HL671795，HL048743和HL108630：这项工作是由美国国立卫生研究院资助。

1.准备SDF-1α聚糖纳米粒子由于在体内递送的目的，消毒的所有容器，移液管，并在制备中使用的提示。 <ol><li>制备下列储备溶液在超纯水：1％硫酸葡聚糖; 1 M氢氧化钠（无菌过滤用PES膜）;在0.2％的冰醋酸0.1％的壳聚糖（过滤器通过0.8和0.22微米的过滤器，并连续调节pH值至5.5，用NaOH之后）; 0.1M的硫酸锌; 15％甘露醇;和0.92毫克/毫升，SDF-1α（在80℃下以等分试样储存，并保持在4℃，一旦解冻）。 </li><li>消毒原液通过0.22微米的滤膜。与鲎变形细胞溶解物（LAL）的凝胶凝块测定中制备的溶液进行评估的内毒素水平。保证水平是&lt;0.06 EU /毫升。 </li><li>添加0.18毫升超纯水，使含有磁搅拌棒在1.5毫升的玻璃小瓶中。在800 RPM设定搅拌速度。加入0.1毫升1％硫酸葡聚糖并搅拌2分钟。添加0.08毫克，SDF-1α（0.087毫升的0.92毫克/毫升的SDF-1α溶液）并搅拌20分钟。 </li><li>添加0.33毫升0.1％脱乙酰壳多糖的溶液，并搅拌5分钟。改变搅拌速度为最大，并添加0.1毫升的0.1M 硫酸锌慢慢用0.1毫升注射器（超过1分钟）。 </li><li>返回搅拌速度800rpm，并搅拌30分钟。添加0.4毫升15％甘露糖醇，搅拌5分钟。将反应混合物转移到1.5ml微量离心管中。离心机在16000 xg离心在4℃下进行10分钟。 注意：甘露醇的存在有利于离心后，颗粒的再悬浮。根据粒料的紧凑性，甘露醇浓度可以变化从0％到5％。每次离心后的颗粒完全悬浮关键是要避免聚集在最终悬浮液中。 </li><li>吸去上清液，并使用移液管除去的液体最后一滴缓慢。中加入0.2ml的5％甘露糖醇。暂停颗粒用0.5毫升29克东东DLE注射器。加入1毫升5％甘露醇。离心在16000×g离心15分钟。 </li><li>重复步骤1.6。 </li><li>吸出上清液。重悬在0.2ml的5％甘露糖醇的颗粒。存储颗粒悬浮液在4℃下。 注意：该微粒悬浮液也可以被冷冻储存在-80℃或冻干。在悬浮液中含5％甘露糖醇是必不可少的，以防止颗粒的聚集冷冻和解冻之后，或冻干和再水化之后。甘露醇可以通过在保存后的悬浮液的离心分离除去。 </li></ol> 2.测量粒度和Zeta电位的粒径和zeta电位是通过动态光散射和电泳光散射，分别进行分析，并在物料清单指示的颗粒分析器。 <ol><li>设置为粒度测量以下参数：累积次数：70;重复次数：4;温度：25℃;稀释剂：水;强度调节：自动。 </li><li>稀释的SDF-1α-DS-CS样品用水（10倍稀释）。加载100微升样品到一次性紫外比色皿的诸如的Eppendorf试管中。插入反应杯进入细胞支架。等待强度调节，以达到“最佳”（〜万厘泊）。开始数据采集。 </li><li>测量完成后，记录直径（nm），而多分散性指数的累积量的结果。平均从各4重复读数的所获得的结果，并计算标准偏差。 </li><li>负载500微升10倍稀释的粒子试样用于zeta电位测量的流动细胞。建立起来用于测量以下参数：累积次数：10;重复次数：5;温度：25℃;稀释剂：水;强度调节：自动。记录的ζ电位（mV）的结果。平均每个重复5次读数的所获得的结果，并计算标准deviatioñ。 </li></ol> 3.