Reversible metallisation of soft UV patterned substrates

Soft UV (365 nm) patterning of ortho-nitrobenzyl functionalized thiol-on-gold self-assembled monolayers (SAMs) using acid catalysis, produces surfaces which can be used for the selective electro-deposition of copper. Exploiting the difference in the reduction peak potential between the photolysed and the masked regions of the SAM allows copper to be deposited selectively on those areas that have been exposed to the light. The copper can be removed by raising the electrode potential. The process is fully reversible so that depositing a pattern of copper, and removing it again is something that can be repeated many times. The copper deposited on the photolysed regions, like copper deposited on bare gold, forms a film of copper oxide, and so it is presumably formed on top of the SAM. Preliminary results for two-photon photocleavage show that it is also possible to implement patterning with sub-wavelength features

Programmable Assembly of DNA-Functionalized Liposomes by DNA

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Nano, copyright © American Chemical Society after peer review and technical editing by publisher. To access the final edited and published work see http://dx.doi.org/10.1021/nn1030093Bionanotechnology involves the use of biomolecules to control both the structure and property of nanomaterials. One of the most studied examples is DNA-directed assembly of inorganic nanoparticles such as gold nanoparticles (AuNPs). However, systematic studies on DNA-linked soft nanoparticles, such as liposomes, are still lacking. We herein report the programmable assembly and systematic characterization of DNA-linked liposomes as a function of liposome size, charge, fluidity, composition, DNA spacer, linker DNA sequence, and salt concentration for direct comparison to DNA-directed assembly of AuNPs. Similar to the assemblies of AuNPs, sharp melting transitions were observed for liposomes where the first derivative of the melting curve full width at half-maximum (fwhm) is equal to or less than 1 °C for all of the tested liposomes, allowing sequence specific DNA detection. We found that parameters such as liposome size, charge, and fluidity have little effect on the DNA melting temperature. Cryo-TEM studies showed that programmable assemblies can be obtained and that the majority of the liposomes maintained a spherical shape in the assembled state. While liposome and AuNP systems are similar in many aspects, there are also important differences that can be explained by their respective physical properties.University of Waterloo || Natural Sciences and Engineering Research Council |

Nature's lessons in design: nanomachines to scaffold, remodel and shape membrane compartments.

Compartmentalisation of cellular processes is fundamental to regulation of metabolism in Eukaryotic organisms and is primarily provided by membrane-bound organelles. These organelles are dynamic structures whose membrane barriers are continually shaped, remodelled and scaffolded by a rich variety of highly sophisticated protein complexes. Towards the goal of bottom-up assembly of compartmentalised protocells in synthetic biology, we believe it will be important to harness and reconstitute the membrane shaping and sculpting characteristics of natural cells. We review different in vitro membrane models and how biophysical investigations of minimal systems combined with appropriate theoretical modelling have been used to gain new insights into the intricate mechanisms of these membrane nanomachines, paying particular attention to proteins involved in membrane fusion, fission and cytoskeletal scaffolding processes. We argue that minimal machineries need to be developed and optimised for employment in artificial protocell systems rather than the complex environs of a living organism. Thus, well-characterised minimal components might be predictably combined into functional, compartmentalised protocellular materials that can be engineered for wide-ranging applications