Edited by David A. Weitz, Harvard University, Cambridge, MA, and approved August 2, 2016 (received for review February 11, 2016)
Chemical reproduction is central to biology, and understanding how chemical systems may give rise to complex systems that form self-reproducing cell-like structures is a leading goal for scientists. Here we use an ultrasensitive optical microscopy technique to directly monitor the formation and dynamics of self-replicating supramolecular structures at the single-particle level. As a result, we are able to quantify the kinetics of these systems and changes in nanoparticle distribution over time. Our ability to observe a variety of complex phenomena may contribute to understanding how cell-like systems can emerge from much simpler chemical components and provides a general route to studying assembly and disassembly on the nanoscale.
Autocatalytic chemical reactions are widely studied as models of biological processes and to better understand the origins of life on Earth. Minimal self-reproducing amphiphiles have been developed in this context and as an approach to de novo “bottom–up” synthetic protocells. How chemicals come together to produce living systems, however, remains poorly understood, despite much experimentation and speculation. Here, we use ultrasensitive label-free optical microscopy to visualize the spontaneous emergence of an autocatalytic system from an aqueous mixture of two chemicals. Quantitative, in situ nanoscale imaging reveals heterogeneous self-reproducing aggregates and enables the real-time visualization of the synthesis of new aggregates at the reactive interface. The aggregates and reactivity patterns observed vary together with differences in the respective environment. This work demonstrates how imaging of chemistry at the nanoscale can provide direct insight into the dynamic evolution of nonequilibrium systems across molecular to microscopic length scales.
↵1J.O.-A. and A.J.B. contributed equally to this work.
Author contributions: J.O.-A., A.J.B., P.K., and S.P.F. designed research; J.O.-A. and A.J.B. performed research; J.O.-A. and A.J.B. contributed new reagents/analytic tools; J.O.-A. and A.J.B. analyzed data; and J.O.-A., A.J.B., P.K., and S.P.F. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1602363113/-/DCSupplemental.
Freely available online through the PNAS open access option.
