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1.
Sci Rep ; 6: 23563, 2016 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-27005829

RESUMO

In this study, a novel photoluminescent quantum dots device with laser-processed microscale patterns has been demonstrated to be used as a white light emitting source. The pulsed laser ablation technique was employed to directly fabricate microscale square holes with nano-ripple structures onto the sapphire substrate of a flip-chip blue light-emitting diode, confining sprayed quantum dots into well-defined areas and eliminating the coffee ring effect. The electroluminescence characterizations showed that the white light emission from the developed photoluminescent quantum-dot light-emitting diode exhibits stable emission at different driving currents. With a flexibility of controlling the quantum dots proportions in the patterned square holes, our developed white-light emitting source not only can be employed in the display applications with color triangle enlarged by 47% compared with the NTSC standard, but also provide the great potential in future lighting industry with the correlated color temperature continuously changed in a wide range.

2.
J Biomed Mater Res A ; 102(7): 2197-207, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23907895

RESUMO

Geometric cues have been used for a variety of cell regulation and tissue regenerative applications. While the function of geometric cues is being recognized, their stability and degradation behaviors are not well known. Here, we studied the influence of degradation on uniaxial-stretch-induced poly(ε-caprolactone) (UX-PCL) ridge/groove arrays and further cellular responses. Results from accelerated hydrolysis in vitro showed that UX-PCL ridge/groove arrays followed a surface-controlled erosion, with an overall geometry remained even at ∼45% film weight loss. Compared to unstretched PCL flat surfaces and/or ridge/groove arrays, UX-PCL ridge/groove arrays achieved an enhanced morphological stability against degradation. Over the degradation period, UX-PCL ridge/groove arrays exhibited an "S-shape" behavior of film weight loss, and retained more stable surface hydrophilicity and higher film mechanical properties than those of unstretched PCL surfaces. Human mesenchymal stem cells (MSCs) aligned better toward UX-PCL ridge/groove arrays when the geometries were remained intact, and became sensitive with gradually declined nucleus alignment and elongation to the geometric degradation of ridges. We speculate that uniaxial stretching confers UX-PCL ridge/groove arrays with enhanced stability against degradation in erosive environment. This study provides insights of how degradation influences geometric cues and further cell responses, and has implications for the design of biomaterials with stability-enhanced geometric cues for long-term tissue regeneration.


Assuntos
Biomimética , Células-Tronco Mesenquimais/metabolismo , Poliésteres/metabolismo , Teste de Materiais , Microscopia Eletrônica de Varredura , Poliésteres/química , Propriedades de Superfície
3.
Beilstein J Nanotechnol ; 4: 632-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24205457

RESUMO

By utilizing the strongly induced plasmon coupling between discrete nano-antennas and quantitatively controlling the crystalline proportions of an underlying Ge2Sb2Te5 (GST) phase-change thin layer, we show that nanoscale light localizations in the immediate proximity of plasmonic nano-antennas can be spatially positioned. Isolated energy hot-spots at a subwavelength scale can be created and adjusted across the landscape of the plasmonic system at a step resolution of λ/20. These findings introduce a new approach for nano-circuitry, bio-assay addressing and imaging applications.

4.
Tissue Eng Part C Methods ; 19(7): 538-49, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23198964

RESUMO

Anisotropic geometries are critical for eliciting cell alignment to dictate tissue microarchitectures and biological functions. Current fabrication techniques are complex and utilize toxic solvents, hampering their applications for translational research. Here, we present a novel simple, solvent-free, and reproducible method via uniaxial stretching for incorporating anisotropic topographies on bioresorbable films with ambitions to realize stem cell alignment control. Uniaxial stretching of poly(ε-caprolactone) (PCL) films resulted in a three-dimensional micro-ridge/groove topography (inter-ridge-distance: ~6 µm; ridge-length: ~90 µm; ridge-depth: 200-900 nm) with uniform distribution and controllable orientation by the direction of stretch on the whole film surface. When stretch temperature (Ts) and draw ratio (DR) were increased, the inter-ridge-distance was reduced and ridge-length increased. Through modification of hydrolysis, increased surface hydrophilicity was achieved, while maintaining the morphology of PCL ridge/grooves. Upon seeding human mesenchymal stem cells (hMSCs) on uniaxial-stretched PCL (UX-PCL) films, aligned hMSC organization was obtained. Compared to unstretched films, hMSCs on UX-PCL had larger increase in cellular alignment (>85%) and elongation, without indication of cytotoxicity or reduction in cellular proliferation. This aligned hMSC organization was homogenous and stably maintained with controlled orientation along the ridges on the whole UX-PCL surface for over 2 weeks. Moreover, the hMSCs on UX-PCL had a higher level of myogenic genes' expression than that on the unstretched films. We conclude that uniaxial stretching has potential in patterning film topography with anisotropic structures. The UX-PCL in conjunction with hMSCs could be used as "basic units" to create tissue constructs with microscale control of cellular alignment and elongation for tissue engineering applications.


