A Powerful CD8+ T-Cell Stimulating D-Tetra-Peptide Hydrogel as a Very Promising Vaccine Adjuvant

Peptide-based hydrogel co-assembled with antibody-drug for enhanced retinal cell uptake and attenuated experimental autoimmune uveitis

Effective treatment of chronic posterior ocular diseases such as uveitis, diabetic retinopathy, and age-related macular degeneration requires improvements in targeted drug delivery strategies. This study introduces a novel injectable drug delivery system co-assembled with a peptide-based hydrogel and secukinumab (SEK), an IL-17A neutralising monoclonal antibody, targeting retinal pigmented epithelium (RPE) cells. Compared to a SEK solution, the SEK loaded hydrogel significantly enhanced the protein uptake (3.7 times higher) by RPE cells in an inflammatory state after 24 hours of treatment and increased the drug concentration in retinal tissues during 20 days of treatment. A single intravitreal injection of the SEK loaded hydrogel effectively suppressed inflammation in a uveitis model. It also reduced the immunoreactivity of microglia and T helper 17 cells, preserved the integrity of the blood-retina barrier, mitigated retinal cell apoptosis, and facilitated the recovery of the retinal function. This delivery system comprising an antibody-drug co-assembled with a peptide-based hydrogel shows promising potential for targeting the retina and treating complex chronic posterior ocular diseases.

Neuropilin-1-target self-assembled peptide nanoparticles contribute to tumor treatment by inducing pyroptosis

BACKGROUND

Expression of the Neuropilin-1 (NRP1) is reported in malignant cells of multiple human tumor types represented as a tumor marker. Targeting NRP1 with a peptide, CK3, is used for tumor molecular imaging, raising the question of the therapeutic potential of CK2, a peptide with a CK3 backbone which enhanced targeting and tumor enrichment properties.

METHODS

The tumor targeting and enrichment capacity of CK2 was detected by IncuCyte, flow cytometry and animal living imaging. To enhance its therapeutic efficacy, we developed a self-assembling peptide nanoparticles Fmoc-Gffy-AP-CK2, incorporating a peptide protective domain (Fmoc), a self-assemble domain (Gffy) and an anti-tumor peptide (AP). In vitro cellular assays and in vivo tumor-xenograft experiments were conducted to evaluate the anti-tumor effect of Fmoc-Gffy-AP-CK2.

RESULTS

While CK3 peptide specifically targets NRP1 in vitro and in vivo, CK2 markedly achieves stronger binding with NRP1 and higher tumor accumulation. Fmoc-Gffy-AP-CK2 exhibits a potent NRP1-dependent cytotoxic effect in vitro and in vivo. Mechanically, Fmoc-Gffy-AP-CK2 triggered caspase3/gasdermin E (GSDME)-mediated pyroptosis. Fmoc-Gffy-AP-CK2 also promotes the response rate of PD-1 checkpoint blockade.

CONCLUSIONS

CK2, When combined with Fmoc-Gffy-AP domain, Demonstrated high anti-tumor efficacy, Providing a novel strategy for tumor treatment.

Ce6-GFFY is a novel photosensitizer for colorectal cancer therapy

Photodynamic therapy is an "old" strategy for cancer therapy featuring clinical safety and rapid working, but suitable photosensitizers for colorectal cancer therapy remain lacking. This study synthesized a novel photosensitizer termed Ce6-GFFY based on a self-assembling peptide GFFY and a photo-responsive molecule chlorin e6 (Ce6). Ce6-GFFY forms macroparticles with a diameter of ∼160 nm and possesses a half-life of 10 h, as well as an ideal tumor-targeting ability in mouse models. Ce6-GFFY effectively penetrates cells and generates numerous reactive oxygen species upon 660 nm laser irradiation. The reactive oxygen species promotes the accumulation of cytotoxic T cells and decrease of myeloid-derived suppressor cells in the tumor microenvironment through immunogenic cell death, thus prohibiting the growth of both primary and metastatic tumors after once treatment. This study not only provides a strategy for photosensitizer development but also confirms a promising application of Ce6-GFFY for colorectal cancer therapy.

Harnessing Mn2+ Ions and Antitumor Peptides: A Robust Hydrogel for Enhanced Tumor Immunotherapy

Immunotherapy has attracted widespread attention because of its durable and effective antitumor properties. However, systemic delivery strategies often result in immune-related off-target toxicity effects and inadequate drug retention at the tumor site, which limits its broader application. In this research, we designed a dual-functional antitumor peptide (N-Pep) that serves as both a therapeutic agent and metal ions (Mn2+) immunomodulator carrier. The rational designed antitumor peptide self-assembles into a hydrogel through coordination with Mn2+ ions (referred to as N-Pep-Mn gel). The multiporous hydrogel network allows for efficient loading of antiprogrammed death-1 antibody (αPD-1). The hydrogel served as a depot for the sustained release of Mn2+ ions and encapsulated αPD-1, effectively activating dendritic cells, polarizing tumor-associated macrophages and enhancing effector T cell infiltration, thereby leading to the effective inhibition of tumor growth through intratumoral and systemic immune responses. Additionally, the hydrogel induces robust immune memory, providing substantial protection against tumor recurrence. These findings underscore the potential of Mn2+ ion-coordinated antitumor peptide hydrogel as an advanced platform for enhancing antitumor immunotherapy.

Enantiomer-Dependent Supramolecular Antibacterial Therapy for Drug-Resistant Bacterial Keratitis

Bacteria have the potential to exhibit divergent stereochemical preferences for different levels of chiral structures, including from molecule, supramolecule, to nanomicroscale helical structure. Accordingly, the structure-activity relationship between chirality and bactericidal activity remains uncertain. In this study, we seek to understand the multivalent molecular chirality effect of chiral supramolecular polymers on antibacterial activity. Two n-butylazobenzene-modified l- and d-tripeptides (abbreviated C4Azo-l-VKK-OH and C4Azo-d-VKK-OH) were synthesized and subsequently self-assembled in water into chiral supramolecular polymers (designated l-Fiber and d-Fiber, respectively). The l-Fiber and d-Fiber displayed comparable nonhelical nanofiber morphologies but exhibited opposite multivalent molecular chirality. A comparative study demonstrated that the l-Fiber exhibited a markedly higher affinity for bacteria, thereby demonstrating significantly enhanced bactericidal efficiency against methicillin-resistant Staphylococcus aureus (MRSA) in comparison to that of the d-Fiber. Following disassembly into monomers via host-guest chemistry, the bactericidal potency of both the l-Fiber and d-Fiber was found to be almost lost, suggesting the multivalent molecular chirality effect. Of note, the l-Fiber exhibited superior efficacy in curing MRSA-infected keratitis in comparison to the d-Fiber. These findings highlight the importance of multivalent molecular chirality in the design and development of chiral supramolecular polymers for antibacterial applications. This research also presents an effective chiral supramolecular antibacterial strategy for the treatment of drug-resistant bacteria-infected keratitis.

