Oriented artificial nanofibers and laser induced periodic surface structures as substrates for Schwann cells alignment.

People with injuries to the peripheral nervous system suffer from paralysis of the facial muscles, fingers and hands or toes and feet, often for the rest of their lives, due to its poor functional regeneration. Therefore, to improve patients' quality of life, there is an urgent need for conduits that effectively support the healing of large defects in nerve pathways through specific guidance of nerve cells. This paper describes two specific methods for achieving directed growth of Schwann cells, a type of glial cells that can support the regeneration of the nerve pathway by guiding the neuronal axons in the direction of their alignment.

Robustness of antiadhesion between nanofibers and surfaces covered with nanoripples of varying spatial period.

Since nanofibers have a high surface-to-volume ratio, van der Waals forces render them attracted to virtually any surface. The high ratio provides significant advantages for applications in drug delivery, wound healing, tissue regeneration, and filtration. Cribellate spiders integrate thousands of nanofibers into their capture threads as an adhesive to immobilize their prey.

Nanopatterning of Bionic Materials.

The nanopatterning of bionic materials, performed by means of laser processes that utilize pulsed laser sources with short and ultrashort pulse durations, is a rapidly growing field [...

Spatial Period of Laser-Induced Surface Nanoripples on PET Determines Repellence.

Bacterial adhesion and biofilm formation on surfaces are associated with persistent microbial contamination, biofouling, and the emergence of resistance, thus, calling for new strategies to impede bacterial surface colonization. Using ns-UV laser treatment (wavelength 248 nm and a pulse duration of 20 ns), laser-induced periodic surface structures (LIPSS) featuring different sub-micrometric periods ranging from ~210 to ~610 nm were processed on commercial poly(ethylene terephthalate) (PET) foils. Bacterial adhesion tests revealed that these nanorippled surfaces exhibit a repellence for that decisively depends on the spatial periods of the LIPSS with the strongest reduction (~91%) in cell adhesion observed for LIPSS periods of 214 nm.

Femtosecond Laser-Processing of Pre-Anodized Ti-Based Bone Implants for Cell-Repellent Functionalization.

Microstructures and nanostructures can be used to reduce the adhesion of the cells on the auxiliary material. Therefore, the aim of our work was to fabricate laser-induced hierarchical microstructures and nanostructures by femtosecond laser-treatment (wavelength 1040 nm, pulse length 350 fs, repetition rates in the kHz range) to reduce the cell adhesion. Additionally, surface chemistry modification by optimized electrochemical anodization was used to further reduce the cell adhesion.

An Improved Transwell Design for Microelectrode Ion-Flux Measurements.

The microelectrode ion flux estimation (MIFE) is a powerful, non-invasive electrophysiological method for cellular membrane transport studies. Usually, the MIFE measurements are performed in a tissue culture dish or directly with tissues (roots, parts of the plants, and cell tissues). Here, we present a transwell system that allows for MIFE measurements on a cell monolayer.

Bio-inspired microneedle design for efficient drug/vaccine coating.

Biomimetics is the interdisciplinary scientific field focused on the study and imitation of biological systems, with the aim of solving complex technological problems. In this paper, we present a new bio-inspired design for microneedles (MNs) and MN arrays, intended for rapidly coating the MNs with drug/vaccine. The biomimetic approach consists in ornamenting the lateral sides of pyramidal MNs with structures inspired by the external scent efferent systems of some European true bugs, which facilitate a directional liquid transport.

Homogeneous application of imaging criteria in a multicenter trial supported by investigator training: A report from the WAKE-UP study.

Background And Purpose: WAKE-UP is a randomized, placebo-controlled trial of thrombolysis in stroke with unknown time of symptom onset using magnetic resonance imaging criteria to determine patients' eligibility. As it is a multicenter trial, homogeneous interpretation of criteria is an important contributor to the trial's success. We describe the investigator image training as well as results of the quality control done by the central image reading board (CIRB).

The external scent efferent system of selected European true bugs (Heteroptera): a biomimetic inspiration for passive, unidirectional fluid transport.

In this work, we present structured capillaries that were inspired by the microstructures of the external scent efferent system as found in different European true bug species (Pentatomidae and Cydnidae). These make use of small, orientated structures in order to facilitate fluid movement towards desired areas where defensive substances are evaporated. Gland channels and microstructures were investigated by means of scanning electron microscopy and abstracted into three-dimensional models.

Adaptive camouflage: what can be learned from the wetting behaviour of the tropical flat bugs and .

The neotropical flat bug species and show a fascinating camouflage principle, as their appearance renders the animal hardly visible on the bark of trees. However, when getting wet due to rain, bark changes its colour and gets darker. In order to keep the camouflage effect, it seems that some species benefit from their ability to hold a water film on their cuticle and therefore change their optical properties when also wetted by water.

Laser-induced optical breakdown spectroscopy of polymer materials based on evaluation of molecular emission bands.

