Peptide gels for controlled release of proteins

N-Hydroxyalkanamide Based Organo/hydrogels as Novel Scaffolds for pH-Dependent Metronidazole and Theophylline Release

The traditional delivery of metronidazole and theophylline presents challenges like bitter taste, variable absorption, and side effects. However, gel-based systems offer advantages including enhanced targeted drug delivery, minimized side effects, and improved patient compliance, effectively addressing these challenges. Consequently, a cost-effective synthesis of N-hydroxyalkanamide gelators with varying alkyl chain lengths was achieved in a single-step reaction procedure. These gelators formed self-assembled aggregates in DMSO/water solvent system, resulting in organo/hydrogels at a minimum gelation concentration of 1.5 % w/v. Subsequently, metronidazole and theophylline were encapsulated within the gel core and released through gel-to-sol transition triggered by pH variation at 37 °C, while maintaining the structural-activity relationship. UV-vis spectroscopy was employed to observe the drug release behavior. Furthermore, in vitro cytotoxicity assays revealed cytotoxic effects against A549 lung adenocarcinoma cells, indicating anti-proliferative activity against human lung cancer cells. Specifically, the gel containing theophylline (16HAD+Th) exhibited cytotoxicity on cancerous A549 cells with IC50 values of 19.23±0.6 μg/mL, followed by the gel containing metronidazole (16HAD+Mz) with IC50 values of 23.75±0.7 μg/mL. Moreover, the system demonstrated comparable antibacterial activity against both gram-negative (E. coli) and gram-positive bacteria (S. aureus).

Biomaterials for Protein Delivery: Opportunities and Challenges to Clinical Translation

The development of biomaterials for protein delivery is an emerging field that spans materials science, bioengineering, and medicine. In this review, we highlight the immense potential of protein-delivering biomaterials as therapeutic options and discuss the multifaceted challenges inherent to the field. We address current advancements and approaches in protein delivery that leverage stimuli-responsive materials, harness advanced fabrication techniques like 3D printing, and integrate nanotechnologies for greater targeting and improved stability, efficacy, and tolerability profiles. We also discuss the demand for highly complex delivery systems to maintain structural integrity and functionality of the protein payload. Finally, we discuss barriers to clinical translation, such as biocompatibility, immunogenicity, achieving reliable controlled release, efficient and targeted delivery, stability issues, scalability of production, and navigating the regulatory landscape for such materials. Overall, this review summarizes insights from a survey of the current literature and sheds light on the interplay between innovation and the practical implementation of biomaterials for protein delivery.

Diverging conformations guide dipeptide self-assembly into crystals or hydrogels

The prediction of dipeptide assembly into crystals or gels is challenging. This work reveals the diverging conformational landscape that guides self-organization towards different outcomes. In silico and experimental data enabled deciphering of the electronic circular dichroism (ECD) spectra of self-assembling dipeptides to reveal folded or extended conformers as key players.

Peptide Hydrogels and Nanostructures Controlling Biological Machinery

Peptides are versatile building blocks for the fabrication of various nanostructures that result in the formation of hydrogels and nanoparticles. Precise chemical functionalization promotes discrete structure formation, causing controlled bioactivity and physical properties for functional materials development. The conjugation of small molecules on amino acid side chains determines their intermolecular interactions in addition to their intrinsic peptide characteristics. Molecular information affects the peptide structure, formation, and activity. In this Perspective, peptide building blocks, nanostructure formation mechanisms, and the properties of these peptide materials are discussed with the results of recent publications. Bioinstructive and stimuli-responsive peptide materials have immense impacts on the nanomedicine field including drug delivery, cellular engineering, regenerative medicine, and biomedicine.