Advanced Immunomodulatory Biomaterials for Therapeutic Applications

The multifaceted biological defense system modulating complex immune responses against pathogens and foreign materials plays a critical role in tissue homeostasis and disease progression. Recently developed biomaterials that can specifically regulate immune responses, nanoparticles, graphene, and functional hydrogels have contributed to the advancement of tissue engineering as well as disease treatment. The interaction between innate and adaptive immunity, collectively determining immune responses, can be regulated by mechanobiological recognition and adaptation of immune cells to the extracellular microenvironment. Therefore, applying immunomodulation to tissue regeneration and cancer therapy involves manipulating the properties of biomaterials by tailoring their composition in the context of the immune system. This review provides a comprehensive overview of how the physicochemical attributes of biomaterials determine immune responses, focusing on the physical properties that influence innate and adaptive immunity. This review also underscores the critical aspect of biomaterial-based immune engineering for the development of novel therapeutics and emphasizes the importance of understanding the biomaterials-mediated immunological mechanisms and their role in modulating the immune system.

Chiral polypeptide hydrogels regulating local immune microenvironment and anti-tumor immune response

The impact of chirality on immune response has attracted great interest in cancer vaccine research recently. However, the study of chiral synthetic polypeptide hydrogels as cancer vaccines as well as of the impact of biomaterials themselves for antitumor immunotherapy has rarely been reported. Here, we show the key role of residue chirality of polypeptide hydrogels in antitumor immunity and local immune microenvironment regulation. Compared to poly(γ-ethyl-L-glutamate)-based hydrogels (L-Gel), poly(γ-ethyl-D-glutamate)-based hydrogels (D-Gel) induces enhanced level of immune cell infiltration. However, D-Gel causes higher levels of suppressive markers on antigen-presenting cells and even induces stronger T cell exhaustion than L-Gel. Finally, D-Gel establishes a local chronic inflammatory and immunosuppressive microenvironment and shows insufficient anti-tumor effects. Conversely, the milder host immune responses induced by L-Gel leads to more effective tumor inhibition. This study provides insights on the role of residue chirality in the regulation of local immune microenvironment and affecting antitumor immune response.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants. Many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K2, which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K2 50:50 with the unfunctionalized K2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K2 produces a robust Th2 immune response and an antigen-specific Th1 immune response superior to alum, a widely used vaccine adjuvant. Together, these results suggest that K2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

Hydrogel-Mediated Jamming of Exosome Communications That Counter Tumor Adaption in the Tumor Immune Microenvironment

Hypoxia, a common occurrence within solid tumors, can stimulate the dissemination of deceptive tumor exosomes, which function as communicative bridges and orchestrate the recruitment of various supportive cell types for enhanced tumor adaptability in a tumor immune microenvironment. Current nanotechnology provides us intelligent strategies to combat the hypoxic tumor microenvironment. However, once exposed to external stimuli, such as chemotherapy, tumor cells simultaneously release malignant signals to develop tumor migration and immunosuppression, posing challenges to clinical practice. Taking advantage of the membrane-targeting therapeutic strategy, the application of a self-assembled short peptide (PepABS-py), affording hydrogels on tumor cell surfaces, can block exosome dissemination with fiber-like nanostructures and effectively limit the systemic adverse effects of traditional therapeutics. Moreover, PepABS-py can attenuate the hypoxic tumor microenvironment in vivo by carrying an inhibitor of the hypoxic tumor-overexpressed CA IX enzyme, where hypoxia is also a crucial regulator to induce tumor exosomes and mediate intercellular communications within the immune system. Herein, its application on jamming exosome communications can target the T cell-related signaling pathway by regulating microRNAs in exosome cargoes and ultimately enhances CD8+ T cell infiltration and alleviates inflammatory monocytes at metastasis sites. Collectively, with the capability of blocking exosome dissemination, PepABS-py can be applied as a promising tumor membrane-targeting therapeutic tool to counter tumor adaption within an immune microenvironment and further advance traditional chemotherapy.

Phe-Phe-Based Macroscopic Supramolecular Hydrogel Construction Strategies and Biomedical Applications

Since the phenylalanine (Phe) dipeptide moiety is referred to as an essential structure for building amyloid-β peptide from Alzheimer's disease, its wonderful assembly ability to form nanofibers has been extensively studied. Cross-linked Phe-Phe-based peptide nanofibers can construct networks, thus encapsulating the drugs to form supramolecular hydrogels. Recently, scientists have proposed a variety of Phe-Phe-based macroscopic supramolecular hydrogels and used them in biomedical applications. Therefore, we summarize the construction strategies of Phe-Phe-based macroscopic supramolecular hydrogels and list their represented biomedical applications (e.g., wound healing, eye protection, cancer therapy, etc.) since the birth of Phe-Phe-based supramolecular hydrogels. In addition, we present the perspectives and challenges of Phe-Phe-based macroscopic peptide hydrogels.

A self-assembling bioactive oligopeptide hydrogel for the treatment of edema following prepuce surgery

Edema of the prepuce is a common clinical complication following circumcision in urology. Nevertheless, the principal method of gauze wrapping in clinical practice has not yet been demonstrated to be an effective solution to the problem of postoperative edema. It is therefore evident that the development of functional dressings for the treatment of post-circumcision edema has considerable potential for both clinical application and translational significance. The objective of this study was to develop a single-component bioactive oligopeptide hydrogel dressing with favorable anti-inflammatory, pro-angiogenesis properties and biosafety for the treatment of edema following prepuce surgery. A hexapeptide (Ac-FFFGHK-OH) hydrogelator was designed and synthesized through the N-terminal modification of a human-derived glycine-histidine-lysine tripeptide (GHK) with an N-acetylated phenylalanine tripeptide (Ac-FFF). The bioactive Ac-FFFGHK-OH hydrogel can be prepared through a facile self-assembly method. Furthermore, a novel experimental animal model of post-circumcision edema in Sprague-Dawley rats was constructed and the in vivo anti-edema effect of the Ac-FFFGHK-OH hydrogel was confirmed. The mechanism of action in relieving edema was also investigated by in vitro cell experiments. This work may inspire alternative thinking for the development of mono-component bioactive oligopeptide hydrogels for the treatment of edema in various diseases.

