Doyeon Bang

Convertible Organic Nanoparticles for Near-Infrared Photothermal Ablation of Cancer Cells†

Well-designed photothermal nanomaterials have attractedthe interest of many scientists pursuing a better means toaccurately diagnose cancer and assess the efficacy of treat-ment, because these materials enable therapies in which thetumor region is pin-pointed with a laser-guided light sourcewithout surgical intervention.

Targetable Gold Nanorods for Epithelial Cancer Therapy Guided by Near-IR Absorption Imaging

Well-designed nanoparticle-mediated, image-guided cancer therapy has attracted interest for increasing the efficacy of cancer treatment. A new class of smart theragnostic nanoprobes employing cetuximab (CET)-conjugated polyethylene glycol (PEG)ylated gold nanorods (CET-PGNRs) is presented; these nanoprobes target epithelial cancer cells using near-infrared light. The cetyltrimethylammonium bromide bilayer on GNRs is replaced with heterobifunctional PEG (COOH-PEG-SH) to serve as a biocompatible stabilizer and to increase specificity. The carboxylated GNRs are further functionalized with CET using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC-NHS) chemistry. To assess the potential of such GNRs, their optical properties, biocompatibility, colloidal stability, in vitro/in vivo binding affinities for cancer cells, absorption imaging, and photothermal therapy effects are investigated. CET-PGNRs exhibit excellent tumor targeting ability and strong potential for simultaneous absorption imaging and photothermal ablation of epithelial cancer cells.

Gadolinium‐Enriched Polyaniline Particles (GPAPs) for Simultaneous Diagnostic Imaging and Localized Photothermal Therapy of Epithelial Cancer

By loading Gd(III) inside NIR-absorbing polyaniline nanostructures, a novel diagnostic and photothermal agent with enhanced MR sensitivity, targeting ability, and photothermal ability to treat epithelial cancer is developed.

The work function of doped polyaniline nanoparticles observed by Kelvin probe force microscopy.

The work function of polyaniline nanoparticles in the emeraldine base state was determined by Kelvin probe force microscopy to be ~270 meV higher than that of similar nanoparticles in the emeraldine salt state. Normal tapping mode atomic force microscopy could not be used to distinguish between the particles due to their similar morphologies and sizes. Moreover, other potential measurement systems, such as using zeta potentials, were not suitable for the measurement of surface charges of doped nanoparticles due to their encapsulation by interfering chemical groups. Kelvin probe force microscopy can be used to overcome these limitations and unambiguously distinguish between the bare and doped polyaniline nanoparticles.

Effectively enhanced sensitivity of a polyaniline-carbon nanotube composite thin film bolometric near-infrared sensor

The polyaniline–carbon nanotube composite thin film bolometric near-infrared sensor exhibited more than a two orders of magnitude sensitivity enhancement over both the polyaniline thin film and carbon nanotube network NIR sensor. We also investigated the mechanism of the effectively enhanced sensitivity of the composite material and demonstrated that it is a synergistic effect due to the higher heat generation of carbon nanotubes and higher temperature coefficient of resistance of polyaniline.

Multimodal label-free detection and discrimination for small molecules using a nanoporous resonator

To detect chemical or biological threats, it is crucial that sensor devices can differentiate various target molecules. In general, each different sensing method has its own strengths and weaknesses due to their respective limitations. For example, although resonant sensors have high sensitivity, they are not able to discriminate target molecules. At the same time, although surface-enhanced Raman spectroscopy is a representative label-free detection method that can discriminate target molecules, its fabrication is often complex and expensive. Here we present a label-free multimodal nanoporous resonator-based system for small molecule detection and discrimination that combines the strengths of each of these sensing methods. Our approach is not only able to improve the sensitivity of the resonant sensor but it can also discriminate the target molecules. Furthermore, the fabrication process is swift (lasting <3 min) and convenient.

Highly sensitive detection of self-aggregated single-walled carbon nanotubes using a DNA-immobilized resonator

By using DNA linkers, we are able to conjugate self-crosslinked SWNTs which could be detected upon hybridization with a DNA immobilized resonator. The DNA immobilized resonator is able to detect SWNTs with a detection limit of 10 ng ml(-1) which was 2-3 orders of magnitude smaller than the reported SWNT toxicity concentration.

One-step electrochemical fabrication of vertically self-organized silver nanograss

Fabrication of one dimensional metal nanomaterials offers many beneficial aspects due to their unique size- and shape-dependent characteristics. However, facile fabrication of a robust one dimensional nanostructure has still remained a great challenge. Here, we developed a new synthetic route of one-step electrochemical deposition of silver nanograss without the assistance of a template. By applying an overpotential of −2.0 V (vs. Ag/AgCl) under aqueous alkaline conditions, silver nanograss with a slight tilt in a randomly oriented direction was spontaneously formed on the working electrode surface. Two applications that utilize advantageous features of this silver nanograss were demonstrated: (i) an efficient surface-enhanced Raman scattering substrate for a chemical sensor and (ii) an enzyme-less hydrogen peroxide sensor. Compared to silver nanowire arrays fabricated using anodized aluminum oxide (AAO) templates, the silver nanograss exhibited comparable hydrogen sensing due to its catalytic hydrogen peroxide reduction activity and produced a much stronger surface-enhanced Raman spectroscopy (SERS) signal due to its innate structure.

Label-free detection of zinc oxide nanowire using a graphene wrapping method.

Zinc oxide nanowires (ZnO NWs) have been attempted to various applications, such as piezoelectric devices, energy harvesting devices, self-powered nanosensors, and biomedical devices. However, recent reports have shown the toxic effect of ZnO NWs. In this report, we described the detection of ZnO NWs, for the first time using reduced graphene oxide (RGO) wrapping method. By wrapping RGO to ZnO NW (RGO-ZnO NW), we are able to aggregate ZnO NWs and increase the sensing performance. The detection measurement is based on the resonance frequency shift derived from mass variation of RGO-ZnO NW adsorption on the DNA immobilized resonator. The resonator is able to detect ZnO NWs with detection limit of 100 ng mL(-1) which is 2 order below the fatal toxic concentration of ZnO NWs in Human Monocyte Macrophages (HMMs). Furthermore, the resonator is able to detect ZnO NWs in real tap water, showing the potential as ZnO NWs screening platform in real environmental aqua system.

A multistep photothermic-driven drug release system using wire-framed Au nanobundles.

Here, wire-framed Au nanobundles (WNBs), which consist of randomly oriented and mutually connected Au wires to form a bundle shape, are synthesized. In contrast to conventional nanoparticles (spheres, rods, cubes, and stars), which exhibit nanostructure only on the surface, cross-sectional view image shows that WNBs have nanostructures in a whole volume. By using this specific property of WNBs, an externally controllable multistep photothermic-driven drug release (PDR) system is demonstrated for in vivo cancer treatment. In contrast to conventional nanoparticles that encapsulate a drug on their surface, WNBs preserve the drug payload in the overall inner volume, providing a drug loading capacity sufficient for cancer therapy. An improved in vivo therapeutic efficacy of PDR therapy is also demonstrated by delivering sufficient amount of drugs to the target tumor region.