Low energy universality and scaling of Van der Waals forces

At long distances interactions between neutral ground state atoms can be described by the Van der Waals potential V(r) =-C6/r^6-C8/r^8 - ... . In the ultra-cold regime atom-atom scattering is dominated by s-waves phase shifts given by an effective range expansion p cot d0 (p) = -1/a0 + r0 p^2/2 + ... in terms of the scattering length a0 and the effective range r0. We show that while for these potentials the scattering length cannot be predicted, the effective range is given by the universal low energy theorem r0 = A + B/a0+ C/a0^2 where A,B and C depend on the dispersion coefficients Cn and the reduced di-atom mass. We confront this formula to about a hundred determinations of r0 and a0 and show why the result is dominated by the leading dispersion coefficient C6. Universality and scaling extends much beyond naive dimensional analysis estimates.Comment: 4 pages, 3 figure

A Fluorescent Glycolipid-Binding Peptide Probe Traces Cholesterol Dependent Microdomain-Derived Trafficking Pathways

10.1371/journal.pone.0002933PLoS ONE38

Testing possibilities for establishing nanodiamond-DNA-conjugates

We report on the biofunctionalization of nanodiamond (ND) surfaces in a two step procedure: chemical modification, resulting in homogeneous and defined surface coating, with following addition of ssDNA. Carboxylation, thymidine coupling and amination methods for chemical modification of diamond surfaces for further functionalization experiments were applied. To enable the coupling process, biomolecules were also chemically modified with functional groups (-NH2). FTIR spectroscopy, fluorescence microscopy and gel electrophoresis were applied for characterizing modified ND particles and bioconjugates and for controlling the coupling success

Initial phases of microbial biofilm formation on opaque, innovative anti-adhesive surfaces using a modular microfluidic system

Biofilms can cause numerous problems, hence it is important to understand their formation on surfaces in order to develop resistant materials and avoidance strategies. Therefore, information is required regarding adhesion processes on surfaces generally and innovative anti-adhesive coatings in particular. Our flow cell system allows biofilms to be monitored in continuous flow conditions, without removing material for postflow imaging. The shown laminar flow ensures the maintenance of highly controlled conditions for biofilm growth. However, carried simulations of the oxygen demands of Escherichia coli cultivated as biofilms under the chosen regime indicate that conditions may become anaerobic, at least at the outlet of the flow cell, after a certain period of time. We report data on the bi ofouling tendencies on coatings generated with the help of direct laser interference patterning on stainless steel surfaces. Data were estimated from images acquired by fluorescence microscopy. Differences between patterned and unpatterned surfaces were not found, which is in accordance with the attachment point theory. Nevertheless, it is particularly important to elucidate in future studies the behavior of microorganisms during their attachment and the effects of variables of potentially sensitive surfaces (such as hydrophobicity, nanotopography, and charge) on their adhesion

Immunosensoren - Universelles Protokoll zur Immobilisierung von Antikörpern für die spezifische Antigen-Detektion

Es wurde ein Protokoll zur stabilen und funktionellen Immobilisierung von Antikörpern über Protein A auf Goldoberflächen für den spezifischen Antigen-Nachweis entwickelt, charakterisiert, optimiert und erfolgreich etabliert.Die Verwendung von hydrophilen Polyethylenglykolkettenals Blockungsreagenz wurde optimiert und in das Funktionalisierungsprotokoll integriert. Um mehrere sequentielle Bindungszyklen reproduzierbar auf einem Chip messes zu können, wurde Natriumhydroxid zur mehrmaligen Regeneration der Antikörper verwendet. Mit zwei unterschiedlichen Antikörpern zur Detektion von phytopathogenen Viruspartikeln konnte die Eignung und die Universalität der erfolgreich adaptierten und etablierten Oberflächenchemie gezeigt werden. Es wurden Konzentrationsreihen vermessen. Die Nachweisgrenze für die phytopathogenen Viruspartikel lagbei 0,9µg/mL. Damit konnte ein Oberflächenplasmonenresonanz (SPR)-basierter Immunosensor zur Detektion von phytopathogenen Viruspartikeln entwickelt und höhere Sensivitäten im Vergleich zu anderen, publizierten Funktionalisierungsprotokollen erreicht werden. Dank der Regeneration der Sensoroberflächeließ sich die Effizienz der Messungen weiter steigern