Browsing by Author "Liu, Ta-Chung"

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A Strategy to Synthesize Ultrahigh-N-Doped Hierarchical Carbons via Induced beta-Sheet from Silk Fibroin by In Situ Electrogelation/Electropolymerization
(2020-04-27)
Liu, Ta-Chung
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Li, Tsung-Yu
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Hung, Pei-Sung
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Liang, Chun-Wei
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Wu, Szu-Chen
Silk fibroin (SF) is recognized for its rich nitrogen content and has been explored for its promising potential in energy storage because of its hexagonal pseudographitic structure from the direct transformation of the unique secondary protein beta-sheet peptides of carbonized SF. In this work, we proposed a novel strategy that combined with in situ electrophoresis and electrogelation of SF as well as the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) for producing high-level nitrogen-doped (N-doped) carbons. A high beta-sheet content of SF can be synthesized in a three-dimensional (3D) inverse opaline skeleton via double-network microstructure (physical beta-sheet cross-linking and chemical PEDOT cross-linking) induced by the hydrophobic EDOTs. This synergistic effect regulating SF distribution and balancing the intra/intermoleeular hydrogen bonding among SF results in boosting beta-sheet contents. Herein, this 3D SF/PEDOT composite inverse opal (SPIO) exhibits a much ultrahigh-coneentrated beta-sheets (46.4%) compared to pure electrogelated SFIO with 16.4% of beta-sheets. After subsequent pyrolysis, a high-level (14.7%) N-doped pseudographitic carbon inverse opal is realized. For evaluation as a pseudocapacitor, this high-level N-doped pseudographitic carbon inverse opal shows a capacitance of 342 F g(-1) at 0.5 A g(-1) and a commendable energy density of 31.7 Wh kg(-1) at an ultrahigh power density of 25009 W kg(-1) (at 50 A g(-1)). After galvanostatic charging/discharging at 15 A g(-1) for 10000 cycles, the sample maintains an impressive capacitance retention of 89.8%.
Designing the Charge Storage Properties of Li-Exchanged Sodium Vanadium Fluorophosphate for Powering Implantable Biomedical Devices
(2019-05-09)
Lai, Chun-Han (Matt)
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Ashby, David S.
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Bashian, Nicholas H.
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Schoiber, Juergen
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Liu, Ta-Chung
The growing demand for bioelectronics has generated widespread interest in implantable energy storage. These implantable bioelectronic devices, powered by a complementary battery/capacitor system, have faced difficulty in miniaturization without compromising their functionality. This paper reports on the development of a promising high-rate cathode material for implantable power sources based on Li-exchanged Na1.5VOPO4F0.5 anchored on reduced graphene oxide (LNVOPF-rGO). LNVOPF is unique in that it offers dual charge storage mechanisms, which enable it to exhibit mixed battery/capacitor electrochemical behavior. In this work, electrochemical Li-ion exchange of the LNVOPF structure is characterized by operando X-ray diffraction. Through designed nanostructuring, the charge storage kinetics of LNVOPF are improved, as reflected in the stored capacity of 107 mAh g(-1) at 20C. A practical full cell device composed of LNVOPF and T-Nb2O5, which serves as a pseudocapacitive anode, is fabricated to demonstrate not only high energy/power density storage (100 Wh kg(-1) at 4000 W kg(-1)) but also reliable pulse capability and biocompatibility, a desirable combination for applications in biostimulating devices. This work underscores the potential of miniaturizing biomedical devices by replacing a conventional battery/capacitor couple with a single power source.
Exploring the correlation between P2P Applications and Network Architecture
(2009)
Chen, Chang-Sheng
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Liu, Ta-Chung
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Su, Chun-Hsien
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交大名義發表
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National Chiao Tung University
Nowadays, P2P applications dominate most of the network traffic and the access pattern poses a serious problem. While some P2P connections are formed within an ISP (or organization), most P2P connections are connected to the rest of the internet, at a high cost to the site. In this paper, we would like to study the topic on how different network architectures (i.e., asymmetric vs. symmetric network) influence the network traffic and the user behaviors with the peer-to-peer (P2P) applications. Many mechanisms could be adopted for improving the network performance of the site.
