Inspired by chasing–escaping behaviors of predator
and swarming
prey in nature, here we demonstrate a concept to create active micromotor
systems from two species of passive microparticles with biomimetic
predator–prey interactions. In this concept, the biomimetic
predator–prey interactions are established in a binary particle
system comprising the diffusiophoretic attractive microparticles (prey
particles) and the diffusiophoretic repulsive ones (predator particles).
In the absence of additional chemical fuels and external fields, the
predator particles are attracted by and constantly chase the swarming
prey particles, which, in response, escape from the former and show
dynamic group reconfigurations because of the local repulsion. Based
on this concept, various synthetic active micromotor systems have
been demonstrated, including active ZnO–TiO2, Ag3PO4–TiO2, and ZnO–AgBr
micromotor systems. As the predator and prey particles are powered
by each other through the biomimetic predator–prey interactions,
the concept proposed here provides an advanced method to develop not
only a class of single micromotors powered by passive particles or
“solid fuels” but also micromotor swarms capable of
manipulating “moving cargo”. In addition, it also illustrates
a proof-of-concept implementation of intelligent micro/nanomotor systems
composed of heterogeneous individuals with complementary or cooperative
functions.
Sodium perchlorate salt (NaClO 4 ) is commonly used as an internal intensity standard in ultraviolet resonance Raman (UVRR) spectroscopy experiments. It is well known that NaClO 4 can have profound effects on peptide stability. The impact of NaClO 4 on protein stability in UVRR experiments has not yet been fully investigated. It is well known from experiment that protein stability is strongly affected by the solution composition (water, salts, osmolytes, etc.). Therefore, it is of the utmost importance to understand the physical basis on which the presence of salts and osmolytes in the solution impact protein structure and stability. The aim of this study is to investigate the effects of NaClO 4 , on the helical stability of an alanine peptide in water. Based upon replica-exchange molecular dynamics data, it was found that NaClO 4 solution strongly stabilizes the helical state and that the number of pure helical conformations found at room temperature is greater than in pure water. A thorough investigation of the anion effects on the first and second solvation shells of the peptide, along with the Kirkwood-Buff theory for solutions, allows us to explain the physical mechanisms involved in the observed specific ion effects. A direct mechanism was found in which ClO 4À ions are strongly attracted to the folded backbone.
Mg-based micromotors have emerged as an extremely attractive artificial micro/nanodevice, but suffered from uncontrollable propulsion and limited motion lifetime, restricting the fulfillment of complex tasks. Here, we have demonstrated Mg-based micromotors composed of Mg microspheres asymmetrically coated with Pt and temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM) hydrogel layers in sequence. They can implement different motion behaviors stemming from the driving mechanism transformation when encountering catalyzed substrates such as H2O2 and respond to both H2O2 concentration and temperature in aqueous environment. The as-constructed Mg-based micromotors are self-propelled by Pt-catalyzed H2O2 decomposition following the self-consuming Mg-H2O reaction. In this case, they could further generate bilateral bubbles and thus demonstrate unique self-limitation motion like hovering when the phase transformation of PNIPAM is triggered by decreasing temperature or when the H2O2 concentration after permeating across the PNIPAM hydrogel layer is high enough to facilitate bubble nucleation. Our work for the first time provides a stimuli-induced “hovering” strategy for self-propelled micromotors, which endows Mg-based micromotors with an intelligent response to the surroundings besides the significant extension of their motion lifetime.
A facile method is reported which involves blending a conjugated electron-extraction polymer with photoactive materials to simplify the fabrication process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.