Peptide Amphiphile Micelle Vaccine Size and Charge Influence the Host Antibody Response

Adjuvant Delivery Method and Nanoparticle Charge Influence Peptide Amphiphile Micelle Vaccine Bioactivity

Vaccines are an indispensable public health measure that have enabled the eradication, near elimination, and prevention of a variety of pathogens. As research continues and our understanding of immunization strategies develops, subunit vaccines have emerged as exciting alternatives to existing whole vaccine approaches. Unfortunately, subunit vaccines often possess weak antigenicity, requiring delivery devices and adjuvant supplementation to improve their utility. Peptide amphiphile micelles have recently been shown to function as both delivery devices and self-adjuvanting systems that can be readily associated with molecular adjuvants to further improve vaccine-mediated host immunity. While promising, many "design rules" associated with the plethora of underlying adjustable parameters in the generation of a peptide amphiphile micelle vaccine have yet to be uncovered. This work explores the impact micellar adjuvant complexation method and incorporated antigen type have on their ability to activate dendritic cells and induce antigen specific responses. Interestingly, electrostatic complexation of CpG to micelles resulted in improved in vitro dendritic cell activation over hydrophobic association and antigen|adjuvant co-localization influenced cell-mediated, but not antibody-mediated immune responses. These exciting results complement those previously published to build the framework of a micelle vaccine toolbox that can be leveraged for future disease-specific formulations.

Effects of Skeleton Structure of Mesoporous Silica Nanoadjuvants on Cancer Immunotherapy

Mesoporous silica nanoparticles (MSNs) have been widely praised as nanoadjuvants in vaccine/tumor immunotherapy thanks to their excellent biocompatibility, easy-to-modify surface, adjustable particle size, and remarkable immuno-enhancing activity. However, the application of MSNs is still greatly limited by some severe challenges including the unclear and complicated relationships of structure and immune effect. Herein, three commonly used MSNs with different skeletons including MSN with tetrasulfide bonds (TMSN), MSN containing ethoxy framework (EMSN), and pure -Si-O-Si- framework of MSN (MSN) are comprehensively compared to study the impact of chemical construction on immune effect. The results fully demonstrate that the three MSNs have great promise in improving cellular immunity for tumor immunotherapy. Moreover, the TMSN performs better than the other two MSNs in antigen loading, cellular uptake, reactive oxygen species (ROS) generation, lymph node targeting, immune activation, and therapeutic efficiency. The findings provide a new paradigm for revealing the structure-function relationship of mesoporous silica nanoadjuvants, paving the way for their future clinical application.

Biomaterial-based delivery platforms for transdermal immunotherapy

Nowadays, immunotherapy is one of the most essential treatments for various diseases and a broad spectrum of disorders are assumed to be treated by altering the function of the immune system. For this reason, immunotherapy has attracted a great deal of attention and numerous studies on different approaches for immunotherapies have been investigated, using multiple biomaterials and carriers, from nanoparticles (NPs) to microneedles (MNs). In this review, the immunotherapy strategies, biomaterials, devices, and diseases supposed to be treated by immunotherapeutic strategies are reviewed. Several transdermal therapeutic methods, including semisolids, skin patches, chemical, and physical skin penetration enhancers, are discussed. MNs are the most frequent devices implemented in transdermal immunotherapy of cancers (e.g., melanoma, squamous cell carcinoma, cervical, and breast cancer), infectious (e.g., COVID-19), allergic and autoimmune disorders (e.g., Duchenne's muscular dystrophy and Pollinosis). The biomaterials used in transdermal immunotherapy vary in shape, size, and sensitivity to external stimuli (e.g., magnetic field, photo, redox, pH, thermal, and even multi-stimuli-responsive) were reported. Correspondingly, vesicle-based NPs, including niosomes, transferosomes, ethosomes, microemulsions, transfersomes, and exosomes, are also discussed. In addition, transdermal immunotherapy using vaccines has been reviewed for Ebola, Neisseria gonorrhoeae, Hepatitis B virus, Influenza virus, respiratory syncytial virus, Hand-foot-and-mouth disease, and Tetanus.

