The present work addresses the length distribution of self-assembled lipid nanotubes (LNTs) by controlling the orientation of the LNTs using an alternating current (ac) electric field in aqueous solutions. The effect of the ac field on the orientation and rotation of individual LNTs was examined to evaluate the optimum orientation frequency by visualizing the individual LNTs in real time. By using the high-frequency ac field, we have successfully measured the length distribution for two different types of LNTs and have quantitatively analyzed the maximum occurrences of the length distribution as well as the extension of the longer length region.
"An individual LNT has thus been found to be useful as a nanoreactor and/or nano-assay device232425262728. Correspondingly, a variety of techniques has been developed for manipulating and integrating LNTs into ordered nanocapillary arrays2930313233343536. "
[Show abstract][Hide abstract] ABSTRACT: Hydrophilic nanotubes formed by lipid molecules have potential applications as platforms for chemical or biological events occurring in an attolitre volume inside a hollow cylinder. Here, we have integrated the lipid nanotubes (LNTs) by applying an AC electric field via plug-in electrode needles placed above a substrate. The off-chip assembly method has the on-demand adjustability of an electrode configuration, enabling the dispersed LNT to be electrically moulded into a separate film of parallel LNT arrays in one-step. The fluorescence resonance energy transfer technique as well as the digital microscopy visualised the overall filling of gold nanoparticles up to the inner capacity of an LNT film by capillary action, thereby showing the potential of this flexible film for use as a high-throughput nanofluidic device where not only is the endo-signalling and product in each LNT multiplied but also the encapsulated objects are efficiently transported and reacted.
[Show abstract][Hide abstract] ABSTRACT: Polyelectrolyte-stabilized polymer nanotubes with high rigidity are electro-optically characterized in the dilute and semidilute regimes. Nanotube alignment with the electric field and subsequent orientation relaxation in the absence of electric field are confirmed by optical microscopy, and a simple UV−vis electro-optical setup is used to detect the transient light transmittance. The effects of ionic strength, pulse duration, electric field strength, and particle concentration on particle alignment and orientation relaxation dynamics were systematically varied. The charge-dependent field-induced interfacial polarization, particularly the double layer polarization, plays a predominant role in the thin-walled nanotube alignment, which diminishes with increasing salt screening, approaching predictions for uncharged dielectric tubes. The experimentally obtained rotary diffusivity from nanotube orientation relaxation dynamics agrees with theoretical predictions, with negligible ionic strength effects, indicating the absence of salt-induced aggregation events. When the scaled particle concentration /* increases from 0.06 to 15, the alignment is slowed by crowding, whereas the measured collective rotary diffusion coefficient increases due to the gradient of orientation probability.
The Journal of Physical Chemistry C 04/2011; 115(17). DOI:10.1021/jp108846t · 4.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Organic nanotubes (ONTs) are tubular nanostructures prepared from small organic molecules or macromolecules. These structures have attracted growing attention because their inner and outer spaces exhibit unique properties that may be exploited for potential applications. In the first part of this review, we describe methodologies to construct well-defined ONTs: how to control the dimensions, discriminate the inner and outer surfaces, and functionalize the nanostructures. The well-defined ONTs contain cylindrical nanospaces that can capture, store, and release various nanomaterials, from small molecules to macromolecules. The ONTs' outer spaces and surfaces play critical roles in dispersibility, organization, and manipulation of the ONTs. In the second part, we describe the ONTs' physicochemical properties and utilization of the inner and outer spaces, emphasizing the advantages of ONTs over other types of nanomaterials. Smaller nanomaterials can be efficiently captured in the nanospaces of the ONTs via selective surface interactions. For example, encapsulation of proteins in the ONT nanospaces prevents them from chemical or thermal denaturation. Furthermore, the encapsulated materials can be released in response to external stimuli, such as pH or temperature, which can alter the surface charge and/or fluidity. These unique properties of ONTs allow them to be utilized for biomaterials and drug delivery applications.
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