Anders Karlsson

Molecular engineering: Networks of nanotubes and containers

We have constructed complex two-dimensional microscopic networks of phospholipid bilayer nanotubes and containers in which we are able to control the connectivity, container size, nanotube length, and angle between the nanotube extensions. Containers within these networks can be chemically differentiated and materials successfully routed between two containers connected by a common nanotube. These networks will enable model systems to be devised for studying confined biochemical reactions, intracellular transport phenomena and chemical computations.

Manipulating the biochemical nanoenvironment around single molecules contained within vesicles

A method to study single-molecule reactions confined in a biomimetic container is described. The technique combines rapid vesicle preparation, optical trapping and fluorescence confocal microscopy for performing simultaneous single-vesicle trapping and single-molecule detection experiments. The collisional environment between a single enzyme and substrate inside a vesicle is characterized by a Brownian dynamics Monte Carlo simulation. q 1999 Elsevier Science B.V. All rights reserved.

Distribution, transport, and production of volatile halocarbons in the upper waters of the ice‐covered high Arctic Ocean

[1]xa0Volatile halogenated compounds (CHBr3, CH2Br2, CHBr2Cl, and CH2ClI) were measured in the water column and in sea ice brine across the Arctic Ocean, from Barrow, Alaska, to Svalbard, during the Beringia 2005 expedition (August–September) with RV/IB Oden. High concentrations of brominated compounds (up to 42 pmol kg−1 of bromoform) were found under multiyear ice in the surface waters over the Makarov Basin and the Lomonosov Ridge, near the North Pole. Even higher concentrations (bromoform up to 160 pmol kg−1) were found in sea ice brine. We propose that the high load of riverine dissolved organic matter that is transported in the Transpolar Drift is a main factor responsible for the high concentration of brominated volatile compounds found in sea ice brine and upper waters and that cycles of freezing and thawing during the transport enhance the transfer of halocarbons to the seawater. The iodinated compound (CH2ClI) showed a completely different distribution with highest concentrations in water of Pacific origin in the mixed layer and upper halocline of the northern Canada Basin and over the Alpha Ridge. In the southern Canada Basin, low concentrations of halocarbons were found in upper waters. Higher concentrations in water of Pacific origin, especially on the continental shelf, indicate production in the shelf regions, likely in the Chukchi Sea and the East Siberian Sea.