covalent-immobilization-proteins-for-single-molecule-force

Covalent Immobilization of Proteins for the Single Molecule Force Spectroscopy

In recent years, atomic force microscopy (AFM) based single molecule force spectroscopy (SMFS) extended our understanding of molecular properties and ...

Munich University of Applied Sciences

Ludwig-Maximilians-Universität München

To allow medical application of an artificial bladder made of biocompatible polyurethane, a long-term stable antibacterial coating is required. Alone, the artificial bladder exhibits no defense against microorganisms. Silver coating provides long-term antibacterial protection by the continuous release of silver ions into aqueous solutions. To control and to prolong the rate of silver ion release, the deposited silver film has to be protected by an inert film of biocompatible polyparylene by means of chemical vapor deposition. In this study, an antibacterial artificial bladder surface was developed by the formation of a sandwich structure consisting of silver and a biocompatible polymer (polyparylene) as a diffusion barrier. Specifically, this study analyzed the correlation between polyparylene thickness and silver release to determine optimal concentrations to combat common bacteria in vitro. The release of silver from sandwich structures was investigated in vitro by testing different thicknesses of polyparylene (0, 190, 540, and 1000 nm) as a diffusion barrier. The best result was demonstrated with a thickness of 190 nm of polyparylene, which yielded a silver dispense rate of 650 pg/(cm(2)⋅min), which would yield bacteriozidal concentrations above 30 μg/l in the bladder volume. The authors confirmed the antibacterial effect in vitro against common urinary tract infection pathogens, namely, Escherichia coli and Staphylococcus cohnii. Inhibition of bacterial growth could be detected within 8 h. A diffusion assay with spherical silver spots showed concentric zones free of bacterial growth. Our results suggest the possible utility of silver-polyparylene coatings as antibacterial agents. 

Microbiological investigation of an antibacterial sandwich layer system.

Hydra propagates asexually by exporting tissue into a bud, which detaches 4 days later as a fully differentiated young polyp. Prerequisite for detachment is activation of fibroblast growth factor receptor (FGFR) signaling. The mechanism which enables constriction and tissue separation within the monolayered ecto- and endodermal epithelia is unknown.

Bud detachment in hydra requires activation of fibroblast growth factor receptor and a Rho-ROCK-myosin II signaling pathway to ensure formation of a basal constriction.

Laser-induced cell transfer has been developed in recent years for the flexible and gentle printing of cells. Because of the high transfer rates and the superior cell survival rates, this technique has great potential for tissue engineering applications. However, the fact that material from an inorganic sacrificial layer, which is required for laser energy absorption, is usually transferred to the printed target structure, constitutes a major drawback of laser based cell printing. Therefore alternative approaches using deep UV laser sources and protein based acceptor films for energy absorption, have been introduced. Nevertheless, deep UV radiation can introduce DNA double strand breaks, thereby imposing the risk of carcinogenesis. Here we present a method for the laser-induced transfer of hydrogels and mammalian cells, which neither requires any sacrificial material for energy absorption, nor the use of UV lasers. Instead, we focus a near infrared femtosecond (fs) laser pulse (λ = 1030 nm, 450 fs) directly underneath a thin cell layer, suspended on top of a hydrogel reservoir, to induce a rapidly expanding cavitation bubble in the gel, which generates a jet of material, transferring cells and hydrogel from the gel/cell reservoir to an acceptor stage. By controlling laser pulse energy, well-defined cell-laden droplets can be transferred with high spatial resolution. The transferred human (SCP1) and murine (B16F1) cells show high survival rates, and good cell viability. Time laps microscopy reveals unaffected cell behavior including normal cell proliferation.

Article	Year
Microbiological investigation of an antibacterial sandwich layer system. Biointerphases\| PubMed ID: 25280843	2014
Bud detachment in hydra requires activation of fibroblast growth factor receptor and a Rho-ROCK-myosin II signaling pathway to ensure formation of a basal constriction. Developmental dynamics : an official publication of the American Association of Anatomists\| PubMed ID: 28411398	2017
Sacrificial-layer free transfer of mammalian cells using near infrared femtosecond laser pulses. PloS one\| PubMed ID: 29718923	2018

Stefanie Sudhop

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