Short Peptides as Powerful Arsenal for Smart Fighting Cancer

Short peptides have been coming around as a strong weapon in the fight against cancer on all fronts-in immuno-, chemo-, and radiotherapy, and also in combinatorial approaches. Moreover, short peptides have relevance in cancer imaging or 3D culture. Thanks to the natural 'smart' nature of short peptides, their unique structural features, as well as recent progress in biotechnological and bioinformatics development, short peptides are playing an enormous role in evolving cutting-edge strategies. Self-assembling short peptides may create excellent structures to stimulate cytotoxic immune responses, which is essential for cancer immunotherapy. Short peptides can help establish versatile strategies with high biosafety and effectiveness. Supramolecular short peptide-based cancer vaccines entered clinical trials. Peptide assemblies can be platforms for the delivery of antigens, adjuvants, immune cells, and/or drugs. Short peptides have been unappreciated, especially in the vaccine aspect. Meanwhile, they still hide the undiscovered unlimited potential. Here, we provide a timely update on this highly active and fast-evolving field.

Nanofibrous MultiDomain Peptide Hydrogels Provide T Cells a 3D, Cytocompatible Environment for Cell Expansion and Antigen-Specific Killing

T cells have the ability to recognize and kill specific target cells, giving therapies based on their potential for treating infection, diabetes, cancer, and other diseases. However, the advancement of T cell-based treatments has been hindered by difficulties in their ex vivo activation and expansion, the number of cells required for sustained in vivo levels, and preferential localization following systemic delivery. Biomaterials may help to overcome many of these challenges by providing a combined means of proliferation, antigen presentation, and cell localization upon delivery. In this work, we studied self-assembling Multidomain Peptides (MDPs) as scaffolds for T cell culture, activation, and expansion. We evaluated the effect of different MDP chemistries on their biocompatibility with T cells and the maintenance of antigen specificity for T cells cultured in the hydrogels. We also examined the potential application of MDPs as scaffolds for T cell activation and expansion and the effect of MDP encapsulation on T cell phenotype. We found high cell viability when T cells were encapsulated in noncationic MDPs, O5 and D2, and superior retention of antigen specificity and tumor-reactivity were preserved in the anionic MDP, D2. Maintenance of antigen recognition by T cells in D2 hydrogels was confirmed by quantifying immune synapses of T Cells engaged with antigen-presenting cancer cells. When 3D cultured in anionic MDP D2 coloaded with anti-CD3, anti-CD28, IL2, IL7, and IL15, we observed successful T cell proliferation evidenced by upregulation of CD27 and CD107a. This study is the first to investigate the potential of self-assembling peptide-based hydrogels as 3D scaffolds for human T cell applications and demonstrates that MDP hydrogels are a viable platform for enabling T cell in vitro activation, expansion, and maintenance of antigen specificity and therefore a promising tool for future T cell-based therapies.

A TLR7 Agonist Conjugated to a Nanofibrous Peptide Hydrogel as a Potent Vaccine Adjuvant

Toll-like receptors (TLRs) recognize pathogen- and damage-associated molecular patterns and, in turn, trigger the release of cytokines and other immunostimulatory molecules. As a result, TLR agonists are increasingly being investigated as vaccine adjuvants, though many of these agonists are small molecules that quickly diffuse away from the vaccination site, limiting their co-localization with antigens and, thus, their effect. Here, the small-molecule TLR7 agonist 1V209 is conjugated to a positively-charged multidomain peptide (MDP) hydrogel, K 2 , which was previously shown to act as an adjuvant promoting humoral immunity. Mixing the 1V209-conjugated K 2 50:50 with the unfunctionalized K 2 produces hydrogels that retain the shear-thinning and self-healing physical properties of the original MDP, while improving the solubility of 1V209 more than 200-fold compared to the unconjugated molecule. When co-delivered with ovalbumin as a model antigen, 1V209-functionalized K 2 produces antigen-specific IgG titers that were statistically similar to alum, the gold standard adjuvant, and a significantly lower ratio of Th2-associated IgG1 to Th1-associated IgG2a than alum, suggesting a more balanced Th1 and Th2 response. Together, these results suggest that K 2 MDP hydrogels functionalized with 1V209 are a promising adjuvant for vaccines against infectious diseases, especially those benefiting from a combined Th1 and Th2 immune response.

Table of Contents

Activation of toll-like receptors (TLRs) stimulates a signaling cascade to induce an immune response. A TLR7 agonist was conjugated to an injectable peptide hydrogel, which was then used to deliver a model vaccine antigen. This platform produced antibody titers similar to the gold standard adjuvant alum and demonstrated an improved balance between Th1- and Th2-mediated immunity over alum.

Modularized viromimetic polymer nanoparticle vaccines (VPNVaxs) to elicit durable and effective humoral immune responses

Virus-like particle (VLP) vaccines had shown great potential during the COVID-19 pandemic, and was thought to be the next generation of antiviral vaccine technology due to viromimetic structures. However, the time-consuming and complicated processes in establishing a current recombinant-protein-based VLP vaccine has limited its quick launch to the out-bursting pandemic. To simplify and optimize VLP vaccine design, we herein report a kind of viromimetic polymer nanoparticle vaccine (VPNVax), with subunit receptor-binding domain (RBD) proteins conjugated to the surface of polyethylene glycol-b-polylactic acid (PEG-b-PLA) nanoparticles for vaccination against SARS-CoV-2. The preparation of VPNVax based on synthetic polymer particle and chemical post-conjugation makes it possible to rapidly replace the antigens and construct matched vaccines at the emergence of different viruses. Using this modular preparation system, we identified that VPNVax with surface protein coverage of 20%-25% had the best immunostimulatory activity, which could keep high levels of specific antibody titers over 5 months and induce virus neutralizing activity when combined with an aluminum adjuvant. Moreover, the polymer nano-vectors could be armed with more immune-adjuvant functions by loading immunostimulant agents or chemical chirality design. This VPNVax platform provides a novel kind of rapidly producing and efficient vaccine against different variants of SARS-CoV-2 as well as other viral pandemics.

Self-Assembled Nanostructures Presenting Repetitive Arrays of Subunit Antigens for Enhanced Immune Response

Infectious diseases pose persistent threats to public health, demanding advanced vaccine technologies. Nanomaterial-based delivery systems offer promising solutions to enhance immunogenicity while minimizing reactogenicity. We introduce a self-assembled vaccine (SAV) platform employing antigen-polymer conjugates designed to facilitate robust immune responses. The SAVs exhibit efficient cellular uptake by dendritic cells (DCs) and macrophages, which are crucial players in the innate immune system. The high-density antigen presentation of this SAV platform enhances the affinity for DCs through multivalent recognition, significantly augmenting humoral immunity. SAV induced high levels of immunoglobulin G (IgG), IgG1, and IgG2a, suggesting that mature DCs efficiently induced B cell activation through multivalent antigen recognition. Universality was confirmed by applying it to respiratory viruses, showcasing its potential as a versatile vaccine platform. Furthermore, we have also demonstrated strong protection against influenza A virus infection with SAV containing hemagglutinin, which is used in influenza A virus subunit vaccines. The efficacy and adaptability of this nanostructured vaccine present potential utility in combating infectious diseases.

