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Optoelectronics

Cavendish Laboratory, Cambridge

Studying at Cambridge

 

Darshana Joshi

Darshana Joshi

PhD student in the Eiser Group


Email:
Office Phone: +44 (0)1223 768146

Biography:

Liquid-liquid interfaces are in ideal surfaces for studying controlled assembly of colloids. In my research I am exploiting the selective and thermally reversible binding of complementary DNA strands to anchor colloids to large oil-droplets (Figure below). We made two observations: Firstly the degree of colloidal adsorption can be tuned reversibly. Secondly, the surface-bound colloids are fully mobile, thus allowing the formation of well-equilibrated target structures. Interestingly, we were able to tune the aggregation behaviour of the surface-bound colloids.  At low bulk surfactant concentrations, the interface-bound colloids form a 2D fluid, but as the surfactant concentration approaches the critical micelle concentration, the surface-bound colloids organise into finite-sized crystalline domains due to micelle-induced depletion forces. Our experimental findings are supported by simulations studies. With the approach presented the creation of complex (multi-component) patterns of self-assembling, surface-bound colloids becomes possible.

 

Key Publications

  • D. Joshi, D. Bargteil, A. Caciagli, J. Burelbach, Z. Xing, A. S. Nunes,  D. E. P. Pinto,  N. A. M. Araujo,  J. Bruijc, Erika Eiser ‘Kinetic control of the coverage of oil droplets by DNA-functionalised colloids’, arXiv:1603.05931v1 (2016).
  • Z. Ruff, S. H. Nathan, R. R. Unwin, M. Zupkauskas, D. Joshi, G. P. C. Salmond, C. P. Grey, E. Eiser ‘Designing disordered materials using DNA-coated colloids of bacteriophage fd and gold’ Faraday Discussions, DOI: 10.1039/c5fd00136f (2015).