Dipeptide-polysaccharides hydrogels through co-assembly

Self-assembling dipeptide hydrogels are attracting attention in food, materials, and biomedicine. However, there are still limitations such as weak hydrogel properties. Herein, we introduced two types of polysaccharides (Arabic gum and citrus pectin) into an alkyl-chain modified dipeptide (C₁₃-tryptophan-tyrosine (C₁₃-WY)) to generate co-assembled C₁₃-WY-arabic gum and C₁₃-WY-pectin hydrogels. The co-assembled hydrogels exhibited enhanced mechanical properties and stability. The G' value of C₁₃-WY-arabic gum and C₁₃-WY-pectin hydrogels was 3 and 10 times larger than that of C₁₃-WY hydrogel, respectively. The addition of Arabic gum and citrus pectin led to the co-assembly and molecular rearrangement. Moreover, co-assembled hydrogels showed more β-sheet structure and hydrogen bonds. Importantly, the self-/co-assembled hydrogels showed low cytotoxicity. We utilized these hydrogels for the encapsulation of docetaxel and they showed a high embedding rate and slow-release. Our findings provide a novel strategy for the development of stable supramolecular peptide hydrogels with good biocompatibility through simple co-assembly.

Hydrogels from a Self-Assembling Tripeptide and Carbon Nanotubes (CNTs): Comparison between Single-Walled and Double-Walled CNTs

Supramolecular hydrogels obtained from the self-organization of simple peptides, such as tripeptides, are attractive soft materials. Their viscoelastic properties can be enhanced through the inclusion of carbon nanomaterials (CNMs), although their presence can also hinder self-assembly, thus requiring investigation of the compatibility of CNMs with peptide supramolecular organization. In this work, we compared single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs) as nanostructured additives for a tripeptide hydrogel, revealing superior performance by the latter. Several spectroscopic techniques, as well as thermogravimetric analyses, microscopy, and rheology data, provide details to elucidate the structure and behavior of nanocomposite hydrogels of this kind.

Cross-linked chitosan/lysozyme hydrogels with inherent antibacterial activity and tuneable drug release properties for cutaneous drug administration

Gels with high drug release sustainability and intrinsic antibacterial properties are of high practical potential for cutaneous drug administration, particularly for wound care and skin disease treatment. This study reports the generation and characterization of gels formed by 1,5-pentanedial-mediated crosslinking between chitosan and lysozyme for cutaneous drug delivery. Structures of the gels are characterized by using scanning electron microscopy, X-ray diffractometry and Fourier-transform infrared spectroscopy. An increase in the mass percentage of lysozyme leads to an increase in the swelling ratio and erosion susceptibility of the resulting gels. The drug delivery performance of the gels can be changed simply by manipulating the chitosan/lysozyme mass-to-mass ratio, with an increase in the mass percentage of lysozyme leading to a decline in the encapsulation efficiency and drug release sustainability of the gels. Not only do all gels tested in this study show negligible toxicity in NIH/3T3 fibroblasts, they also demonstrate intrinsic antibacterial effects against both Gram-negative and Gram-positive bacteria, with the magnitude of the effect being positively related to the mass percentage of lysozyme. All these warrant the gels to be further developed as intrinsically antibacterial carriers for cutaneous drug administration.

Self-Assembled Peptide Nanostructures for ECM Biomimicry

Proteins are functional building blocks of living organisms that exert a wide variety of functions, but their synthesis and industrial production can be cumbersome and expensive. By contrast, short peptides are very convenient to prepare at a low cost on a large scale, and their self-assembly into nanostructures and gels is a popular avenue for protein biomimicry. In this Review, we will analyze the last 5-year progress on the incorporation of bioactive motifs into self-assembling peptides to mimic functional proteins of the extracellular matrix (ECM) and guide cell fate inside hydrogel scaffolds.

