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1.
Chembiochem ; 21(4): 477-480, 2020 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-31397042

RESUMO

MicroRNAs (miRNAs) are short RNAs that regulate the expression of complementary messenger RNAs and are involved in numerous human diseases. However, current detection techniques lack the sensitivity to detect miRNAs of low abundance. Moreover, at a length of 20-25 bases, miRNAs are too short for the reverse transcription (RT) polymerase chain reaction (PCR). Here we have developed a new, rapid, and simple miRNA detection system utilizing an RT primer containing a DNA tag at the 5'-end to increase the length of the cDNA. This strategy increases the length of the hybridized tagged primer and the complementary template DNA, as well as the melting temperature of the primer⋅template DNA duplex. PCR efficiency is thus increased, thereby enhancing miRNA detection sensitivity.

2.
Nanoscale ; 10(41): 19249-19253, 2018 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-30141815

RESUMO

We report a novel preparation method for a graphene/TiO2 nanohybrid using a supramolecular biomaterial (CDT1). CDT1 can offer an increase in the dispersibility of graphene in water and subsequent complexation of graphene and TiO2. This nanohybrid was applied to a perovskite solar cell and success was achieved in improving its photoelectric conversion efficiency.

3.
ACS Omega ; 2(4): 1424-1430, 2017 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-31457514

RESUMO

A new method for producing a dispersed gold nanoparticle (Au NP) array to anchor probe DNAs onto a DNA-sensing electrode has been developed. A homogenous gold sulfide (Au2S) core (precursor of Au NP) was biomineralized in the cavity of a mutant apoferritin (K98E) with enhanced negative outer-surface charges. We employed a slow chemical reaction system utilizing a stable cationic gold complex. K98E could attract the gold complex, and Au2S NPs were synthesized. K98E enabled dispersed placement of the synthesized Au2S core onto a cationic 3-aminopropyltriethoxysilane (APTES) layer on a substrate. UV-ozone treatment eliminated the protein shells and APTES layer. X-ray photoelectron spectroscopy confirmed that the Au2S core was reduced to Au NPs under the same treatment. Atomic force microscopy (AFM) clearly showed that the combination of apoferritin versatility, chemical system design, and UV-ozone treatment successfully produced a dispersed Au NP array on the substrate.

4.
ACS Omega ; 2(9): 5478-5485, 2017 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31457816

RESUMO

Fibrous nanomaterials have been widely employed toward the improvement of photovoltaic devices. Their light-trapping capabilities, owing to their unique structure, provide a direct pathway for carrier transport. This paper reports the improvement of perovskite solar cell (PSC) performance by a well-dispersed TiO2-coated gold nanowire (GNW) in a TiO2 cell layer. We used an artificially designed cage-shaped protein to synthesize a TiO2-coated GNW in aqueous solution under atmospheric pressure. The artificially cage-shaped protein with gold-binding peptides and titanium-compound-biomineralizing peptides can bind GNWs and selectively deposit a thin TiO2 layer on the gold surface. The TiO2-coated GNW incorporated in the photoelectrodes of PSCs increased the external quantum efficiency within the range of 350-750 nm and decreased the internal resistance by 12%. The efficient collection of photogenerated electrons by the nanowires boosted the power conversion efficiency by 33% compared to a typical mesoporous-TiO2-nanoparticle-only electrode.

5.
Nanotechnology ; 27(42): 425401, 2016 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-27632684

RESUMO

In this work, we demonstrate homogeneously distributed In0.3Ga0.7N/GaN quantum disks (QDs), with an average diameter below 10 nm and a high density of 2.1 × 10(11) cm(-2), embedded in 20 nm tall nanopillars. The scalable top-down fabrication process involves the use of self-assembled ferritin bio-templates as the etch mask, spin coated on top of a strained In0.3Ga0.7N/GaN single quantum well (SQW) structure, followed by a neutral beam etch (NBE) method. The small dimensions of the iron cores inside ferritin and nearly damage-free process enabled by the NBE jointly contribute to the observation of photoluminescence (PL) from strain-relaxed In0.3Ga0.7N/GaN QDs at 6 K. The large blueshift of the peak wavelength by over 70 nm manifests a strong reduction of the quantum-confined Stark effect (QCSE) within the QD structure, which also agrees well with the theoretical prediction using a 3D Schrödinger equation solver. The current results hence pave the way towards the realization of large-scale III-N quantum structures using the combination of bio-templates and NBE, which is vital for the development of next-generation lighting and communication devices.

