Aerodynamic behavior of lipid microtubule aerosols

Lipid microtubules are a promising vehicle for drug delivery to respiratory tract tissues. Targeted delivery requires an understanding of tubule aerod ynamic behavior, for which predictive relations are available but have not been experimentally validated. This work compares predicted and observed tu bule sedimentation behavior in a sheared flow environment such as that expe rienced in conducting airways. Lipid microtubules formed From 1,2-bis(10,12 -tricosadiynoyl)-sn-glycero-3- phosphocholine (DC8,9PC) were nebulized from water suspension for 60 min and recaptured in a Stober spiral duct aerosol centrifuge. Samples were analyzed by light microscopy and atomic force mic roscopy. Tubules were straight with uniform diameter similar to 0.6 mu m, a nd remained straight during aerosolization and recapture. Observed aerodyna mic behavior, as aerodynamic equivalent diameter, was compared with behavio r predicted by fiber aerosol equations gleaned from the literature. Best ag reement was obtained when tubule aerosol was modeled as partially hydrated thin-walled cylinders. These results were consistent with previous results for DC8-9PC aerosol and with expectations for evaporative core water loss f rom tubule ends. (C) 1999 Elsevier Science Ltd. All rights reserved.