Smart Plastic Antibody Material for Hemoglobin Tailored by Silica Surface Imprinting and with Charged Binding Sites: Its use as Ionophore in Potentiometric Transduction

JORNADAS DE ELECTROQUÍMICA E INOVAÇÃO 2013Human hemoglobin (Hb) is a globular metalloprotein, present in the blood and involved in gas transport. Hb-associated disturbances are related to several diseases, such thalassemia, anemia, heart disease and leukemia, or to side-effects from other diseases, such as cancer. Overall, it is of great importance to know the concentration of Hb in the blood in many health-related conditions. There are many methods described in the literature for determining Hb. Most of these rely on antibody/antigen interactions, due to the high selectivity of the affinity reaction taking place between these biomolecules. However, the use of antibodies for Hb determination in routine clinical use is very expensive, due to the high cost of the material, the need for special handling and storage, and the non-reusability. These constraints may be limited by replacing natural antibodies by plastic receptors, obtained by molecular imprinting procedures. Thus, this work describes a novel smart plastic antibody material (SPAM) by surface imprinting technique for the detection of Hb and its application to design small, portable and low cost potentiometric devices. The SPAM material was obtained by linking Hb to silica nanoparticles and allowing its subsequent interaction with different vinyl monomers, of different chemical functions and ionic charges. Control materials were designed in parallel to assess the ability of establishing stereochemical recognition of Hb and the effect of the kind/charge of the monomers employed. Scanning Electron Microscopy analysis confirmed the surface modification of the silica material used for imprint. All materials were mixed with PVC/plasticizer and applied as selective membranes in potentiometric transduction. Suitable emf variations were detected only for selective membranes having a SPAM material and a charged lipophilic anionic additive. All control materials were unable to produce a potentiometric response. Overall, good features were obtained for SPAM-based selective membranes carrying an anionic lipophilic additive. In HEPES buffer of pH 5, limits of detection were 43.8μg/mL for a linear response after 83.8μg/mL with a cationic slope of +40.4mV/decade. Good selectivity was also observed against other coexisting biomolecules. The analytical application was conducted successfully, showing accurate and precise results

Organisational Identity as a Barrier to Widening Access in Scottish Universities

Widening access policy has historically focused on tackling the socioeconomic barriers to university access faced by prospective students from under-represented groups, but increasingly policy makers are seeking to also address the barriers to wider access posed by undergraduate admissions policies. In this vein, the Scottish Government has recently called upon universities to set separate academic entry requirements for socioeconomically disadvantaged applicants which recognise that “the school attainment of disadvantaged learners often does not reflect their full potential” and which better reflect the minimum needed to succeed in higher education. In this paper, we draw on in-depth interviews with admissions personnel at eighteen Scottish universities to explore the scope for more progressive admissions policies of this kind in light of universities’ identities as organisations and in light of corresponding organisational strategies for position-taking in global and national higher education fields. We present a theoretical model and an empirical illustration of three hierarchically-ordered ideal types of organisational identity—globally competitive, nationally selective, and locally transformative—and show that the more dominant of these tend to constrain the development of more progressive admissions policies. This is because globally competitive and, to a lesser extent, nationally selective organisational identities are understood to require admission of the ‘brightest and best’, conceptualised as those with the highest levels of prior academic attainment who can be expected to succeed at university and beyond as a matter of course. We conclude that universities must recognise and redress the implicitly exclusionary nature of their organisational identities if genuine progress on widening access is to be made

Dynamical reentrance and geometry imposed quantization effects in Nb-AlOx-Nb Josephson junction arrays

In this paper, we report on different phenomena related to the magnetic properties of artificially prepared highly ordered (periodic) two-dimensional Josephson junction arrays (2D-JJA) of both shunted and unshunted Nb-AlOx-Nb tunnel junctions. By employing mutual-inductance measurements and using a high-sensitive bridge, we have thoroughly investigated (both experimentally and theoretically) the temperature and magnetic field dependence of complex AC susceptibility of 2D-JJA. We also demonstrate the use of the scanning SQUID microscope for imaging the local flux distribution within our unshunted arrays