6.
J Biosci Bioeng ; 122(5): 528-532, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27133793

RESUMO

We have developed an easy and rapid screening method of peptide aptamers with high affinity for a target material TiO2 using M13 phage-display and panning procedure. In a selection step, the phage-substrate complexes and Escherichia coli cells were directly applied by electric pulse for electroporation, without separating the objective phages from the TiO2 nanoparticles. Using this simple and rapid method, we obtained a novel peptide aptamer (named ST-1 with the sequence AYPQKFNNNFMS) with highly strong binding activity for TiO2. A cage-shaped protein fused with both ST-1 and an available carbon nanotube-affinity peptide was designed and produced in E. coli. The multi-functional supraprotein could efficiently mineralize a titanium-compound around the surface of single-wall carbon nanotubes (SWNTs), indicating that the ST-1 is valuable in the fabrication of nano-composite materials with titanium-compounds. The structural analysis of ST-1 variants indicated the importance of the N-terminal region (as a motif of AXPQKX6S) of the aptamer in the TiO2-binding activity.


Assuntos
Aptâmeros de Peptídeos/isolamento & purificação , Técnicas de Visualização da Superfície Celular/métodos , Eletroporação/métodos , Titânio/química , Aptâmeros de Peptídeos/química , Bacteriófagos/química , Bacteriófagos/genética , Sítios de Ligação , Corantes/química , Escherichia coli , Nanocompostos/química , Nanopartículas/química , Nanotubos de Carbono/química , Especificidade por Substrato
7.
ACS Appl Mater Interfaces ; 8(12): 8192-200, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26943894

RESUMO

An alternative way to construct a stable p-n junction on graphene-based field effect transistor (G-FET) through physical adsorption of ferritin (spherical protein shell) is presented. The produced p-n junction on G-FET could also operate through water-gate. Native ferritins are known to be negatively charged in wet condition; however, we found that native negatively charged ferritins became positively charged after performing electron beam (EB)-irradiation. We utilized this property to construct p-n junction on G-FET. We found also that EB-irradiation could remove the effect of charged impurity adsorbed on graphene layer, thus the Dirac point was adjusted to gate voltage Vg = 0.


Assuntos
Ferritinas/química , Grafite/química
8.
Nanotechnology ; 26(28): 285601, 2015 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-26112188

RESUMO

We produced a thermostable TiO2-(anatase)-coated multi-walled-carbon-nanotube (MWNT) nanocomposite for use in dye-sensitized solar cells (DSSCs) using biological supuramolecules as catalysts. We synthesized two different sizes of iron oxide nanoparticles (NPs) and arrayed the NPs on a silicon substrate utilizing two kinds of genetically modified cage-shaped proteins with silicon-binding peptide aptamers on their outer surfaces. Chemical vapor deposition (CVD) with the vapor-liquid-solid phase (VLS) method was applied to the substrate, and thermostable MWNTs with a diameter of 6 ± 1 nm were produced. Using a genetically modified cage-shaped protein with carbon-nanomaterials binding and Ti-mineralizing peptides as a catalyst, we were able to mineralize a titanium compound around the surface of the MWNT. The products were sintered, and thin TiO2-layer-coated MWNTs nanocomoposites were successfully produced. Addition of a 0.2 wt% TiO2-coated MWNT nanocomposite to a DSSC photoelectrode improved current density by 11% and decreased electric resistance by 20% compared to MWNT-free reference DSSCs. These results indicate that a nanoscale TiO2-layer-coated thermostable MWNT structure produced by our mutant proteins works as a superior electron transfer highway within TiO2 photoelectrodes.


