Browsing by Author "Liu, Dean-Mo"

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A flexible drug delivery chip for the magnetically-control led release of anti-epileptic drugs
(2009-11-03)
Huang, Wei-Chen
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Hu, Shang-Hsiu
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Liu, Kun-Ho
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Chen, San-Yuan
;
Liu, Dean-Mo
A flexible drug delivery device was designed and fabricated using electrophoretic deposition of drug-carrying magnetic core-shell Fe(3)O(4) at SiO(2) nanoparticles onto an electrically conductive flexible PET substrate. The PET substrate was first patterned to a desired layout and subjected to deposition. In doing so, a uniform and nanoporous membrane could be produced. After lamination of the patterned membranes, a final chip-like device of thickness less than 0.5 mm is formed that is used for controlled delivery of an anti-epileptic drug, i.e., ethosuximide (ESM). The release of useful drugs can be controlled by directly modulating the magnetic field, and the chip is capable of demonstrating a variety of release profiles (i.e., slow release, sustained release, step-wise release and burst release profiles). These profiles can follow a wide spectrum of patterns ranging from zero to pulsatile release kinetics depending on the mode of magnetic operation. When the magnetic field was removed, the release behavior was instantly ceased, and vice versa. A preliminary in-vivo study using Long-Evans rat model has demonstrated a significant reduction in spike-wave discharge after the ESM was burst released from the chip under the same magnetic induction as in-vitro, indicating the potential application of the drug delivery chip. The flexible and membrane-like drug delivery chip utilizes drug-carrying magnetic nanoparticles as the building blocks that ensure a rapid and precise response to magnetic stimulus. Moreover, the flexible chip may offer advantages over conventional drug delivery devices by improvement of dosing precision, ease of operation, wider versatility of elution pattern, and better compliance. (C) 2009 Elsevier B.V. All rights reserved.
A Multifunctional Nanodevice Capable of Imaging, Magnetically Controlling, and In Situ Monitoring Drug Release
(2009-11-09)
Hu, Shang-Hsiu
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Kuo, Kuan-Ting
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Tung, Wei-Lin
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Liu, Dean-Mo
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Chen, San-Yuan
The multifunctional nanodevice described here integrates nanoscaled imaging, targeting, and controlled drug delivery, as well as the capability to monitor, in situ, the amount of drug released from the nanodevice with single-cell resolution. The nanodevice is composed of a polymer core/single-crystal iron oxide shell nanostructure bonded to a quantum dot. It shows outstanding release and retention characteristics via an external on/off manipulation of a high-frequency magnetic field. Upon magnetic stimulation, the single-crystal iron oxide shell demonstrates formation of nanometer-sized polycrystal domains of varying orientation. This allows a variation between retention and slow release of the drug. Further stimulation causes permanent rupturing of the shell, causing release of the drug in a burst-like manner. The quantum dot bonded to the nanodevice provides optical information for in situ monitoring of the drug release through use of a magnetic field. Remote control drug release from the nanodevice in a cancerous cell line (HeLa) was successfully accomplished using the same induction scenario. When nanodevices equipped with quantum dots are taken into cancerous cells, they are able to provide real-time drug dose information through a corresponding variation in emission spectrum. The nanodevice designed in this study has achieved its potential as a cell-based drug-delivery system for therapeutic applications.
A nanoporous optically transparent CdS-pHEMA hybrid with high optical sensing capability to dielectric liquids
(2009-03-04)
Liao, Hung-Chou
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Liu, Yen-Yu
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Chen, San-Yuan
;
Liu, Dean-Mo
;
材料科學與工程學系
A hydrogel-based functional hybrid with highly uniformly dispersed nanoparticulate CdS semiconductors is proposed. The hybrid is synthesized using an in situ polymerization following an in situ chemical reduction, where the resulting particle size and the distribution of CdS nanocrystals (NCs) can be narrowly manipulated. The hybrids, containing a relatively small amount of the CdS NCs, exhibit a pronounced photoluminescence spectrum shift when in contact with a number of dielectric liquids and such a pronounced dielectric-confinement effect has been experimentally verified and modeled in this study. The sensing capability of the hybrids with respect to dielectric liquids or molecules can be optically characterized and varied depending upon the intensity of the dielectric environment surrounding the hybrids. This work suggests that the transparent, nanoporous CdS-pHEMA hybrids can be used as highly efficient optical sensing materials.
