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.