Assuntos
Corantes/química , Nanocompostos/química , Nanotubos de Carbono/química , Fotoquímica/métodos , Titânio/química , Técnicas Eletroquímicas , Elétrons , Ferritinas/química , Ferritinas/genética , Nanotubos de Carbono/ultraestrutura , Energia Solar
9.
Sci Rep ; 5: 9371, 2015 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-25792119

RESUMO

Quantum dots photonic devices based on the III-V compound semiconductor technology offer low power consumption, temperature stability, and high-speed modulation. We fabricated GaAs nanodisks (NDs) of sub-20-nm diameters by a top-down process using a biotemplate and neutral beam etching (NBE). The GaAs NDs were embedded in an AlGaAs barrier regrown by metalorganic vapor phase epitaxy (MOVPE). The temperature dependence of photoluminescence emission energies and the transient behavior were strongly affected by the quantum confinement effects of the embedded NDs. Therefore, the quantum levels of the NDs may be tuned by controlling their dimensions. We combined NBE and MOVPE in a high-throughput process compatible with industrial production systems to produce GaAs NDs with tunable optical characteristics. ND light emitting diode exhibited a narrow spectral width of 38 nm of high-intensity emission as a result of small deviation of ND sizes and superior crystallographic quality of the etched GaAs/AlGaAs layer.

10.
ChemSusChem ; 7(10): 2805-10, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25111295

RESUMO

We designed and mass-produced a versatile protein supramolecule that can be used to manufacture a highly efficient dye-sensitized solar cell (DSSC). Twelve single-walled carbon-nanotube (SWNT)-binding and titanium-mineralizing peptides were genetically integrated on a cage-shaped dodecamer protein (CDT1). A process involving simple mixing of highly conductive SWNTs with CDT1 followed by TiO2 biomineralization produces a high surface-area/weight TiO2 -(anatase)-coated intact SWNT nanocomposite under environmentally friendly conditions. A DSSC with a TiO2 photoelectrode containing 0.2 wt % of the SWNT-TiO2 nanocomposite shows a current density improvement by 80% and a doubling of the photoelectric conversion efficiency. The SWNT-TiO2 nanocomposite transfers photon-generated electrons from dye molecules adsorbed on the TiO2 to the anode electrode swiftly.


Assuntos
Proteínas de Bactérias/química , Corantes/química , Proteínas de Ligação a DNA/química , Nanocompostos/química , Titânio/química , Técnicas Eletroquímicas , Microscopia Eletrônica de Transmissão , Nanocompostos/ultraestrutura , Fotoquímica/métodos , Energia Solar , Análise Espectral Raman
11.
Colloids Surf B Biointerfaces ; 118: 25-30, 2014 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-24727527

RESUMO

The adsorption mechanism of titanium-binding peptide (TBP) on metal oxide substrates was investigated by evaluating the adsorption behavior of ferritins with various alanine-substituted TBPs. Results revealed that (a) a positively charged amino acid, lysine (K) or arginine (R), in TBP can anchor ferritin to negative zeta-potential substrates, (b) the adsorption force of K is stronger than R, and (c) local electrostatic interactions and flexibility of TBP directly affect adsorption. Based on these findings, selective ferritin adsorption on SiO2 with TiOX patterned surfaces in a surfactant-free condition was demonstrated. Alanine-substituted TBP with one positively charged amino acid (K) and one negatively charged amino acid (D), achieved ferritin-selective adsorption without a surfactant. The importance of controlled electrostatic forces between TBP and a substrate for selective adsorption without a surfactant was clearly demonstrated.