Peptide-based assembled nanostructures that can direct cellular responses

Natural originated materials have been well-studied over the past several decades owing to their higher biocompatibility compared to the traditional polymers. Peptides, consisting of amino acids, are among the most popular programable building blocks, which is becoming a growing interest in nanobiotechnology. Structures assembled using those biomimetic peptides allow the exploration of chemical sequences beyond those been routinely used in biology. In this Review, we discussed the most recent experimental discoveries on the peptide-based assembled nanostructures and their potential application at the cellular level such as drug delivery. In particular, we explored the fundamental principles of peptide self-assembly and the most recent development in improving their interactions with biological systems. We believe that as the fundamental knowledge of the peptide assemblies evolves, the more sophisticated and versatile nanostructures can be built, with promising biomedical applications.

The influence of component structural arrangement on peptide vaccine immunogenicity

Peptide-based subunit vaccines utilise minimal immunogenic components (i.e. peptides) to generate highly specific immune responses, without triggering adverse reactions. However, strong adjuvants and/or effective delivery systems must be incorporated into such vaccines, as peptide antigens cannot induce substantial immune responses on their own. Unfortunately, many adjuvants are too weak or too toxic to be used in combination with peptide antigens. These shortcomings have been addressed by the conjugation of peptide antigens with lipidic/ hydrophobic adjuvanting moieties. The conjugates have shown promising safety profiles and improved immunogenicity without the help of traditional adjuvants and have been efficient in inducing desired immune responses following various routes of administration, including subcutaneous, oral and intranasal. However, not only conjugation per se, but also component arrangement influences vaccine efficacy. This review highlights the importance of influence of the vaccine chemical structure modification on the immune responses generated. It discusses a variety of factors that affect the immunogenicity of peptide conjugates, including: i) self-adjuvanting moiety length and number; ii) the orientation of epitopes and self-adjuvanting moieties in the conjugate; iii) the presence of spacers between conjugated components; iv) multiepitopic arrangement; and v) the effect of chirality on vaccine efficacy.

Vasoactive Intestinal Peptide Amphiphile Micelle Chemical Structure and Hydrophobic Domain Influence Immunomodulatory Potentiation

Vasoactive intestinal peptide (VIP) is a neuropeptide capable of downregulating innate immune responses in antigen presenting cells (APCs) by suppressing their pro-inflammatory cytokine secretion and cell surface marker expression. Though VIP's bioactivity could possibly be leveraged as a treatment for transplant tolerance, drug delivery innovation is required to overcome its intrinsically limited cellular delivery capacity. One option is to employ peptide amphiphiles (PAs) which are lipidated peptides capable of self-assembling into micelles in water that can enhance cellular association. With this approach in mind, a series of triblock VIP amphiphiles (VIPAs) has been synthesized to explore the influence of block arrangement and hydrophobicity on micelle biocompatibility and bioactivity. VIPA formulation has been found to influence the shape, size, and surface charge of VIPA micelles (VIPAMs) as well as their cytotoxicity and immunomodulatory effects. Specifically, the enclosed work provides strong evidence that cylindrical VIPAMs with aspect ratios of 1.5-150 and moderate positive surface charge are able to potentiate the bioactivity of VIP limiting TNF-α secretion and MHC II and CD86 surface expression on APCs. With these criteria, we have identified PalmK-(EK)₄-VIP as our lead formulation, which showed comparable or enhanced anti-inflammatory effects relative to the unmodified VIP at all dosages evaluated. Additionally, the relationships between peptide block location and lipid block size provide further information on the chemical structure-function relationships of PA micelles for the delivery of VIP as well as potentially for other peptides more broadly.

