Self-Assembly and Photopolymerization of Diacetylene Molecules on Surface of Magnetite Nanoparticles

T. P. Vinod,김진권,이석우,Ji Hoon Chang 대한화학회 2008 Bulletin of the Korean Chemical Society Vol.29 No.4

An amphiphilic diacetylene compound was deposited on the surface of nano sized magnetite particles (Fe₃O₄) using a self-assembly method. The diacetylene molecular assembly formed on the surface of nanoparticle was subjected to photopolymerization. This resulted in the formation of a polymeric assembly on the surface of the nanoparticles in which the adjacent diacetylene molecules were connected through conjugated covalent networks. The presence of immobilized polymer species on the surface of nanoparticles is expected to protect them from agglomeration and ripening, thereby stabilizing their physical properties. In this work, Fe3O4 nanoparticles were prepared by chemical coprecipitation method and the diacetylene molecule 10,12-pentacosadiynoic acid (PCDA) was anchored to the surface of Fe3O4 nanoparticles through its carboxylate head group. Irradiation of UV light on the nanoparticles containing immobilized diacetylenes resulted in the formation of a polymeric assembly. Presence of diacetylene molecules on the surface of nanoparticles was confirmed by X-ray photoelectron spectroscopy and FT-IR measurements. Photopolymerization of the diacetylene assembly was detected by UV-Visible spectroscopy. Magnetic properties of the nanoparticles coated with polymeric assembly were investigated with SQUID and magnetic hysteresis showed superparamagnetic behaviors. The results put forward a simple and effective method for achieving polymer coating on the surface of magnetic nanoparticle.

Self-Assembly and Photopolymerization of Diacetylene Molecules on Surface of Magnetite Nanoparticles

Vinod, T.P.,Chang, Ji-Hoon,Kim, Jin-Kwon,Rhee, Seog-Woo Korean Chemical Society 2008 Bulletin of the Korean Chemical Society Vol.29 No.4

An amphiphilic diacetylene compound was deposited on the surface of nano sized magnetite particles ($Fe_3O_4$) using a self-assembly method. The diacetylene molecular assembly formed on the surface of nanoparticle was subjected to photopolymerization. This resulted in the formation of a polymeric assembly on the surface of the nanoparticles in which the adjacent diacetylene molecules were connected through conjugated covalent networks. The presence of immobilized polymer species on the surface of nanoparticles is expected to protect them from agglomeration and ripening, thereby stabilizing their physical properties. In this work, $Fe_3O_4$ nanoparticles were prepared by chemical coprecipitation method and the diacetylene molecule 10,12- pentacosadiynoic acid (PCDA) was anchored to the surface of $Fe_3O_4$ nanoparticles through its carboxylate head group. Irradiation of UV light on the nanoparticles containing immobilized diacetylenes resulted in the formation of a polymeric assembly. Presence of diacetylene molecules on the surface of nanoparticles was confirmed by X-ray photoelectron spectroscopy and FT-IR measurements. Photopolymerization of the diacetylene assembly was detected by UV-Visible spectroscopy. Magnetic properties of the nanoparticles coated with polymeric assembly were investigated with SQUID and magnetic hysteresis showed superparamagnetic behaviors. The results put forward a simple and effective method for achieving polymer coating on the surface of magnetic nanoparticle.

Nanoparticle Ferrite Multilayers Prepared by New Self-Assembling Sequential Adsorption Method

Kim, Yeong-Il,Kang, Ho-Jun,Kim, Don,Lee, Choong-Sub Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.5