Assuntos
Aminoácidos/química , Peptídeos/química , Tensoativos/química , Titânio/química , Adsorção , Cromatografia por Troca Iônica , Ferritinas/química , Modelos Moleculares , Polissorbatos/química , Dióxido de Silício/química , Análise Espectral , Eletricidade Estática
12.
J Nanosci Nanotechnol ; 14(4): 3193-201, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24734754

RESUMO

(Apo)ferritins are cage-shaped proteins which have recently received a great deal of attention because the inner cavity of the protein shell can be used as a size-restricted reaction field for the synthesis of nanomaterials. The biomineralization behavior and inorganic nanoparticle (NP) synthesis mechanism of (apo)ferritin in solution systems have been studied but the mineralization behavior of (apo)ferritin on the substrates has not yet been well studied. Here, we conducted quantitative and kinetic analyses of the mineralization behavior of immobilized (apo)ferritin on a polyelectrolyte multilayer (PEM) using quartz crystal microbalance (QCM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) techniques. We demonstrated that the (apo)ferritin immobilized on a substrate synthesizes a ferrihydrite core within the confines of the protein cage; similar to a solution dispersed system. In addition, we applied a ferritin/apoferritin blended monolayer to the study of iron mineralization and revealed that biomineralization in this system is spatially selective. It is important to understand the mineralization mechanisms for the synthesis of other functional NPs as this approach has potential for a broad range of magnetic, catalytic, and biomedical sensing applications.


Assuntos
Ferritinas/química , Proteínas Imobilizadas/química , Ferro/química , Minerais/química , Adsorção , Animais , Apoproteínas/química , Compostos Férricos/química , Cavalos , Microscopia Eletrônica de Varredura , Espectroscopia Fotoeletrônica , Técnicas de Microbalança de Cristal de Quartzo
13.
Colloids Surf B Biointerfaces ; 113: 338-45, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24121077

RESUMO

We used a quartz crystal microbalance (QCM) to quantitatively characterize solid-phase poly(ethylene glycol) modification (PEGylation) of apoferritin that was electrostatically immobilized on the surface of a polyelectrolyte multilayer. The solid-phase PEGylation processes were monitored by analyzing QCM frequency shifts, which showed that the PEG chains were covalently introduced onto the surface of the immobilized apoferritin. We investigated the effect of PEG concentration, PEG molecular weight, and two-dimensional coverage of the immobilized apoferritin on the solid-phase PEGylation process in addition to the surface properties of the PEGylated apoferritin film, such as wettability and protein adsorption capacity. Since the reaction field is more spatially restricted in solid-phase PEGylation than in traditional aqueous-phase PEGylation, this study shows that a ferritin protein cage is potentially useful as a tailored building block, one that has well-defined structures different from the PEGylated ferritin prepared by an aqueous-phase approach.


Assuntos
Polietilenoglicóis/química , Polímeros/química , Apoferritinas/química , Peso Molecular , Propriedades de Superfície
14.
Langmuir ; 29(40): 12483-9, 2013 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-24028443

RESUMO

The first six peptides of multifunctional titanium binding peptide-1 bestowed recombinant L-ferritin, minT1-LF, was genetically engineered and used to fabricate multilayered nanoparticle architecture. The multifunctionality of minT1-LF enables specific binding of nanoparticle-accommodated minT1-LF to the silicon substrate surface and wet biochemical fabrication of gate oxide layer by its biomineralization activity. Three-dimensional (3D) nanoparticle architecture with multilayered structure was fabricated by the biological layer-by-layer method and embedded in a metal oxide-semiconductor device structure as a charge storage node of a flash memory device. The 3D-integrated multilayered nanoparticle architecture successfully worked as a charge storage node in flash memory devices that exhibited improved charge storage capacity compared with that of a conventional monolayer structure device.


