Giant unilamellar vesicles investigated by optical stretching, fluorescence microscopy and image analysis

Abstract

Consulta en la Biblioteca ETSI Industriales (Riunet)

[ES] In this project giant unilamellar vesicles made of di erent phospholipids are produced by electroformation and rehydration methods. The vesicles contained sucrose inside and were suspended in a glucose solution. The vesicle average size obtained is between 10 and 60 micrometers, although a wide dispersion was found, from 300 nm up to 1000 micrometers. The Young's modulus of the vesicle membranes is obtained by optical stretching. For the stretcher, several methods are tested, especially focusing on improving and simplifying the set up and the procedures. In the chip that showed better results, optical bres are inserted in syringe needles that protects them when handling, and needles are placed in a socket built on a microscope glass slide. Vesicles are stretched with two lasers with a maximum power of 300 mW, exerting a maximum force at the membrane surface of 20 pN. Deformations are determined by image analysis with Matlab. Several image tools are implemented, noise-removing and image enhancement for identifying data, and extraction of image characteristics to obtain the measurements. The software is implemented in a graphic interface to allow to control the parameters manually. For a vesicle composition 75% DOPC 25% Asolectin and a diameter of 18.36 0.41 m the Young's modulus was determined from an elastic shell model as Y = 3.35 1.23 Pa.