Antibacterial and anti-encrustation biodegradable polymer coating for urinary catheter.

Bacterial biofilm and crystalline deposits are the common causes of failure of long-term indwelling urinary catheter. Bacteria colonise the catheter surface causing serious infections in the urinary tract and encrustations that can block the catheter and induce trauma in patients. In this study, the strategy used to resist bacterial adhesion and encrustation represents a combination of the antibacterial effects of norfloxacin and silver nanoparticles and the PLGA-based neutralisation of alkali products of urea hydrolysis gained through the degradation of the polymer in an aqueous milieu.

Influence of the Microstructure and Silver Content on Degradation, Cytocompatibility, and Antibacterial Properties of Magnesium-Silver Alloys In Vitro.

Implantation is a frequent procedure in orthopedic surgery, particularly in the aging population. However, it possesses the risk of infection and biofilm formation at the surgical site. This can cause unnecessary suffering to patients and burden on the healthcare system.

Rapid and label-free detection of protein a by aptamer-tethered porous silicon nanostructures.

Protein A, which is secreted by and displayed on the cell membrane of Staphylococcus aureus is an important biomarker for S. aureus. Thus, its rapid and specific detection may facilitate the pathogen identification and initiation of proper treatment.

Hemodynamic aspects of reduced platelet adhesion on bioinspired microstructured surfaces.

Occlusion by thrombosis due to the absence of the endothelial cell layer is one of the most frequent causes of failure of artificial vascular grafts. Bioinspired surface structures may have a potential to reduce the adhesion of platelets contributing to hemostasis. The aim of this study was to investigate the hemodynamic aspects of platelet adhesion, the main cause of thrombosis, on bioinspired microstructured surfaces mimicking the endothelial cell morphology.

A modular segmented-flow platform for 3D cell cultivation.

In vitro 3D cell cultivation is promised to equate tissue in vivo more realistically than 2D cell cultivation corresponding to cell-cell and cell-matrix interactions. Therefore, a scalable 3D cultivation platform was developed. This platform, called pipe-based bioreactors (pbb), is based on the segmented-flow technology: aqueous droplets are embedded in a water-immiscible carrier fluid.

Biomimetic surface modification with bolaamphiphilic archaeal tetraether lipids via liposome spreading.

Through investigations of the self-assembly behavior of three different tetraether lipids, the authors successfully established a solid supported, biomimetic tetraether lipid membrane via liposome spreading. These bolaamphiphilic lipids are the main compound in membranes of archaea, extremophile microorganisms, which underwent an enormous adaptation to extreme conditions in their natural environment with regard to temperature, pH, and high salt concentrations. Starting from a mathematical point of view, the authors calculated hydrophilic-lipophilic balance values for each lipid and recognized a wide difference in self-assembly potentials relying on size and hydrophilic properties of the lipid head groups.

Preparation and characterization of poly(L-histidine)/poly(L-glutamic acid) multilayer on silicon with nanometer-sized surface structures.

The specific design and modification of surfaces is of great interest, especially for functional surfaces and medical applications. In order to obtain films on a surface, the layer-by-layer deposition of polyelectrolytes represents a well-established methodology. The alternating deposition of poly(L-histidine) and poly(L-glutamic acid) results in a defined, continuous surface coating that was thoroughly characterized using X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, ellipsometry, X-ray reflectometry, atomic force microscopy, scanning electron microscopy, contact angle, and electrokinetic measurements.

Dependence of the initial adhesion of biofilm forming Pseudomonas putida mt2 on physico-chemical material properties.

Bacterial adhesion is strongly dependent on the physico-chemical properties of materials and plays a fundamental role in the development of a growing biofilm. Selected materials were characterized with respect to their physico-chemical surface properties. The different materials, glass and several polymer foils, showed a stepwise range of surface tensions (γ(s)) between 10.

Biomimetic assembly of polyelectrolyte multilayers containing phosvitin monitored with reflectometric interference spectroscopy.

Coatings of biomaterials or implants that facilitate biomineralization possess a great potential for applications focused to the replacement, augmentation, and regeneration of bone tissue. Biomimetic approaches utilize biomolecules for either templating or supporting the crystallization process. One of these promising biomolecules is phosvitin (PV), an egg yolk protein known to transport and store inorganic phosphates and calcium ions.

Colloidal force spectroscopy and cell biological investigations on biomimetic polyelectrolyte multilayer coatings composed of chondroitin sulfate and heparin.

