Yu-Te Liao

Fabrication and characterization of plastic-based flexible dye-sensitized solar cells consisting of crystalline mesoporous titania nanoparticles as photoanodes

We fabricated a highly efficient (with a solar-to-electricity conversion efficiency (η) of 5.51%), plastic-based, flexible dye-sensitized solar cell (DSSC). The photoanode was made of a crystalline mesoporous TiO2 film using a low-temperature electrophoretic deposition (EPD) process and compression treatment. The crystalline mesoporous TiO2 film was composed of secondary mesoporous TiO2 nanoparticles (MTNs, ca. 260 nm in size), synthesized by an aggregation of primary TiO2 nanocrystallites. In contrast to commercial TiO2 nanoparticles (i.e., P90, ca. 15.9 nm in size) that are widely used in DSSCs, the synthesized MTN-based film exhibited a higher surface area and porosity that increased dye adsorption, promoted effective electron transport, and enhanced light scattering, as evidenced by analysis of reflectance and absorbance spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). We also optimized the compression pressure for MTN- and P90-based DSSCs in order to achieve maximum efficiency. We further systematically investigated the cause for the enhanced conversion efficiency of MTN-based DSSCs by measuring incident photon-to-electron conversion efficiency (IPCE) curves and electrochemical impedance spectra (EIS). IPCE results explained the increase in the short-circuit photocurrent density (JSC) for MTN-based DSSCs, and EIS results indicated that MTN-based DSSCs exhibited a larger diffusion coefficient (Deff), longer effective diffusion length (Ln), longer electron lifetime (τe), and lower charge transfer resistance (Rk), resulting in a higher power conversion efficiency. The MTN-based DSSC fabricated in the study showed great potential for application in plastic-based DSSCs using room temperature procedures.

Liver cancer cells: Targeting and prolonged-release drug carriers consisting of mesoporous silica nanoparticles and alginate microspheres

A new microsphere consisting of inorganic mesoporous silica nanoparticles (MSNs) and organic alginate (denoted as MSN@Alg) was successfully synthesized by air-dynamic atomization and applied to the intracellular drug delivery systems (DDS) of liver cancer cells with sustained release and specific targeting properties. MSN@Alg microspheres have the advantages of MSN and alginate, where MSN provides a large surface area for high drug loading and alginate provides excellent biocompatibility and COOH functionality for specific targeting. Rhodamine 6G was used as a model drug, and the sustained release behavior of the rhodamine 6G-loaded MSN@Alg microspheres can be prolonged up to 20 days. For targeting therapy, the anticancer drug doxorubicin was loaded into MSN@Alg microspheres, and the (lysine)4-tyrosine-arginine-glycine-aspartic acid (K4YRGD) peptide was functionalized onto the surface of MSN@Alg for targeting liver cancer cells, hepatocellular carcinoma (HepG2). The results of the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay and confocal laser scanning microscopy indicate that the MSN@Alg microspheres were successfully uptaken by HepG2 without apparent cytotoxicity. In addition, the intracellular drug delivery efficiency was greatly enhanced (ie, 3.5-fold) for the arginine-glycine-aspartic acid (RGD)-labeled, doxorubicin-loaded MSN@Alg drug delivery system compared with the non-RGD case. The synthesized MSN@Alg microspheres show great potential as drug vehicles with high biocompatibility, sustained release, and targeting features for future intracellular DDS.

A metal-free, high nitrogen-doped nanoporous graphitic carbon catalyst for an effective aerobic HMF-to-FDCA conversion

We report a metal-free catalysis of the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acids (FDCA), employing zeolitic-imidazole framework (ZIF-8) derived, nitrogen-doped nanoporous carbon (denoted as NNC) as an effective heterogeneous catalyst. The effect of high graphitic nitrogen loading in the NNC on the catalytic production of FDCA was demonstrated and discussed.

Prussian Blue Derived Nanoporous Iron Oxides as Anticancer Drug Carriers for Magnetic‐Guided Chemotherapy

New nanoporous iron oxide nanoparticles with superparamagnetic behavior were successfully synthesized from Prussian blue (PB) nanocubes through a thermal conversion method and applied to the intracellular drug-delivery systems (DDS) of bladder cancer cells (i.e., T24) with controlled release and magnetic guiding properties. The results of the MTT assay and confocal laser scanning microscopy indicate that the synthesized iron oxide nanoparticles were successfully uptaken by T24 cells with excellent biocompatibility. An anticancer drug, that is, cisplatin, was used as a model drug, and its loading/release behavior was investigated. The intracellular drug delivery efficiency was greatly enhanced for the cisplatin-loaded, PB-derived, magnetic-guided drug-delivery system compared with the non-drug case. The synthesized nanomaterials show great potential as drug vehicles with high biocompatibility, controlled release, and magnetic targeting features for future intracellular DDS.

De Novo Synthesis of Gold-Nanoparticle-Embedded, Nitrogen-Doped Nanoporous Carbon Nanoparticles (Au@NC) with Enhanced Reduction Ability

A de novo synthesis of gold‐nanoparticle‐embedded, nitrogen‐doped nanoporous carbon nanoparticles (Au@NC) was investigated in this work. Chloroauroic acid was encapsulated inside zeolitic imidazolate framework‐8 (ZIF‐8) nanoparticles during the synthesis and later reduced into gold nanoparticles. The as‐synthesized gold‐nanoparticle‐embedded ZIF‐8 (Au@ZIF‐8) was then carbonized into Au@NC to enhance the stability of the nanoporous support. The results show that Au@NC exhibits a porous structure containing 3 wt % of gold. 2‐Methylimidazole provided an abundant amount of nitrogen (19 wt %) on the carbon matrix, which resulted in a hydrophilic and positively charged surface that is useful for the reduction of 4‐nitrophenol. The results of the catalytic reaction indicate that synthesized Au@NC could act as an effective catalyst with a turnover frequency (TOF) of 1185 g−1 s−1, which is higher than that of conventional naked Au nanoparticles (TOF: 339 g−1 s−1) and that of Au nanoparticles on activated carbon (TOF: 89 g−1 s−1). We propose that the enhanced performance of Au@NC resulted from homogeneous distribution of Au nanoparticles along with the hydrophilic and positively charged nitrogen‐doped carbon surface.