The nanoparticle magnetite of which diameter was about 3 nm was synthesized in a homogeneous aqueous solution without a template. The synthesized magnetite nanoparticle was easily oxidized to maghemite in an ambient condition. The magnetic properties of the ferrite nanoparticle show superparamagnetism at room temperature and its blocking temperature is around 93 K. Modifying the sequential adsorption method of metal bisphosphonate, we have prepared a multilayer thin film of the ferrite nanoparticle on planar substrates such as glass, quartz and Si wafer. In this multilayer the ferrite nanoparticle layer and an alkylbisphosphonate layer are alternately placed on the substrates by simple immersion in the solutions of the ferrite nanoparticle and 1, 10-decanediylbis (phosphonic acid) (DBPA), alternately. This is the first example, as far as we know, of nanoparticle/alkyl-bisphosphonate multilayer which is an analogy of metal bisphosphonate multilayer. UV-visible absorption and infrared reflection-absorption studies show that the growth of each layer is very systematic and the film is considerably optically transparent to visible light of 400-700 nm. Atomic force microscopic images of the film show that the surface morphology of the film follows that of the substrate in μm-scale image and the nanoparticle-terminated surface is differentiated from the DBPA-terminated one in nm-scale image. The magnetic properties of this ferrite/DBPA thin film are almost the same as those of the ferrite nanoparticle powder only.

Preparation of Gold Nanoisland Arrays from Layer-by-Layer Assembled Nanoparticle Multilayer Films

Hyung Y. Choi,Michael S. Guerrero,Michael Aquino,Chuhee Kwon,Young-Seok Shon 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.2

This article introduces a facile nanoparticle self-assembly/annealing method for the preparation of nanoisland films. First, nanoparticle-polymer multilayer films are prepared with layer-by-layer assembly. Nanoparticle multilayer films are then annealed at ~ 500℃in air to evaporate organic matters from the films. During the annealing process, the nanoparticles on the solid surface undergo nucleation and coalescence, resulting in the formation of nanostructured gold island arrays. By controlling the overall thickness (number of layers) of nanoparticle multilayer films, nanoisland films with various island density and different average sizes are obtained. The surface property of gold nanoisland films is further controlled by the self-assembly of alkanethiols, which results in an increased surface hydrophobicity of the films. The structure and characteristics of these nanoisland film arrays are found to be quite comparable to those of nanoisland films prepared by vacuum evaporation method. However, this self-assembly/annealing protocol is simple and requires only common laboratory supplies and equipment for the entire preparation process.

Preparation of Gold Nanoisland Arrays from Layer-by-Layer Assembled Nanoparticle Multilayer Films

Choi, Hyung-Y.,Guerrero, Michael S.,Aquino, Michael,Kwon, Chu-Hee,Shon, Young-Seok Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.2

This article introduces a facile nanoparticle self-assembly/annealing method for the preparation of nanoisland films. First, nanoparticle-polymer multilayer films are prepared with layer-by-layer assembly. Nanoparticle multilayer films are then annealed at $~500^{\circ}C$ in air to evaporate organic matters from the films. During the annealing process, the nanoparticles on the solid surface undergo nucleation and coalescence, resulting in the formation of nanostructured gold island arrays. By controlling the overall thickness (number of layers) of nanoparticle multilayer films, nanoisland films with various island density and different average sizes are obtained. The surface property of gold nanoisland films is further controlled by the self-assembly of alkanethiols, which results in an increased surface hydrophobicity of the films. The structure and characteristics of these nanoisland film arrays are found to be quite comparable to those of nanoisland films prepared by vacuum evaporation method. However, this self-assembly/annealing protocol is simple and requires only common laboratory supplies and equipment for the entire preparation process.

Double Convective Assembly Coatings of FePt Nanoparticles to Prevent Particle Coalescence during Annealing

Hwang, Yeon Materials Research Society of Korea 2011 한국재료학회지 Vol.21 No.3

FePt nanoparticles suspension was synthesized by reduction of platinum acetylacetonate and decomposition of iron pentacarbonyl in the presence of oleic acid and oleyl amine. FePt nanoparticles were coated on a substrate by convective assembly from the suspension. To prevent the coalescence during the annealing of FePt nanoparticles double convective coatings were tried. First convective coating was for silica particle assembly on a silicon substrate and second one was for FePt nanoparticles on the previously coated silica layers. It was observed by scanning electron microscopy (SEM) that FePt nanoparticles were dispersed on the silica particle surface. After annealing at $700^{\circ}C$ for 30 minutes under nitrogen atmosphere, FePt nanoparticles on silica particles were maintained in a dispersed state with slight increase of particle size. On the contrary, FePt nanoparticles that were directly coated on silicon substrate showed severe particle growth after annealing due to the close-packing of nanoparticles during assembly. The size variation during annealing was also verified by X-ray diffractometer (XRD). It was suggested that pre-coating, which offered solvent flux oppose to the capillary force between FePt nanoparticles, was an effective method to prevent coalescence of nano-sized particles under high temperature annealing.

