Determination of the size distribution of non-spherical nanoparticles by electric birefringence-based methods

The in situ determination of the size distribution of dispersed non-spherical nanoparticles is an essential characterization tool for the investigation and use of colloidal suspensions. In this work, we test a size characterization method based on the measurement of the transient behaviour of the birefringence induced in the dispersions by pulsed electric fields. The specific shape of such relaxations depends on the distribution of the rotational diffusion coefficient of the suspended particles. We analyse the measured transient birefringence with three approaches: the stretched-exponential, Watson-Jennings, and multiexponential methods. These are applied to six different types of rod-like and planar particles: PTFE rods, goethite needles, single- and double-walled carbon nanotubes, sodium montmorillonite particles and gibbsite platelets. The results are compared to electron microscopy and dynamic light scattering measurements. The methods here considered provide good or excellent results in all cases, proving that the analysis of the transient birefringence is a powerful tool to obtain complete size distributions of non-spherical particles in suspension.Financial support of this investigation by Junta de Andalucía, Spain (grant No. PE2012-FQM0694) and University of Granada (Program “Proyectos de investigación precompetitivos”) is gratefully acknowledged

Oral Vaccine Delivery: The Coming Age of Particulate Vaccines to Elicit Mucosal Immunity

With the evolution of different challenging diseases, there is an urgent need of vaccine development against them to save millions of lives around the world. Particlulate delivery system plays an important role by acting as self-adjuvant in form of particles and thus assisting the immunogenicity of vaccines. Particulate vaccines have shown to have improved uptake by antigen presenting cells as compared to the soluble antigen. Traditional injectable vaccines are generally poor inducers of mucosal immunity and are therefore less effective against infections at the mucosal site. Mucosal vaccines have been reported to provide additional secretory antibody mediated protection at the mucosal site of entry of the pathogen. In this chapter, we discuss the benefits of particulate drug delivery systems for oral delivery, the role of immune system in the gut, and a case study ofa novel particulate vaccine formulated into oral dissolving film for immunization via the buccal route. Key formulation components, process parameters and their biophysical characterizations have been discussed as well