Engineering the shape of nanoparticles has emerged as an effective approach for optimizing their physical/chemical properties. In particular, two-dimensional (2D) nanostructures with their high surface area/volume ratio have opened up exciting opportunities for developing advanced anisotropic materials and facilitating chemical processes that demand high levels of surface interactions. Although the great potential of low-dimensional 2D nanoswimmers has been suggested by theoretical works, very little experimental study has been undertaken thus far. Here we fabricated a low-dimensional magnetic nanomotor based on discotic barium ferrite nanoplates. We demonstrated that the “fuel-to-motion” behavior and the enhanced diffusion of nanoswimmers are not limited to just 0D nanospheres or 1D nanorods but are also applicable to 2D nanoplates. In addition, the 2D nanoswimmers showed excellent catalytic performance in removing molecular and particle stains on cloth likely due to their catalytic activity as well as active locomotion that enhanced microconvection of solution. This study validated a new self-powered nanomachine for cleaning application without any requirement of surfactants or external mechanical energy.
Controlling colloidal self-assemblies using external forces is essential to develop modern electrooptical and biomedical devices. Importantly, shape anisotropic colloids can provide optical properties such as birefringence. Here we demonstrate that external temperature gradients can be effective in controlling nematic liquid crystalline (LC) order in suspensions of plate-like colloids also known as nanoplates. Nanoplates, in an isotropic suspension, wherein their orientations are random, could be effectively moved using a temperature gradient environment causing a phase transition to LC nematic phase. Such controllably formed nematic phase featured large nematic monodomains and enabled topologically more stable structures that were evident from the absence of hedgehog-type defects which are typically found in nematics formed spontaneously via nucleation and growth mechanism in a sufficiently high concentration suspension of nanoplates. Due to their high surface area-to-volume ratio and excellent thermophoretic properties, nanoplates can prove to be ideal candidates for transport of biomolecules through temperature varying environments.
Colloidal liquid crystals (LCs) that bridge colloidal and liquid crystal sciences are in the limelight of active research due to their fundamental importance and promising technological applications in diverse fields such as topology, biology, and photonics [1-3]. Anisotropic colloidal nanoparticles, such as nanorods and nanoplates, suspended in a liquid host are known to undergo phase transition from fluid to liquid crystalline phases above a certain concentration of the guest nanoparticles [4,5]. At low concentrations, the anisotropic colloidal nanoparticles have random orientations that maximize the configurational entropy and stabilize the isotropic fluid phase; in contrast, at higher concentrations, the translational entropy gained from orientational order exceeds the loss in configurational entropy, resulting into a nematic phase [6]. It should be noted that a longrange orientational order can also be induced in the isotropic phase of colloidal particles using external fields [7][8][9].
We studied isotropic-nematic (I-N) phase separation via gravity sedimentation in suspensions of plate-like colloidal particles of identical thickness but different lateral sizes (diameters). It is well-known that I-N phase transition occurs at a higher concentration for particles with larger aspect ratio (thickness/diameter) than for particles with smaller aspect ratio. Here we report that for the larger aspect ratios of nanoplates, gravity-driven I-N phase separation is faster. In a homogenously mixed I-N biphasic suspension of nanoplates, nematic tactoids nucleate, grow, and then undergo sedimentation in gravity, leading to the formation of a clear horizontal interface between the I and N phase. For I-N coexistent suspension of nanoplates with different aspect ratios but the same amount of nematic fractions, the larger the aspect ratio, the faster the formation of nematic tactoids and interface between isotropic liquid and nematic liquid crystal phase. The tactoid formation rate is governed by the rotational and translational diffusion rates, which are faster at larger aspect ratios. The time required for I-N separation (t*, seconds) varies inversely with the mean aspect ratio (< ξ >) of nanoplates and follows the relation, t* = α < ξ >n, where α = 0.97 ± 1.30 s and n = −2.1 ± 0.2. The phase separation kinetics studied in our experiments offers guidance for the selection of aspect ratio of nanoplates for samples to be studied at the International Space Station (ISS).
Oil spills caused by damaged oil rigs, ruptured pipelines, and tankers can have immediate and long-term detrimental effects on marine systems and aquatic life. Herein we further develop the merit of an oil spill recovery technique called oil herding. A herder is an amphiphilic oil-collecting surfactant which is applied to spray around the oil spill areas and is able to retract oil slicks, transforming them from a large thin layer to a small thick bulk. This herding treatment greatly simplifies further in-situ burning and the recycle process. The natural konjac glucomannan (KGM) material could be functionalized and examined here as an oil herder, which has the great advantage of nontoxicity, biocompatibility, and adaptability. Moreover, functionalized KGM is a non-ionic surfactant with no Krafft temperature. The absence of Krafft temperature gives KGM surfactants the unique ability to retain surfactant ability at temperatures nearing 0 °C. It unlocks a new direction for efficient oil herders within low temperature water areas, especially for oil spills treatment in Arctic waters, in the offshore safety control.
Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO 4 ) 2 ·H 2 O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C 4 H 9 ) 4 NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior. Video LinkThe video component of this article can be found at
Background: Acyclovir, BCS Class III drug is commercially available as 3 % w/w eye ointment for multiple applications. Acyclovir nanoemulsions can be proposed to reduce dose because of improved permeation characteristics. Further, the development of in situ ophthalmic gels can be advantageous to reduce the number of applications due to increased mucoadhesion and sustaining effect. Objective: The purpose of this study was the development and evaluation of nanoemulsions based in situ gels of Acyclovir (1% w/w) as potential ophthalmic delivery systems. Methods: Nanoemulsions of Acyclovir were developed by Phase Inversion Temperature method using Capmul MCM, stearyl amine and Kolliphor RH 40 as liquid lipid, charge inducer and surfactant, respectively selected on the basis of Acyclovir solubility studies in the oil phase and emulsification ability of surfactants. These nanoemulsions were further developed into in situ ophthalmic gels using gellan gum and Methocel K4M. Results: The developed gels showed a sustained effect in vitro release studies and improved goat corneal permeation in ex vivo studies when compared to marketed ointment. HET-CAM studies concluded the absence of irritation potential, while in vivo irritation study in Wistar rats showed the absence of erythema and swelling of eyes after visual inspection for 72 hours. Histopathological studies on isolated rat corneas showed no abnormalities in anterior corneal epithelium and corneal stroma without any epithelial hyperplasia. Acyclovir nanoemulsions based in situ ophthalmic gel showed increased corneal deposition and permeation in rat eyes. Conclusion: The improved potential of developed ophthalmic gels was proven due to the reduced frequency of application compared to the marketed ointment in animal studies.
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.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.