A new type of gadodiamide-conjugated amphiphilic chitosan nanoparticle and its use for MR imaging with significantly enhanced contrastability
(2019-01-01)
Huang, Wei-Ting
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Ko, Yi-Ping
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Kuo, Ting-Yu
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Larsson, Mikael
;
Chang, Min-Chih
Magnetic resonance imaging (MRI) has been one of the most frequently-used diagnostic tools with high dimensional precision and positioning accuracy in clinical practices. To achieve contrast enhancement, utilization of high-efficient MR imaging contrast agents becomes a prime consideration and is indispensably reinforced the diagnosis precision, especially for the emerging precision medicine. Gadolinium (Gd)-based complexes has been widely used in current clinical MRI operations, however, numerous side effects were reported and highlighted in clinic. Those drawbacks render specific unmet needs to be clinically and technically improved with a new version of Gd-based compound. Here we report a newly-synthesized amphiphilic Gadodiamide-conjugated carboxymethyl-hexanoyl chitosan (termed as CHC-Gd) hybrid. The gadodiamide was selected is due to its smallest molecular size among other Gd-based complexes reported in literature, which assumed to give least influence on the resulting physicochemical properties such as colloidal stability, nanostructural evolution, and cytocompability, particularly self-assembly capability, of the resulting hybrid upon practical uses. Experimental outcomes showed a successful synthesis of the CHC-Gd hybrid using a one-pot synthesis protocol, where the gadodiamide complexes were covalently attached to the carboxyl groups along the CHC backbone. Self-assembly behavior can be observed to form a sphere-like nanoparticle of 100-200 nm in size as of amphiphilic native CHC macromolecule. Experimental outcomes indicated a largely improved cytocompatibility of the hybrid, compared with free Gd, suggesting the Gd+3 ions were well stabilized in the CHC nanostructure. Excellent contrastability in-vitro and in particular in vivo were measured, where for in-vivo test, a 10-40-folded reduction in dosage, compared with clinical Gd dose, was used and demonstrated a comparative-to-better imaging resolution and brightness. Therefore, from this preliminary investigation, a potential translation to clinical practice through the use of newly-synthesized amphiphilic CHC-Gd hybrid appears to be relatively promising.
A novel dual-structure, self-healable, polysaccharide based hybrid nanogel for biomedical uses
(2011)
Lin, Li-Jih
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Larsson, Mikael
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Liu, Dean-Mo
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材料科學與工程學系
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Department of Materials Science and Engineering
A new unique dual-structure hydrogel composed of nanostructures of amphiphilic chitosan (CHC) dispersed in a sodium alginate matrix (SAL) is presented. The successful creation of the composite is based on combining chitosan and sodium alginate without precipitation or agglomeration, which has not been previously reported. The CHC/SAL composite gels present a number of properties making them attractive for biomedical applications, in particular as implantable depot gels or in dermal applications. The gels are shown to form rapidly upon exposure of the combination solution to Ca(2+) containing gelation medium. The formed gels have storage moduli similar to soft tissue and display shear reversible gelation with fast recovery of mechanical properties, in addition to self-healing capability at certain compositions. The gels exhibit moderate swelling in deionized water and low swelling in simulated body fluid and cell culture media. The drug release from the composite gels is demonstrated using the hydrophobic drug all-trans retinoic acid, which is used in cancer and skin disorder therapies. The drug release initially occurs through a Fickian mechanism for a fraction of the loaded drug, where the fraction released during this process depends on release media and gel composition. A large fraction of the loaded drug can be retained for long term depot drug delivery. Furthermore, the CHC/SAL gels are determined to have low toxicity and skin irritation.
