Living systems use fuel-driven supramolecular polymers such as actin to control important cell functions. Fuel molecules like ATP are used to control when and where such polymers should assemble and ...disassemble. The cell supplies fresh ATP to the cytosol and removes waste products to sustain steady states. Artificial fuel-driven polymers have been developed recently, but keeping them in sustained non-equilibrium steady states (NESS) has proven challenging. Here we show a supramolecular polymer that can be kept in NESS, inside a membrane reactor where ATP is added and waste removed continuously. Assembly and disassembly of our polymer is regulated by phosphorylation and dephosphorylation, respectively. Waste products lead to inhibition, causing the reaction cycle to stop. Inside the membrane reactor, however, waste can be removed leading to long-lived NESS conditions. We anticipate that our approach to obtain NESS can be applied to other stimuli-responsive materials to achieve more life-like behaviour.
Homochirality is a fundamental feature of living systems, and its origin is still an unsolved mystery. Previous investigations showed that external physical forces can bias a spontaneous symmetry ...breaking process towards deterministic enantioselection. But can the macroscopic shape of a reactor play a role in chiral symmetry breaking processes? Here we show an example of chirality transfer from the chiral shape of a 3D helical channel to the chirality of supramolecular aggregates, with the handedness of the helical channel dictating the direction of enantioselection in the assembly of an achiral molecule. By combining numerical simulations of fluid flow and mass transport with experimental data, we demonstrated that the chiral information is transferred top-down thanks to the interplay between the hydrodynamics of asymmetric secondary flows and the precise spatiotemporal control of reagent concentration fronts. This result shows the possibility of controlling enantioselectively molecular processes at the nanometer scale by modulating the geometry and the operating conditions of fluidic reactors.
•Microfluidics can be used for up-scaled processing of covalent-organic frameworks.•Microfluidics offers an exquisite control over mixing regimes.•Mixing regimes can tailor the shape, morphology and ...surface integration of COFs.•Microfluidics can reveal morphogenesis of COFs via simulated microgravity.
Nearly twenty years since the discovery of covalent-organic frameworks (COFs), most of the research on these materials has been focused on the rational design of new structures. Recently, the quest for discovering the functionalities and potential applications of these crystalline materials has attracted the attention of many researchers. While the number of reports regarding these two aspects within the COF research area is continuously growing, in order to achieve their full potential, the processability aspect of COFs also needs to be addressed. In this review article, we examine the opportunities that flow-based technologies offer regarding (a) the continuous synthesis of COFs, and (b) the processing of these materials into functional surfaces and devices (e.g. thin films and 3D structures), both aspects being ultimately amenable to industrial scale up.
Coordination polymers (CPs), including metal–organic frameworks (MOFs), are crystalline materials with promising applications in electronics, magnetism, catalysis, and gas storage/separation. ...However, the mechanisms and pathways underlying their formation remain largely undisclosed. Herein, we demonstrate that diffusion‐controlled mixing of reagents at the very early stages of the crystallization process (i.e., within ≈40 ms), achieved by using continuous‐flow microfluidic devices, can be used to enable novel crystallization pathways of a prototypical spin‐crossover MOF towards its thermodynamic product. In particular, two distinct and unprecedented nucleation‐growth pathways were experimentally observed when crystallization was triggered under microfluidic mixing. Full‐atom molecular dynamics simulations also confirm the occurrence of these two distinct pathways during crystal growth. In sharp contrast, a crystallization by particle attachment was observed under bulk (turbulent) mixing. These unprecedented results provide a sound basis for understanding the growth of CPs and open up new avenues for the engineering of porous materials by using out‐of‐equilibrium conditions.
We show that human‐made self‐assembled materials, such as porous coordination polymers, can follow distinct growth pathways in a given energy landscape in response to a controlled diffusion of reagents.
Microfluidic technologies have emerged as advanced tools for surface‐enhanced Raman spectroscopy (SERS). They have proved to be particularly appealing for in situ and real‐time detection of analytes ...at extremely low concentrations and down to the 10 × 10−15 m level. However, the ability to prepare reconfigurable and reusable devices endowing multiple detection capabilities is an unresolved challenge. Herein, a microfluidic‐based method that allows an extraordinary spatial control over the localization of multiple active SERS substrates in a single microfluidic channel is presented. It is shown that this technology provides for exquisite control over analyte transport to specific detection points, while avoiding cross‐contamination; a feature that enables the simultaneous detection of multiple analytes within the same microfluidic channel. Additionally, it is demonstrated that the SERS substrates can be rationally designed in a straightforward manner and that they allow for the detection of single molecules (at concentrations as low as 10−14 m). Finally, it is shown that rapid etching and reconstruction of SERS substrates provides for reconfigurable and reusable operation.
A microfluidic approach for surface‐enhanced Raman spectroscopy (SERS) substrate fabrication and multiple analyte detection is presented. Combining the controlled diffusion of analytes with pneumatic clamp actuation enables the spatially controlled synthesis of custom shaped SERS substrates, where regioselective localization and detection is ensured. The method enables the reconfiguration and reuse of these substrates without cross‐contamination, hence generating SERS barcodes.
The aggregation of achiral sulfonatophenyl‐ and phenyl‐meso‐substituted diprotonated porphyrins to chiral J‐aggregates is a hierarchical noncovalent polymerization process preceded by a critical ...nucleation stage. This allows significant enantiomeric excesses by the formation of a few primary nuclei and the control of their growth by the effect that flows (imperfect mixing) have on the secondary nucleation of the J‐aggregate particles. In addition, the results strongly suggest that when only one species of aggregate predominates, the CD signals of the three excitonic bands in the visible region (around 420, 490, and 700 nm) show the same sign. Thus, differences on their relative sign would be due to the presence of different species.
How to avoid the racemic: The aggregation of achiral sulfonatophenyl‐ and phenyl‐meso‐substituted diprotonated porphyrins is a noncovalent polymerization process preceded by a critical nucleation stage that yields chiral J‐aggregates. Significant enantiomeric excesses are obtained by the formation of a few first nuclei and the control of their growth by the effect of flows (imperfect mixing) on the diffusion of clusters and J‐aggregate particles (see figure).
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