To promote osteoblast adhesion and proliferation on (bio)material surfaces, biomimetic coatings resembling the natural extracellular matrix (ECM) are desirable. The glycosamino glycans (GAGs) chondroitin sulfate (CS) and heparin (HEP) are promising candidates for a biomimetic coating since they are two of the most prevalent noncollagenous biomolecules constituting the ECM. Coatings containing CS and HEP were prepared employing the "layer by layer" technique yielding polyelectrolyte multilayers (PEMs).

Biomimetic organic-inorganic nanocomposite coatings for titanium implants. In vitro and in vivo biological testing.

Recently described organic-inorganic nanocomposite coatings of the chemical composition: (PLL/PGA)(10)CaP[(PLL/PGA)(5)CaP](4) (coating A) and (PLL/PGA)(10)CaP[(PLL/PGA)(5)CaP](4)(PLL/PGA)(5) (coating B), applied to chemically etched titanium plates, have been tested by extensive cell culture tests and in vivo biological experiments, with uncoated titanium plates serving as controls. Before testing, coated samples were stored for extended periods of time (from 2 weeks to 8 months) under dry, sterile conditions. Cells of the cell-lines MC3T3-E1 and/or SAOS-2 were used for the following cell culture tests: initial adhesion (4 h) and proliferation (up to 21 days), cell activity (XTT test), morphology, synthesis of collagen type I and alkaline phosphatase activity (all incubation up to 21 days).

Two-photon techniques in tissue engineering.

Purpose: NIR radiation in the range of about 800 nm is less absorbed by biological tissues and is suited for triggering photonic effects using femtosecond pulsed Ti:Sa lasers. Especially in the life sciences, two-photon techniques are gaining greater importance. We introduce two laser applications for tissue engineering: the autofluorescent visualization of cells seeded on 3D scaffolds after two-photon excitation; and the manufacturing of 3D-structured hydrogel-like scaffolds by triggering free-radical polymerization processes within polymerizable precursors.

Atomic force microscopy to characterize the molecular size of prion protein.

The conformational transition of alpha-helix-rich cellular prion protein (PrP(C)) to an isomer with high beta-sheet content is associated with transmissible spongiform encephalopathies. With the ultimate long-term goal of using imaging techniques to study PrP aggregation, we report the results of initial experiments to determine whether PrP molecules could be visualized as single molecules, and if the observed size corresponded to the calculated size for PrP. The investigation of single molecules, and not those embedded into larger aggregates, was the key in our experimental approach.

Evanescent field Sensors Based on Tantalum Pentoxide Waveguides - A Review.

Evanescent field sensors based on waveguide surfaces play an important rolewhere high sensitivity is required. Particularly tantalum pentoxide (Ta₂O₅) is a suitablematerial for thin-film waveguides due to its high refractive index and low attenuation.Many label-free biosensor systems such as grating couplers and interferometric sensors aswell as fluorescence-based systems benefit from this waveguide material leading toextremely high sensitivity.

Comparison between RGD-peptide-modified titanium and borosilicate surfaces.

The use of synthetic peptides containing adhesive sequences, such as the Arg-Gly-Asp (RGD) motif, represents a promising strategy to control biological interactions at the cell-material interface. These peptides are known to improve the tissue-material contact owing to highly specific binding to cellular membrane receptors known as integrins, thereby promoting the adhesion, migration and proliferation of cells. The peptides were coupled to borosilicate glass and titanium surfaces using silanisation chemistry.

Segmented flow generation by chip reactors for highly parallelized cell cultivation.

Micro system technology offers convenient tools for the production of handling devices for small liquid volumes which can be used in cell cultivation. Here, a modular system for the rapid generation of cell suspension aliquots is presented. The system is used to produce and analyze high numbers of well-separated culture volumes.

Sampling and monitoring in bioprocessing using microtechniques.

In this review we describe aspects of interactions between bioreactors and analytical systems including microsystems. Principles of bioprocess monitoring are summarized, before we focus on the miniaturization of sampling systems guaranteeing bioprocess sterility and providing analytical systems with a liquid sample. The application of negative dielectrophoresis as a new principle for cell retention in a sampling system is described followed by theoretical aspects and results.

Blood cell adhesion on sensor materials studied by light, scanning electron, and atomic-force microscopy.

Unwanted interactions of biomedical sensors with surrounding tissues, body fluids, and cells are one of the most crucial problems affecting their long-term stability. In vivo processes were simulated in a computer-controlled bioreactor connected to a flow chamber system. Optical sensor materials were inserted into a parallel-plate chamber and monitored by light microscopy in order to get information about the number of adhered cells.