A Polylactide-Based Micellar Adjuvant Improves the Intensity and Quality of Immune Response

Micelles from amphiphilic polylactide-block-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (PLA-b-P(NAS-co-NVP)) block copolymers of 105 nm in size were characterized and evaluated in a vaccine context. The micelles were non-toxic in vitro (both in dendritic cells and HeLa cells). In vitro fluorescence experiments combined with in vivo fluorescence tomography imaging, through micelle loading with the DiR near infrared probe, suggested an efficient uptake of the micelles by the immune cells. The antigenic protein p24 of the HIV-1 was successfully coupled on the micelles using the reactive N-succinimidyl ester groups on the micelle corona, as shown by SDS-PAGE analyses. The antigenicity of the coupled antigen was preserved and even improved, as assessed by the immuno-enzymatic (ELISA) test. Then, the performances of the micelles in immunization were investigated and compared to different p24-coated PLA nanoparticles, as well as Alum and MF59 gold standards, following a standardized HIV-1 immunization protocol in mice. The humoral response intensity (IgG titers) was substantially similar between the PLA micelles and all other adjuvants over an extended time range (one year). More interestingly, this immune response induced by PLA micelles was qualitatively higher than the gold standards and PLA nanoparticles analogs, expressed through an increasing avidity index over time (>60% at day 365). Taken together, these results demonstrate the potential of such small-sized micellar systems for vaccine delivery.

Enhancing therapeutic performance of personalized cancer vaccine via delivery vectors

In recent years, personalized cancer vaccines have gained increasing attention as emerging immunotherapies with the capability to overcome interindividual differences and show great benefits for individual patients in the clinic due to the highly tailored vaccine formulations. A large number of materials have been studied as delivery vectors to enhance the therapeutic performance of personalized cancer vaccines, including artificial materials, engineered microorganisms, cells and cell derivatives. These delivery vectors with distinct features are employed to change antigen biodistributions and to facilitate antigen uptake, processing and presentation, improving the strength, velocity, and duration of the immune response when delivered by different strategies. Here, we provide an overview of personalized cancer vaccine delivery vectors, describing their materials, physicochemical properties, delivery strategies and challenges for clinical transformation.

Peptide-based supramolecular vaccine systems

Currently approved replication-competent and inactivated vaccines are limited by excessive reactogenicity and poor safety profiles, while subunit vaccines are often insufficiently immunogenic without co-administering exogenous adjuvants. Self-assembling peptide-, peptidomimetic-, and protein-based biomaterials offer a means to overcome these challenges through their inherent modularity, multivalency, and biocompatibility. As these scaffolds are biologically derived and present antigenic arrays reminiscent of natural viruses, they are prone to immune recognition and are uniquely capable of functioning as self-adjuvanting vaccine delivery vehicles that improve humoral and cellular responses. Beyond this intrinsic immunological advantage, the wide range of available amino acids allows for facile de novo design or straightforward modifications to existing sequences. This has permitted the development of vaccines and immunotherapies tailored to specific disease models, as well as generalizable platforms that have been successfully applied to prevent or treat numerous infectious and non-infectious diseases. In this review, we briefly introduce the immune system, discuss the structural determinants of coiled coils, β-sheets, peptide amphiphiles, and protein subunit nanoparticles, and highlight the utility of these materials using notable examples of their innate and adaptive immunomodulatory capacity.