Facile Preparation of Carbohydrate-Containing Adjuvants Based on Self-Assembling Glycopeptide Conjugates

Carbohydrates are intriguing biomolecules possessing diverse biological activities, including immune stimulating capability. However, their biomedical applications have been limited by their complex and heterogeneous structures. In this study, we have utilized a self-assembling glycopeptide conjugate (GPC) system to produce uniform nanoribbons appending homogeneous oligosaccharides with multivalency. This system successfully translates the nontrivial structural differences of oligomannoses into varied binding affinities to C-type lectin receptors (CLRs). We have shown that GPCs could promote the CLR-mediated endocytosis of ovalbumin (OVA) antigen, and two mannotriose-modified peptides F3m2 and F3m5 exhibit potent activity in inducing antigen-presenting cell maturation, as indicated by increased CD86 and MHCII expression. In vivo studies demonstrated that GPCs, combined with OVA antigen, significantly enhanced OVA-specific antibody production. Specifically, F3m2 and F3m5 exhibited the highest immunostimulatory effects, eliciting both Th1- and Th2-biased immune responses and promoting differentiation of CD4+ and CD8+  T cells. These findings highlight the potential of GPCs as vaccine adjuvants, and showcase their versatility in exploiting the biological functions of carbohydrates.

A Transformable Supramolecular Bispecific Cell Engager for Augmenting Natural Killer and T Cell-Based Cancer Immunotherapy

Immune cells are pivotal in cancer immunotherapy, yet their therapeutic effectiveness is often hampered by limited tumor infiltration and inhibitory tumor microenvironments. An alkaline phosphatase (ALP)-responsive and transformable supramolecular bis-specific cell engager (Supra-BiCE) to harness natural killer (NK)/T cells for effective cancer immunotherapy is introduced here. The Supra-BiCE, consisting of both SA-P (a phosphorylated peptide targeting and blocking programmed cell death ligand 1 (PD-L1)) and SA-T (a phosphorylated peptide targeting and blocking T cell immunoglobulin and ITIM domain (TIGIT)) is constructed by a simple co-assembling strategy. Upon intravenous administration, Supra-BiCE self-assembles into nanoribbons and interacts with NK/T cells via TIGIT. Notably, these nanoribbons undergo transformation into long nanofibrils within ALP-overexpressing tumor regions, resulting in enhanced binding affinities of Supra-BiCE to both PD-L1 and TIGIT. Consequently, this leads to the accumulation and retention of NK/T cells within tumor regions. Furthermore, the combinatorial blockade of checkpoints by Supra-BiCE activates infiltrating NK/T cells. Moreover, the adjustable peptide ratio in Supra-BiCE enables customization for optimal therapeutic effects against distinct tumor types. Particularly, Supra-BiCE (T:P = 1:3) achieved 98.27% tumor suppression rate against colon carcinoma model. Overall, this study offers a promising tool for engaging NK and T cells for cancer immunotherapy.

Designing Hydrogels for Immunomodulation in Cancer Therapy and Regenerative Medicine

The immune system not only acts as a defense against pathogen and cancer cells, but also plays an important role in homeostasis and tissue regeneration. Targeting immune systems is a promising strategy for efficient cancer treatment and regenerative medicine. Current systemic immunomodulation therapies are usually associated with low persistence time, poor targeting to action sites, and severe side effects. Due to their extracellular matrix-mimetic nature, tunable properties and diverse bioactivities, hydrogels are intriguing platforms to locally deliver immunomodulatory agents and cells, as well as provide an immunomodulatory microenvironment to recruit, activate, and expand host immune cells. In this review, the design considerations, including polymer backbones, crosslinking mechanisms, physicochemical nature, and immunomodulation-related components, of the hydrogel platforms, are focused on. The immunomodulatory effects and therapeutic outcomes in cancer therapy and tissue regeneration of different hydrogel systems are emphasized, including hydrogel depots for delivery of immunomodulatory agents, hydrogel scaffolds for cell delivery, and immunomodulatory hydrogels depending on the intrinsic properties of materials. Finally, the remained challenges in current systems and future development of immunomodulatory hydrogels are discussed.

Peptide-containing nanoformulations: Skin barrier penetration and activity contribution

Transdermal drug delivery presents a less invasive pathway, circumventing the need to pass through the gastrointestinal tract and liver, thereby reducing drug breakdown, initial metabolism, and gastrointestinal discomfort. Nevertheless, the unique composition and dense structure of the stratum corneum present a significant barrier to transdermal delivery. This article presents an overview of the current developments in peptides and nanotechnology to address this challenge. Initially, we sum up peptide-containing nanoformulations for transdermal drug delivery, examining them through the lenses of both inorganic and organic materials. Particular emphasis is placed on the diverse roles that peptides play within these nanoformulations, including conferring functionality upon nanocarriers and enhancing the biological efficacy of drugs. Subsequently, we summarize innovative strategies for enhancing skin penetration, categorizing them into passive and active approaches. Lastly, we discuss the therapeutic potential of peptide-containing nanoformulations in addressing a range of diseases, drawing insights from the biological activities and functions of peptides. Furthermore, the challenges hindering clinical translation are also discussed, providing valuable insights for future advancements in transdermal drug delivery.

Biomimetic nanomedicines for precise atherosclerosis theranostics

Atherosclerosis (AS) is a leading cause of the life-threatening cardiovascular disease (CVD), creating an urgent need for efficient, biocompatible therapeutics for diagnosis and treatment. Biomimetic nanomedicines (bNMs) are moving closer to fulfilling this need, pushing back the frontier of nano-based drug delivery systems design. This review seeks to outline how these nanomedicines (NMs) might work to diagnose and treat atherosclerosis, to trace the trajectory of their development to date and in the coming years, and to provide a foundation for further discussion about atherosclerotic theranostics.

Heteroantigen-assembled nanovaccine enhances the polyfunctionality of TILs against tumor growth and metastasis

The dysfunction of tumor infiltrating lymphocytes (TILs) directly correlates with out of control of tumor growth and metastasis. New approaches and insightful clarity for rescuing TILs dysfunction are urgently needed. Here, we design two heterogenous antigens based on MHC-I epitope and MHC-II epitope from tumor, and assemble heterogenous antigens by electrostatic interactions and π-π stacking into heteroantigen-assembled nanovaccine (HANV). HANV not only significantly increases the abundance of CD8+ and CD4+ TILs, but also elicits stronger polyfunctionality of CD8+ and CD4+ TILs in vivo. Enhanced polyfunctionality of CD8+ and CD4+ TILs positively correlate to suppression of tumor growth and metastasis in melanoma-bearing mouse models. We also validate that nucleotide-binding oligomerization domain-containing protein 2 (NOD2) dominantly enhances anti-tumor capacity of TILs in a temporal immunoregulation manner. This work presents a new insight in developing HANV as a rational strategy to shape TILs polyfunctionality for tumor growth and metastasis.

