Nanoscience and Nanometrology

The aim of this paper is the preparation and characterization of drug delivery systems for a potential brain delivery by intranasal administration. It is possible to reach the central nervous system with alternative routes through which therapeutic agents can bypass the blood brain barrier: that is the nasal administration. Intranasal drug administration is non-invasive and it could be a promising drug delivery method for patients who suffer from chronic and crippling Central Nervous System diseases. Among the formulation strategies for enhanced nose to brain drug delivery, the use of colloidal carriers has became a revolutionary approach. The success of a therapeutic strategy by using nanocarriers depends on their ability to entrap drugs, to penetrate through anatomical barriers, to efficiently release the incorporated drugs, to show a good stability in nanometric size range and good biocompatibility. The use of vesicular systems (niosomes), in nose to brain delivery is here presented. One of the major problems associated with nasal administration is the rapid removal of drugs or drug delivery systems, from the deposition site through mucociliary clearance. This effect is responsible of reduction of contact time between drug or drug delivery systems and nasal epithelium. This problem could be solved by coating nanocarriers with a mucoadhesive agent: chitosan. In this paper the preparation and characterization of hybrid niosomes by Tween 20 and Tween 21 together with dicetyl phosphate or Span 20 and the cationic polyelectrolyte chitosan are described in order to obtain intranasal drug delivery systems. In particular through dynamic light scattering, laser Doppler electrophoresis and fluorescence measurements the aggregation behavior between vesicles and polyelectrolyte can be monitored. Overall phenomenology is well described in terms of the re-entrant condensation and charge inversion behavior, observed in different colloidal systems. The physical stability of hybrid niosomes obtained by the three different surfactants was also evaluated.