Eijiro Miyako

Semiconducting Polymer Nanobioconjugates for Targeted Photothermal Activation of Neurons

Optogenetics provides powerful means for precise control of neuronal activity; however, the requirement of transgenesis and the incapability to extend the neuron excitation window into the deep-tissue-penetrating near-infrared (NIR) region partially limit its application. We herein report a potential alternative approach to optogenetics using semiconducting polymer nanobioconjugates (SPNsbc) as the photothermal nanomodulator to control the thermosensitive ion channels in neurons. SPNsbc are designed to efficiently absorb the NIR light at 808 nm and have a photothermal conversion efficiency higher than that of gold nanorods. By virtue of the fast heating capability in conjunction with the precise targeting to the thermosensitive ion channel, SPNsbc can specifically and rapidly activate the intracellular Ca(2+) influx of neuronal cells in a reversible and safe manner. Our study provides an organic nanoparticle based strategy that eliminates the need for genetic transfection to remotely regulate cellular machinery.

Photothermic regulation of gene expression triggered by laser-induced carbon nanohorns

The development of optical methods to control cellular functions is important for various biological applications. In particular, heat shock promoter-mediated gene expression systems by laser light are attractive targets for controlling cellular functions. However, previous approaches have considerable technical limitations related to their use of UV, short-wavelength visible (vis), and infrared (IR) laser light, which have poor penetration into biological tissue. Biological tissue is relatively transparent to light inside the diagnostic window at wavelengths of 650–1,100 nm. Here we present a unique optical biotechnological method using carbon nanohorn (CNH) that transforms energy from diagnostic window laser light to heat to control the expression of various genes. We report that with this method, laser irradiation within the diagnostic window resulted in effective heat generation and thus caused heat shock promoter-mediated gene expression. This study provides an important step forward in the development of light-manipulated gene expression technologies.

Near-infrared laser-triggered carbon nanohorns for selective elimination of microbes

Carbon nanomaterials, such as carbon nanohorns and carbon nanotubes, have attracted considerable attention for their biomedical applications. We report here the first application of carbon nanohorns (CNHs) as potent laser therapeutic agents for highly selective elimination of microorganisms. This is the first report, supported by direct observations, of the highly selective elimination of yeast and bacteria (Saccharomyces cerevisiae and Escherichia coli) by employing molecular recognition element–CNH complexes and a near-infrared laser.

Carbon Nanotube–Polymer Composite for Light‐Driven Microthermal Control

Carbon nanotubes (CNTs) have attracted considerable attention because of their various applications. In particular, the development of functional CNT–polymer composites has been a hot research topic in the last years. However, contrary to many theoretical expectations, the physical potential of CNT–polymer composites has not been fully utilized because of the low dispersibility of CNTs in polymer matrices. Therefore, surface engineering of the CNTs is considered to be indispensable for exploiting their physical potential. Here, we present a novel organic-solvent-dispersible single-walled CNT (SWNT) complex that has good dispersibility in poly(dimethylsiloxane) (PDMS)—a model polymer matrix which represents an attractive material for lab-on-a-chip technologies, such as microor nanofabrication. Controlling the temperature of a reaction mixture on a chip is of particular importance for many such applications. A light-driven PDMS microchip that encapsulates the SWNT complexes was shown to be capable of ultrarapid temperature control in a microspace. Covalent and noncovalent functionalizations of SWNTs are useful techniques for improving the dispersibility of the nanotubes in organic solvents. Covalent functionalization, however, disrupts the one-dimensional electronic structure and the desirable optical properties of the SWNTs. The noncovalent approach, on the other hand, is considered to be a promising technique because it results in better retention of the electronic structure of the CNTs. We therefore synthesized a phospholipid, PL, bovine serum albumin, BSA, functionalized single-walled nanotube, SWNT, (PL– BSA–SWNT) complex by using a noncovalent technique (see Figure 1a and the Supporting Information for details). The BSA molecules bind noncovalently to the surface of the SWNTs through hydrophobic interactions, p–p interactions, and interactions via the amine functionalities of the protein. The hydrophobic alkyl chains of the PL increase the dispersibility of the BSA-functionalized SWNT (BSA– SWNT) complexes in both nonaqueous solvents and the PDMS polymer matrix. Pristine SWNTs and the BSA– SWNT complex are not dispersible in dichloromethane (Figure 1b, 1 and 2), whereas the PL–BSA–SWNT complex is readily dispersible in various organic solvents, but not in water (Figure 1b, 3–7). Bundle-free or isolated SWNTs have been reported to exhibit characteristic signals in the visible (Vis) and near-infrared (NIR) regions of their optical absorbance spectra as a result of van Hove transitions. The Vis/NIR optical absorption spectrum of a dispersion of the PL–BSA–SWNT complex in dichloromethane showed first metallic (M11) and second semiconducting (S22) bands in the ranges 440–600 nm and 550–800 nm, respectively (Figure 1c). In addition, we structurally characterized the PL– BSA–SWNT complex by means of atomic force microscopy Figure 1. Organic-solvent-dispersible SWNT complex. a) Image of the PL–BSA–SWNT complex. b) Photographs of dispersions of various SWNT constructs (1: SWNT, 2: BSA–SWNT, 3–7: PL–BSA–SWNT) in organic solvents (1–3: dichloromethane, 4: chloroform, 5: toluene, 6: ethyl acetate) and in water (7). c) Vis/NIR spectrum of a PL–BSA– SWNT/dichloromethane solution (350 mgmL ). d) AFM image of PL– BSA–SWNT complexes deposited on a mica substrate (left), and height profiles [nm] along lines 1–3 (right).