Mesoporous Silica Nanoparticles as pH-Responsive Carrier for the Immune-Activating Drug Resiquimod Enhance the Local Immune Response in Mice

Nanoparticle-based delivery systems for cancer immunotherapies aim to improve the safety and efficacy of these treatments through local delivery to specialized antigen-presenting cells (APCs). Multifunctional mesoporous silica nanoparticles (MSNs), with their large surface areas, their tunable particle and pore sizes, and their spatially controlled functionalization, represent a safe and versatile carrier system. In this study, we demonstrate the potential of MSNs as a pH-responsive drug carrier system for the anticancer immune-stimulant R848 (resiquimod), a synthetic Toll-like receptor 7 and 8 agonist. Equipped with a biotin-avidin cap, the tailor-made nanoparticles showed efficient stimuli-responsive release of their R848 cargo in an environmental pH of 5.5 or below. We showed that the MSNs loaded with R848 were rapidly taken up by APCs into the acidic environment of the lysosome and that they potently activated the immune cells. Upon subcutaneous injection into mice, the particles accumulated in migratory dendritic cells (DCs) in the draining lymph nodes, where they strongly enhanced the activation of the DCs. Furthermore, simultaneous delivery of the model antigen OVA and the adjuvant R848 by MSNs resulted in an augmented antigen-specific T-cell response. The MSNs significantly improved the pharmacokinetic profile of R848 in mice, as the half-life of the drug was increased 6-fold, and at the same time, the systemic exposure was reduced. In summary, we demonstrate that MSNs represent a promising tool for targeted delivery of the immune modulator R848 to APCs and hold considerable potential as a carrier for cancer vaccines.

The Versatile Manipulations of Self-Assembled Proteins in Vaccine Design

Protein assemblies provide unique structural features which make them useful as carrier molecules in biomedical and chemical science. Protein assemblies can accommodate a variety of organic, inorganic and biological molecules such as small proteins and peptides and have been used in development of subunit vaccines via display parts of viral pathogens or antigens. Such subunit vaccines are much safer than traditional vaccines based on inactivated pathogens which are more likely to produce side-effects. Therefore, to tackle a pandemic and rapidly produce safer and more effective subunit vaccines based on protein assemblies, it is necessary to understand the basic structural features which drive protein self-assembly and functionalization of portions of pathogens. This review highlights recent developments and future perspectives in production of non-viral protein assemblies with essential structural features of subunit vaccines.

Self-Assembled Multi-Epitope Peptide Amphiphiles Enhance the Immune Response against Enterovirus 71

Subunit vaccines consist of non-genetic material, such as peptides or proteins. They are considered safe because they have fewer side effects; however, they have low immunogenicity when used alone. We aimed to enhance the immune response of peptide-based vaccines by using self-assembled multimeric peptide amphiphiles (PAs). We designed two epitope PAs by conjugating epitope peptides from Enterovirus 71 (EV71) virus particle (VP) 1 and VP3 capsid proteins with different fatty acid chain lengths (VP1PA and VP3PA). These PAs self-assembled into supramolecular structures at a physiological pH, and the resulting structures were characterized using atomic force microscopy. Multi-epitope PAs (m-PAs) consisted of a 1:1 mixture of VP1PA and VP3PA solutions. To evaluate immunogenicity, m-PA constructs were injected with adjuvant subcutaneously into female Balb/c mice. Levels of antigen-specific immunoglobulin G (IgG) and IgG1 in m-PA-injected mice serum samples were analyzed using ELISA and Western blotting. Additionally, cytokine production stimulated by each antigen was measured in splenocytes cultured from immunized mice groups. We found that m-PA showed improved humoral and cellular immune responses compared to the control and peptide groups. The sera from m-PA immunized mice group could neutralize EV71 infection and protect host cells. Thus, self-assembled m-PAs can promote a protective immune response and can be developed as a potential platform technology to produce peptide vaccines against infectious viral diseases.

Leveraging the modularity of biomaterial carriers to tune immune responses

Biomaterial carriers offer modular features to control the delivery and presentation of vaccines and immunotherapies. This tunability is a distinct capability of biomaterials. Understanding how tunable material features impact immune responses is important to improve vaccine and immunotherapy design, as well as clinical translation. Here we discuss the modularity of biomaterial properties as a means of controlling encounters with immune signals across scales - tissue, cell, molecular, and time - and ultimately, to direct stimulation or regulation of immune function. We highlight these advances using illustrations from recent literature across infectious disease, cancer, and autoimmunity. As the immune engineering field matures, informed design criteria could support more rational biomaterial carriers for vaccination and immunotherapy.

