• Title, Summary, Keyword: polymeric particles

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Removal of Endotoxins and Nucleic Acids Using Submicron-sized Polymeric Particles

  • Kim, Chan Wha;Chokyun Rha
    • Journal of Microbiology and Biotechnology
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    • v.6 no.3
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    • pp.189-193
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    • 1996
  • Submicron-sized polymeric particles (SSPP) were used to remove nucleic acids and endotoxins from cell lysates. The positively charged SSPP selectively adsorb nucleic acids and endotoxins and form complexes with them. The complexes can be easily removed by sedimentation or centrifugation. The removal of nucleic acids and endotoxins using SSPP also can be accomplished in the presence of cell and cell debris. Therefore, nucleic acids and endotoxins can be removed in an initial step of the down-stream processes. In bakers yeast and E. coli lysate systems, the level of DNA could be reduced more than three orders of magnitudes and endotoxins more than seven orders of magnitudes concurrently willi the cell debris removal process using SSPP.

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Spherical-shape Y2SiO5:Ce Phosphor Prepared from Organic Precursor Solution by Spray Pyrolysis (고분자 전구체 용액으로부터 분무열분해법에 의해 합성되어진 구형 형상의 Y2SiO5:Ce 형광체)

  • Kang, H.S.;Kang, Y.C.;Park, H.D.;Shul, Y.G.
    • Korean Journal of Materials Research
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    • v.13 no.3
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    • pp.180-184
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    • 2003
  • Ce-doped $Y_2$SiO$_{5}$ phosphor particles of spherical morphology, fine size, high crystallinity and high photoluminescence (PL) intensity were prepared by spray pyrolysis. When nitrate precursor solution is adopted, hollow particles were formed by uneven drying rate between surface and inside of droplet. Citric acid and ethylene glycol were introduced as polymeric precursor to control the morphology of particles. When polymeric solution is adopted, polymeric chain is formed by the esterification reaction between carboxyl and hydroxy groups of citric acid and ethylene glycol, and considered as controlling the drying characteristics of droplet. $Y_2$$SiO_{5}$ :Ce phosphor particles prepared from polymeric precursor solution were spherical, filled, fine size and not agglomerate before and after post heat treatment. The optimum doping concentration of cerium was 0.5 mol% of overall solution concentration. The optimum amount of TBOS of high PL intensity and pure crystallinity of X2-type $Y_2$$SiO _{5}$ was 105% of stoichiometric amount. The PL intensity of $Y_2$X$/_{5}$ :Ce phosphor particles prepared using the polymeric precursor solution was 164% of that of the nitrate precursor solution due to homogeneous composition and good morphology.y.

Gd$_2O_3$:Eu phosphor particles with spherical and filled morphology

  • Roh, Hyun-Sook;Kang, Yun-Chan;Park, Hee-Dong;Park, Seung-Bin
    • 한국정보디스플레이학회:학술대회논문집
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    • pp.253-256
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    • 2002
  • $Gd_2O_3$:Eu phosphor particles were prepared by largescale ultrasonic spray pyrolysis process. The morphological control of $Gd_2O_3$:Eu particles in spray pyrolysis was performed by adding polymeric precursors into spray solution containing nitrate salts. The effect of composition and amount of polymeric precursors on the morphology, crystallinity, and photoluminescence characteristics of $Gd_2O_3$:Eu particles was investigated. The influence of chain length of PEG on the morphology and photoluminescence intensity was investigated. $Gd_2O_3$:Eu particles prepared from aqueous solution containing no polymeric precursors had a hollow structure and rough surfaces after annealing process. The phosphor particles prepared from solution containing 0.1M CA and 0.lM PEG with high molecular weight as 1,500 had a spherical and filled morphology and the highest photoluminescence intensity, which was 48% higher than that of the $Y_2O_3$:Eu commercial product.

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Y2O3:Eu Phosphor Particles Prepared by Spray Pyrolysis from Solution Containing Flux and Polymeric Precursor (융제 및 고분자 첨가 용액으로부터 분무 열분해 공정에 의해 합성한 Y2O3:Eu 형광체)

  • Lee, Chang Hee;Jung, Kyeong Youl;Choi, Joong Gill;Kang, Yun Chan
    • Korean Chemical Engineering Research
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    • v.43 no.1
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    • pp.80-84
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    • 2005
  • Nano-sized $Y_2O_3:Eu$ phosphor particles were prepared by ultrasonic spray pyrolysis. The effect of polymeric precursor and lithium carbonate flux on the morphology and luminescence characteristics of nano-sized $Y_2O_3:Eu$ phosphor particles was investigated. When using the spray solution containing both the polymeric precursor and the flux, the $Y_2O_3:Eu$ particles with spherical shape and micron size were turned into nano-sized $Y_2O_3:Eu$ phosphor particles during the post-treatment at high temperature. The mean size of $Y_2O_3:Eu$ phosphor particles was affected by the contents of polymeric precursors and lithium carbonate flux, and preparation temperature. The as-prepared particles by spray pyrolysis at high temperature from solution containing high contents of polymeric precursors had good photoluminescence intensity under vacuum ultraviolet after post-treatment above $1,000^{\circ}C$. The prepared nano-sized $Y_2O_3:Eu$ phosphor particles had comparable photoluminescence intensity under vacuum ultraviolet light with that of the commercial $Y_2O_3:Eu$ phosphor particles prepared by solid state reaction method.

