The fascinating world of nanoparticle research

Bioinspired out-of-equilibrium systems will set the scene for the next generation of molecular materials with active, adaptive, autonomous, emergent and intelligent behavior. Indeed life provides the best demonstrations of complex and functional out-of-equilibrium systems: cells keep track of time, communicate, move, adapt, evolve and replicate continuously. Stirred by the understanding of biological principles, artificial out-of-equilibrium systems are emerging in many fields of soft matter science. Here we put in perspective the molecular mechanisms driving biological functions with the ones driving synthetic molecular systems. Focusing on principles that enable new levels of functionalities (temporal control, autonomous structures, motion and work generation, information processing) rather than on specific material classes, we outline key cross-disciplinary concepts that emerge in this challenging field. Ultimately, the goal is to inspire and support new generations of autonomous and adaptive molecular devices fueled by self-regulating chemistry.

Materials learning from life: concepts for active, adaptive and autonomous molecular systems

Dissipative self-assembly is exploited by nature to control important biological functions, such as cell division, motility and signal transduction. The ability to construct synthetic supramolecular assemblies that require the continuous consumption of energy to remain in the functional state is an essential premise for the design of synthetic systems with lifelike properties. Here, we show a new strategy for the dissipative self-assembly of functional supramolecular structures with high structural complexity. It relies on the transient stabilization of vesicles through noncovalent interactions between the surfactants and adenosine triphosphate (ATP), which acts as the chemical fuel. It is shown that the lifetime of the vesicles can be regulated by controlling the hydrolysis rate of ATP. The vesicles sustain a chemical reaction but only as long as chemical fuel is present to keep the system in the out-of-equilibrium state. The lifetime of the vesicles determines the amount of reaction product produced by the system.

Dissipative self-assembly of vesicular nanoreactors.

Two conceptual strategies for encoding information into self-assembling building blocks highlight opportunities and challenges in the realization of programmable colloidal nanostructures.

http://fulltext.calis.edu.cn/nature/nmat/14/1/nmat4184.pdf

Programmable self-assembly

We demonstrate the formation of supramolecular peptide nanofibers that display dynamic instability; i.e., they are formed by competing assembly and disassembly reactions, where assembly is favored away from equilibrium. The systems are based on competitive catalytic transacylation and hydrolysis, producing a self-assembling aromatic peptide amphiphile from amino acid precursors that temporarily exceeds the critical gelation concentration, until the competing hydrolytic reaction takes over. Analysis by atomic force microscopy shows consecutive nanofiber formation and shortening. The process results in macroscopically observable temporary hydrogelation, which may be repeated upon refueling the system with further addition of the chemically activated amino acid precursor. Nonequilibrium nanostructures open up opportunities for mimicry of the behavior of dynamic gels found in natural systems and provide components for future adaptive nanotechnologies.

/pdf/peptide-nanofibers-with-dynamic-instability-through-5f91x471to.pdf

Peptide Nanofibers with Dynamic Instability through Nonequilibrium Biocatalytic Assembly

Nanoscience has been promoted as a major technological revolution, and yet its influence outside of the laboratory has been relatively small. From our survey of recent progress, we conclude that as nanoscience fragments into subdisciplines and researchers become ever more specialized, there is increasingly little advancement toward the emergence of research themes that may unite and elevate nanoscience toward having an impact of the magnitude achieved by the steam engine, electricity, medicine, and the Internet. We suggest that one avenue for nanoscience to break this impasse is to venture beyond static structures into domain of dynamic nanomaterials that organize and/or function when displaced from thermodynamic equilibrium. We highlight recent work from our laboratory in this emerging area and also suggest some possible future applications for responsive and nonequilibrium nanosystems/materials.

Ozge Guney-Altay

Papers

Responsive and Nonequilibrium Nanomaterials