Rational Design of Antigen Incorporation Into Subunit Vaccine Biomaterials Can Enhance Antigen-Specific Immune Responses

Peptide subunit vaccines increase safety by reducing the risk of off-target responses and improving the specificity of the induced adaptive immune response. The immunogenicity of most soluble peptides, however, is often insufficient to produce robust and lasting immunity. Many biomaterials and delivery vehicles have been developed for peptide antigens to improve immune response while maintaining specificity. Peptide nanoclusters (PNC) are a subunit peptide vaccine material that has shown potential to increase immunogenicity of peptide antigens. PNC are comprised only of crosslinked peptide antigen and have been synthesized from several peptide antigens as small as 8 amino acids in length. However, as with many peptide vaccine biomaterials, synthesis requires adding residues to the peptide and/or engaging amino acids within the antigen epitope covalently to form a stable material. The impact of antigen modifications made to enable biomaterial incorporation or formation is rarely investigated, since the goal of most studies is to compare the soluble antigen with biomaterial form of antigen. This study investigates PNC as a platform vaccine biomaterial to evaluate how peptide modification and biomaterial formation with different crosslinking chemistries affect epitope-specific immune cell presentation and activation. Several types of PNC were synthesized by desolvation from the model peptide epitope SIINFEKL, which is derived from the immunogenic protein ovalbumin. SIINFEKL was altered to include extra residues on each end, strategically chosen to enable multiple conjugation chemistry options for incorporation into PNC. Several crosslinking methods were used to control which functional groups were used to stabilize the PNC, as well as the reducibility of the crosslinking. These variations were evaluated for immune responses and biodistribution following in vivo immunization. All modified antigen formulations still induced comparable immune responses when incorporated into PNC compared to unmodified soluble antigen alone. However, some crosslinking methods led to a significant increase in desirable immune responses while others did not, suggesting that not all PNC were processed the same. These results help guide future peptide vaccine biomaterial design, including PNC and a wide variety of conjugated and self-assembled peptide antigen materials, to maximize and tune the desired immune response.

The potential impact of trigonelline loaded micelles on Nrf2 suppression to overcome oxaliplatin resistance in colon cancer cells

Nuclear factor erythroid 2-related factor 2 (Nrf2) has a pivotal role in promoting chemoresistance by regulation of antioxidants and detoxification enzymes. Trigonelline is one of the major alkaloids in raw coffee which has been recently introduced as potent inhibitor of Nrf2. This study investigated the role of trigonelline and trigonelline loaded micelles in Nrf2 inhibition to break down oxaliplatin resistance in colon cancer cells. The PCL-PEG-PCL and PLA-PCL-PEG-PCL-PLA copolymers and trigonelline loaded micelles were prepared and characterized for fourier transforms infrared (FTIR), hydrogen nuclear magnetic resonance (¹H-NMR), carbon nuclear magnetic resonance (¹³C-NMR) spectroscopy, particle size, zeta potential, scanning electron microscopy (SEM) and entrapment efficiency. Cell viability and apoptosis were evaluated by using MTT and flow cytometry assays, respectively. Nrf2, MRP1, NQO1, HO-1, Bax, and Bcl2 gene expressions were examined by qRT-PCR. Our results revealed that micelles had spherical shapes with narrow sizes and zeta potential indexes of - 9.06 ± 6.94 mV for trigonelline loaded 3Block and - 7.47 ± 6.08 mV for trigonelline loaded 5Block micelles. After Nrf2 inhibition by trigonelline, antioxidant response element (ARE) related gene expressions were decreased (p < 0.05) with a significantly higher impact by trigonelline loaded micelles (p < 0.05). Trigonelline loaded micelles also strongly decreased IC50 value of oxaliplatin in resistant colon cancer cells (p < 0.05). Furthermore, trigonelline loaded 5Block micelle increased oxaliplatin-induced apoptosis in a Nrf2/ARE dependent manner. Altogether, the current study suggests that delivery of trigonelline loaded micelles as potent Nrf2 inhibitors can be considered as a promising strategy to overcome oxaliplatin resistance in colon cancer patients.