Assuntos
Nanoestruturas/química , Microscopia Eletrônica de Transmissão , Nanoestruturas/ultraestrutura , Semicondutores , Volatilização
15.
Langmuir ; 29(41): 12737-43, 2013 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-24041254

RESUMO

The interparticle distance between nanoparticles (NPs) dispersed on on SiO2 was shown to be controlled by PEGylation. Ferritins with nanoparticle cores were prepared and PEGylated with poly(ethylene glycol)s (PEGs) of two different molecular weights. It was shown that the thickness of the PEG layer on the ferritin surface determines the interparticle distance under short Debye lengths. Under conditions where the Debye length was greater than the PEG layer thickness, distance between ferritins increased due to the electrostatic repulsive force. Results suggest that the PEG layer accommodated a small amount of counterions insufficient to cancel the ferritin outer surface charges. Simulation showed that ferritins adsorbed randomly and interparticle distance can be predicted theoretically. We demonstrate that PEGylated ferritins, that is, NP cores, can be dispersed on a surface with interval distances between particles determined by the combination of the ionic strength of the solution and the molecular weight of the PEG.


Assuntos
Ferritinas/química , Ácido Poliglicólico/química , Adsorção , Peso Molecular , Tamanho da Partícula , Dióxido de Silício/química , Eletricidade Estática , Propriedades de Superfície
16.
Nanotechnology ; 24(28): 285301, 2013 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-23787817

RESUMO

We successfully fabricated defect-free, distributed and sub-20-nm GaAs quantum dots (named GaAs nanodisks (NDs)) by using a novel top-down technique that combines a new bio-template (PEGylated ferritin) and defect-free neutral beam etching (NBE). Greater flexibility was achieved when engineering the quantum levels of ND structures resulted in greater flexibility than that for a conventional quantum dot structure because structures enabled independent control of thickness and diameter parameters. The ND height was controlled by adjusting the deposition thickness, while the ND diameter was controlled by adjusting the hydrogen-radical treatment conditions prior to NBE. Photoluminescence emission due to carrier recombination between the ground states of GaAs NDs was observed, which showed that the emission energy shift depended on the ND diameters. Quantum level engineering due to both diameter and thickness was verified from the good agreement between the PL emission energy and the calculated quantum confinement energy.


Assuntos
Arsenicais/química , Gálio/química , Nanoestruturas/química , Nanotecnologia/métodos , Pontos Quânticos , Biotecnologia/métodos , Ferritinas/química , Microscopia Eletrônica de Varredura , Nanoestruturas/ultraestrutura , Tamanho da Partícula , Polietilenoglicóis/química
17.
Yeast ; 30(1): 1-11, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23348717

RESUMO

The N-end rule pathway degrades proteins bearing a destabilization-inducing amino acid at the N-terminus. In this proteolytic system, Ubr ubiquitin ligases recognize and ubiquitylate substrates intended for degradation. Schizosaccharomyces pombe has two similar Ubr proteins, Ubr1 and Ubr11. Both proteins have unique roles in various cellular processes, although the ubr1∆ strain shows more severe defects. However, their involvement in the N-end rule pathway is unclear, and even the N-end rule pathway-dependent proteolytic activity has not been demonstrated in Sz. pombe. Here, we show that: (a) Sz. pombe has the N-end rule pathway in which only Ubr11, but not Ubr1, is responsible; and (b) the C-terminal fragment of the meiotic cohesin Rec8 (denoted as Rec8c) generated by separase-mediated cleavage is an endogenous substrate of the N-end rule pathway. Forced overexpression of stable Rec8c was deleterious in mitosis and caused a loss of the mini-chromosome. In unperturbed mitosis without overexpression, the rate of mini-chromosome loss was five-fold higher in the ubr11∆ strain. Since Rec8 is normally produced in meiosis, we examined whether meiosis and sporulation were affected in the ubr11∆ strain. In unperturbed meiosis, chromosome segregation occurred almost normally and viable spores were produced in the ubr11∆ cells, irrespective of the presence of undegraded endogenous Rec8c peptides.