量化SDF-1α的颗粒<ol><li>稀游离形式的SDF-1α为0.01，0.02，0.03，0.04，和0.05毫克/毫升在1.3倍的Laemmli样品缓冲液中的浓度。稀释6微升的SDF-1α-DS-CS样品用40微升1.3倍Laemmli样品缓冲液中。 （准备含有0.25M三盐酸，pH值7.5，8％SDS，40％甘油，0.05毫克/毫升溴酚蓝，和8％的2-巯基乙醇的Laemmli 4倍储备缓冲。除以原液成小等份，并保持在-20 °下单使用。） </li><li>加热该样品在100℃下进行10分钟。涡流在10分钟的加热时间以完全离解的颗粒两次样品（各为10秒的最大速度）。冷却样品至室温2分钟。离心机在10,000 XG为0.5-1分钟打倒冷凝水。再次涡旋拌匀。 注意：在这一点上，将样品溶液应当清楚，没有可见的沉淀物存在。 </li><li>负载10＃181;升样品/孔至4-20％SDS凝胶。运行电泳在200V进行20分钟。染色用考马斯亮蓝染色的蛋白质凝胶。 </li><li>审查的SDF-1α使用分子成像器和光密度分析软件的蛋白条带密度。计算针对与游离的SDF-1α标准建造的标准曲线的粒子的SDF-1α的量。 </li></ol> 4. 体外释放试验<ol><li>在1混合用Dulbecco磷酸盐缓冲盐水，SDF-1α聚糖颗粒不含钙和镁（D-PBS）：1的比例（体积/体积）。 </li><li>划分颗粒悬浮到0.05毫升等分在1.5ml管。加载样品到管的底部。避免引入气泡或扰乱液体的表面上。用封口膜密封的管的顶部。 注：在这样做时，液体将在管混合器随后顶部至底部在旋转过程中保持在底部。 </li><li>旋转的管子在37＃176; C对一个旋转微管混合器。从管中取出等分试样，在指定的时间，并立即离心样品在16000×g离心10分钟，在4℃。 </li><li>分离上清液和小球，并重新构成粒料与0.05毫升D-PBS。存储所述样品在-20℃。之后所有的样品被收集，如上所述检查在SDS凝胶上清液和颗粒。 </li></ol> 5.迁移实验此测定法测定的SDF-1α的趋化活性。 SDF-1α，其在细胞表面上的受体（CXCR4）的相互作用导致对SDF-1α梯度的细胞迁移的影响。在该测定中，将细胞加载到上部井和SDF-1α溶液低级阱（通过半透膜从下部井分离）成。 <ol><li>稀SDF-1α（游离或颗粒结合形式），在一个3-FO迁移缓冲液（含有0.5％牛血清白蛋白的RPMI-1640培养基）LD连续稀释至最终浓度为100，33，11，3.7，1.2，0.41，0.14，和0.05纳克/毫升。 </li><li>添加0.6毫升稀释的SDF-1α溶液或迁移缓冲液只（阴性对照）对一个井在24孔板中。添加0.57毫升迁移缓冲井（输入单元控制）。孵育在37℃下30分钟。放置一个可渗透性细胞培养插管，如上的下部井顶部Transwell小（孔径为5μm，直径6.5毫米）。负载0.1毫升Jurkat细胞（5×10 5）插入Transwell小插入。直接加载0.03毫升细胞到输入单元的控制良好。孵育板在37℃下2小时，在5％CO 2的培养箱中培养。 </li><li>取出Transwell小刀片。传送已迁移到低孔中，以一个4毫升聚苯乙烯管中的细胞。计数迁移的细胞用流式细胞仪。 </li><li>计算迁移作为输入细胞数目（在输入单元的控制以及X 100/30单元编号）中negat数字的减法后的百分比香港专业教育学院对照（细胞迁移到仅含有迁移缓冲液的孔中）。 </li></ol>