Synthesis of mesoporous silica nanoparticle-encapsulated alginate microparticles for sustained release and targeting therapy

This study reports the synthesis of mesoporous silica nanoparticle-encapsulated alginate microparticles (MSN@Alg) for sustained release and targeting therapy. The MSN@Alg was synthesized by air dynamical atomization, and the effects of several critical factors including concentration of alginate solution, flow rate of alginate solution, flow rate of air, the distance between nozzle and calcium bath, and stirring rate of calcium on the particle size of the synthesized MSN@Alg were investigated. For studying the sustained release properties of the MSN@Alg, rhodamine 6G (R6G) was used as a model drug, and we compared the release properties of R6G/MSN and R6G/MSN@Alg using different concentrations of alginate, concentrations and volumes of phosphate-buffered saline (PBS) buffer solutions. The sustained release behavior of the R6G/MSN@Alg system can be prolonged to 20 days with an optimal condition of 1 mg R6G/MSN@Alg to 2 mL PBS (10 mM). To achieve targeting therapy, an anticancer drug, doxorubicin (Dox), was loaded into MSN@Alg, and a arginine, glycine, and aspartic acid (RGD)-based peptide was functionalized onto the surface of MSN@Alg for the purpose of specific targeting. The results showed that the intracellular drug delivery efficiency was greatly enhanced (i.e., 3.5-folds) for the Dox/MSN@Alg-RGD drug delivery system.

Enhanced Charge Collection in MOF-525–PEDOT Nanotube Composites Enable Highly Sensitive Biosensing

Abstract With the aim of a reliable biosensing exhibiting enhanced sensitivity and selectivity, this study demonstrates a dopamine (DA) sensor composed of conductive poly(3,4‐ethylenedioxythiophene) nanotubes (PEDOT NTs) conformally coated with porphyrin‐based metal–organic framework nanocrystals (MOF‐525). The MOF‐525 serves as an electrocatalytic surface, while the PEDOT NTs act as a charge collector to rapidly transport the electron from MOF nanocrystals. Bundles of these particles form a conductive interpenetrating network film that together: (i) improves charge transport pathways between the MOF‐525 regions and (ii) increases the electrochemical active sites of the film. The electrocatalytic response is measured by cyclic voltammetry and differential pulse voltammetry techniques, where the linear concentration range of DA detection is estimated to be 2 × 10−6–270 × 10−6 m and the detection limit is estimated to be 0.04 × 10−6 m with high selectivity toward DA. Additionally, a real‐time determination of DA released from living rat pheochromocytoma cells is realized. The combination of MOF5‐25 and PEDOT NTs creates a new generation of porous electrodes for highly efficient electrochemical biosensing.

Mesoporous TiO2 Embedded with a Uniform Distribution of CuO Exhibit Enhanced Charge Separation and Photocatalytic Efficiency

Mixed metal oxide nanoparticles have interesting physical and chemical properties, but synthesizing them with colloidal methods is still challenging and often results in very heterogeneous structures. Here, we describe a simple method to synthesize mesoporous titania nanoparticles implanted with a uniform distribution of copper oxide nanocrystals (CuO@MTs). By calcining a titanium-based metal-organic framework (MIL-125) in the presence of Cu ions, we can trap the Cu in the TiO2 matrix. Removal of the organic ligand creates mesoporosity and limits phase separation so that tiny CuO nanocrystals form in the interstices of the TiO2. The CuO@MTs exhibits superior performance for photocatalytic hydrogen evolution (4760 μmol h-1) that is >90 times larger than pristine titania.

Fabrication of inorganic hydroxyapatite nanoparticles and organic biomolecules-dual encapsulated alginate microspheres

Inorganic hydroxyapatite nanoparticles (HANPs) and two kinds of organic biomolecules (i.e., fluorescent dye rhodamine 6G and protein lysozyme) were coencapsulated into alginate microspheres through an air dynamical atomization with optimized operation conditions. The synthesized microspheres have several advantages: HANP provides osteoconductivity and mechanical strength, rhodamine 6G (R6G) and lysozyme act as model drugs, and alginate provides excellent biocompatibility and carboxylate functionality. The results of fluorescent microscopic images indicated the successful dual encapsulation of HANPs and lysozyme inside the alginate microspheres. Furthermore, the results of 3- (4,5-cimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay showed that the fabricated alginate microspheres could be uptaken by HepG2 without apparent cytotoxicity. The dual encapsulated alginate microspheres fabricated in this study show great potential in many biomedical applications.

Gelatin-functionalized mesoporous silica nanoparticles with sustained release properties for intracameral pharmacotherapy of glaucoma

Herein, pilocarpine-loaded gelatin-covered mesoporous silica nanoparticles (denoted as p/GM) were intracamerally administrated into the anterior chamber for the reduction of intraocular pressure (IOP). The in vitro release profile shows that p/GM demostrates a high release percentage (50%) with a long-lasting release profile (36 days). The in vivo studies showed the maintenance of IOP in eye with ocular hypertension for 21 days.