Recent Advances in Nanotechnology for Dendritic Cell-Based Immunotherapy

Dendritic cells (DCs) are the most important antigen-presenting cells that determine cancer immune responses by regulating immune activation and tolerance, especially in the initiation stage of specific responses. Manipulation of DCs to enhance specific antitumor immune response is considered to be a powerful tool for tumor eradication. Nanotechnology, which can incorporate multifunction components and show spatiotemporal control properties, is of great interest and is widely investigated for its ability to improve immune response activity against cancer and even for prevention and avoiding recurrence. In this mini-review, we aim to provide a general view of DC-based immunotherapy, including that involving the promising nanotechnology. Particularly we discuss: (1) manipulation or engineering of DCs for adoptive vaccination, (2) employing DCs as a combination to more existing therapeutics in tumor treatment, and (3) direct modulation of DCs in vivo to enhance antigen presentation efficacy and priming T cells subsequently. We comprehensively discuss the updates on the application of nanotechnology in DC-based immunotherapy and provide some insights on the challenges and opportunities of DC-based immunotherapeutics, including the potential of nanotechnology, against cancers.

Vaxign-ML: supervised machine learning reverse vaccinology model for improved prediction of bacterial protective antigens

MOTIVATION

Reverse vaccinology (RV) is a milestone in rational vaccine design, and machine learning (ML) has been applied to enhance the accuracy of RV prediction. However, ML-based RV still faces challenges in prediction accuracy and program accessibility.

RESULTS

This study presents Vaxign-ML, a supervised ML classification to predict bacterial protective antigens (BPAgs). To identify the best ML method with optimized conditions, five ML methods were tested with biological and physiochemical features extracted from well-defined training data. Nested 5-fold cross-validation and leave-one-pathogen-out validation were used to ensure unbiased performance assessment and the capability to predict vaccine candidates against a new emerging pathogen. The best performing model (eXtreme Gradient Boosting) was compared to three publicly available programs (Vaxign, VaxiJen, and Antigenic), one SVM-based method, and one epitope-based method using a high-quality benchmark dataset. Vaxign-ML showed superior performance in predicting BPAgs. Vaxign-ML is hosted in a publicly accessible web server and a standalone version is also available.

AVAILABILITY AND IMPLEMENTATION

Vaxign-ML website at http://www.violinet.org/vaxign/vaxign-ml, Docker standalone Vaxign-ML available at https://hub.docker.com/r/e4ong1031/vaxign-ml and source code is available at https://github.com/VIOLINet/Vaxign-ML-docker.

SUPPLEMENTARY INFORMATION

Supplementary data are available at Bioinformatics online.

Materials for Immunotherapy

Breakthroughs in materials engineering have accelerated the progress of immunotherapy in preclinical studies. The interplay of chemistry and materials has resulted in improved loading, targeting, and release of immunomodulatory agents. An overview of the materials that are used to enable or improve the success of immunotherapies in preclinical studies is presented, from immunosuppressive to proinflammatory strategies, with particular emphasis on technologies poised for clinical translation. The materials are organized based on their characteristic length scale, whereby the enabling feature of each technology is organized by the structure of that material. For example, the mechanisms by which i) nanoscale materials can improve targeting and infiltration of immunomodulatory payloads into tissues and cells, ii) microscale materials can facilitate cell-mediated transport and serve as artificial antigen-presenting cells, and iii) macroscale materials can form the basis of artificial microenvironments to promote cell infiltration and reprogramming are discussed. As a step toward establishing a set of design rules for future immunotherapies, materials that intrinsically activate or suppress the immune system are reviewed. Finally, a brief outlook on the trajectory of these systems and how they may be improved to address unsolved challenges in cancer, infectious diseases, and autoimmunity is presented.

