A scalable synthesis of adjuvanting antigen depots based on metal-organic frameworks

Thermostability of tetanus toxoid vaccine encapsulated in metal-organic frameworks

Most vaccines require refrigerated transport and storage, which is costly, challenging in low-resource settings, and results in the loss of up to 50% of vaccines globally due to "cold-chain" failures. Here, tetanus toxoid vaccine (TT) was thermostabilized by encapsulation within a metal-organic framework (MOF), zeolitic imidazolate framework-8 (TT@ZIF-8). Its physicochemical properties were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and confocal microscopy. Unencapsulated TT fell below the 80% activity threshold within 4 days at 40˚C and 60˚C according to immunoassay analysis. Aqueous suspensions of TT@ZIF-8 also declined below 80% activity within a week at both temperatures, likely due to MOF degradation in water. Dried TT@ZIF-8 performed better, retaining 80% stability for 33 days at 40˚C and 22 days at 60˚C. When TT@ZIF-8 was suspended in a non-aqueous mixture of propylene glycol and ethanol, it remained 80% stable for approximately 4 months at 40˚C and 2.5 months at 60˚C. Arrhenius modeling predicted this formulation may qualify for "controlled temperature chain" designation, allowing partial vaccine removal from the cold chain. These studies suggest that MOF encapsulation of vaccines like TT can enable dramatic improvements in vaccine stability during storage without refrigeration.

Rational Design of Metal-Organic Frameworks for Pancreatic Cancer Therapy: from Machine Learning Screening to In Vivo Efficacy

Despite improvements in cancer survival rates, metastatic and surgery-resistant cancers, such as pancreatic cancer, remain challenging, with poor prognoses and limited treatment options. Enhancing drug bioavailability in tumors, while minimizing off-target effects, is crucial. Metal-organic frameworks (MOFs) have emerged as promising drug delivery vehicles owing to their high loading capacity, biocompatibility, and functional tunability. However, the vast chemical diversity of MOFs complicates the rational design of biocompatible materials. This study employed machine learning and molecular simulations to identify MOFs suitable for encapsulating gemcitabine, paclitaxel, and SN-38, and identified PCN-222 as an optimal candidate. Following drug loading, MOF formulations are improved for colloidal stability and biocompatibility. In vitro studies on pancreatic cancer cell lines have shown high biocompatibility, cellular internalization, and delayed drug release. Long-term stability tests demonstrated a consistent performance over 12 months. In vivo studies in pancreatic tumor-bearing mice revealed that paclitaxel-loaded PCN-222, particularly with a hydrogel for local administration, significantly reduced metastatic spread and tumor growth compared to the free drug. These findings underscore the potential of PCN-222 as an effective drug delivery system for the treatment of hard-to-treat cancers.

A Self-Adjuvanting Large Pore 2D Covalent Organic Framework as a Vaccine Platform

Vaccines are one of the greatest human achievements in public health, as they help prevent the spread of diseases, reduce illness and death rates, saving thousands of lives with few side effects. Traditional vaccine development is centered around using live attenuated or inactivated pathogens, which is expensive and has resulted in vaccine-associated illnesses. Advancements have led to the development of safer subunit vaccines, which contain recombinant proteins isolated from pathogens. Their short half-life and small size make most subunit vaccines less immunogenic. Here, we introduce a large pore 2D covalent organic framework (COF), PyCOFamide, as a promising solution for an effective subunit platform. Our study demonstrates that simple adsorption of a model antigen, ovalbumin (OVA), onto PyCOFamide (OVA@COF) significantly enhances humoral and cell-mediated immune response compared to free OVA. OVA@COF exhibited heightened immune cell activation and acts as an antigen reservoir, facilitating antigen-presenting cell trafficking to the draining lymph nodes, amplifying the humoral immune response. Additionally, the breakdown of the COF releases monomers that adjuvant the activation of immune cells vital to creating strong immunity. This platform offers a potential avenue for safer, more effective subunit vaccines.

