Biomedical subjects

Celestino Padeste

Publications and source records attributed to Celestino Padeste.

5 recordsLinked to original sources

PubMed2006

Nanostructured bio-functional polymer brushes.

Structured poly(glycidyl methracrylate) (poly-GMA) brushes have been grafted onto flexible fluoro-polymer films using a radiation grafting process. The reactive epoxide of poly-GMA provides the basis for a versatile biofunctionalization of the grafted brushes. Structure definition by extreme ultraviolet (EUV) exposure allowed nanometer-scale resolution of periodic patterns. By variation of the exposure dose the height of the grafted structures can be adapted in a wide range. Derivatization of the grafted brushes included reaction with various amines with different side chains, hydrolysis of the epoxide to diols to increase protein resistance and introduction of ionic groups to yield poly-electrolytes. As an example for biofunctionalization, biotin was linked to the grafted brush and biofunctionality was demonstrated in a competitive biotin-streptavidin assay. In this article we also present a brief review of other approaches to obtain structured biofunctional polymer brushes.

Fluorocarbons↗

PubMed2004

Molecular assembly of redox-conductive ferrocene-streptavidin conjugates--towards bio-electrochemical devices.

Peptidic spacers, 0.4 and 2 nm in length, were used to couple ferrocene moieties to streptavidin. The resulting conjugates were immobilised on electrode surfaces using biotin binding. The electron transfer through multilayers of the conjugates is strongly dependent on the length of the spacer between the protein and the attached ferrocene. A monolayer of the long-linker conjugate immobilised on interdigitated microelectrode arrays was found to electrochemically bridge the 2 microm wide non-conductive gap between the electrodes. The redox current through the layer is dependent on external parameters such as the applied voltage difference between the two electrode arrays or the temperature. The long-range electrochemical conductivity in combination with the biotin binding capability is a prerequisite for the application of the conjugates in future bio-electrochemical devices.

Adsorption↗

PubMed2004

Preparation of micro- and nanopatterns of polymer chains grafted onto flexible polymer substrates.

In this work a simple novel method for preparing micro- and nanoscale patterns of polymer chains grafted onto flexible polymer substrates is described. A combination of the two techniques of radiation grafting and "grafting-from" has been made. This combination makes it possible to prepare grafted structures having micro- or nanoscale lateral dimensions that are determined by the electron beam or X-ray irradiation patterns used. The height of the grafted features can be controlled by the irradiation dose or such grafting reaction conditions as time, temperature, or monomer concentration. Our first results for nanopatterned samples demonstrate resolution comparable to those of other polymer-based lithography processes.

Journal Article↗

PubMed2003

Redox labelled avidin for enzyme sensor architectures.

Conjugates of avidin with ferrocene and with microperoxidase 8 have been used as electrochemically active molecular building blocks. Assemblies of the conjugates with biotinylated glucose oxidase or lactate oxidase on gold electrodes were tested as enzyme sensors for glucose and lactate. The electrochemical detection is based either on ferrocene-mediated oxidation of the substrate in oxygen-free solution, or on microperoxidase-catalysed reduction of H2O2 which is enzymatically produced from the substrate and molecular oxygen. Glucose and lactate were detectable with both detection principles in concentrations down to 1 or 0.1 mM, respectively. The molecular architecture concept allows quick adaptation of the sensors to other analytes, and it provides a platform for arrays of sensors with different selectivity.

Avidin↗

PubMed2002

Photolithographic generation of protein micropatterns for neuron culture applications.

Standard positive photoresist techniques were adapted to generate micropatterns of proteins on glass and oxide surfaces. Both lift-off and plasma-etching techniques were used to transfer the photoresist pattern into a layer of covalently immobilised protein. The surface properties of the areas adjacent to the patterns were altered by chemical surface modification. Using a combination of the lift-off and the etching process complementary patterns of two different proteins were generated. The biochemical and biological functionality of the protein patterns were assessed by immunostaining and by investigating the outgrowth of neurites from neurons plated on the patterned substrates. The investigated patterning processes are compatible with microstructuring and thin film processes, and may be used to generate functional surfaces for sensor and neuron culture applications.

Animals↗