Nanorobots Constructed from Nanoclay: Using Nature to Create Self-Propelled Autonomous Nanomachines (original) (raw)
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ACS Nano, 2012
We describe nanoscale tools in the form of autonomous and remotely guided catalytically self-propelled InGaAs/ GaAs/(Cr)Pt tubes. These rolled-up tubes with diameters in the range of 280À600 nm move in hydrogen peroxide solutions with speeds as high as 180 μm s À1. The effective transfer of chemical energy to translational motion has allowed these tubes to perform useful tasks such as transport of cargo. Furthermore, we observed that, while cylindrically rolled-up tubes move in a straight line, asymmetrically rolled-up tubes move in a corkscrew-like trajectory, allowing these tubes to drill and embed themselves into biomaterials. Our observations suggest that shape and asymmetry can be utilized to direct the motion of catalytic nanotubes and enable mechanized functions at the nanoscale.
Nano Revolution: Pioneering the Future of Water Reclamation with Micro/Nanorobots
Nanoscale advances, 2024
Earth's freshwater reserves are alarmingly limited, with less than 1% readily available. Factors such as industrialisation, population expansion, and climate change are compounding the scarcity of clean water. In this context, self-driven, programmable micro-and nano-scale synthetic robots offer a potential solution for enhancing water monitoring and remediation. With the aid of these innovative robots, diffusion-limited reactions can be overcome, allowing for active engagement with target pollutants, such as heavy metals, dyes, nano-and micro-plastics, oils, pathogenic microorganisms, and persistent organic pollutants. Herein, we introduced and reviewed recent influential and advanced studies on micro-/nanorobots (MNR) carried out over the past decade. Typical works are categorized by propulsion modes, analyzing their advantages and drawbacks in detail and looking at specific applications. Moreover, this review provides a concise overview of the contemporary advancements and applications of micro-/ nano-robots in water-cleaning applications.
Halloysite Nanotubes: Controlled Access and Release by Smart Gates
Nanomaterials (Basel, Switzerland), 2017
Hollow halloysite nanotubes have been used as nanocontainers for loading and for the triggered release of calcium hydroxide for paper preservation. A strategy for placing end-stoppers into the tubular nanocontainer is proposed and the sustained release from the cavity is reported. The incorporation of Ca(OH)₂ into the nanotube lumen, as demonstrated using transmission electron microscopy (TEM) imaging and Energy Dispersive X-ray (EDX) mapping, retards the carbonatation, delaying the reaction with CO₂ gas. This effect can be further controlled by placing the end-stoppers. The obtained material is tested for paper deacidification. We prove that adding halloysite filled with Ca(OH)₂ to paper can reduce the impact of acid exposure on both the mechanical performance and pH alteration. The end-stoppers have a double effect: they preserve the calcium hydroxide from carbonation, and they prevent from the formation of highly basic pH and trigger the response to acid exposure minimizing the p...
Interfacial Self-Assembly in Halloysite Nanotube Composites
Langmuir, 2019
A self-assembly of clay nanotubes in functional arrays for the production of organized organic/inorganic heterostructures is described. These 50-nm-diameter natural alumosilicate nanotubes are biocompatible. Halloysite allows for 10−20 wt % chemical/drug loading into the inner lumen, and it gives an extended release for days and months (anticorrosion, self-healing, flame-retardant, antifouling, and antibacterial composites). The structured surfaces of the oriented nanotube micropatterns enhance interactions with biological cells, improving their capture and inducing differentiation in stem cells. An encapsulation of the cells with halloysite enables control of their growth and proliferation. This approach was also developed for spill petroleum bioremediation as a synergistic process with Pickering oil emulsification. We produced 2−5-nmdiameter particles (Au, Ag, Pt, Co, Ru, Cu−Ni, Fe 3 O 4 , ZrO 2 , and CdS) selectively inside or outside the aluminosilicate clay nanotubes. The catalytic hydrogenation of benzene and phenol, hydrogen production, impacts of the metal core−shell architecture, the metal particle size, and the seeding density were optimized for highefficiency processes, exceeding the competitive industrial formulations. These core−shell mesocatalysts are based on a safe and cheap natural clay nanomaterial and may be scaled up for industrial applications.
Biomimetic cell-mediated three-dimensional assembly of halloysite nanotubes
Chemical …, 2013
Biomimetic architectural assembly of clay nanotube shells on yeast cells was demonstrated producing viable artificial hybrid inorganic-cellular structures (armoured cells). These modified cells were preserved for one generation resulting in the intact second generation of cells with delayed germination.
Catalytic Nanomotors: Autonomous Movement of Striped Nanorods
ChemInform, 2004
Rod-shaped particles, 370 nm in diameter and consisting of 1 µm long Pt and Au segments, move autonomously in aqueous hydrogen peroxide solutions by catalyzing the formation of oxygen at the Pt end. In 2-3% hydrogen peroxide solution, these rods move predominantly along their axis in the direction of the Pt end at speeds of up to 10 body lengths per second. The dimensions of the rods and their speeds are similar to those of multiflagellar bacteria. The force along the rod axis, which is on the order of 10 -14 N, is generated by the oxygen concentration gradient, which in turn produces an interfacial tension force that balances the drag force at steady state. By solving the convection-diffusion equation in the frame of the moving rod, it was found that the interfacial tension force scales approximately as SR 2 γ/µDL, where S is the area-normalized oxygen evolution rate, γ is the liquid-vapor interfacial tension, R is the rod radius, µ is the viscosity, D is the diffusion coefficient of oxygen, and L is the length of the rod. Experiments in ethanol-water solutions confirmed that the velocity depends linearly with the product Sγ, and scaling experiments showed a strong dependence of the velocity on R and L. The direction of motion implies that the gold surface is hydrophobic under the conditions of the experiment. Tapping-mode AFM images of rods in air-saturated water show soft features that are not apparent in images acquired in air. These features are postulated to be nanobubbles, which if present in hydrogen peroxide solutions, would account for the observed direction of motion.
MULTIFARIOUS APPLICATIONS OF HALLOYSITE NANOTUBES: A REVIEW
n ) ( ) 4 S e P ] R T S F c d S h 6T ] c T a 6 % c S % Rev. Adv. Mater. Sci. 30 (2012) 282-295 Abstract. Natural tubules Halloysite are unique and versatile material formed by surface weathering of aluminosilicate minerals and comprises of different proportion of aluminum, silicon, hydrogen, and oxygen. It has chemical formula of Al 4 Si 4 O 10 (OH) 8 . 4H 2 O. Nanotubular geometry of halloysites exhibit nanoscale dimensions. Basically, this tubular arrangement varies with different regions. HNTs have high mechanical strength and modulus and these features make it an ideal