Methods for research on immune complement activation on modified sensor surfaces

We have developed a methodological system consisting of a new surface sensitive quartz crystal microbalance with dissipation monitoring (QCM-D) sensor surfaces together with different surface modification methods for the investigation of surface associated complement activation in human sera. The QCM-D surface, 10 mm in diameter, was modified by spin-coating of poly(urethane urea) (PUUR) and polystyrene (PS). Some sensor surfaces were also sputtered with titanium (Ti) or modified by hydrophobic self-assembled monolayer (SAM) of an 18-carbon alkane thiol with a ---CH₃ end group. The amount of surface deposited complement protein was investigated by incubation of the modified sensor surfaces in human sera, followed by incubation with antibodies directed against complement factor 3c (C3c). The amounts of bound anti-C3c were then used as an arbitrary measure of surface induced complement activation. The order of complement activation of the different surfaces, as judged by three separate measurements per surface modification, was PUUR>PS=SAM>Ti. The Ti surface had a similar low degree of anti-C3c binding as the negative controls (heat inactivated sera). The novel QCM-D methodology was found to be very simple, accurate, sensitive and well suited as a screening method for complement activation and protein adsorption on different materials. We also compared the sensitivity of QCM-D method with surface plasmon resonance (SPR) for the quantification of protein adsorption and complement activation on gold sensor surfaces. The QCM-D method was equally sensitive as the SPR for the detection of protein adsorption from a solution independently if low flow rate (5 μl/min) was used. A slight increase in sensitivity was found at higher flow rate (30 μl/min). However, we found it difficult to use the SPR method on the Ti, PS and PUUR surfaces due to decreased light penetration of the modified SPR sensor chip.     

Complete 1H and 13C NMR assignments of aurasperone A and fonsecinone A, two bis-naphthopyrones produced by Aspergillus aculeatus

Complete assignments of 1H and 13C NMR chemical shifts of the polyketides aurasperone A and fonsecinone A were made by means of nuclear Overhauser enhancement and heteronuclear NMR correlation experiments. These compounds were isolated for the first time from Aspergillus aculeatus, an endophytic fungus obtained from leaves of Melia azedarach(Meliaceae).     

Dissociative recombination cross section and branching ratios of protonated dimethyl disulfide and N-methylacetamide

Dimethyl disulfide (DMDS) and N-methylacetamide are two first choice model systems that represent the disulfide bridge bonding and the peptide bonding in proteins. These molecules are therefore suitable for investigation of the mechanisms involved when proteins fragment under electron capture dissociation (ECD). The dissociative recombination cross sections for both protonated DMDS and protonated N-methylacetamide were determined at electron energies ranging from 0.001 to 0.3 eV. Also, the branching ratios at 0 eV center-of-mass collision energy were determined. The present results give support for the indirect mechanism of ECD, where free hydrogen atoms produced in the initial fragmentation step induce further decomposition. We suggest that both indirect and direct dissociations play a role in ECD.     

Dry deposition of elemental iodine on skin,hair, and clothing from air

Hairless rats, clothes, human hair, filter paper and water were exposed to gaseous elemental iodine in a glass chamber for 60–120 minutes. The deposition of gaseous elemental iodine on skin and lung of rats, human hair, water, clothes and paper were investigated by measuring iodine content in the exposed material by epithermal neutron activation analysis (ENAA). For measurement of the iodine concentration in the chamber air, elemental iodine in the air was collected by continuously sucking air through an active charcoal column. The trapped iodine in the active charcoal was then determined by ENAA. The measured deposition velocity in the test chamber of gaseous elemental iodine on skin, clothing, hair and water ranges from 0.006 on filter paper and water to about 0.05 cm/s on skin and clothes. The variation of elemental iodine concentration in air of the glass chamber was investigated by collecting and analyzing air samples at various time intervals. The results show that the variation with time in the concentration of the iodine can be described by an exponential function.     

Flexible active matrix addressed displays manufactured by printing and coating techniques

A flexible electrochromic active matrix addressed display, including 8 × 8 pixels, is demonstrated by using solution processing based on standard printing and coating manufacturing techniques. Each organic electrochromic display (OECD) pixel and its corresponding organic electrochemical transistor (OECT) are located on different sides of the flexible PET substrate. Electronic vias generated through the plastic substrate connects each OECD pixel with one addressing OECT. When comparing this display with actively addressed OECDs with all its components located on the same side, the present approach based on this electronic via substrate provides an enhanced pixel resolution and a relatively more simplified manufacturing process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012