the ability of the gelator to interact and retain rifampicin within the gel induced structural changes in its nanofiber network and mechanical properties. Furthermore, PDNP inclusion enabled laser-induced drug release, preventing growth of a Gram-negative E. coli . Overall, our work provides a significant advance in designing smart materials for controlled drug delivery applications.

Supramolecular gels have been an area of interest in many research fields. They provide a means to understand assembly of nanostructures, and through the use of amino acid- and peptide-based gelators they can give insights into the similar assembly pathways of their more complex structural counterparts. Bio-inspired metal coordination, such as histidine-copper coordination, in the supramolecular assembly of these gelators is one method for furthering our understanding and development of these materials. Metal-gelator coordination mimics biologically relevant metal-peptide coordination, thus influencing hydrogel self-assembly and mechanical properties, including biodegradability, biocompatibility, tunability, and recyclablity, while the metal coordination can functionalize the gels to allow for widespread applications in biomedical industries (e.g., drug delivery), waste management, and catalysis. This review aims to discuss recent insights into the supramolecular assembly of gels involving metal ions, as well as a few key areas of application using metal interactions and incorporation., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Bio-organometallic ferrocene-containing amino acids and peptides have been reported to form gels and are interesting to study due to their structural properties and applications for biological purposes. In this study, a ferrocene-dicarboxylic acid derivative of the dipeptide tryptophan-tryptophan was investigated. The indolic nitrogen in the amino acid tryptophan is important for biological functions due to its role in hydrogen bonding. Here, intermolecular interactions with the indolic nitrogen allow this conjugate to self-assemble into a fibrous supramolecular structure that forms a stable gel. Rheological analysis demonstrates the self-healing nature of this gel. Interestingly, X-ray analysis of this ferrocene-peptide conjugate reveals close contacts involving tryptophan, in particular the indole NH group in interactions with an adjacent neighboring molecule., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)