Protein and Peptide Biomaterials for Engineered Subunit Vaccines and Immunotherapeutic Applications

Although vaccines have been the primary defense against widespread infectious disease for decades, there is a critical need for improvement to combat complex and variable diseases. More control and specificity over the immune response can be achieved by using only subunit components in vaccines. However, these often lack sufficient immunogenicity to fully protect, and conjugation or carrier materials are required. A variety of protein and peptide biomaterials have improved effectiveness and delivery of subunit vaccines for infectious, cancer, and autoimmune diseases. They are biodegradable and have control over both material structure and immune function. Many of these materials are built from naturally occurring self-assembling proteins, which have been engineered for incorporation of vaccine components. In contrast, others are de novo designs of structures with immune function. In this review, protein biomaterial design, engineering, and immune functionality as vaccines or immunotherapies are discussed.

A study on a special DNA nanotube assembled from two single-stranded tiles

Single-stranded tile (SST) strategy offers precise control over the circumferences of nanotubes while the kinetic trap in the process of the self-assembly prevents the formation of wider tubes. Here, we report a simple and efficient method to build DNA nanotubes using only 2 SSTs via one-pot annealing. The diameters of the 2-SST nanotubes were much larger than what the kinetic trap theory would predict, indicating a new mechanism was at play in the formation of these nanotubes. Further investigation suggested that the 2-SST nanotubes were assembled through a hierarchical pathway that involved an intermediate formation of 2-SST nano-lines.

Chiral Polypeptide Thermogels Induce Controlled Inflammatory Response as Potential Immunoadjuvants

The in vivo implanted biomaterials are known to induce inflammatory response and recruit immune cells, which could be used as robust adjuvants for immunotherapy. However, the degree of inflammatory response induced by the implanted biomaterials is hard to control. In this work, we reported the application of three kinds of thermogels from the polypeptide methoxy poly(ethylene glycol)-polyalanine (mPEG-PAla) with various chiralities to regulate the levels of inflammatory responses in vivo. The mPEG-PLAla (EG₄₅LA₂₈) and mPEG-PDAal (EG₄₅DA₂₇) thermogels exhibited comparable storage modulus ( G') and loss modulus ( G″), both of which were about two times higher than the values of the racemic mPEG-PAla (EG₄₅RA) thermogel. The component d-alanine in the polypeptide thermogels led to controlled tissue inflammation after subcutaneous injection, and the content of d-alanine could adjust the level of inflammation. The expression of tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in subcutaneous tissue around the injected thermogel EG₄₅DA₂₇ were 3.62, 1.52, and 4.55 times the levels of those after EG₄₅RA thermogel injection and 4.52, 7.38, and 7.96 times the levels of those after EG₄₅LA₂₈ injection, respectively. The results indicated that the chiral polypeptide thermogels could induce a controllable inflammatory response in vivo and exhibit great potential as an efficient adjuvant for immunotherapy.

Self-assembled micro-fibres by oxime connection of linear peptide amphiphiles

Linear peptide amphiphiles are excellent biocompatible scaffolds for the hierarchical self-assembly of one-dimensional nano-structures in aqueous media. However, their structural exploration and screening of self-assembling properties are often limited by time-consuming synthesis and purification steps. We here describe the application of an oxime bond as a powerful synthetic tool towards the conjugation of peptide heads bearing a hydroxylamine group with hydrophobic aldehyde tails. This methodology allowed the quick preparation of a small library of oxime-connected peptide amphiphiles, whose supramolecular screening revealed nano-to-micro-fibrillation with dependency on their chemical structure. These results demonstrate the simplicity and the synthetic potential of the oxime conjugation for the preparation of peptide amphiphiles with improved self-assembling capabilities.

