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Equitable global access to vaccines requires overcoming challenges associated with complex immunization schedules and their associated economic burdens that hinder delivery in under‐resourced environments. The rabies vaccine, for example, requires multiple immunizations for effective protection and each dose is cost prohibitive, and therefore inaccessibility disproportionately impacts low‐ and middle‐income countries. In this work, an injectable hydrogel depot technology for sustained delivery of commercial inactivated rabies virus vaccines is developed. In a mouse model, it is shown that a single immunization of a hydrogel‐based rabies vaccine elicited comparable antibody titers to a standard prime‐boost bolus regimen of a commercial rabies vaccine, despite these hydrogel vaccines comprising only half of the total dose delivered in the bolus control. Moreover, these hydrogel‐based vaccines elicited similar antigen‐specific T‐cell responses and neutralizing antibody responses compared to the bolus vaccine. Notably, it is demonstrated that while the addition of a potent clinical Toll‐like receptor 4 (TLR4) agonist adjuvant to the gels slightly improved binding antibody responses, inclusion of this adjuvant to the inactivated virion vaccine is detrimental to neutralizing responses. Taken together, these results suggest that these hydrogels can enable an effective regimen compression and dose‐sparing strategy for improving global access to vaccines.

Physically associated hydrogels (PHs) capable of reversible transitions between solid and liquid‐like states have enabled novel strategies for 3D printing, therapeutic drug and cell delivery, and regenerative medicine. Among the many design criteria (e.g., viscoelasticity, cargo diffusivity, biocompatibility) for these applications, engineering PHs for extrudability is a necessary and critical design criterion for the successful application of these materials. As the development of many distinct PH material systems continues, a strategy to determine the extrudability of PHs a priori will be exceedingly useful for reducing costly and time‐consuming trial‐and‐error experimentation. Here, a strategy to determine the property–function relationships for PHs in injectable drug delivery applications at clinically relevant flow rates is presented. This strategy—validated with two chemically and physically distinct PHs—reveals material design spaces in the form of Ashby‐style plots that highlight acceptable, application‐specific material properties. It is shown that the flow behavior of PHs does not obey a single shear‐thinning power law and the implications for injectable drug delivery are discussed. This approach for generating design criteria has potential for streamlining the screening of PHs and their utility in applications with varying geometrical (i.e., needle diameter) and process (i.e., flow rate) constraints.

Monoclonal antibodies (mAbs) are a staple in modern pharmacotherapy. Unfortunately, these biopharmaceuticals are limited by their tendency to aggregate in formulation, resulting in poor stability and often requiring low concentration drug formulations. Existing excipients designed to stabilize formulations are often limited by their toxicity and tendency to form particles such as micelles. Here, the ability of a simple “drop‐in,” amphiphilic copolymer excipient to enhance the stability of high concentration formulations of clinically relevant mAbs without altering their pharmacokinetics or injectability is demonstrated. Through interfacial rheology and surface tension measurements, it is demonstrated that the copolymer excipient competitively adsorbs to formulation interfaces. Further, through determination of monomeric composition and retained bioactivity after stressed aging, it is shown that this excipient confers a significant stability benefit to high concentration antibody formulations. Finally, it is demonstrated that the excipient behaves as an inactive ingredient, having no significant impact on the pharmacokinetic profile of a clinically relevant antibody in mice. This amphiphilic copolymer excipient demonstrates promise as an additive to create stable, high concentration antibody formulations, thereby enabling improved treatment options such as a route‐of‐administration switch from low concentration intravenous (IV) to high concentration subcutaneous (SC) delivery while reducing dependence on the cold chain.

When properly deployed, the immune system can eliminate deadly pathogens, eradicate metastatic cancers, and provide long‐lasting protection from diverse diseases. Unfortunately, realizing these remarkable capabilities is inherently risky as disruption to immune homeostasis can elicit dangerous complications or autoimmune disorders. While current research is continuously expanding the arsenal of potent immunotherapeutics, there is a technological gap when it comes to controlling when, where, and how long these drugs act on the body. Here, this study explored the ability of a slow‐releasing injectable hydrogel depot to reduce dose‐limiting toxicities of immunostimulatory CD40 agonist (CD40a) while maintaining its potent anticancer efficacy. A previously described polymer‐nanoparticle (PNP) hydrogel system is leveraged that exhibits shear‐thinning and yield‐stress properties that are hypothesized to improve locoregional delivery of CD40a immunotherapy. Using positron emission tomography, it is demonstrated that prolonged hydrogel‐based delivery redistributes CD40a exposure to the tumor and the tumor draining lymph node (TdLN), thereby reducing weight loss, hepatotoxicity, and cytokine storm associated with standard treatment. Moreover, CD40a‐loaded hydrogels mediate improved local cytokine induction in the TdLN and improve treatment efficacy in the B16F10 melanoma model. PNP hydrogels, therefore, represent a facile, drug‐agnostic method to ameliorate immune‐related adverse effects and explore locoregional delivery of immunostimulatory drugs.

Biofouling on the surface of implanted medical devices and biosensors severely hinders device functionality and drastically shortens device lifetime. Poly(ethylene glycol) and zwitterionic polymers are currently considered “gold‐standard” device coatings to reduce biofouling. To discover novel anti‐biofouling materials, a combinatorial library of polyacrylamide‐based copolymer hydrogels is created, and their ability is screened to prevent fouling from serum and platelet‐rich plasma in a high‐throughput parallel assay. It is found that certain nonintuitive copolymer compositions exhibit superior anti‐biofouling properties over current gold‐standard materials, and machine learning is used to identify key molecular features underpinning their performance. For validation, the surfaces of electrochemical biosensors are coated with hydrogels and their anti‐biofouling performance in vitro and in vivo in rodent models is evaluated. The copolymer hydrogels preserve device function and enable continuous measurements of a small‐molecule drug in vivo better than gold‐standard coatings. The novel methodology described enables the discovery of anti‐biofouling materials that can extend the lifetime of real‐time in vivo sensing devices.