Gene-Embedded Nanostructural Biotic-Abiotic Optoelectrode Arrays Applied for Synchronous Brain Optogenetics and Neural Signal Recording
(2019-03-27)
Huang, Wei-Chen
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Chi, Hui-Shang
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Lee, Yi-Chao
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Lo, Yu-Chun
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Liu, Ta-Chung
Optogenetics is a recently established neuromodulation technique in which photostimulation is used to manipulate neurons with high temporal and spatial precision. However, sequential genetic and optical insertion with double brain implantation tends to cause excessive tissue damage. In addition, the incorporation of light-sensitive genes requires the utilization of viral vectors, which remains a safety concern. Here, by combining device fabrication design, nanotechnology, and cell targeting technology, we developed a new gene-embedded optoelectrode array for neural implantation to enable spatiotemporal electroporation (EP) for gene delivery/transfection, photomodulation, and synchronous electrical monitoring of neural signals in the brain via one-time implantation. A biotic-abiotic neural interface (called PG) composed of reduced graphene oxide and conductive polyelectrolyte 3,4-ethylenedioxythiophene-modified amphiphilic chitosan was developed to form a nanostructural hydrogel with assembled nanodomains for encapsulating nonviral gene vectors (called PEI-NT-pDNA) formulated by neurotensin (NT) and polyethylenimine (PEI)-coupled plasmid DNA (pDNA). The PG can maintain high charge storage ability to respond to a minimal current of 125 mu A for controllable gene delivery. The in vitro analysis of PG-PEI-NT-pDNA on the microelectrode array chip showed that the microelectrodes provided electrically inductive electropermeabilization, which permitted gene transfection into localized rat adrenal pheochromocytoma cells with a strong green fluorescent protein expression that was up to 8-fold higher than that in nontreated cells. Furthermore, the in vivo implantation enabled on-demand spatiotemporal gene transfection to neurons with 10-fold enhancement of targeting ability compared with astrocytes. Finally, using the real optogenetic opsin channelrhodopsin-2, the flexible neural probe incorporated with an optical waveguide fiber displayed photoevoked extracellular spikes in the thalamic ventrobasal region after focal EP for only 7 days, which provided a proof of concept for the use of photomodulation to facilitate neural therapies.
Highly sensitive/selective 3D nanostructured immunoparticle-based interface on a multichannel sensor array for detecting amyloid-beta in Alzheimer's disease
(2018-01-01)
Liu, Ta-Chung
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Lee, Yi-Chao
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Ko, Chiung-Yuan
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Liu, Ren-Shyan
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Ke, Chien-Chih
Accumulation of beta-amyloid (A beta) peptides is highly associated with Alzheimer's disease (AD) progression in prevailing studies. The successful development of an ultrasensitive detection assay for A beta is a challenging task, especially from blood-based samples. Methods: We have developed a one-step electrophoresis/electropolymerization strategy for preparing a CSIP hierarchical immunoelectrochemical interface that is easily integrated into a PoCT device. The interface includes conductive silk fibroin-based immunoparticles (CSIPs) via electropolymerized Poly(3,4-ethylenedioxythiophene) (PEDOT) bridging to enable on-site electrochemical detection of serum amyloid-beta(42) (A beta(42)) and -beta(40) (A beta(40)) peptides from an AD blood test. In addition, micro-positron emission tomography (microPET) neuroimaging and behavioral tests were simultaneously performed. Results: This nanostructured conductive interface favors penetration of water-soluble biomolecules and catalyzes a redox reaction, providing limits of detection (LOD) of 6.63 pg/mL for A beta(40) and 3.74 pg/mL for A beta(42). Our proof-of-concept study confirms that the multi-sensing electrochemical immunosensor array (MEIA) platform enables simultaneous measurement of serum A beta(42) and A beta(40) peptide levels and is more informative in early stage AD animals than amyloid-labeling A beta plaque PET imaging and behavioral tests. Conclusion: We believe this study greatly expands the applications of silk fibroin-based materials, is an important contribution to the advancement of biomaterials, and would also be valuable in the design of new types of multichannel electrochemical immunosensor arrays for the detection of other diseases.
