Preparation of capsule-like particles containing single-core and their application to medical analysis

碘化合物和Gd化合物分别被用作X射线CT和磁共振成像的造影剂。这些现有的化合物可能会在患者身上引发过敏反应等不良事件，因此不能给这样的人服用。核壳纳米颗粒是预防过敏反应的良好候选者，因为壳材料可以阻止造影剂进入生命系统。在本工作中，提出了几种对比剂纳米粒子的硅包覆方法，并用斯托伯法对AgI纳米粒子进行硅包覆，以找出控制壳层厚度的反应条件。以氯化银和碘化钾为原料，3-羟丙基三甲氧基硅烷(MPS)为硅烷偶联剂，二甲胺(DMA)为催化剂，制备了AgI纳米粒子。当MMPs用量为4.5×10~(-5)、水为20M、MDMA为0.01、AgI为1 mm时，可制得AgI-SiO_2核壳粒子。当正硅酸乙酯浓度从0.005增加到0.04M时，二氧化硅壳层厚度可以在15~28 nm之间变化。采用Stober法制备了平均粒径为30.9 nm的二氧化硅颗粒。在水/丙醇溶液中，加入27.7M H2O、0.001 M Gd(NO_3)_3、0.5M尿素、1g/L聚乙烯吡咯烷酮(PVP)，二氧化硅颗粒悬浮液体积分数为0.001%，均相沉淀法在80℃下合成了尺寸为57.4nmSiO_2-Gd核壳颗粒。在SiO_2-Gd核壳粒子悬浮液的存在下，用0.0133 mTEOS和0.002 M氢氧化钠对SiO_2-Gd核壳粒子进行了后续的SiO_2包覆。因此，可以得到平均尺寸为71.2 nm的多层SiO_2-Gd-SiO_2核壳粒子。这些颗粒在磁共振图像中表现出明显的增强。

Iodine compounds and gadolinium compounds have been used as contrast agents for X-ray CT and magnetic resonance imaging, respectively. These existing compounds may provoke adverse events as allergic reactions in patients, so that they can not be administered to such people. Core-shell nanoparticles are good candidates for prevention of allergic reactions because the shell materials can keep the contrast agents from living systems. In present works, several methods for silica-coating of contrast agent nanoparticles are proposed.Silica-coating of AgI nanoparticles with a Stober method was carried out to find out reaction conditions for control of the shell thickness. The AgI nanoparticles were prepared from AgCIO_4 and KI with the use of 3-mercaptopropyltrimethoxysilane (MPS) as a silane coupling agent and dimethylamine (DMA) catalyst for alkoxide hydrolysis. AgI-silica core-shell particles could be prepared with the use of 4.5×10^<-5> MMPS, 20M water, 0.01 MDMA and 1 mM AgI. Silica shell thickness could be varied from 15 to 28 nm with an increase in the TEOS concentration from 0.005 to 0.04M.A preparation method for multilayered silica-Gd-silica core-shell particles is proposes. Silica particles with an average size of 30.9 nm were prepared by the Stober method. Silica-Gd core-shell particles with a size of 57.4 nm were synthesized by a homogeneous precipitation method at 80℃ in water/propanol solution with 27.7 M H_2O, 0.001 M Gd (NO_3)_3, 0.5 M urea and 1 g/l polyvinylpyrrolidone in the presence of 0.001 vol% suspension of the silica particles. Succeeding silica-coating of the silica-Gd core-shell particles was performed with 0.0133 MTEOS and 0.002 M NaOH in the presence of a suspension of silica-Gd core-shell particles. Consequently, multilayered silica-Gd-silica core-shell particles with an average size of 71.2 nm could be obtained. These particles exhibited clear enhancement in magnetic resonance images.