Assuntos
Proteínas Fúngicas/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Schizosaccharomyces/enzimologia , Ubiquitina-Proteína Ligases/metabolismo , Deleção de Genes , Fosfoproteínas/metabolismo , Proteólise , Ubiquitinação
18.
Colloids Surf B Biointerfaces ; 102: 435-40, 2013 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-23010127

RESUMO

We investigated the origin of selective adsorption of titanium-binding ferritin (TBF), the outer surface of which is genetically modified with titanium-binding peptides (TBPs). By varying pH conditions (7-9), TBF adsorption behavior onto amphoteric and acidic oxide substrates was observed using atomic force microscopy, and the zeta potential of substrates was measured. This suggests that a TBP interacted with local charges such as -O(-), -OH(+), and -OH(2)(+) on substrates regardless of the constituent elements of the substrate, which makes it possible for TBF to adsorb on TiO(X), ZrO(2), Fe(2)O(3), and SiO(2) substrates despite the presence of an overall electrostatic repulsive force between TBF and the substrates. This also suggests that a surfactant, TWEEN20, can completely hamper attractive interaction between TBF and acidic oxide, but amphoteric oxide can withstand TWEEN20 interference.


Assuntos
Ferritinas/química , Peptídeos/química , Titânio/química , Compostos Férricos/química , Microscopia de Força Atômica , Dióxido de Silício/química , Zircônio/química
19.
Opt Express ; 20(22): 24856-63, 2012 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-23187252

RESUMO

We demonstrate a chiral meta-molecule in the ultraviolet (UV) and visible (VIS) regions using a complex of Au nanoparticles (NPs) and rod-shaped tobacco mosaic virus (TMV). Au NPs five nm in diameter are uniformly formed on peptide-modified TMV. The peptide-modified TMV with uniform-sized Au NPs has improved dispersion in solution. A negative circular dichroism (CD) peak is produced around 540 nm, at plasmonic resonance wavelength of Au NPs. Additionally, modification of a CD peak in the UV region is observed. Attaching NPs to a virus causes the enhancement and modification of CD peaks in both the UV and VIS regions. Our results open a new avenue for the preparation of three dimensional chiral metamaterials at optical frequencies.


Assuntos
Engenharia Genética , Ouro/química , Nanopartículas Metálicas/química , Vírus do Mosaico do Tabaco/química , Vírus do Mosaico do Tabaco/genética , Absorção , Dicroísmo Circular , Nanopartículas Metálicas/ultraestrutura , Soluções , Espectrofotometria Ultravioleta , Vírus do Mosaico do Tabaco/ultraestrutura
20.
J Colloid Interface Sci ; 378(1): 44-50, 2012 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-22564766

RESUMO

In this study, we quantitatively analyzed the electrostatic blend adsorption of ferritin and apoferritin onto the surface of the precursor films by using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The precursor films were successively prepared by the alternate adsorption of poly(diallyldimethylammonium chloride) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS) in the presence of 150 mM NaCl concentration onto the QCM substrate. We observed a monolayer adsorption of both ferritin and apoferritin by means of electrostatic interaction onto the outermost PDDA surface at pH 10.0. Under this condition, the composition of ferritin and apoferritin within the monolayer is linearly dependent on their ratios in the blended solution, thus showed an ideal blend adsorption behavior. The perfectly identical structure of ferritin and apoferritin should be contributed to this ideal blend adsorption behavior. We also studied the effects of total concentrations of their solution on ferritin and apoferritin blend adsorption. This study on the blend adsorption of ferritin and apoferritin by electrostatic interaction will be applied to the fabrication of multi-components homogeneous NP array because apoferritin can accommodate a variety of nanometer size inorganic materials within their interior spaces.


Assuntos
Apoferritinas/química , Nanoestruturas/química , Polietilenos/química , Polímeros/química , Compostos de Amônio Quaternário/química , Ácidos Sulfônicos/química , Animais , Cavalos , Concentração de Íons de Hidrogênio , Tamanho da Partícula , Cloreto de Sódio/química , Eletricidade Estática
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