Development of an Oral Delivery System for Live Adenovirus Based on Bionic Chrysanthemum Sporopollenin Exine Armor

Background: The oral application of adenovirus is hindered by its poor in vitro storage stability and rapid degradation by gastric acid. To address this, a biomimetic oral adenovirus delivery system (CSP-AdV@LYO) was constructed based on three key properties of natural chrysanthemum sporopollenin (CSP): chemical inertness, intelligent "acid-shrinking/alkali-swelling" responsiveness, and mucosal adhesion via its spike structures, aiming to enhance oral stability and delivery efficiency. Methods: First, low-allergenic chrysanthemum pollen was screened using proteomics and a zebrafish allergy model. High-purity sporopollenin (SPO) was then extracted via an acidolysis method, followed by systematic characterization of its morphology, particle size, zeta potential, contact angle, and reversible acid-shrinking/alkali-swelling behavior. Subsequently, a CSP-AdV@LYO formulation was prepared by optimizing a cryoprotectant formulation (sucrose:gelatin = 1:1) and a vacuum loading process. Its protective and release properties were evaluated in vitro using simulated gastric and intestinal fluids, and its long-term stability was assessed. Further in vivo studies in mice assessed its intestinal colonization efficiency. The adhesion mechanism of the sporopollenin spike structures was investigated through mucosal retention experiments. Results: Mucosal retention experiments confirmed that the spike structures on the sporopollenin surface enhanced retention by approximately 3-fold through mechanical interlocking compared to smooth particles. In long-term stability tests, the viral genome copy number retention rate was improved more than 10-fold compared to the virus stock solution. The system enabled a steady and controlled release of the virus in simulated intestinal fluid, with the released virus maintaining its infectivity. In vivo studies demonstrated that CSP-AdV@LYO promoted efficient intestinal colonization and reduced acute mortality from 75% (AdV@LYO group) to 25%. Conclusions: By leveraging the unique physicochemical properties of chrysanthemum sporopollenin, this study successfully developed a biomimetic oral delivery system for live adenovirus that provides gastric acid protection, intelligent pH-responsive release, and mucosal adhesion. This system significantly enhances the oral stability and intestinal delivery efficiency of adenovirus while reducing systemic exposure risks. It offers a novel biomimetic strategy for the oral delivery of adenovirus and other biological macromolecules.