Laser-induced breakdown spectroscopy (LIBS) for composition analysis of polymer materials results in optical spectra containing atomic and ionic emission lines as well as molecular emission bands. In the present work, the molecular bands are analyzed to obtain spectroscopic information about the plasma state in an effort to quantify the content of different elements in the polymers. Polyethylene (PE) and a rubber material from tire production are investigated employing 157nmF laser and 532nm Nd:YAG laser ablation in nitrogen and argon gas background or in air.

Enhanced CaEntry and Tyrosine Phosphorylation Mediate Nanostructure-Induced Endothelial Proliferation.

Nanostructured substrates have been recognized to initiate transcriptional programs promoting cell proliferation. Specifically -catenin has been identified as transcriptional regulator, activated by adhesion to nanostructures. We set out to identify processes responsible for nanostructure-induced endothelial -catenin signaling.

Nanopatterned polymer substrates promote endothelial proliferation by initiation of β-catenin transcriptional signaling.

Control of endothelial phenotype involves a variety of signaling pathways and transcriptional regulators, including the junctional protein β-catenin. This multifunctional signaling molecule is part of adhesion contacts in the endothelium and is able to translocate into the nucleus to activate genetic programs and control proliferation and the fate of the cells. We investigated the influence of laser-generated nanopatterns on polymeric cell culture substrates on endothelial tissue architecture, proliferation and β-catenin signaling.

Microgrinding of lensed fibers by means of a scanning-probe microscope setup.

We describe a precision grinding procedure that allows treating a previously etched fiber tip to conform to predefined shapes, including hemispherical and axial conical (axicon) lenses. The grinding method is based on mechanical polishing with the fiber tip moving in a translational mode inside a conical polishing surface. The grinding procedure is performed in a homemade scanning probe microscope equipped with a shear-force sensor based on a piezoelectric tuning fork as well as with capacitor position sensors.

Proliferation of aligned mammalian cells on laser-nanostructured polystyrene.

Biomaterial surface chemistry and nanoscale topography are important for many potential applications in medicine and biotechnology as they strongly influence cell function, adhesion and proliferation. In this work, we present periodic surface structures generated by linearly polarized KrF laser light (248 nm) on polystyrene (PS) foils. These structures have a periodicity of 200-430 nm and a depth of 30-100 nm, depending on the angle of incidence of the laser beam.

UV surface modification of a new nanocomposite polymer to improve cytocompatibility.

A novel modified nanocomposite was studied for the adhesion and proliferation of the human umbilical vein endothelial cell (HUVEC) line EA.hy926. The nanocomposite under investigation was poly(carbonate-urea)urethane with silsesquioxane nano-cages, here in the form of a mixture of two polyhedral oligomeric silsesquioxanes.

Incorporation of a lauric acid-conjugated GRGDS peptide directly into the matrix of a poly(carbonate-urea)urethane polymer for use in cardiovascular bypass graft applications.

Gly-Arg-Gly-Asp-Ser (GRGDS) was modified by conjugation to lauric acid (LA) to facilitate incorporation into the matrix of a poly(carbonate-urea)urethane (PCU) used in vascular bypass grafts. GRGDS and LA-GRGDS were synthesized using solid phase Fmoc chemistry and characterized by high performance liquid chromatography and Fourier transform infrared spectroscopy. LA-GRGDS was passively coated and incorporated as nanoparticle dispersion on the PCU films.

Simple and versatile methods for the fabrication of arrays of live mammalian cells.

Single-step methods for the generation of patterned surfaces on hydrogels are presented. Poly(vinyl alcohol) films covalently bonded on glass cover slips and commercially available hydrogel-coated polystyrene plates were used as cell-repellent surfaces. Cell-adhesive domains were created by spotting dilute solutions of sodium hypochlorite onto the surfaces.

Cell microarrays on photochemically modified polytetrafluoroethylene.

We studied the adhesion, proliferation, and viability of human umbilical vein endothelial cells (HUVEC) and human embryonic kidney cells (HEK) on modified spots at polytetrafluoroethylene (PTFE) surfaces. The viability of the cells was assessed using an aqueous non-radioactive cell proliferation assay. Round spots with a diameter of 100 microm were modified by exposure to the ultraviolet (UV) light of a Xe(2)(*)-excimer lamp at a wavelength of 172 nm in an ammonia atmosphere employing a contact mask.

Adhesion and proliferation of human vascular cells on UV-light-modified polymers.

We studied the adhesion and proliferation of human umbilical-vein endothelial cells (HUVEC) and human aortic smooth-muscle cells (HASMC) on modified polymer samples. The polymers under investigation were either PTFE (polytetrafluoroethylene) or PET [poly(ethylene terephthalate)], which are among the most frequently employed biomaterials in reconstructive medicine. The polymer surfaces were modified by exposure to the UV light of an excited-xenon-dimer (Xe2*) Excimer lamp (Heraeus-Noblelight, Hanau, Germany) at a wavelength of 172 nm in an NH3 atmosphere.