Carbon nanotube–liposome supramolecular nanotrains for intelligent molecular-transport systems

Biological network systems, such as inter- and intra-cellular signalling systems, are handled in a sophisticated manner by the transport of molecular information. Over the past few decades, there has been a growing interest in the development of synthetic molecular-transport systems. However, several key technologies have not been sufficiently realized to achieve optimum performance of transportation methods. Here we show that a new type of supramolecular system comprising of carbon nanotubes and liposomes enables the directional transport and controlled release of carrier molecules, and allows an enzymatic reaction at a desired area. The study highlights important progress that has been made towards the development of biomimetic molecular-transport systems and various lab-on-a-chip applications, such as medical diagnosis, sensors, bionic computers and artificial biological networks.

Enzyme-facilitated enantioselective transport of (S)-ibuprofen through a supported liquid membrane based on ionic liquids

Coupling lipase reactions with a supported liquid membrane (SLM) based on ionic liquids showed facilitative and selective permeation of (S)-ibuprofen through the SLM, indicating successful optical resolution of a racemic mixture using the enzyme-facilitative SLM.

Light-driven liquid metal nanotransformers for biomedical theranostics

Room temperature liquid metals (LMs) represent a class of emerging multifunctional materials with attractive novel properties. Here, we show that photopolymerized LMs present a unique nanoscale capsule structure characterized by high water dispersibility and low toxicity. We also demonstrate that the LM nanocapsule generates heat and reactive oxygen species under biologically neutral near-infrared (NIR) laser irradiation. Concomitantly, NIR laser exposure induces a transformation in LM shape, destruction of the nanocapsules, contactless controlled release of the loaded drugs, optical manipulations of a microfluidic blood vessel model and spatiotemporal targeted marking for X-ray-enhanced imaging in biological organs and a living mouse. By exploiting the physicochemical properties of LMs, we achieve effective cancer cell elimination and control of intercellular calcium ion flux. In addition, LMs display a photoacoustic effect in living animals during NIR laser treatment, making this system a powerful tool for bioimaging.

Photofunctional nanomodulators for bioexcitation.

A single organism comprises diverse types of cells. To acquire a detailed understanding of the biological functions of each cell, comprehensive control and analysis of homeostatic processes at the single-cell level are required. In this study, we develop a new type of light-driven nanomodulator comprising dye-functionalized carbon nanohorns (CNHs) that generate heat and reactive oxygen species under biologically transparent near-infrared (NIR) laser irradiation. By exploiting the physicochemical properties of the nanohorns, cellular calcium ion flux and membrane currents were successfully controlled at the single-cell level. In addition, the nanomodulator allows a remote bioexcitation of tissues during NIR laser exposure making this system a powerful tool for single-cell analyses and innovative cell therapies.

Photoinduced antiviral carbon nanohorns

Nanocarbons, such as carbon nanohorns (CNH) and carbon nanotubes, are materials of interest in many fields of science and technology because of their remarkable physical properties. We report here a novel approach for using NIR laser-driven CNH as an antiviral agent. NIR laser-driven functional CNH complexes could open the way to a new range of antiviral materials.

Self-Assembled Carbon Nanotube Honeycomb Networks Using a Butterfly Wing Template as a Multifunctional Nanobiohybrid

Insect wings have many unique and complex nano/microstructures that are presently beyond the capabilities of any current technology to reproduce them artificially. In particular, Morpho butterflies are an attractive type of insect because their multifunctional wings are composed of nano/microstructures. In this paper, we show that carbon nanotube-containing composite adopts honeycomb-shaped networks when simply self-assembled on Morpho butterfly wings used as a template. The unique nano/microstructure of the composites exhibits multifunctionalities such as laser-triggered remote-heating, high electrical conductivity, and repetitive DNA amplification. Our present study highlights the important progress that has been made toward the development of smart nanobiomaterials for various applications such as digital diagnosis, soft wearable electronic devices, photosensors, and photovoltaic cells.