Peptide Hydrogels as Immunomaterials and Their Use in Cancer Immunotherapy Delivery

Peptide-based hydrogel biomaterials have emerged as an excellent strategy for immune system modulation. Peptide-based hydrogels are supramolecular materials that self-assemble into various nanostructures through various interactive forces (i.e., hydrogen bonding and hydrophobic interactions) and respond to microenvironmental stimuli (i.e., pH, temperature). While they have been reported in numerous biomedical applications, they have recently been deemed promising candidates to improve the efficacy of cancer immunotherapies and treatments. Immunotherapies seek to harness the body's immune system to preemptively protect against and treat various diseases, such as cancer. However, their low efficacy rates result in limited patient responses to treatment. Here, the immunomaterial's potential to improve these efficacy rates by either functioning as immune stimulators through direct immune system interactions and/or delivering a range of immune agents is highlighted. The chemical and physical properties of these peptide-based materials that lead to immuno modulation and how one may design a system to achieve desired immune responses in a controllable manner are discussed. Works in the literature that reports peptide hydrogels as adjuvant systems and for the delivery of immunotherapies are highlighted. Finally, the future trends and possible developments based on peptide hydrogels for cancer immunotherapy applications are discussed.

Peptide Assemblies for Cancer Therapy

Supramolecular assemblies made by the self-assembly of peptides are finding an increasing number of applications in various fields. While the early exploration of peptide assemblies centered on tissue engineering or regenerative medicine, the recent development has shown that peptide assemblies can act as supramolecular medicine for cancer therapy. This review covers the progress of applying peptide assemblies for cancer therapy, with the emphasis on the works appeared over the last five years. We start with the introduction of a few seminal works on peptide assemblies, then discuss the combination of peptide assemblies with anticancer drugs. Next, we highlight the use of enzyme-controlled transformation or shapeshifting of peptide assemblies for inhibiting cancer cells and tumors. After that, we provide the outlook for this exciting field that promises new kind of therapeutics for cancer therapy.

Stimulus-responsive peptide hydrogels: a safe and least invasive administration approach for tumor treatment

Tumours, with increasing mortality around the world, have bothered human beings for decades. Enhancing the targeting of antitumor drugs to tumour tissues is the key to enhancing their antitumor effects. The tumour microenvironment is characterised by a relatively low pH, overexpression of certain enzymes, redox imbalance, etc. Therefore, smart drug delivery systems that respond to the tumour microenvironment have been proposed to selectively release antitumor drugs. Among them, peptide hydrogels as a local drug delivery system have received much attention due to advantages such as high biocompatibility, degradability and high water-absorbing capacity. The combination of peptide segments with different physiological functions allows for tumour targeting, self-aggregation, responsiveness, etc. Morphological and microstructural changes in peptide hydrogels can occur when utilising the inherent pathological microenvironment of tumours to trigger drug release, which endows such systems with limited adverse effects and improved therapeutic efficiency. Herein, this review outlined the driving forces, impact factors, and sequence design in peptide hydrogels. We also discussed the triggers to induce the transformation of peptide-based hydrogels in the tumour microenvironment and described the advancements of peptide-based hydrogels for local drug delivery in tumour treatment. Finally, we gave a brief perspective on the prospects and challenges in this field.

Accelerating the prediction and discovery of peptide hydrogels with human-in-the-loop

The amino acid sequences of peptides determine their self-assembling properties. Accurate prediction of peptidic hydrogel formation, however, remains a challenging task. This work describes an interactive approach involving the mutual information exchange between experiment and machine learning for robust prediction and design of (tetra)peptide hydrogels. We chemically synthesize more than 160 natural tetrapeptides and evaluate their hydrogel-forming ability, and then employ machine learning-experiment iterative loops to improve the accuracy of the gelation prediction. We construct a score function coupling the aggregation propensity, hydrophobicity, and gelation corrector Cg, and generate an 8,000-sequence library, within which the success rate of predicting hydrogel formation reaches 87.1%. Notably, the de novo-designed peptide hydrogel selected from this work boosts the immune response of the receptor binding domain of SARS-CoV-2 in the mice model. Our approach taps into the potential of machine learning for predicting peptide hydrogelator and significantly expands the scope of natural peptide hydrogels.

Engineered cell-based therapies in ex vivo ready-made CellDex capsules have therapeutic efficacy in solid tumors

Encapsulated cell-based therapies for solid tumors have shown promising results in pre-clinical settings. However, the inability to culture encapsulated therapeutic cells prior to their transplantation has limited their translation into clinical settings. In this study, we created a wide variety of engineered therapeutic cells (ThC) loaded in micropore-forming gelatin methacryloyl (GelMA) hydrogel (CellDex) capsules that can be cultured in vitro prior to their transplantation in surgically debulked solid tumors. We show that both allogeneic and autologous engineered cells, such as stem cells (SCs), macrophages, NK cells, and T cells, proliferate within CellDex capsules and migrate out of the gel in vitro and in vivo. Furthermore, tumor cell specific therapeutic proteins and oncolytic viruses released from CellDex capsules retain and prolong their anti-tumor effects. In vivo, ThCs in pre-manufactured Celldex capsules persist long-term and track tumor cells. Moreover, chimeric antigen receptor (CAR) T cell bearing CellDex (T-CellDex) and human SC releasing therapeutic proteins (hSC-CellDex) capsules show therapeutic efficacy in metastatic and primary brain tumor resection models that mimic standard of care of tumor resection in patients. Overall, this unique approach of pre-manufactured micropore-forming CellDex capsules offers an effective off-the-shelf clinically viable strategy to treat solid tumors locally.

MC1R Peptide Agonist Self-Assembles into a Hydrogel That Promotes Skin Pigmentation for Treating Vitiligo

Vitiligo, a common skin disease that seriously affects 0.5-2.0% of the worldwide population, lacks approved therapeutics due to a wide range of adverse side effects. As a key regulator of skin pigmentation, MC1R may be an effective therapeutic target for vitiligo. Herein, we report an MC1R peptide agonist that directly self-assembles into nanofibrils that form a hydrogel matrix under normal physiological conditions. This hydrogel exhibits higher stability than free peptides, sustained release, rapid recovery from shear-thinning, and resistance to enzymatic proteolysis. Furthermore, this peptidal MC1R agonist upregulates tyrosinase, tyrosinase-related protein-1 (TYRP-1), and tyrosinase-related protein-2 (TYRP-2) to stimulate melanin synthesis. More importantly, MC1R agonist hydrogel promotes skin pigmentation in mice more potently than free MC1R agonist. This study supports the development of this MC1R agonist hydrogel as a promising pharmacological intervention for vitiligo.