Implantable Graphene-based Neural Electrode Interfaces for Electrophysiology and Neurochemistry in In Vivo Hyperacute Stroke Model
(2016-01-13)
Liu, Ta-Chung
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Chuang, Min-Chieh
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Chu, Chao-Yi
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Huang, Wei-Chen
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Lai, Hsin-Yi
Implantable microelectrode arrays have attracted considerable interest due to their high temporal and spatial resolution recording of neuronal activity in tissues. We herein presented an implantable multichannel neural probe with multiple real-time monitoring of neural-chemical and neural-electrical signals by a nonenzymatic neural-chemical interface, which was designed by creating the newly developed reduced graphene oxide-gold oxide (rGO/Au2O3) nanocomposite electrode. The modified electrode on the neural probe was prepared by a facile one-step cyclic voltammetry (CV) electrochemical method with simultaneous occurrence of gold oxidation and GOs reduction to induce the intimate attachment by electrostatic interaction using chloride ions (Cl-). The rGO/Au2O3-modified electrode at a low deposition scan rate of 10 mVs(-1) displayed significantly improved electrocatalytic activity due to large active areas and well-dispersive attached rGO sheets. The in vitro amperometric response to H2O2 demonstrated a fast response of less than 5 s and a very low detection limit of 0.63 mu M. In in vivo hyperacute stroke model, the concentration of H2O2 was measured as 100.48 +/- 4.52 mu M for rGO/Au2O3 electrode within 1 h photothrombotic stroke, which was much higher than that (71.92 mu M +/- 2.52 mu M) for noncoated electrode via in vitro calibration. Simultaneously, the somatosensory-evoked potentials (SSEPs) test provided reliable and precise validation for detecting functional changes of neuronal activities. This newly developed implantable probe with localized rGO/Au2O3 nanocomposite electrode can serve as a rapid and reliable sensing platform for practical H2O2 detection in the brain or for other neural-chemical molecules in vivo.
Improvement in photovoltaic performance for hybrid P3HT/elongated CdS nanocrystals solar cells with F-doped SnO(2) arrays
(2010-01-01)
Liao, Hung-Chou
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Lin, Chin-Ching
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Chen, Yu-Wei
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Liu, Ta-Chung
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Chen, San-Yuan
Hybrid CdS/P3HT photovoltaic devices using F-doped SnO(2) (FTO)-coated ZnO nanorod arrays as electrodes were studied in this work. The crystalline FTO, made using low-cost spray pyrolysis deposition (SPD), displayed a nominally complete and uniform coating over the entire outer surface of the ZnO nanorods. The photovoltaic performance of the CdS/P3HT photovoltaic devices increased with the FTO-coated ZnO nanorod length and thickness of the FTO layer, due to improvement in collecting photogenerated electrons, which results in the increased short circuit current density (J(SC)) and fill factor (FF) of the devices. The incorporation of CdS into the P3HT greatly enhanced the JSC of the devices with a nanorod FTO electrode. The power conversion efficiency (PCE) of the device with a ZnO nanorod length of 320 nm was increased from 0.37% for P3HT without CdS to 1.8% with CdS of AR = 1 (spherical shape). With a further increase of the AR of the CdS nanocrystal to 4, the PCE was further increased up to 2.6%. However, longer CdS nanocrystals conversely caused deterioration in PCE as a result of the nanorod array morphology. These results indicate that, although increased nanorod length could improve the photocurrent and efficiency, other factors, such as P3HT infiltration, nanorod array morphology and CdS nanocrystal length are required for obtaining the optimal performance of these devices.
Improvement in photovoltaic performance for hybrid P3HT/elongated CdS nanocrystals solar cells with F-doped SnO2 arrays
(2010-01-01)
Liao, Hung-Chou
;
Lin, Chin-Ching
;
Chen, Yu-Wei
;
Liu, Ta-Chung
;
Chen, San-Yuan
Hybrid CdS/P3HT photovoltaic devices using F-doped SnO2 (FTO)-coated ZnO nanorod arrays as electrodes were studied in this work. The crystalline FTO, made using low-cost spray pyrolysis deposition (SPD), displayed a nominally complete and uniform coating over the entire outer surface of the ZnO nanorods. The photovoltaic performance of the CdS/P3HT photovoltaic devices increased with the FTO-coated ZnO nanorod length and thickness of the FTO layer, due to improvement in collecting photogenerated electrons, which results in the increased short circuit current density (J(SC)) and fill factor (FF) of the devices. The incorporation of CdS into the P3HT greatly enhanced the JSC of the devices with a nanorod FTO electrode. The power conversion efficiency (PCE) of the device with a ZnO nanorod length of 320 nm was increased from 0.37% for P3HT without CdS to 1.8% with CdS of AR = 1 (spherical shape). With a further increase of the AR of the CdS nanocrystal to 4, the PCE was further increased up to 2.6%. However, longer CdS nanocrystals conversely caused deterioration in PCE as a result of the nanorod array morphology. These results indicate that, although increased nanorod length could improve the photocurrent and efficiency, other factors, such as P3HT infiltration, nanorod array morphology and CdS nanocrystal length are required for obtaining the optimal performance of these devices.
