Study of the charge distribution on liposome particles aerosolized by air-jet atomization.

BACKGROUND

Air-jet atomization is a common technique used for the generation of therapeutic aerosols from liposome suspensions for drug delivery to the lungs. Although the technique does not use an electric field, the aerosols generated by this technique are still charged, and this may affect respiratory drug deposition.

METHODS

In this study, the charge distribution of liposomes aerosolized by an air-jet atomizer was measured using a tandem differential mobility analyzer (TDMA) technique. The liposomes, composed of a mixture of two amphiphilic lipids and cholesterol, were synthesized by the dehydration-rehydration vesicle method. The effect of the precursor suspension properties, such as medium composition, pH, conductivity, and lipid mass concentration, on the charge distribution of the liposome aerosols was studied.

RESULTS AND CONCLUSIONS

Results showed that the atomized liposomes have a bipolar charge distribution, and the number-fraction of charged liposome aerosols was influenced strongly by properties of the precursor solution under investigation. Liposomes synthesized in deionized water were observed to carry much higher charges than those synthesized in phosphate-buffered saline (PBS). Increasing the lipid mass concentration in the precursor suspension resulted in a decrease in the charge on the aerosols. Thus, the precursor suspension properties--composition, pH, and conductivity--can be used to control the magnitude of charge on liposome aerosols and to synthesize engineered liposome particles for the pulmonary delivery of drugs with controlled alveolar deposition and controlled delivery to alveolar macrophages.