Biomaterials for vaccine-based cancer immunotherapy

The development of therapeutic cancer vaccines as a means to generate immune reactivity against tumors has been explored since the early discovery of tumor-specific antigens by Georg Klein in the 1960s. However, challenges including weak immunogenicity, systemic toxicity, and off-target effects of cancer vaccines remain as barriers to their broad clinical translation. Advances in the design and implementation of biomaterials are now enabling enhanced efficacy and reduced toxicity of cancer vaccines by controlling the presentation and release of vaccine components to immune cells and their microenvironment. Here, we discuss the rational design and clinical status of several classes of cancer vaccines (including DNA, mRNA, peptide/protein, and cell-based vaccines) along with novel biomaterial-based delivery technologies that improve their safety and efficacy. Further, strategies for designing new platforms for personalized cancer vaccines are also considered.

Synthetic Charge-Invertible Polymer for Rapid and Complete Implantation of Layer-by-Layer Microneedle Drug Films for Enhanced Transdermal Vaccination

The utility of layer-by-layer (LbL) coated microneedle (MN) skin patches for transdermal drug delivery has proven to be a promising approach, with advantages over hypodermal injection due to painless and easy self-administration. However, the long epidermal application time required for drug implantation by existing LbL MN strategies (15-90 min) can lead to potential medication noncompliance. Here, we developed a MN platform to shorten the application time in MN therapies based on a synthetic pH-induced charge-invertible polymer poly(2-(diisopropylamino) ethyl methacrylate- b-methacrylic acid) (PDM), requiring only 1 min skin insertion time to implant LbL films in vivo. Following MN-mediated delivery of 0.5 μg model antigen chicken ovalbumin (OVA) in the skin of mice, this system achieved sustained release over 3 days and led to an elevated immune response as demonstrated by significantly higher humoral immunity compared with OVA administration via conventional routes (subcutaneously and intramuscularly). Moreover, in an ex vivo experiment on human skin, we achieved efficient immune activation through MN-delivered LbL films, demonstrated by a rapid uptake of vaccine adjuvants by the antigen presenting cells. These features, rapid administration and the ability to elicit a robust immune response, can potentially enable a broad application of microneedle-based vaccination technologies.

Aptamer-displaying peptide amphiphile micelles as a cell-targeted delivery vehicle of peptide cargoes

Peptide amphiphile micelles (PAMs) are attractive vehicles for the delivery of a variety of therapeutic and prophylactic peptides. However, a key limitation of PAMs is their lack of preferential targeting ability. In this paper, we describe our design of a PAM system that incorporates a DNA oligonucleotide amphiphile (antitail amphiphile-AA) to form A/PAMs. A cell-targeting DNA aptamer with a 3' extension sequence (tail) complementary to the AA is annealed to the surface to form aptamer-displaying PAMs (Aptamer~A/PAMs). Aptamer~A/PAMs are small, anionic, stable nanoparticles capable of delivering a large mass percentage peptide amphiphile (PA) compared to targeting DNA components. Aptamer~A/PAMs are stable for over 4 h in the presence of biological fluids. Additionally, the aptamer retains its cell-targeting properties when annealed to the A/PAM, thus leading to enhanced delivery to a specifically-targeted B-cell leukemia cell line. This exciting modular technology can be readily used with a library of different targeting aptamers and PAs, capable of improving the bioavailability and potency of the peptide cargo.

Immunomodulatory vasoactive intestinal peptide amphiphile micelles

Two different vasoactive intestinal peptide (VIP) amphiphiles have been formulated which readily form micelles of varying shapes. Interestingly, VIP micelle structure has been found to directly correlate to anti-inflammatory behavior providing evidence that these biomaterials can serve as a promising new therapeutic modality.