Layer-by-layer assembly for ultrathin energy-harvesting films: Piezoelectric and triboelectric nanocomposite films

Lee, Seokmin,Yeom, Bongjun,Kim, Younghoon,Cho, Jinhan Elsevier 2019 Nano energy Vol.56 No.-

<P><B>Abstract</B></P> <P>Energy-harvesting devices such as piezoelectric and triboelectric nanogenerators (NGs), which can convert mechanical energy into electricity, are under development to be combined with various electronics. In particular, the rapid progress in microscale electronics such as nanorobotics or microelectromechanical devices has strongly increased the demand for ultrathin film devices. Therefore, the thickness, highly uniform structure, chemical composition, interfacial adhesion/interactions, and electrical performance of electrically active films should be carefully considered for high-performance ultrathin energy-harvesting devices. This review focuses on how layer-by-layer (LbL) assembly as a kind of thin film technology can be effectively applied to ultrathin piezoelectric and triboelectric films, and furthermore enhance device performance. First, we introduce the basics of various LbL assemblies using electrostatic, hydrogen-bonding, and covalent-bonding interactions. Then, the LbL-assembly-assisted piezoelectric and triboelectric NGs reported to date are reviewed. Finally, we briefly present perspectives on the direction of LbL assembly for the realization of various ultrathin piezoelectric and triboelectric NGs with high performance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Basics of layer-by-layer assembly. </LI> <LI> Layer-by-layer assembly using Piezoelectric and ferroelectric materials. </LI> <LI> Piezoelectric and triboelectric films using layer-by-layer assembly. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>This paper introduces the background of layer-by-layer assembly, and reviews its applications to piezoelectric and triboelectric films.</P> <P>[DISPLAY OMISSION]</P>

Bridging the nanogap electrodes with gold nanoparticles using dielectrophoresis technique

Sanjeev Kumar,윤석왕,김길호 한국물리학회 2009 Current Applied Physics Vol.9 No.1

We report the assembling of 20 nm gold nanoparticles into the nanogap electrodes by dielectrophoresis (DEP) technique. DEP was performed on electrodes with different gap size values. While the frequency and the applied peak to peak voltage were maintained at 1 MHz and 3 V, respectively, DEP time was varied in accordance with electrodes gap size. Interestingly, some novel assembling was observed during the dielectrophoresis process and the nanogaps were bridged by nanoparticles either forming ring shaped bridges or linear bridges. The assembling of nanoparticles in different form is attributed to the positive DEP effect. This effect is seen to be influenced significantly by the time parameter during which DEP was performed. Results show the promise of dielectrophoresis in controlled engineering of nanoparticles assembly. We report the assembling of 20 nm gold nanoparticles into the nanogap electrodes by dielectrophoresis (DEP) technique. DEP was performed on electrodes with different gap size values. While the frequency and the applied peak to peak voltage were maintained at 1 MHz and 3 V, respectively, DEP time was varied in accordance with electrodes gap size. Interestingly, some novel assembling was observed during the dielectrophoresis process and the nanogaps were bridged by nanoparticles either forming ring shaped bridges or linear bridges. The assembling of nanoparticles in different form is attributed to the positive DEP effect. This effect is seen to be influenced significantly by the time parameter during which DEP was performed. Results show the promise of dielectrophoresis in controlled engineering of nanoparticles assembly.