A Fluorinated Supramolecular Self-Assembled Peptide as Nanovaccine Adjuvant for Enhanced Cancer Vaccine Therapy

Adjuvants play an important role in enhancing vaccine-induced immune protection. Adequate cellular uptake, robust lysosomal escape, and subsequent antigen cross-presentation are critical steps for vaccine adjuvants to effectively elicit cellular immunity. Here, a fluorinated supramolecular strategy to generate a series of peptide adjuvants by using arginine (R) and fluorinated diphenylalanine peptide (DP) is adopted. It is found that the self-assembly ability and antigen-binding affinity of these adjuvants increase with the number of fluorine (F) and can be regulated by R. By comparison, 4RDP(F5) shows the strongest binding affinity with model antigen ovalbumin (OVA) and the best performance in dendritic cells maturation and antigen's lysosomal escape, which contributes to the subsequent antigen cross-presentation. As a consequence, 4RDP(F5)-OVA nanovaccine generates a strong cellular immunity in a prophylactic OVA-expressing EG7-OVA lymphoma model, leading to long-term immune memory for resisting tumor challenge. What's more, 4RDP(F5)-OVA nanovaccine in combination with anti-programmed cell death ligand-1 (anti-PD-L1) checkpoint blockade could effectively elicit anti-tumor immune responses and inhibit tumor growth in a therapeutic EG7-OVA lymphoma model. Overall, this study demonstrates the simplicity and effectiveness of fluorinated supramolecular strategies for constructing adjuvants and might provide an attractive vaccine adjuvant candidate for cancer immunotherapy.

A Cascade-Targeted Enzyme-Instructed Peptide Self-Assembly Strategy for Cancer Immunotherapy through Boosting Immunogenic Cell Death

Immunogenic cell death (ICD) approaches by encumbering mitochondrial functions provide great promise for the treatment of malignant tumors, but these kinds of ICD strategies are still in their infancy. Here, one multifunctional drug-loaded, cascade-targeted, and enzyme-instructed self-assembling peptide nanomedicine (Comp. 4) for ICD-based cancer therapy is constructed. Comp. 4 consists of 1) lonidamine (LND) that specifically interferes with mitochondrial functions; 2) a programmed death ligand 1 (PD-L1) binding peptide sequence (NTYYEDQG) and a mitochondria-specific motif (triphenylphosphonium, TPP) that can sequentially control the cell membrane and mitochondria targeting capacities, respectively; and 3) a -G^D F^D Fp^D Y- assembly core to in situ organize peptide assemblies responsive to alkaline phosphatase (ALP). Comp. 4 demonstrates noticeable structural and morphological transformations in the presence of ALP and produces peptide assemblies in mouse colon cancer cells (CT26) with high expressions of both ALP and PD-L1. Moreover, the presence of PD-L1- and mitochondria-specific motifs can assist Comp. 4 for effective endocytosis and endosomal escape, forming peptide assemblies and delivering LND into mitochondria. Consequently, Comp. 4 shows superior capacities to in vivo induce abundant mitochondrial oxidative stress, provoke robust ICD responses, and produce an immunogenic tumor microenvironment, successfully inhibiting CT26 tumor growth by eliciting a systemic ICD-based antitumor immunity.

Bioactive Peptide Nanodrugs Based on Supramolecular Assembly for Boosting Immunogenic Cell Death-Induced Cancer Immunotherapy

Immunogenic cell death (ICD)-induced immunotherapy holds promise for complete elimination and long-term protective immune responses against cancer by combining direct tumor cell killing and antitumor immune response. Some therapeutic approaches (such as hyperthermia, photodynamic therapy, or radiotherapy) and inducers (certain chemotherapy drugs, oncolytic viruses) have been devoted to initiating and/or boosting ICD, leading to the activation of tumor-specific immune responses. Recently, supramolecular assembled bioactive peptide nanodrugs have been employed to improve the efficacy of ICD-induced cancer immunotherapy by increasing tumor targeted accumulation as well as responsive release of ICD inducers, directly inducing high levels of ICD and realizing the simultaneous enhancement of immune response through the immune function of the active peptide itself. Here, the authors review bioactive peptide nanodrugs based on supramolecular assembly, mainly as an intelligent delivery system, a direct ICD inducer and an immune response enhancer, for boosting ICD induced cancer immunotherapy. The functions of diverse bioactive peptides used in the construction of nanodrugs are described. The design of a supramolecular assembly, the mechanism of boosting ICD, and synergetic effects of bioactive peptides combined immunotherapy are critically emphasized.

Utilization of Stimuli-Responsive Biomaterials in the Formulation of Cancer Vaccines

Immunology research has focused on developing cancer vaccines to increase the number of tumor-specific effector cells and their ability to fight cancer over the last few decades. There is a lack of professional success in vaccines compared to checkpoint blockade and adoptive T-cell treatment. The vaccine's inadequate delivery method and antigen selection are most likely to blame for the poor results. Antigen-specific vaccines have recently shown promising results in preclinical and early clinical investigations. To target particular cells and trigger the best immune response possible against malignancies, it is necessary to design a highly efficient and secure delivery method for cancer vaccines; however, enormous challenges must be overcome. Current research is focused on developing stimulus-responsive biomaterials, which are a subset of the range of levels of materials, to enhance therapeutic efficacy and safety and better regulate the transport and distribution of cancer immunotherapy in vivo. A concise analysis of current developments in the area of biomaterials that respond to stimuli has been provided in brief research. Current and anticipated future challenges and opportunities in the sector are also highlighted.

Magnetic nanoparticles enhance the cellular immune response of dendritic cell tumor vaccines by realizing the cytoplasmic delivery of tumor antigens

Dendritic cells (DCs)-based tumor vaccines have the advantages of high safety and rapid activation of T cells, and have been approved for clinical tumor treatment. However, the conventional DC vaccines have some severe problems, such as poor activation of DCs in vitro, low level of antigen presentation, reduced cell viability, and difficulty in targeting lymph nodes in vivo, resulting in poor clinical therapeutic effects. In this research, magnetic nanoparticles Fe3O4@Ca/MnCO3 were prepared and used to actively and efficiently deliver antigens to the cytoplasm of DCs, promote antigen cross-presentation and DC activation, and finally enhance the cellular immune response of DC vaccines. The results show that the magnetic nanoparticles can actively and quickly deliver antigens to the cytoplasm of DCs by regulating the magnetic field, and achieve cross-presentation of antigens. At the same time, the nanoparticles degradation product Mn2+ enhanced immune stimulation through the interferon gene stimulating protein (STING) pathway, and another degradation product Ca2+ ultimately promoted cellular immune response by increasing autophagy. The DC vaccine constructed with the magnetic nanoparticles can more effectively migrate to the lymph nodes, promote the proliferation of CD8+ T cells, prolong the time of immune memory, and produce higher antibody levels. Compared with traditional DC vaccines, cytoplasmic antigen delivery with the magnetic nanoparticles provides a new idea for the construction of novel DC vaccines.