A novel multifunctional nano-platform with enhanced anti-cancer and photoacoustic imaging modalities using gold-nanorod-filled silica nanobeads
(2013)
Chen, Po-Jung
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Hu, Shang-Hsiu
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Fan, Chih-Tai
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Li, Meng-Lin
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Chen, You-Yin
The novel nano-seaurchin structure is characteristic of high-density and well-dispersed gold nanorods in one mesoporous silica nanobead. This nanoplatform provided increased photothermal stability, stable photoacoustic signal and highly efficient hyperthermia effect both in vitro and in vivo, indicating a powerful theranostic modality.
A pH-responsive amphiphilic chitosan-pyranine core-shell nanoparticle for controlled drug delivery, imaging and intracellular pH measurement
(2014)
Chou, Hao-Syun
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Hsiao, Meng-Hsuan
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Hung, Wei-Yang
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Yen, Tin-Yo
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Lin, Hui-Yi
A pH-responsive multifunctional core-shell nanoparticle, named CHC-PY nanoparticle, was successfully synthesized through electrostatic interaction of a thin shell of fluorescent pyranine dye (PY) with amphiphilic carboxymethylhexanoyl chitosan (CHC) nanoparticles. Upon encapsulating an anticancer drug, camptothecin (CPT), the CHC-PY nanoparticles exhibited an excellent drug loading efficiency (>95%). The resulting CPT-loaded CHC-PY nanoparticles also exhibited efficient cell internalization and good pH-responsive behavior. After being internalized (via efficient endocytosis pathway), the presence of fluorescent PY shell showed a pH-dependent emission characteristic which allowed the internalized CHC-PY nanoparticles acting as an indicator to distinguish the acidic microenvironment of cancerous cells, compared with normal cells. The pH-sensitive PY shell also acted as a modulator to control the CPT release wherein a higher release rate was detected at lower pH value, which is essentially a potential therapeutic niche for anticancer purposes. This new type of CHC-PY core-shell nanoparticle provides multiple functionality, where a synergistic performance of nanotherapeutics, imaging and even diagnosis at a cellular resolution can be achieved simultaneously.
A temperature-induced and shear-reversible assembly of latanoprost-loaded amphiphilic chitosan colloids: Characterization and in vivo glaucoma treatment
(2014-07-01)
Hsiao, Meng-Hsuan
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Chiou, Shih-Hwa
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Larsson, Mikael
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Hung, Kuo-Hsuan
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Wang, Yi-Ling
Hydrogels composed of assembled colloids is a material class that is currently receiving much interest and shows great promise for use in biomedical applications. This emerging material class presents unique properties derived from the combination of nanosized domains in the form of colloidal particles with a continuous gel network and an interspersed liquid phase. Here we developed an amphiphilic chitosan based, thermogelling, shear-reversible colloidal gel system for improved glaucoma treatment and addressed how preparation procedures and loading with the anti-glaucoma drug latanoprost and commonly used preservative benzalkonium chloride influenced the mechanical properties of and drug release from the colloidal gels. The results highlight that incorporated substances and preparation procedures have effects both on mechanical properties and drug release, but that the release of drug loaded in the colloidal carriers is mainly limited by transport out of the carriers, rather than by diffusion within the gel. The developed colloidal chitosan based gels hold outstanding biomedical potential, as confirmed by the ease of preparation and administration, low cytotoxicity in MTT assay, excellent biocompatibility and lowering of intraocular pressure for 40 days in a rabbit glaucoma model. The findings clearly justify further investigations towards clinical use in the treatment of glaucoma. Furthermore, the use of this shear-reversible colloidal gel could easily be extended to localized treatment of a number of critical conditions, from chronic disorders to cancer, potentially resulting in a number of new therapeutics with improved clinical performance. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Amphiphilically-modified gelatin nanoparticles: Self-assembly behavior, controlled biodegradability, and rapid cellular uptake for intracellular drug delivery
(2011)
Li, Wei-Ming
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Liu, Dean-Mo