CdTe 나노입자의 자기조립과정을 통한 나노리본 합성

오수연 ( Seo Yeoun Oh ),강완규 ( Wan Kyu Kang ),강정원 ( Jeong Won Kang ),김기섭 ( Ki Sub Kim ),이흔 ( Huen Lee ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.6

CdTe nanoribbons feature their unique optical properties compared with CdTe nanoparticles. Slow oxidation of tellurium ions on CdTe nanoparticles resulted in the organization of individual nanoparticle into nanoribbons. The light-controlled self-assembly of CdTe nanoparticles led to twisted ribbons. It was found that irradiation improved the oxidation of tellurium ions, Transmission electron microscopy (TEM) were performed to characterize the synthesized nanostructures and showed nanowires were twisted after self-assembly. The photoluminescence was slightly blueshifted from 550 to 544 nm. This synthetic procedure could potentially provide a key step toward the fabrication of nanowires.

<i>In Situ</i> Nanoadjuvant-Assembled Tumor Vaccine for Preventing Long-Term Recurrence

Le, Quoc-Viet,Suh, Juhan,Choi, Jin Joo,Park, Gyu Thae,Lee, Jung Weon,Shim, Gayong,Oh, Yu-Kyoung American Chemical Society 2019 ACS NANO Vol.13 No.7

<P>Although immune checkpoint inhibitors have emerged as a breakthrough in cancer therapy, a monotherapy approach is not sufficient. Here, we report an immune checkpoint inhibitor-modified nanoparticle for an <I>in situ</I>-assembled tumor vaccine that can activate immune systems in the tumor microenvironment and prevent the long-term recurrence of tumors. Adjuvant-loaded nanoparticles were prepared by entrapping imiquimod (IQ) in photoresponsive polydopamine nanoparticles (IQ/PNs). The surfaces of IQ/PNs were then modified with anti-PDL1 antibody (PDL1Ab-IQ/PNs) for <I>in situ</I> assembly with inactivated tumor cells and immune checkpoint blocking of PDL1 (programmed cell death 1 ligand 1). The presence of anti-PDL1 antibodies on IQ/PNs increased the binding of nanoparticles to CT26 cancer cells overexpressing PDL1. Subsequent near-infrared (NIR) irradiation induced a greater photothermal anticancer effect against cells treated with PDL1Ab-IQ/PNs than cells treated with plain PNs or unmodified IQ/PNs. To mimic the tumor microenvironment, we cocultured bone marrow-derived dendritic cells with CT26 cells treated with various nanoparticle formulations and NIR irradiated. This coculture study revealed that NIR-inactivated, PDL1Ab-IQ/PN-bound CT26 cells induced maturation of dendritic cells to the greatest extent. Following a single intravenous administration of different nanoparticle formulations in CT26 tumor-bearing mice, PDL1Ab-IQ/PNs showed greater tumor tissue accumulation than unmodified nanoparticles. Subsequent NIR irradiation of mice treated with PDL1Ab-IQ/PNs resulted in tumor ablation. In addition to primary tumor ablation, PDL1Ab-IQ/PNs completely prevented the growth of a secondarily challenged CT26 tumor at a distant site, producing 100% survival for up to 150 days. A long-term protection study revealed that treatment with PDL1Ab-IQ/PNs followed by NIR irradiation inhibited the growth of distant, secondarily challenged CT26 tumors 150 days after the first tumor inoculation. Moreover, increased infiltration of T cells was observed in tumor tissues treated with PDL1Ab-IQ/PNs and NIR-irradiated, and T cells isolated from splenocytes of mice in which tumor recurrence was prevented showed active killing of CT26 cells. These results suggest that PDL1Ab-IQ/PNs in conjunction with NIR irradiation induce a potent, <I>in situ</I>-assembled, all-in-one tumor vaccine with adjuvant-containing nanoparticle-bound, inactivated tumor cells. Such <I>in situ</I> nanoadjuvant-assembled tumor vaccines can be further developed for long-term prevention of tumor recurrence without the need for chemotherapy.</P> [FIG OMISSION]</BR>