José Sánchez-González

Langmuir-Blodgett films of biopolymers: a method to obtain protein multilayers

In this work, we present a methodology for choosing the best experimental conditions for transferring protein Langmuir films onto solid substrates. As an example of applying the proposed methodology, we used monolayers of the protein bovine serum albumin, which is a very stable protein and is of great interest in the development of immunosensors. Langmuir-Blodgett (LB) films of this protein, on different solid substrates, were obtained and characterized as a function of pH, surface pressure, temperature, and contact angle. The compressibility modulus, the spreading entropy, and the fraction of desorbed protein sections were used as control parameters to find these conditions. A careful analysis of these parameters shows that there is a window on the values of these experimental parameters in which the LB films are best formed. Our methodology can be applied to other biomacromolecules to find the best conditions to form LB films from isotherm measurements.

The Excellent Mechanical Properties of Cork: A Novel Approach through the Analysis of Contact Stress

In many technological applications of cork, this biomaterial is under strongly localized contact stresses, which largely differ from the homogeneous distribution of stresses of the typical uniaxial compression tests. Indentation tests constitute an excellent form of determining the behavior of the materials under localized stresses. In the present study, the applicability of Hertzian and Brinell indentation tests to the evaluation of the mechanical properties of cork is tested. One of the main conclusions of the study is that the elastic anisotropy of the material is related to the anisotropic structure of the different sections cut from a cork sample, a clear difference between the back tangential section and the other sections being observed.