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Chen, San-Yuan
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材料科學與工程學系
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Department of Materials Science and Engineering
An amphiphilic gelatin macromolecule capable of self-assembling to form micelle-like nanospheres for entrapping hydrophobic therapeutic molecules was successfully synthesized by grafting hydrophobic hexanoyl anhydrides to the amino groups of primitive gelatin. The substitution and grafting efficiency of the modified gelatin displayed a concentration-dependent manner toward the hexanoyl anhydride. The particle size and stability of the resulting self-assembled nanoparticles strongly depend on the degree of substitution of the gelatin. These gelatin nanoparticles exhibited an outstanding cytocompatibility and highly efficient drug encapsulation efficiency. The drug release profile of the anticancer agent (camptothecin) from the amphiphilic gelatin nanoparticles shows that the drug release mechanism is dominated by a combined effect of diffusion and degradation. Furthermore, a tunable sustained release and degradation behavior can be controlled by changing the degree of substitution of the gelatin. This new type of amphiphilic gelatin nanoparticles with controlled biodegradability and rapid cellular internalization may serve in the intracellular delivery of specific proteins or genes, permitting a novel design for intracellularly-based nanotherapy.
An amphiphilic silicone-modified polysaccharide molecular hybrid with in situ forming of hierarchical superporous architecture upon swelling
(2012)
Huang, Wei-Chen
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Chen, San-Yuan
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Liu, Dean-Mo
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材料科學與工程學系
;
Department of Materials Science and Engineering
Most hydrogels face the challenge that extensive water uptake deteriorates their mechanical integrity, which restricts potential uses and, in some cases, reduces therapeutic performance in biomedical applications. Motivated by the concept that structural optimization was able to improve the mechanical properties whilst maintaining a high water uptake, in this work we designed a new type of strong network, i.e. PDMS-crosslinked-NOCC polymer networks (PMSC CAPNs), by esterification between cross-linked PDMS diol (bis(hydroxyalkyl) terminated polydimethylsiloxane, silicone) and NOCC (N,O-carboxymethyl chitosan). By manipulating the cross-linked density with PDMS, a hierarchical structure in which PDMS-rich microgels were randomly distributed within the underlying PMSC hydrogel could be tailored through the control of polymer-polymer and polymer-solvent interactions. Besides, the resulting hybrid hydrogel displayed an efficient self-foaming capability to create in situ a hierarchical superporous microarchitecture upon swelling. The swelling behavior accounted for by Flory-Rehner theory indicated that the PDMS macromonomeric crosslinker not only caused the development of a superporous microarchitecture under solvation effects but also escalated both strength and elasticity to the final hydrogel. A new swelling model based on spectroscopic examination of the PMSC CAPNs was successfully proposed, which nicely defined the unique structural transition of the hydrogel upon swelling. We also envision the potential development of such a hybrid hydrogel for advanced biomedical applications.
BaMgAl10O17 : Eu blue phosphors with MgO coating and microwave irradiation
(2008-02-01)
Kuo, Kuan-Ting
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Lee, Shu-Ping
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Chen, San-Yuan
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Cheng, Bing-Ming
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Lu, Hsiao-Chi
Europium-activated barium magnesium aluminate (BaMgAl10O17:Eu (BAM)) phosphor particles were modified by surface coating with MgO using a polyol method. The photoluminescence (PL) properties of the MgO-coated BAM phosphors showed slightly improved blue-emission intensity compared to the unmodified ones, and reached a stronger peak intensity with 5.25% MgO coating, under vacuum ultraviolet (VUV) 147 nm excitation. Upon microwave irradiation on the MgO-coated BAM phosphors, the PL properties of the MgO-coated phosphors exhibited a much enhanced relative PL ratio, and a maximum relative PL ratio can be achieved when as high as 10.5% MgO was deposited on the phosphor surface. However, for mechanically ground phosphor powder, it was found that although the intensity of the MgO-coated BAM turned stronger with increasing MgO concentration under microwave irradiation, the purity of the resulting luminescence was slightly disrupted by the presence of a new peak near 470 nm, corresponding to BaMg3Al14O25 compound. (C) 2007 Elsevier Ltd. All rights reserved.