Nanovaccine Based on a Biepitope Antigen to Potentiate the Immunogenicity of a Neoantigen

Specific neoantigens are promising candidates for personalized cancer vaccines and immunotherapies, whereas the low immunogenicity and physicochemical variability are the main challenges in clinical trials. Herein, based on the rational design of neoantigens, we developed biepitope nanovaccines via integrating CD4⁺ with CD8⁺ T cell epitopes. A class of amphiphilic peptides composed of biepitope and hydrophilic amino acids can form well-defined nanostructures, thus incorporating functional sequences into an artificial platform. Cellular uptake studies demonstrated the enhanced endocytosis of biepitope neoantigens in dendritic cells (DCs). Such designed biepitopes can further stimulate the maturation of DCs, as validated by the upregulation of costimulatory molecules and secreted proinflammatory cytokines, which show the potential ability to prime T cells and evoke specific cellular immunity. The inspiring prophylactic and therapeutic efficacy of biepitope nanovaccines was evaluated in murine colon cancer. In contrast to individual CD8⁺ T cell epitopes, the rationally designed biepitope nanovaccines can efficiently provoke immune activation and potentiate antitumor immunity both in vitro and in vivo, presenting an alternative strategy for neoantigen vaccines.

Chiral polypeptide nanoparticles as nanoadjuvants of nanovaccines for efficient cancer prevention and therapy

The chirality of bioactive molecules is closely related to their functions. D-amino acids commonly distributed in the bacterial cell walls trigger a robust anti-infective immune response. Inspired by that, two kinds of chiral polypeptides, poly(L-phenylalanine)-block-poly(L-lysine) (PL-K) and poly(L-phenylalanine)-block-poly(D-lysine) (PD-K), were synthesized and used as nanoadjuvants of nanovaccines for cancer prevention and therapy. The amphiphilic polypeptides self-assembled into nanoparticles with a diameter of about 30 nm during ultrasonic-assisted dissolution in phosphate-buffered saline. The nanovaccines PL-K-OVA and PD-K-OVA were easily prepared by mixing solutions of PL-K or PD-K and the model antigen chicken ovalbumin (OVA), respectively, with loading efficiencies of almost 100%. Compared to PL-K-OVA, PD-K-OVA more robustly induced dendritic cell maturation, antigen cross-presentation, and adaptive immune response. More importantly, it effectively prevented and treated the OVA-expressed B16-OVA melanoma model. PD-K-OVA achieved a tumor inhibition rate of 94.9% and even 97.0% by combining with anti-PD-1 antibody. Therefore, the chiral polypeptide nanoparticles represent simple, efficient, and extensively applicable nanoadjuvants for various nanovaccines.

Self-Assembly, Bioactivity, and Nanomaterials Applications of Peptide Conjugates with Bulky Aromatic Terminal Groups

The self-assembly and structural and functional properties of peptide conjugates containing bulky terminal aromatic substituents are reviewed with a particular focus on bioactivity. Terminal moieties include Fmoc [fluorenylmethyloxycarbonyl], naphthalene, pyrene, naproxen, diimides of naphthalene or pyrene, and others. These provide a driving force for self-assembly due to π-stacking and hydrophobic interactions, in addition to the hydrogen bonding, electrostatic, and other forces between short peptides. The balance of these interactions leads to a propensity to self-assembly, even for conjugates to single amino acids. The hybrid molecules often form hydrogels built from a network of β-sheet fibrils. The properties of these as biomaterials to support cell culture, or in the development of molecules that can assemble in cells (in response to cellular enzymes, or otherwise) with a range of fascinating bioactivities such as anticancer or antimicrobial activity, are highlighted. In addition, applications of hydrogels as slow-release drug delivery systems and in catalysis and other applications are discussed. The aromatic nature of the substituents also provides a diversity of interesting optoelectronic properties that have been demonstrated in the literature, and an overview of this is also provided. Also discussed are coassembly and enzyme-instructed self-assembly which enable precise tuning and (stimulus-responsive) functionalization of peptide nanostructures.

Dynamic Imine Bonding Facilitates Mannan Release from a Nanofibrous Peptide Hydrogel

Recently, there has been increased interest in using mannan as an immunomodulatory bioconjugate. Despite notable immunological and functional differences between the reduced (R-Man) and oxidized (O-Man) forms of mannan, little is known about the impact of mannan oxidation state on its in vivo persistence or its potential controlled release from biomaterials that may improve immunotherapeutic or prophylactic efficacy. Here, we investigate the impact of oxidation state on the in vitro and in vivo release of mannan from a biocompatible and immunostimulatory multidomain peptide hydrogel, K2(SL)6K2 (abbreviated as K2), that has been previously used for the controlled release of protein and small molecule payloads. We observed that O-Man released more slowly from K2 hydrogels in vitro than R-Man. In vivo, the clearance of O-Man from K2 hydrogels was slower than O-Man alone. We attributed the slower release rate to the formation of dynamic imine bonds between reactive aldehyde groups on O-Man and the lysine residues on K2. This imine interaction was also observed to improve K2 + O-Man hydrogel strength and shear recovery without significantly influencing secondary structure or peptide nanofiber formation. There were no observed differences in the in vivo release rates of O-Man loaded in K2, R-Man loaded in K2, and R-Man alone. These data suggest that, after subcutaneous injection, R-Man naturally persists longer in vivo than O-Man and minimally interacts with the peptide hydrogel. These results highlight a potentially critical, but previously unreported, difference in the in vivo behavior of O-Man and R-Man and demonstrate that K2 can be used to normalize the release of O-Man to that of R-Man. Further, since K2 itself is an adjuvant, a combination of O-Man and K2 could be used to enhance the immunostimulatory effects of O-Man for applications such as infectious disease vaccines and cancer immunotherapy.

Self-Assembling Peptide-Based Functional Biomaterials

Peptides can self-assemble into various hierarchical nanostructures through noncovalent interactions and form functional materials exhibiting excellent chemical and physical properties, which have broad applications in bio-/nanotechnology. The self-assembly mechanism, self-assembly morphology of peptide supramolecular architecture and their various applications, have been widely explored which have the merit of biocompatibility, easy preparation, and controllable functionality. Herein, we introduce the latest research progress of self-assembling peptide-based nanomaterials and review their applications in biomedicine and optoelectronics, including tissue engineering, anticancer therapy, biomimetic catalysis, energy harvesting. We believe that this review will inspire the rational design and development of novel peptide-based functional bio-inspired materials in the future.

