Particle Design and Inhalation Delivery of Iodine for Upper Respiratory Tract Infection Therapy

Diseases caused by upper respiratory tract (URT) and pulmonary infections have been a serious threat to human health for millennia and lack of targeted effective therapeutic techniques. In this study, two kinds of cyclodextrin particles with typical particle shapes of nanocubes and microbars were synthesized through a facile process. Subsequently, the particles were used as carriers for loading and stabilizing iodine and characterizations were performed to demonstrate the loading mechanism. Next-generation impactor (NGI) experiments showed that iodine-loaded microbars (I(2)@microbars) had a deposition rate of 79.75% in URT, while iodine-loaded nanocubes (I(2)@nanocubes) were delivered to the deep lungs with a fine particle fraction (FPF) of 46.30%. Minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) indicated that the iodine-loaded nanocubes and microbars had similar bactericidal effect to povidone iodine solution. Cell viability studies and extracellular pro-inflammatory factor (TNF-α, IL-1β, IL-6) evaluations demonstrate noncytotoxic effects of the blank carriers and anti-inflammatory effects of iodine-loaded samples. The irritation of the rat pharynx by I(2)@microbars was evaluated for the behavioral observations, body weight changes, histopathological studies, and TNF-α, IL-1β, and IL-6 levels in pharyngeal tissues. The results showed that I(2)@microbars had no irritation to rat pharyngeal tissues at therapeutic doses. In conclusion, the present study provides novel treatment of URT infections via supramolecular cyclodextrin carriers for URT local therapy with iodine loading by a solvent-free method, which enhances the stability and reduces the inherent irritation without inhibiting their antimicrobial effects. GRAPHICAL ABSTRACT: Two kinds of cyclodextrin particles with typical shapes of microbars and nanocubes were synthesized by a facile process. Subsequently, iodine was successfully loaded into the particles by gas–solid interaction. The iodine-loaded microbars showed air dynamics characteristics for inhalation delivery to the upper respiratory tract with little alveolar deposition in the lungs [Image: see text]