Bioactive TiO2 ultrathin film with worm-like mesoporosity for controlled drug delivery
(2012-04-01)
Chao, Chih-Shin
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Liu, Kun-Ho
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Tung, Wei-Lin
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Chen, San-Yuan
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Liu, Dean-Mo
Ultrathin mesoporous TiO2 coatings with a wormhole-like architecture were synthesized using evaporation-induced self-assembly method. The morphological and chemical structures of TiO2 films were characterized using small-angle and large-angle X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transformed infrared spectrometry (FTIR). The films demonstrated a thickness of similar to 120 nm and open-porous nanostructure. By taking advantage of the tortuosity of the worm-like mesoporous architecture associated with the chemistry of the TiO2 film, a sustained drug release using ibuprofen and vancomycin as model molecules from the film was determined. Besides, adhesion behavior of osteoblast cells, together with an in vitro apaptitic formation substantiated the cytocompatibility and bioactivity of the mesoporous TiO2 films. Such combined bioactive and drug-releasing functions of the TiO2 films with worm-like mesoporosity ensure an improved therapeutic performance for potential applications included orthopedics, dentistry, and drug delivery. (C) 2011 Elsevier Inc. All rights reserved.
Biomedical applications and colloidal properties of amphiphilically modified chitosan hybrids
(2013-09-01)
Larsson, Mikael
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Huang, Wei-Chen
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Hsiao, Meng-Hsuan
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Wang, Yen-Jen
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Nyden, Magnus
Chitosan is among the most abundant biopolymers on earth and has been either used or exhibited potential in a wide variety of industrial and biomedical applications. With the advancement of materials technologies, chitosan has been chemically modified to self-assemble into nanoarchitectures that are usable in advanced biomedical applications, such as drug nanocarriers, macroscopic injectables, tissue-engineering scaffolds, and nanoimaging agents. Colloidal amphiphilically modified chitosan (AMC) is a relatively recent material receiving increased attention with numerous publications addressing the medical advantages of specific systems. To date, many reviews have focused on the synthesis and biomedical properties of chitosan-based biomaterials, but a comprehensive study focusing on the colloidal properties of AMC in relation to biomedical performance appears to be lacking. This review provides a survey of the field, critically reviewing the colloidal properties and biomedical performance of AMC systems, such as nanoparticle drug delivery systems and macroscopic medical devices. Finally, the future development, market potential, and clinical implications of these promising colloidal-structured biomaterials are summarised. (C) 2013 Elsevier Ltd. All rights reserved.
Biomedical nanoparticle carriers with combined thermal and magnetic responses
(2009-02-01)
Liu, Ting-Yu
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Hu, Shang-Hsiu
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Liu, Dean-Mo
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Chen, San-Yuan
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Chen, I-Wei
Several biocompatible polymers are capable of large responses to small temperature changes around 37 degrees C In water, their responses include shrinkage and swelling as well as transitions in wettability. These properties have been harnessed for biomedical applications such as tissue engineering scaffolds and drug delivery carriers. A soft material/hard material hybrid in which a magnetic: metal or oxide is embedded in a temperature-responsive polymer matrix can combine the thermal sensitivity with magnetic signatures. Importantly, nanosizing such construct brings about new desirable features of extremely fast thermal response time, small magnetic hysteresis and enhanced magnetic susceptibility. Remote magnetic maneuvering and heating of the hybrid nanocolloids makes possible such applications as high-throughput enzyme separation and cell screening. Robust drug release on demand may also be obtained using these colloids and nanoparticle-derived thin film devices of combined thermal magnetic sensitivity. (C) 2008 Elsevier Ltd. All rights reserved.