From design to clinic: Engineered peptide nanomaterials for cancer immunotherapy

Immunotherapy has revolutionized the field of cancer therapy. Nanomaterials can further improve the efficacy and safety of immunotherapy because of their tunability and multifunctionality. Owing to their natural biocompatibility, diverse designs, and dynamic self-assembly, peptide-based nanomaterials hold great potential as immunotherapeutic agents for many malignant cancers, with good immune response and safety. Over the past several decades, peptides have been developed as tumor antigens, effective antigen delivery carriers, and self-assembling adjuvants for cancer immunotherapy. In this review, we give a brief introduction to the use of peptide-based nanomaterials for cancer immunotherapy as antigens, carriers, and adjuvants, and to their current clinical applications. Overall, this review can facilitate further understanding of peptide-based nanomaterials for cancer immunotherapy and may pave the way for designing safe and efficient methods for future vaccines or immunotherapies.

Hydrogel-guided strategies to stimulate an effective immune response for vaccine-based cancer immunotherapy

Cancer vaccines have attracted widespread interest in tumor therapy because of the potential to induce an effective antitumor immune response. However, many challenges including weak immunogenicity, off-target effects, and immunosuppressive microenvironments have prevented their broad clinical translation. To overcome these difficulties, effective delivery systems have been designed for cancer vaccines. As carriers in cancer vaccine delivery systems, hydrogels have gained substantial attention because they can encapsulate a variety of antigens/immunomodulators and protect them from degradation. This enables hydrogels to simultaneously reverse immunosuppression and stimulate the immune response. Meanwhile, the controlled release properties of hydrogels allow for precise temporal and spatial release of loads in situ to further enhance the immune response of cancer vaccines. Therefore, this review summarizes the classification of cancer vaccines, highlights the strategies of hydrogel-based cancer vaccines, and provides some insights into the future development of hydrogel-based cancer vaccines.

Universal and Translational Nanoparticulate CpG Adjuvant

CpG, an agonist of toll-like receptor 9 (TLR9), has become a novel adjuvant that substantially potentiates cellular immunity. However, this agonist may increase systemic toxicity by diffusing into blood after administration and is difficult to be internalized by immune cells to reach TLR9 located in endosomes as a result of the characteristics of negative charge of CpG. Here, we applied a scalable and controllable flash nanocomplexation technology to prepare nanoparticulate CpG adjuvant (npCpG), CpG encapsulated in a physical cross-linking network of protamine and TPP. The nanoadjuvant could redirect CpG into draining lymph nodes to reduce systemic diffusion to improve safety. Further, a combination of npCpG and influenza H1N1 hemagglutinin antigen showed excellent humoral and cellular immunity, evoking high levels of antibodies and cytokines and inducing a great expansion of splenocytes in immunized mice. Also, the nanoadjuvant combined with ovalbumin antigen led to a potent cytotoxic T-cell response, substantially inhibited tumor growth, and improved the survival rate of mice in a melanoma model. This study showed the universal performances of npCpG in infectious disease prevention and tumor immunotherapy to demonstrate the translational potential.

Supramolecular Hydrogel-Wrapped Gingival Mesenchymal Stem Cells in Cutaneous Radiation Injury

Radiation-induced skin wound/dermatitis is one of the common side effects of radiotherapy or interventional radiobiology. Gingiva-derived mesenchymal stem cells (GMSCs) were indicated to have therapeutic potentials in skin diseases. However, stem cells are prone to spread and difficult to stay in the skin for a long time, limiting their curative effects and application. This study investigated the therapeutic efficacy of Nap-GDFDFpDY (pY-Gel) self-assembled peptide hydrogel-encapsulated GMSCs to treat ¹³⁷Cs γ-radiation-induced skin wounds in mice. The effects were evaluated by skin damage score, hind limb extension measurement and histological and immunohistochemical analysis. In vivo studies showed that pY-Gel self-assembled peptide hydrogel-encapsulated GMSCs could effectively improve wound healing in irradiated skin tissues. In addition, it was found that GMSCs conditioned medium (CM) could promote the proliferation, migration and DNA damage repair ability of skin cells after irradiation in human keratinocyte cell line HaCaT and normal human dermal fibroblasts (HFF). Mechanistically, GMSCs-CM can promote the expression of epidermal growth factor receptor (EGFR), signal transducers and activators of transcription 3 (STAT3) and matrix metalloproteinases (MMPs), suggesting that activation of the EGFR/STAT3 signaling pathway may be involved in the repair of skin cells after exposure to radiations. In conclusion, pY-Gel self-assembled peptide hydrogel-encapsulated GMSCs have a beneficial therapeutic effect on radiation-induced cutaneous injury and may serve as a basis of novel cells therapeutic approach.

Short Peptide-Based Smart Thixotropic Hydrogels †

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.

Peptide-Based Hydrogels: New Materials for Biosensing and Biomedical Applications

Peptide-based hydrogels have attracted increasing attention for biological applications and diagnostic research due to their impressive features including biocompatibility and biodegradability, injectability, mechanical stability, high water absorption capacity, and tissue-like elasticity. The aim of this review will be to present an updated report on the advancement of peptide-based hydrogels research activity in recent years in the field of anticancer drug delivery, antimicrobial and wound healing materials, 3D bioprinting and tissue engineering, and vaccines. Additionally, the biosensing applications of this key group of hydrogels will be discussed mainly focusing the attention on cancer detection.

Vitamin C supramolecular hydrogel for enhanced cancer immunotherapy

Vitamin C (VitC) has shown great promise to promote cancer immunotherapy, however, its high hydrophilicity makes it quickly excreted, leading to limited therapeutic efficiency even with frequent high-dose administration. Herein, we provide a pioneering report about the employment of VitC amphiphile self-assembled nanofiber hydrogels for enhanced cancer immunotherapy. Specifically, driven by hydrogen bonding and hydrophobic interactions, the synthesized VitC amphiphile, consisting of a hydrophilic VitC headgroup and a hydrophobic alkyl chain, could self-assemble into an injectable nanofiber hydrogel with self-healing properties. The formed VitC hydrogel not only serves as a reservoir for VitC but also acts as an effective delivery platform for stimulator of interferon genes (STING) agonist-4 (SA). Interestingly, the VitC hydrogel itself exhibits antitumor effects by upregulating genes related to interferon (IFN) signaling, apoptotic signaling and viral recognition and defense. Moreover, the SA-encapsulated VitC hydrogel (SA@VitC hydrogel) synergistically activated the immune system to inhibit the progression of both local and abscopal tumors.