Stainless steel surface functionalization for immobilization of antibody fragments for cardiovascular applications

Stainless steel 316 L material is commonly used for the production of coronary and peripheral vessel stents. Effective biofunctionalization is a key to improving the performance and safety of the stents after implantation. This paper reports the method for the immobilization of recombinant antibody fragments (scFv) on stainless steel 316 L to facilitate human endothelial progenitor cell (EPC) growth and thus improve cell viability of the implanted stents for cardiovascular applications. The modification of stent surface was conducted in three steps. First the stent surface was coated with titania based coating to increase the density of hydroxyl groups for successful silanization. Then silanization with 3 aminopropyltriethoxysilane (APTS) was performed to provide the surface with amine groups which presence was verified using FTIR, XPS, and fluorescence microscopy. The maximum density of amine groups (4.8*10(-5) mol/cm(2)) on the surface was reached after reaction taking place in ethanol for 1 h at 60 °C and 0.04M APTS. On such prepared surface the glycosylated scFv were subsequently successfully immobilized. The influence of oxidation of scFv glycan moieties and the temperature on scFv coating were investigated. The fluorescence and confocal microscopy study indicated that the densest and most uniformly coated surface with scFv was obtained at 37 °C after oxidation of glycan chain. The results demonstrate that the scFv cannot be efficiently immobilized without prior aminosilanization of the surface. The effect of the chemical modification on the cell viability of EPC line 55.1 (HucPEC-55.1) was performed indicating that the modifications to the 316 L stainless steel are non-toxic to EPCs.

Selective condensation of DNA by aminoglycoside antibiotics

The condensing effect of aminoglycoside antibiotics on the structure of double-stranded DNA was examined. The selective condensation of DNA by small molecules is an interesting approach in biotechnology. Here, we present the interaction between calf thymus DNA and three types of antibiotic molecules: tobramycin, kanamycin, and neomycin. Several techniques were applied to study this effect. Atomic force microscopy, transmission electron microscopy images, and nuclear magnetic resonance spectra showed that the interaction of tobramycin with double-stranded DNA caused the rod, toroid, and sphere formation and very strong condensation of DNA strands, which was not observed in the case of other aminoglycosides used in the experiment. Studies on the mechanisms by which small molecules interact with DNA are important in understanding their functioning in cells, in designing new and efficient drugs, or in minimizing their adverse side effects. Specific interactions between tobramycin and DNA double helix was modeled using molecular dynamics simulations. Simulation study shows the aminoglycoside specificity to bend DNA double helix, shedding light on the origins of toroid formation. This phenomenon may lighten the ototoxicity or nephrotoxicity issues, but also other adverse reactions of aminoglycoside antibiotics in the human body.

[Biological tests of sol-gel biomaterials]

Recently, the sol-gel based biomaterials are extendedly investigated in emphasis on theirs medical applications. In this respect it is important to investigate the influence of sol-gel matrices on biological systems. The results of laboratory and biological testing of water extracts of sol-gels are presented in this work. It was proved that it is possible to construct the sol-gels that are not cytotoxic for which the haemolytic reactions fulfils the foreseen norms. This can be achieved by heating the materials in certain temperatures (higher than 350 degrees C). This effect can also be reached by suitably long aging (minimum 6 months).

Guest editorial: special section on coherence domain optical methods in biomedical science and clinics

This Special Section Guest Editorial provides an overview of the topical area and an introduction to the articles featured in the special section.

Guest Editorial: Special Section on Interferometry in Biomedicine, Part II

This Special Section Guest Editorial provides an overview of the topical area and an introduction to the articles featured in the special section.

Guest editorial: special section on interferometry in biomedicine, part I

This Special Section Guest Editorial provides an overview of the topical area and an introduction to the articles featured in the special section.

High precision Twyman-Green interferometer for the measurement of ophthalmic surfaces

PURPOSE

We developed a method for measuring ophthalmic surfaces based on a Twyman-Green interferometer.

METHODS

To demonstrate the accuracy, we measured the anterior surface of four used hard contact lenses and evaluated the interference pattern with phase shift technique. The obtained interferograms were evaluated by an image processing system.

RESULTS

The interferometric resolution of the measurement is up to lambda/20 (30 nm) which refers to a dioptric resolution of about delta D = 10(-3) m(-1) for typical anterior radii of curvature. The dioptric maps were calculated from the height distribution. As we used a focus tracking distance measurement setup with an accuracy of 10 microns we could determine the absolute value of the dioptric number to be delta D approximately 0.04 m-1. To demonstrate the accuracy we tested contact lenses which were specified to have a spherical anterior surface. Obviously, the topography of contact lenses changes when worn. We measured astigmatic deviations up to 0.6 D in the central zone of the lenses. We briefly discuss the possibilities of this method concerning a topographer for measuring the fine corneal surface structure.

CONCLUSIONS

The presented Twyman-Green interferometer with distance measurement and image processing system is a very accurate method for measuring the topographic properties of ophthalmic surfaces. The method may also be useful for studying the distribution of the tear layer on the contact lens, or the corneal topography.

Biomechanical investigation of the hyoid bone using speckle interferometry

Speckle interferometry is a non-destructive measurement technique using a laser. The principles of the method are described. Human hyoid bones (n = 10) were investigated. Loads were applied to individual points on the anterior surface of the body of hyoid bones. All hyoid bones showed an asymmetric displacement. The displacement was greatest in a plane vertical to the load. An evaluation of fracture behavior is possible due to the displacement pattern.