Assuntos
Materiais Biomiméticos/farmacologia , Biomimética/métodos , Diferenciação Celular/efeitos dos fármacos , Células-Tronco Mesenquimais/citologia , Desenvolvimento Muscular/efeitos dos fármacos , Poliésteres/farmacologia , Estresse Mecânico , Anisotropia , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Interações Hidrofóbicas e Hidrofílicas , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Desenvolvimento Muscular/genética , Fatores de Tempo , Técnicas de Cultura de Tecidos
5.
Appl Opt ; 50(35): 6536-42, 2011 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-22193133

RESUMO

This paper reports a maskless multiple-beam laser lithography technique for large-area nanostructure/microstructure fabrication. This lithography technique can flexibly generate arbitrary nanostructures/microstructures over a large area at a high speed. The feature size of the nanostructures/microstructures can be controlled by exposure time and moving speed of the nanostage. Functional predesigned patterns, including split-ring resonator metamaterials for terahertz waves, can be obtained. More complicated structures can be made by single- and double-exposure schemes to make hybrid nanostructures/microstructures and tune surface plasmonic resonance properties. Meanwhile, microstructures with large height to lateral dimension ratios (2.5D microstructures) fabricated on silicon substrates can be used as mold tools for soft lithography. This technology shows its unique capacity to create various nanostructures/microstructures for extensive applications.


Assuntos
Nanoestruturas/química , Nanotecnologia/métodos , Impressão , Ouro/química , Lasers , Nanotecnologia/instrumentação , Silício/química , Ressonância de Plasmônio de Superfície , Propriedades de Superfície
6.
Appl Opt ; 50(31): G74-9, 2011 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22086052

RESUMO

A novel hybrid approach to fabricate large-area well-ordered Ag/Au bimetallic nanodot arrays and its potential applications for biosensing is investigated. With the combination of laser interference lithography and the thermal annealing technique, Ag/Au bimetallic nanodots about ~50 nm are formed inside periodic nanodisk arrays at a dimension of ~530 nm on quartz substrates. Extinction spectra of the fabricated nanostructures show their localized surface plasmon resonance (LSPR) can be well controlled by Au concentration, which offers a means to flexibly tune the optical properties of the nanodot arrays. To study the sensitivity of the nanodot arrays, resonance wavelength changes per refractive index unit (RIU) are performed in different surrounding environments. This shows a 94% increase in peak shift per refractive index unit (nanometers/RIU) compared to the nanodot arrays formed only by thermal annealing. These results demonstrate a feasible approach to improve LSPR-based biosensor performance.

8.
Biomacromolecules ; 8(3): 807-16, 2007 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-17274653

RESUMO

Ultrathin poly(epsilon-caprolactone) (PCL) films were fabricated through biaxially drawn films made from three different methods, namely, spin casting, 2-roll milling, and solution casting. Biaxial drawn spin cast films yield thickness of 1.2 microm which is 9 and 12 times thinner that 2-roll mill and solvent cast films, respectively. The films fabricated were found to exhibit different drawing ratios. 2-roll mill film exhibits the highest drawing ratio of 4 x 4 while spin cast films can only draw up to a ratio of 2 x 2. The morphology of the films, studied using a polarized microscope and atomic force microscope, showed fine fibrillar networks of different thicknesses. Biaxially drawn 2-roll mill and solvent cast films showed thicker fibrils as compared to those for the spin cast films. Such a difference can be attributed to larger spherulites caused by slower cooling rates during melt pressing for both 2-roll mill and solvent cast films and smaller spherulites because of fast cooling during evaporation for spin cast films. Thermal analysis through differential scanning calorimetry revealed a slight increase in the peak-melting temperature after biaxial drawing. A drop in percentage crystallinity was also noted. The result of the water vapor transmission rate (WVTR) was found to be dependent on fabrication techniques that determine the spherulites formation. It was also found that the WVTR was inversely proportional to the thickness of the films. Tensile strength and modulus of the films showed significant improvements after biaxial stretching. By identifying the unique strengths of each individual PCL film produced via different techniques, it is possible to apply to different areas of membrane tissue engineering such as dermatology, ophthalmology, vascular graft engineering, and soft tissue regeneration.


Assuntos
Poliésteres/química , Engenharia Tecidual/métodos , Bioquímica/métodos , Cristalização , Temperatura Alta , Substâncias Macromoleculares/química , Microscopia de Força Atômica , Polímeros/química , Regeneração , Solventes/química , Estresse Mecânico , Temperatura , Resistência à Tração , Engenharia Tecidual/instrumentação , Água/química
9.
Appl Opt ; 43(15): 3145-50, 2004 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-15176204

RESUMO

A one-wavelength tuning method is proposed to solve the tuning difficulty in a tunable optical filter based on cascaded cells. This method ensures that the optical path difference variation of all of the cells for the tuning is less than one wavelength and lowers the relative tuning accuracy requirement. Simulations show that different cells have different cross talk and loss deterioration when they undergo an error in optical path difference between the O-ray and the E-ray. An optimal error ratio in each cell is obtained. Under the error ratio, the deterioration from the random error in every cell is further simulated.

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