Dually functionalized dendrimer for stimuli-responsive release of active ingredients into the skin

The skin, our largest organ, protects against environmental dangers but is vulnerable to various conditions like infections, eczema, dermatitis, psoriasis, skin cancer, and age-related collagen and elastin degradation. Its outer layer, the water-impermeable epidermis, presents challenges for passive drug delivery to the lower living layers of the skin. An ideal dermal delivery system should penetrate the epidermis and release treatments over time. We report a stimuli-activated nanocarrier that slowly releases active ingredients under skin-specific conditions. Using a fourth-generation polyamidoamine (PAMAM), dendrimer functionalized with poly(2-ethyl-2-oxazoline) and palmitoyl pentapeptide-4, we show a controlled release of biologically active therapeutics into the dermis of the skin for 24 h. Ex vivo studies demonstrate that our nanocarrier system delivers cargo to the dermis and is non-toxic to skin fibroblasts. As a proof of principle, we demonstrate a system that effectively enhances collagen production in human dermal fibroblasts by co-delivering all-trans retinol and palmitoyl pentapeptide-4. Our nanosystem surpasses the effects of individual components. This nanocarrier offers a promising approach for targeted dermal delivery, potentially improving treatment efficacy for various skin conditions while minimizing adverse effects associated with traditional formulations. STATEMENT OF SIGNIFICANCE: In this manuscript we introduce a stimuli-responsive nanocarrier based on a G4-PAMAM dendrimer functionalized with poly(2-ethyl-2-oxazoline) (POZ) and palmitoyl pentapeptide-4, designed to deliver biomolecules specifically to the skin. The nanocarrier enables controlled, stimuli-triggered release under skin-specific conditions (pH 5, 37 °C), enhancing dermal penetration and minimizing release at neutral pH or lower temperatures. This work improves traditional dendrimer systems by reducing toxicity through POZ, ensuring controlled delivery without invasive techniques like iontophoresis, and co-delivering both a small molecule (all-trans-retinol) and a collagen-stimulating peptide for enhanced therapeutic effects. This system addresses major drug delivery challenges, sets a new precedent for safer, multifunctional nanomaterials, and advances dendrimer chemistry, opening new possibilities in targeted therapies, skin treatments, and materials science.

Testing the Antigenic Potential of Transmembrane Proteins To Develop a Thermostable Tuberculosis MOF-Liposomal Vaccine

Tuberculosis is one of the deadliest infectious diseases and continues to be a major health risk in many parts of the world. Even today, the century-old Bacillus Calmette-Guerin (BCG) vaccine is the only formulation on the market and is ineffective for several sections of the global population responsible for transmission. In the search for antigens that can mount a robust immune response, we have reported the recombinant expression and purification of two novel membrane proteins, the Cation transporter protein V (CtpV) and the Mycobacterial copper transporter B (MctB) present on the membrane surface of Mycobacterium tuberculosis. CtpV was tested as an antigen against the plasma of tuberculosis patients and was found to have a unique immune response profile compared with more commonly studied tuberculosis (TB) antigens. CtpV and MctB were reconstituted into proteoliposomes─individually and in combination─to stabilize them in a lipid bilayer and create a nanoparticle vaccine platform. In vivo experiments demonstrated that when delivered with an adjuvant, these antigens generated a robust Th1-biased T-cell response in mice, with the combination of both antigens performing the best and generating a response comparable to BCG. Since tuberculosis vaccines often need to be shipped to areas with fluctuating power supply, we encapsulated the proteoliposomes and the adjuvant in ZIF-8 to create a shelf-stable formulation. Complementary in vivo studies were carried out to confirm that the ZIF-8 coating did not interfere with or compromise the immunogenicity of the antigens.