Copper Oxide-Modified Polymeric Composite Elecrodes for Amperometric Detection of Carbohydrates in LCEC Analysis

  • 정혜경;박종만
    • Bulletin of the Korean Chemical Society
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    • v.18 no.9
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    • pp.952-957
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    • 1997
  • Modified polymeric composite electrodes having highly dispersed CuO particles through the electrode matrix were prepared for LCEC or flow injection analysis of carbohydrates. The composite electrodes were prepared by incorporating carbon black and highly dispersed copper oxide particles in polystyrene matrix cross-linked with divinylbenzene. The analytical characteristics of the electrodes for LCEC and flow injection analysis of carbohydrates were evaluated. Improved performance in LCEC and flow injection analysis of carbohydrates is demonstrated in terms of sensitivity, reproducibility, stability and surface renewability. It was possible to get improved performance of the electrodes as well as adaptability of the electrodes for practical applications by employing highly dispersed catalyst particles through the electrode matrix and robust polymeric electrode matrix.

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Surface Modification of Colloidal Silica Nanoparticles: Controlling the size and Grafting Process

  • He, Wentao;Wu, Danhua;Li, Juan;Zhang, Kai;Xiang, Yushu;Long, Lijuan;Qin, Shuhao;Yu, Jie;Zhang, Qin
    • Bulletin of the Korean Chemical Society
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    • v.34 no.9
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    • pp.2747-2752
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    • 2013
  • Surface modification of colloidal silica nanoparticles without disrupting the electric double layer of nanoparticles is a major challenge. In the work, silane was employed to modify colloidal silica nanoparticles without inducing bridge flocculation obviously. The effect of pH value of the silica sol, the amount of silane in feed, and reaction temperature on the graft amount and the final size of modified particles was investigated. The increased weight loss by TG and the appearance of $T_2$ and $T_3$ except for $Q_2$ and $Q_3$ signals by CP/MAS $^{29}Si$ NMR of the modified samples verified the successful grafting of silane. The graft amount reached 0.57 mmol/g, which was slightly lower than theory value, and the particle size remained nearly the same as unmodified particles for acidic silica sol at the optimum condition. For alkaline silica sol after modification, aggregates composed of several nanoparticles connected together with silane moleculars as the bridge appeared.

Electrohydrodynamic Spray Drying Using Co-axial Nozzles for Protein Encapsulation (단백질 캡슐화를 위한 동축 이중 노즐을 사용한 전기분무건조법)

  • Ho, Hwan-Ki;Park, Se-Hyun;Park, Chul-Ho;Lee, Jong-Hwi
    • Polymer(Korea)
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    • v.33 no.4
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    • pp.353-357
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    • 2009
  • Spray drying is an effective and stable process, which has been widely used to produce pharmaceutical powders. In the traditional spray drying process, it was not quite easy to control the aggregation and the size of particles. Particularly, the preparation of polymeric particles was relatively hard compared to the preparation of food and pharmaceutical ingredients, typically organic materials of small molecular weights. In this study, modification of a conventional spray dryer was tried to use electrical charge and co-axial nozzles to prepare polymeric particles. Poly(ethylene glycol) and poly (D,L-lactide-co-glycolide) were used as the inner polymeric materials, and lactose as the outer shell materials. The results showed that electrohydrodynamic spray-dried particles had a relatively uniform size and particle morphology, and the aggregation of particles could be suppressed compared to the conventional spray-dried particles. The electrohydrodynamic spray-dried powders consisted of spherical particles of $2{\sim}5{\mu}m$ diameters.

Electrospraying of Polymeric Microparticles and its Application to Fabrication of Porous Membrane (고분자 미세입자의 전기분사와 다공성 박막 제작에의 응용)

  • Jeong, Young Hun;Oh, Hana
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.5
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    • pp.126-133
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    • 2015
  • Recently, there has been demand for polymeric porous membranes in various fields, such as environmental engineering, pharmaceutics, tissue engineering, drug delivery, biology, and fuel cells. In this study, it is proposed that a polymer particle-based porous membrane can be fabricated using electrospraying and sintering processes. Electrospraying can fabricate polymeric particles with diameters ranging from several micrometers to tens of nanometers without the cumbersome particle aggregation problem. Additionally, the particles can be sintered through thermo-compression under the glass transition temperature. In this study, a polymethyl methacrylate particle-based porous membrane with an average pore size of less than 500 nm is fabricated using the proposed method.

Polymeric Interactions of Dispersant and Binder in Aqueous Silicon Nitride Suspensions (질화규소 현탁액에서 분산제와 결합제의 상호작용연구)

  • Kim, Bong-Ho;Kim, Myong-Ho;Lee, Soo;Paik, Un-Gyu
    • Journal of the Korean Ceramic Society
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    • v.32 no.8
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    • pp.901-908
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    • 1995
  • In aqueous slurry processing of silicon nitride, the interaction of dispersant and binder used as polymeric processing additives on the silicon nitride particle surface was studied to identify the effect of these processing polymeric additives on the ceramic powder processing. The adsoprtion isotherm study of anionic organic molecule as dispersant and nonionic organic molecules as binder of silicon nitricde was studied to investigate the effect of these processing organic additives on the physicochemical properties of silicon nitride particles. As anionic molecule adsorbed onto silicon nitrice surface, the IEP of silicon nitride shifted toward acidic pH and changed the stability of silicon nitride particle. However, the adsorption of binder as nonionic organic molecule onto silicon nitride surface did not changed the IEP but caused the decrease of electrostatic potentials of silicon nitride. These distinctive adsorption behaviors of organic additives on silicon nitride particles can be closely correlated to the stability of silicon nitride particles suspended in aqueous media.

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