Peptide–Metal Organic Framework Swimmers that Direct the Motion toward Chemical Targets

Abstract

Highly efficient and robust chemical motors are expected for the application in microbots that can selectively swim toward targets and accomplish their tasks in sensing, labeling, and delivering. However, one of major issues for such development is that current artificial swimmers have difficulty controlling their directional motion toward targets like bacterial chemotaxis. To program synthetic motors with sensing capability for the target-directed motion, we need to develop swimmers whose motions are sensitive to chemical gradients in environments. Here we create a new intelligent biochemical swimmer by integrating metal organic frameworks (MOFs) and peptides that can sense toxic heavy metals in solution and swim toward the targets. With the aid of Pb-binding enzymes, the peptide-MOF motor can directionally swim toward PbSe quantum dots (QD) by sensing pH gradient and eventually complete the motion as the swimmer reaches the highest gradient point at the target position in solution. This type of technology could be evolved to miniaturize chemical robotic systems that sense target chemicals and swim toward target locations.

Evolution of Self‐Propelled Objects: From the Viewpoint of Nonlinear Science

“…[170] Here, we will give some examples of artificial self-propelled objects that could "sense" their environmental physicochemical conditions. [175][176][177][178][179][180] As elf-propelled dropletd riven by the Marangonif low (section 2.2.3) can also response to an external gradiento fp H, [177] rare earth metal concentration, [178,179] surfactant concentration, [180] or light intensity. The object can spontaneously move even though its environment is homogeneous, in which its movingd irection is random.…”

“…Once the environment becomes asymmetrical, the force balance is broken, and the object tends to move toward specific directions determined by the gradientoft he environmental condition. [175][176][177][178][179][180] As elf-propelled dropletd riven by the Marangonif low (section 2.2.3) can also response to an external gradiento fp H, [177] rare earth metal concentration, [178,179] surfactant concentration, [180] or light intensity. [84] Once the external gradient generates inhomogeneity on the interface of the droplet, the Marangoni flow is induced from low to high interfacial tensionr egions, and thus the dropleti sp ropelled toward the direction with low interfacial tension( Figure 5).…”

Recent Progress on Bioinspired Self‐Propelled Micro/Nanomotors via Controlled Molecular Self‐Assembly

“…Furthermore, autonomous MOF swimmers were designed to show directed movement toward the targeted PbSe QDs in the presence of Pb‐binding urease (Figure C II) . Upon addition of EDTA, MOF swimmers partially destroyed and released the hydrophobic DPA peptides, and the hydrophobic peptides in turn were self‐assembled at the MOF/water interface to produce surface tension gradients.…”

Structural and functional diversity among amyloid proteins: Agents of disease, building blocks of biology, and implications for molecular engineering

“…In a pair of studies, Ikezoe et al encased diphenylalanine peptides in a metal‐organic framework (MOF) comprised of copper ions and organic linker molecules. Upon contact with water, hydrophobic peptides reorganize inside the MOF, creating a large surface‐tension gradient to power translational motion across the water's surface (Ikezoe et al, , ). Results like these establish amyloid‐based nanowires as an elegant alternative to traditional nanotechnologies, and they pave the way for investigation into further applications.…”