Multifunctional 3D Patternable Drug-Embedded Nanocarrier-Based Interfaces to Enhance Signal Recording and Reduce Neuron Degeneration in Neural Implantation
(2015-07-22)
Huang, Wei-Chen
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Lai, Hsin-Yi
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Kuo, Li-Wei
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Liao, Chia-Hsin
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Chang, Po-Hsieh
Newly reduced graphene oxide/gold oxide neural-chemical interface on multi-channel neural probes to enhance the electrochemical properties for biosensors
(2016-01-01)
Liu, Ta-Chung
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Chu, Chao-Yi
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Chen, You-Yin
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Chen, San-Yuan
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材料科學與工程學系
In this study, a facile one-step Cyclic Voltammetry (CV) electrophoresis was proposed for designing a reduced graphene oxide/gold oxide (rGO/AuOx) modified electrode by using chloride ions (Cl-) with the simultaneous occurrence of gold oxidation and GO reduction to induce the intimate attachment of negatively charged rGO sheets on the positively charged Au+/Au3+ clusters by electrostatic interaction. The surface microstructure and the oxygen functional groups of rGO/AuOx can be tuned by controlling the dissolution rate of gold via the deposition scan rate. At a low deposition scan rate, the rGO/AuOx electrode with well-dispersive rGO sheets and large active sites can induce rapid electron transfer to promote H2O2 detection. The amperometric response results displayed a relative fast response of less than 5 s with a low detection limit of 0.63 mu M (S/N = 3). Also, the rGO/AuOx neural-chemical interface can be modified at the multi-channels on neural probe and they exhibited excellent sensing performance to H2O2. The results demonstrated that the rGO/AuOx modified electrode integrated with a neural probe using this one-step electrochemical deposition can provide a faster response and higher sensitivity by optimizing and controlling the surface microstructures of rGO/AuOx, which would serve as a platform for medical application such as biosensors for multi-sensing.
Remotely nano-rupturable yolk/shell capsules for magnetically-triggered drug release
(2011)
Hu, Shang-Hsiu
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Chen, You-Yin
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Liu, Ta-Chung
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Tung, Tsan-Hua
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Liu, Dean-Mo
Yolk/shell capsules containing a volume/hydrophobicity transformable core and an ultra-thin silica shell have been prepared. When an external magnetic field induced the temperature, the cores exhibit a significant triggering size shrinkage and the diameter decreases more than 10 times, causing solid shells destruction and physical collapse, leading to drug burst release.
Synergistic hierarchical silicone-modified polysaccharide hybrid as a soft scaffold to control cell adhesion and proliferation
(2014-08-01)
Huang, Wei-Chen
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Liu, Kun-Ho
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Liu, Ta-Chung
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Liu, Dean-Mo
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Chen, San-Yuan
In this study, a new type of polydimethylsiloxane-modified chitosan (PMSC) amphiphilic hydrogel was developed as a soft substrate to explore cellular responses for dermal reconstruction. The hydrogel wettability, mechanical stiffness and topography were controllable through manipulation of the degree of esterification (DE) between hydrophobic polydimethylsiloxane (PDMS) and hydrophilic N,O-(carboxymethyl)-chitosan (NOCC). Based on microphase separation, the incorporation of PDMS into NOCC increased the stiffness of the hybrid through the formation of self-assembled aggregates, which also provided anchor sites for cell adhesion. As the DE exceeded 0.39, the size of the PDMS-rich aggregates changed from nanoscale to microscale. Subsequently, the hierarchical architecture resulted in an increase in the tensile modulus of the hybrid gel up to fourfold, which simultaneously provided mechano-topographic guidance and allowed the cells to completely spread to form spindle shapes instead of forming a spherical morphology, as on NOCC (DE = 0). The results revealed that the incorporation of hydrophobic PDMS not only impeded acidic damage resulting from NOCC but also acted as an adhesion modification agent to facilitate long-term cell adhesion and proliferation on the soft substrate. As proved by the promotion on long-term type-I collagen production, the PMSC hybrid with self-assembled mechano-topography offers great promise as an advanced scaffold material for use in healing applications. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.