Chong Rae Park

Preparation and Exceptional Lithium Anodic Performance of Porous Carbon-Coated ZnO Quantum Dots Derived from a Metal–Organic Framework

Hierarchically porous carbon-coated ZnO quantum dots (QDs) (~3.5 nm) were synthesized by a one-step controlled pyrolysis of the metal-organic framework IRMOF-1. We have demonstrated a scalable and facile synthesis of carbon-coated ZnO QDs without agglomeration by structural reorganization. This unique microstructure exhibits outstanding electrochemical performance (capacity, cyclability, and rate capability) when evaluated as an anode material for lithium ion batteries.

Biodistribution and anti-tumor efficacy of doxorubicin loaded glycol-chitosan nanoaggregates by EPR effect

An in vivo tumor targeting test of glycol-chitosan nanoaggregates was carried out with FITC-conjugated glycol-chitosan nanoaggregates (FTC-GC) and the doxorubicin conjugated glycol-chitosan (GC-DOX). To investigate its biodistribution in tumor-bearing rats, glycol-chitosan was labeled with fluorescein isothiocyanate (FITC), which formed nanoaggregates with a diameter of about 250 nm in aqueous media. GC-DOX nanoaggregates containing acid-sensitive spacers were prepared. The GC-DOX formed micelle-like nanoaggregates spontaneously in aqueous media. GC-DOX nanoaggregates had a narrow and unimodal size distribution, and its hydrodynamic diameter measured by dynamic light scattering ranged from 250 to 300 nm. A loading content of doxorubicin into GC-DOX nanoaggregates as high as 38%, with 97% loading efficiency, could be obtained using a physical entrapment method. A tumor-bearing animal model was developed by inoculating tumor cells into the back of a rat. The FTC-GC nanoaggregates were injected into the tail vein of tumor-bearing rats and their tissue distribution was examined. The FTC-GC nanoaggregates were distributed mainly in kidney, tumor and the liver and were scarcely observed in other tissues. They were maintained at a high level for 8 days and their distribution in tumor tissues increased gradually. This suggests that chitosan nanoaggregates accumulate passively in the tumor tissue due to the enhanced permeability and retention (EPR) effect. Doxorubicin loaded GC-DOX nanoaggregates (DOX/GC-DOX) were injected into the tail vein of tumor-bearing rats and their anti-tumor effect was examined. Tumor growth was suppressed over 10 days.

Nanophotosensitizers toward advanced photodynamic therapy of Cancer

UNLABELLED Photodynamic therapy (PDT) is a non-invasive treatment modality for selective destruction of cancer and other diseases and involves the colocalization of light, oxygen, and a photosensitizer (PS) to achieve photocytotoxicity. Although this therapeutic method has considerably improved the quality of life and life expectancy of cancer patients, further advances in selectivity and therapeutic efficacy are required to overcome numerous side effects related to classical PDT. The application of nanoscale photosensitizers (NPSs) comprising molecular PSs and nanocarriers with or without other biological/photophysical functions is a promising approach for improving PDT. In this review, we focus on four nanomedical approaches for advanced PDT: (1) nanocarriers for targeted delivery of PS, (2) introduction of active targeting moieties for disease-specific PDT, (3) stimulus-responsive NPSs for selective PDT, and (4) photophysical improvements in NPS for enhanced PDT efficacy. HIGHLIGHTS ► Conservation of normal tissues demands non-invasive therapeutic methods. ► PDT is a light-activated, non-invasive modality for selective destruction of cancers.► Success of PDT requires further advances to overcome the limitations of classical PDT. ►Nanophotosensitizers help improve target selectivity and therapeutic efficacy of PDT.

Effects of pre-carbonization on porosity development of activated carbons from rice straw

Abstract To investigate the pre-carbonization effect on the porosity development in activated carbons, two types of activated carbons were manufactured from rice straws by the one-stage and two-stage processes, respectively. Despite of the differences in thermal history of the two processes, pore-drilling and pore-widening occurred simultaneously to increase the micro and mesopore volumes up to the activation temperature of 800°C, above which pore-widening effect was however dominant, leading to the increase of mesopore volume. The micropore volume of the one-stage activated carbons (denoted S1AC) was considerably decreased, whereas that of the two-stage activated carbons (denoted S2AC) rarely changed with the increase of activation time. S2AC exhibited higher values of the BET surface area, micro and mesopore volumes than those of S1AC. This was attributed to the effect of the pre-carbonization that ensures the formation of relatively less defective carbonaceous structures.

Preparation of Highly Moisture‐Resistant Black‐Colored Metal Organic Frameworks

A straightforward method for significantly improving the moisture resistance of MOFs is described. In the proposed method, MOFs are subjected to thermal treatment, thus inducing the formation of an amorphous carbon coating on the MOF surfaces that prevents hydrolysis. This approach should open up new practical applications for MOFs in areas hitherto unexplored due to concerns regarding moisture sensitivity.