Characterization and drug release behavior of chip-like amphiphilic chitosan-silica hybrid hydrogel for electrically modulated release of ethosuximide: an in vitro study
(2011)
Huang, Wei-Chen
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Lee, Tai-Jung
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Hsiao, Chi-Sheng
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Chen, San-Yuan
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Liu, Dean-Mo
The hydrogel response under environmental induction often decreases with time because of the mechanical weakness of polymeric hydrogels. Therefore, to reinforce the conventional hydrogels with improved responsiveness and service performance to an external stimulus, a hybrid hydrogel consisting of an amphiphilic chitosan and inorganic silica with a minimal concentration of organic cross-linker was made in order to ascertain the biocompatibility of resulting hydrogels and improve stimulus-induced responsiveness. The hybrid hydrogels generally illustrated a rapid drug (ethosuximide, ESM) release profile over a time period of less than 60 minutes. However, after assembling the hybrid hydrogels into a chip-like device, the sandwiched hybrid showed, under a number of applied DC voltages, a variety of release profiles from a burst-like to slow-elution pattern. A release mechanism was proposed and can be successfully explained as a result of combined effects of electrophoretic and electroosmotic operations. Kinetic analysis indicated that the ESM released from the chip-like device is essentially a shuttle between the swelling-controlled pattern and the diffusion-controlled mechanism, depending on the chemical compositions that were used to prepare the hybrid hydrogels under a given DC electrical field. The hybrid hydrogel chip-like device designed in this work has experimentally proved its technical potential as an electrically responsive drug delivery system to meet various biomedical demands.
Characterization and Structure Evolution of Ca-Al-CO(3) Hydrotalcite Film for High Temperature CO(2) Adsorption
(2010-07-01)
Wu, Chih-Hsiang
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Chang, Yen-Po
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Chen, San-Yuan
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Liu, Dean-Mo
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Yu, Ching-Tsung
In this work, monodispersed layered double hydroxide (Ca-Al LDHs) nanoparticles were synthesized by hydrothermal coprecipitation. Uniform thin films of layered double hydroxide on porous anodic aluminum oxide (AAO) substrates were formed by a direct precipitation process in a homogeneous suspension containing monodispersed Ca-Al layered double hydroxide nanoparticles. It was found that the formation of a designed hydrotalcite-like phase is strongly dependent on the [Ca2-]/ [Al(3+)] ratios, and that a minor CaCO(3) phase could possibly form simultaneously, which is attributed to the greater insolubility of CaCO(3) and the incompatibility of the ionic size of Al and Ca. The optimal CO(2) adsorption capacity appears in the layered Ca-OH-Al structure with the composition ratio of 3:1. Furthermore, the CO(2) adsorption mechanism varies with treatment temperature. Below 400 degrees C, the CO(2) adsorption is attributed to the LDH structure with a large surface area and pore volume, but above that the adsorption is due to the formation of CaCO(3) and CaO. The permeation behavior and CO(2) absorption can be explained by a preferable chemical and physical absorption of CO(2) on the layered double hydroxide and porous structure of the membrane.
Characterization and Structure Evolution of Ca-Al-CO3 Hydrotalcite Film for High Temperature CO2 Adsorption
(2010-07-01)
Wu, Chih-Hsiang
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Chang, Yen-Po
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Chen, San-Yuan
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Liu, Dean-Mo
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Yu, Ching-Tsung
In this work, monodispersed layered double hydroxide (Ca-Al LDHs) nanoparticles were synthesized by hydrothermal coprecipitation. Uniform thin films of layered double hydroxide on porous anodic aluminum oxide (AAO) substrates were formed by a direct precipitation process in a homogeneous suspension containing monodispersed Ca-Al layered double hydroxide nanoparticles. It was found that the formation of a designed hydrotalcite-like phase is strongly dependent on the [Ca2-]/ [Al3+] ratios, and that a minor CaCO3 phase could possibly form simultaneously, which is attributed to the greater insolubility of CaCO3 and the incompatibility of the ionic size of Al and Ca. The optimal CO2 adsorption capacity appears in the layered Ca-OH-Al structure with the composition ratio of 3:1. Furthermore, the CO2 adsorption mechanism varies with treatment temperature. Below 400 degrees C, the CO2 adsorption is attributed to the LDH structure with a large surface area and pore volume, but above that the adsorption is due to the formation of CaCO3 and CaO. The permeation behavior and CO2 absorption can be explained by a preferable chemical and physical absorption of CO2 on the layered double hydroxide and porous structure of the membrane.