Novel Gels: An Emerging Approach for Delivering of Therapeutic Molecules and Recent Trends

Gels are semisolid, homogeneous systems with continuous or discrete therapeutic molecules in a suitable lipophilic or hydrophilic three-dimensional network base. Innovative gel systems possess multipurpose applications in cosmetics, food, pharmaceuticals, biotechnology, and so forth. Formulating a gel-based delivery system is simple and the delivery system enables the release of loaded therapeutic molecules. Furthermore, it facilitates the delivery of molecules via various routes as these gel-based systems offer proximal surface contact between a loaded therapeutic molecule and an absorption site. In the past decade, researchers have potentially explored and established a significant understanding of gel-based delivery systems for drug delivery. Subsequently, they have enabled the prospects of developing novel gel-based systems that illicit drug release by specific biological or external stimuli, such as temperature, pH, enzymes, ultrasound, antigens, etc. These systems are considered smart gels for their broad applications. This review reflects the significant role of advanced gel-based delivery systems for various therapeutic benefits. This detailed discussion is focused on strategies for the formulation of different novel gel-based systems, as well as it highlights the current research trends of these systems and patented technologies.

Engineered protein nanodrug as an emerging therapeutic tool

Functional proteins are the most versatile macromolecules. They can be obtained by extraction from natural sources or by genetic engineering technologies. The outstanding selectivity, specificity, binding activity, and biocompatibility endow engineered proteins with outstanding performance for disease therapy. Nevertheless, their stability is dramatically impaired in blood circulation, hindering clinical translations. Thus, many strategies have been developed to improve the stability, efficacy, bioavailability, and productivity of therapeutic proteins for clinical applications. In this review, we summarize the recent progress in the fabrication and application of therapeutic proteins. We first introduce various strategies for improving therapeutic efficacy via bioengineering and nanoassembly. Furthermore, we highlight their diverse applications as growth factors, nanovaccines, antibody-based drugs, bioimaging molecules, and cytokine receptor antagonists. Finally, a summary and perspective for the future development of therapeutic proteins are presented.

Peptide hydrogels for affinity-controlled release of therapeutic cargo: Current and potential strategies

The development of devices for the precise and controlled delivery of therapeutics has grown rapidly over the last few decades. Drug delivery materials must provide a depot with delivery profiles that satisfy pharmacodynamic and pharmacokinetic requirements resulting in clinical benefit. Therapeutic efficacy can be limited due to short half-life and poor stability. Thus, to compensate for this, frequent administration and high doses are often required to achieve therapeutic effect, which in turn increases potential side effects and systemic toxicity. This can potentially be mitigated by using materials that can deliver drugs at controlled rates, and material design principles that allow this are continuously evolving. Affinity-based release strategies incorporate a myriad of reversible interactions into a gel network, which have affinities for the therapeutic of interest. Reversible binding to the gel network impacts the release profile of the drug. Such affinity-based interactions can be modulated to control the release profile to meet pharmacokinetic benchmarks. Much work has been done developing affinity-based control in the context of polymer-based materials. However, this strategy has not been widely implemented in peptide-based hydrogels. Herein, we present recent advances in the use of affinity-controlled peptide gel release systems and their associated mechanisms for applications in drug delivery.

Supramolecular Hydrogels for Protein Delivery in Tissue Engineering

Therapeutic proteins, such as growth factors (GFs), have been used in tissue engineering (TE) approaches for their ability to provide signals to cells and orchestrate the formation of functional tissue. However, to be effective and minimize off-target effects, GFs should be delivered at the target site with temporal control. In addition, protein drugs are typically sensitive water soluble macromolecules with delicate structure. As such, hydrogels, containing large amounts of water, provide a compatible environment for the direct incorporation of proteins within the hydrogel network, while their release rate can be tuned by engineering the network chemistry and density. Being formed by transient crosslinks, afforded by non-covalent interactions, supramolecular hydrogels offer important advantages for protein delivery applications. This review describes various types of supramolecular hydrogels using a repertoire of diverse building blocks, their use for protein delivery and their further application in TE contexts. By reviewing the recent literature on this topic, the merits of supramolecular hydrogels are highlighted as well as their limitations, with high expectations for new advances they will provide for TE in the near future.