Advanced energy storage device: a hybrid BatCap system consisting of battery–supercapacitor hybrid electrodes based on Li4Ti5O12–activated-carbon hybrid nanotubes

The battery–supercapacitor hybrid electrode, consisting of both faradaic rechargeable battery components and non-faradaic rechargeable supercapacitor components in a single electrode, is successfully developed using Li4Ti5O12–activated carbon (LTO–AC) hybrid nanotubes in a negative electrode for an advanced energy storage device. Li4Ti5O12 and PVA-derived activated carbon are hybridized with morphological control over the one-dimensional (1D) tubular structures via an in situ sol–gel reaction combined with electrospinning, followed by a hydrothermal reaction and appropriate heat treatment. The prepared LTO–AC hybrid nanotubes are tested at a variety of charge–discharge rates as anode materials for use in lithium-ion rechargeable batteries that deliver a specific capacity in the range of 128–84 mA h g−1 over a 100–4000 mA g−1 charge–discharge rate in the potential range 1.0–2.5 V vs. Li/Li+. The hybridized LTO–AC hybrid nanotubes electrode is included in a new type of hybrid energy storage cell, denoted as BatCap, as the negative electrode using commercialized activated carbon (AC) as the positive electrode. The hybrid BatCap cell exhibits a high energy density of 32 W h kg−1 and a high power density of 6000 W kg−1, comparable to the properties of a typical AC symmetric capacitor.

Electrochemical capacitors based on electrodeposited ruthenium oxide on nanofibre substrates

Electrodeposition of RuO2 on electrospun TiO2 nanorods using cyclic voltammetry is shown to increase the capacitance of RuO2 .T his phenomenon can be attributed to the large surface areas of the nanorods. Among several ranges of deposition, the range from 0.25 to 1.45 V with respect to Ag/AgCl was effective. The electrode deposited with this range exhibited a specific capacitance of 534 F g −1 after deposition for 10 cycles with a scan rate of 50 mV s −1 .T he structural water content in RuO2 was quite different depending on the deposition potential range. Higher amounts of structural water increased the charge storage capability. The stability of the electrode was tested using cyclic voltammetry over 300 cycles.

MOF-derived ZnO and ZnO@C composites with high photocatalytic activity and adsorption capacity

Nanostructured ZnO materials have unique and highly attractive properties and have inspired interest in their research and development. This paper presents a facile method for the preparation of novel ZnO-based nanostructured architectures using a metal organic framework (MOF) as a precursor. In this approach, ZnO nanoparticles and ZnO@C hybrid composites were produced under several heating and atmospheric (air or nitrogen) conditions. The resultant ZnO nanoparticles formed hierarchical aggregates with a three-dimensional cubic morphology, whereas ZnO@C hybrid composites consisted of faceted ZnO crystals embedded within a highly porous carbonaceous species, as determined by several characterization methods. The newly synthesized nanomaterials showed relatively high photocatalytic decomposition activity and significantly enhanced adsorption capacities for organic pollutants.

Effect of multi-walled carbon nanotube dispersion on the electrical, morphological and rheological properties of polycarbonate/multi-walled carbon nanotube composites

The effect of a multiwalled carbon nanotube (MWCNT) dispersion on the electrical, morphological and rheological properties of polycarbonate (PC)/MWCNT composites was investigated, with and without pretreating the MWCNTs with hydrogen peroxide oxidation and lyophilization. The resulting PC/treated MWCNT composites showed higher electrical conductivity than the PC/untreated MWCNT composites. The morphological behavior indicated the treated composites to have greater dispersion of MWCNTs in the PC matrix. In addition, the electromagnetic interference shielding efficiency (EMI SE) of the treated composites was higher than that of the untreated ones. Rheological studies of the composites showed that the complex viscosity of the treated composites was higher than the untreated ones due to increased dispersion of the MWCNTs in the PC matrix, which is consistent with the electrical conductivity, EMI SE and morphological studies of the treated composites. The latter results suggested that the increased electrical conductivity and EMI SE of the treated composites were mainly due to the increased dispersion of MWCNTs in the PC matrix.

Preparation of a freestanding, macroporous reduced graphene oxide film as an efficient and recyclable sorbent for oils and organic solvents

In this work, we report the preparation of reduced graphene oxide (rGO)-based freestanding recyclable oil adsorbents via an environmentally friendly one-step low-temperature thermal reduction process. The heating rate was adjusted to successfully control the macroporosity of the rGO films (rGOFs), thereby modulating the adsorption behaviors. The adsorption capacities for a variety of organic solvents and oil species, measured as the percentage weight gain, were measured. Adsorption capacities up to 4500% of the initial rGOF weight were achieved. The films displayed excellent stability over 10 cycles of use and regeneration without incurring significant structural damage or a decrease in the oil adsorption properties. These results suggested that the rGOF-based oil adsorbents may potentially be useful as next-generation oil adsorbent materials for the remediation of the maritime ecosystem in the wake of a massive oil spill.