Controlled pulsatile drug release from a ferrogel by a high-frequency magnetic field
(2007-09-18)
Hu, Shang-Hsiu
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Liu, Ting-Yu
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Liu, Dean-Mo
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Chen, San-Yuan
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材料科學與工程學系
Controlled Rupture of Magnetic Polyelectrolyte Microcapsules for Drug Delivery
(2008-10-21)
Hu, Shang-Hsiu
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Tsai, Chia-Hui
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Liao, Chen-Fu
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Liu, Dean-Mo
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Chen, San-Yuan
In this study, a magnetic-sensitive microcapsule was prepared using Fe3O4/poly(allylamine) (Fe3O4/PAH) polyelectrolyte to construct the shell. Structural integrity, microstructural evolution, and corresponding release behaviors of fluorescence dyes and doxorubicin were systematically investigated. Experimental observations showed that the presence of the magnetic nanoparticles in the shell structure allowed the shell structure to evolve from nanocavity development to final rupture of the shell under a given magnetic stimulus of different time durations. Such a microstructural evolution of the magnetic sensitive shell structure explained a corresponding variation of the drug release profile, from relatively slow release to burst-like behavior at different stages of stimulus. It has proposed that the presence of magnetic nanoparticles produced heat, due to magnetic energy dissipation (as Brown and Neel relaxations), and mechanical vibration and motion that induced stress development in the thin shell. Both mechanisms significantly accelerated the relaxation of the shell structure, causing such a microstructural evolution. With such a controllable microstructural evolution of the magnetic-sensitive shell structure, active substances can be well-regulated in a manageable manner with a designable profile according to the time duration under magnetic field. A cell culture study also indicated that the magnetic-sensitive microcapsules allowed a rapid uptake by the A549 cell line, a cancerous cell line, suggesting that the magnetic-sensitive microcapsule with controllable rupturing behavior of the shell offers a potential and effective drug carrier for anticancer applications.
Core-shell CuInS(2)/ZnS quantum dots assembled on short ZnO nanowires with enhanced photo-conversion efficiency
(2009-01-01)
Kuo, Kuan-Ting
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Liu, Dean-Mo
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Chen, San-Yuan
;
Lin, Chin-Ching
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材料科學與工程學系
A novel quantum-dot-based solar cell assembly consisting of core-shell Zn-doped CuInS(2)@ZnS (Zn-CIS@ZnS) quantum dots associated with short ZnO (5 mu m in length) nanowires was developed and systematically investigated in terms of its nanostructure and optical properties, associated with corresponding solar cell parameters, i.e., V(OC), J(SC), fill factor (FF). In this investigation, the photo-conversion efficiency of the Zn-CIS-based solar cells without the presence of the ZnS shell can be readily tuned by controlling the Zn/Cu ratio. Furthermore, the efficiency was significantly improved upon the deposition of a thin ZnS shell on these Zn-CIS QDs, where a significant enhancement in short-circuit current density (J(SC)) by 88% was observed because the ZnS coating is able to effectively eliminate excited electron recombination and enhance the charge transfer efficiency from Zn-CIS QDs to ZnO nanowires. Power-conversion efficiency as high as 0.71% can be attained, which is improved more than 2-3 times compared with that without ZnS coating. Such a unique nanoarchitecture through coupling with both core-shell QDs and short ZnO nanowires suggests a promising design for a quantum dot-based solar cell with considerably improved power-conversion efficiency.