Parameters affecting the transscleral delivery of two positively charged proteins of comparable size

Publication date: 15 April 2017 Source:International Journal of Pharmaceutics, Volume 521, Issues 1–2 Author(s): Maria Aurora Grimaudo, Elena Tratta, Silvia Pescina, Cristina Padula, Patrizia Santi, Sara Nicoli Apart from molecular weight and net surface charge, there are other macromolecule-related factors that could, in principle, influence their diffusion across biological tissues, such as shape, conformability, water solubility and surface charge distribution. Lysozyme and cytochrome c, proteins with comparable molecular weight, isoelectric point and net surface charge in physiological conditions (approx. +7.8), are suitable model compounds for comparative studies, in particular to find out if other properties can have a role in the permeation across the sclera. The comparison between lysozyme and cytochrome c permeability was conducted by studying the permeation across the sclera and the choroid-Bruch’s membrane and the diffusion across a hyaluronan gel-matrix. Melanin binding tests and the measurement of the electroosmosis flow during transscleral iontophoresis allowed for the evaluation of macromolecules affinity for the ocular tissues. Finally, anodal iontophoresis was applied to further confirm the interaction of the two proteins with the sclera. The data here collected show that two proteins with very similar MW, p K a and charge can display very different diffusion properties across biological barriers. In particular, these differences can be attributed...
Source: International Journal of Pharmaceutics - Category: Drugs & Pharmacology Source Type: research