Mixing subattolitre volumes in a quantitative and highly parallel manner with soft matter nanofluidics

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Abstract

Handling and mixing ultrasmall volumes of reactants in parallel can increase the throughput1,2 and complexity3 of screening assays while simultaneously reducing reagent consumption1. Microfabricated silicon and plastic can provide reliable fluidic devices4,5,6,7,8, but cannot typically handle total volumes smaller than 1 × 10–12 l. Self-assembled soft matter nanocontainers9,10,11,12,13,14,15,16 can in principle significantly improve miniaturization and biocompatibility, but exploiting their full potential is a challenge due to their small dimensions17. Here, we show that small unilamellar lipid vesicles can be used to mix volumes as small as 1 × 10–19 l in a reproducible and highly parallelized fashion. The self-enclosed nanoreactors are functionalized with lipids of opposite charge to achieve reliable fusion. Single vesicles encapsulating one set of reactants are immobilized on a glass surface and then fused with diffusing vesicles of opposite charge that carry a complementary set of reactants. We find that 85% of the 1 × 106 cm–2 surface-tethered nanoreactors undergo non-deterministic fusion, which is leakage-free in all cases, and the system allows up to three to four consecutive mixing events per nanoreactor.

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Figure 1: Mixing of subattolitre volumes by fusion of SUVs of opposite charge.
Figure 2: Characterization of operational performance of the platform.
Figure 3: Consecutive mixing events triggered in single target reactors.

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Acknowledgements

D.S. would like to acknowledge financial support from the Lundbeck Foundation Center for Biomembranes in Nanomedicine, the Danish Councils for Independent and Strategic Research and the University of Copenhagen programmes of excellence ‘UNIK Synthetic Biology’, ‘Single Molecule Nanoscience’ and ‘BioScaRT’.

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D.S. designed and supervised the project. S.M.C. and P-Y.B. conducted most experiments and data analysis and contributed equally to this work. S.M.C. and D.S. wrote the paper. All authors helped design experiments, discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Dimitrios Stamou.

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The authors declare no competing financial interests.

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Christensen, S., Bolinger, PY., Hatzakis, N. et al. Mixing subattolitre volumes in a quantitative and highly parallel manner with soft matter nanofluidics. Nature Nanotech 7, 51–55 (2012). https://doi.org/10.1038/nnano.2011.185

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