Mn and Zn-Doped Multivariate Metal-Organic Framework as a Metalloimmunological Adjuvant to Promote Protection Against Tuberculosis Infection

A first-in-class vaccine adjuvant delivery system, Mn-ZIF, is developed by incorporating manganese (Mn) into the zinc-containing zeolitic-imidazolate framework-8 (ZIF-8). The mixed metal approach, which allowed for tunable Mn doping, is made possible by including a mild reducing agent in the reaction mixture. This approach allows up to 50% Mn, with the remaining 50% Zn within the ZIF. This multivariate approach exhibits significantly decreased cytotoxicity compared to ZIF-8. The porous structure of Mn-ZIF enables the co-delivery of the STING agonist cyclic di-adenosine monophosphate (CDA) through post-synthetic loading, forming CDA@Mn-ZIF. The composite demonstrated enhanced cellular uptake and synergistic activation of the cGAS-STING pathway, producing proinflammatory cytokines and activating antigen-presenting cells (APCs). In a preclinical Mycobacterium tuberculosis (Mtb) model, CDA@Mn-ZIF formulates with the CysVac2 fusion protein elicited a potent antigen-specific T-cell response and significantly reduced the mycobacterial burden in the lungs of infected mice. These findings highlight the potential of CDA@Mn-ZIF as a promising adjuvant for subunit vaccines, offering a novel approach to enhancing vaccine efficacy and protection against infectious diseases such as tuberculosis.

Biomimetic functionalized metal organic frameworks as multifunctional agents: Paving the way for cancer vaccine advances

Biomimetic functionalized metal-organic frameworks (Fn-MOFs) represent a cutting-edge approach in the realm of cancer vaccines. These multifunctional agents, inspired by biological systems, offer unprecedented opportunities for the development of next-generation cancer vaccines. The vast surface area, tunable pore size, and diverse chemistry of MOFs provide a versatile scaffold for the encapsulation and protection of antigenic components, crucial for vaccine stability and delivery. This work delves into the innovative design and application of Fn-MOFs, highlighting their role as carriers for immune enhancement and their potential to revolutionize vaccine delivery. By mimicking natural processes, Fn-MOFs, with their ability to be functionalized with a myriad of chemical and biological entities, exhibit superior biocompatibility and stimuli-responsive behavior and facilitate targeted delivery to tumor sites. This review encapsulates the latest advancements in Fn-MOF technology, from their synthesis and surface modification to their integration into stimuli-responsive and combination therapies. It underscores the significance of biomimetic approaches in overcoming current challenges in cancer vaccine development, such as antigen stability and immune evasion. By leveraging the biomimetic nature of Fn-MOFs, this work paves the way for innovative strategies in cancer vaccines, aiming to induce potent and long-lasting immune responses against malignancies.

The Promise and Potential of Metal-Organic Frameworks and Covalent Organic Frameworks in Vaccine Nanotechnology

The immune system's complexity and ongoing evolutionary struggle against deleterious pathogens underscore the value of vaccination technologies, which have been bolstering human immunity for over two centuries. Despite noteworthy advancements over these 200 years, three areas remain recalcitrant to improvement owing to the environmental instability of the biomolecules used in vaccines─the challenges of formulating them into controlled release systems, their need for constant refrigeration to avoid loss of efficacy, and the requirement that they be delivered via needle owing to gastrointestinal incompatibility. Nanotechnology, particularly metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), has emerged as a promising avenue for confronting these challenges, presenting a new frontier in vaccine development. Although these materials have been widely explored in the context of drug delivery, imaging, and cancer immunotherapy, their role in immunology and vaccine-related applications is a recent yet rapidly developing field. This review seeks to elucidate the prospective use of MOFs and COFs for biomaterial stabilization, eliminating the necessity for cold chains, enhancing antigen potency as adjuvants, and potentializing needle-free delivery of vaccines. It provides an expansive and critical viewpoint on this rapidly evolving field of research and emphasizes the vital contribution of chemists in driving further advancements.