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The authors declare that they have no competing financial interests.

如上所述，在DS-CS纳米颗粒通过电荷中和聚阴离子（DS）和聚阳离子（CS）的分子之间形成。由于电荷相互作用的分子碰撞时容易发生时，聚合物溶液和搅拌速度的混合期间的浓度是对所产生的粒子的大小是至关重要的。一个总的趋势是，越来越稀释DS和CS的解决方案15和更高的搅拌速度导致更小的粒子。 所述SDF-1α聚糖纳米颗粒的制剂可以改变。例如，SDF-1α/ DS / CS在这?...

硫酸葡聚糖（DS）和脱乙酰壳多糖（CS）与多个取代带负电荷的硫酸基（在DS）的多糖，或带正电荷的胺基（脱乙酰CS）。当在水溶液中混合时，两种多糖形成通过静电相互作用的聚电解质复合物。所得复合物可以形成大的聚集体将相分离的水溶液（沉淀），或小颗粒是水可分散的（胶体）。有助于这些成果的具体条件已被广泛研究，并进行了总结，并详细示出在最近的评论1。在这些条件下，用于生产水可分散的颗粒的两个基本要求是相反电荷的聚合物必须1）有显著不同摩尔质量;和2）被混合在一个非化学计量比。这些条件将允许由电荷产生的电荷中性络合聚合物链段中和，以分隔并形成颗粒的核，和过量的聚合物，以形成外壳1。在这个协议中所描述的聚糖颗粒旨在用于肺部递送，并且被设计成净负电荷，和纳米尺寸。的负的表面电荷降低了蜂窝颗粒2,3的吸收的可能性。纳米尺寸的颗粒有利于通过远端气道的通道。为了实现这一目标，DS在这一制备中所用的量是过量的CS（重量比3：1）;和高分子量的DS（重均分子量50万）和低分子量的CS（分子量范围50-190 kDa的，75-85％脱乙酰化）被使用。 SDF-1α是干细胞归巢因子，其发挥通过其趋化活性的归巢功能。 SDF-1α起着寻和维护的造血干细胞在骨髓中的重要作用，并在招募PROGE的NITOR细胞的损伤修复4,5外围组织。 SDF-1α具有肝素结合位点在其蛋白序列，其允许蛋白结合到肝素/硫酸乙酰肝素，形式二聚体，被保护免受蛋白酶（CD26 / DPPIV）失活，并通过细胞表面受体与靶细胞相互作用6-8。 DS也有类似的结构性质肝素/硫酸乙酰肝素;因此，SDF-1α对DS中的结合将是类似于其天然的聚合物配位体。 在下面的协议中，我们描述了SDF-1α-DS-CS纳米颗粒的制备。该程序表示先前已经研究了9所述的制剂中的一个。该协议最初是改编自VEGF-DS-CS纳米粒子10进行调查。一个小规模的制备进行了说明，可以很容易地按比例放大以相同储备溶液和制备条件。制备后，该颗粒的特征在于BÝ检查其尺寸，zeta电位，SDF-1α结合的程度， 在体外释放时间，以及掺入的SDF-1α活性。

<table border="0" cellpadding="0" cellspacing="0" width="489">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:255px;">Name</td>
			<td style="width:136px;">Company</td>
			<td style="width:99px;">Catalog number</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dextran sulfate</td>
			<td>Fisher</td>
			<td>BP1585-100</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Chitosan, low molecular weight&#160;</td>
			<td>Sigma</td>
			<td>448869</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Zinc sulfate heptahydrate</td>
			<td>Sigma</td>
			<td>204986</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">D-Mannitol</td>
			<td>Sigma</td>
			<td>M9546</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">UltraPure water&#160;</td>
			<td>Invitrogen&#160;</td>
			<td>10977-023</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">SDF-1&#945;</td>
			<td>Prepared according to reference 8.</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Syringe filter, PES membrane 0.22 um.&#160;&#160;&#160;</td>
			<td>Millipore</td>
			<td>SLGP033RS</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Magnetic Micro Stirring Bars (2 x 7 mm)</td>
			<td>Fisher&#160;</td>
			<td>14-513-63</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Glass vial Kit; SUN-SRi</td>
			<td>Fisher&#160;</td>
			<td>14-823-182</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Delsa Nano C Particle Analyzer&#160;</td>
			<td>Backman Coulter</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Eppendorf UVette Cuvets</td>
			<td>Eppendorf</td>
			<td>952010069</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">4&#8211;20% Mini-PROTEAN TGX Gel</td>
			<td>Bio-Rad</td>
			<td>456-1096</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">GelCode Blue Safe Protein Stain</td>
			<td>Fisher&#160;</td>
			<td>PI-24592</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Molecular Imager VersaDoc MP 4000 System</td>
			<td>BioRad</td>
			<td>170-8640</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Corning Transwell Permeable Supports</td>
			<td>Corning</td>
			<td>3421</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Accuri C6 Flow Cytometer</td>
			<td>BD Biosciences</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dulbecco&#8217;s phosphate buffered saline&#160;</td>
			<td>Sigma</td>
			<td>D8537</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Pyrogent plus kit</td>
			<td>Fisher</td>
			<td>NC9753738</td>
		</tr>
	</tbody>
</table>

preparation and characterization of sdf-1&#945;-chitosan-dextran sulfate nanoparticles

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under appropriate conditions. The glycan nanoparticles are useful carriers for protein factors, which facilitate the in vivo delivery of the proteins and sustain their retention in the targeted tissue. The glycan polyelectrolyte complexes are also ideal for protein delivery, as the incorporation is carried out in aqueous solution, which reduces the likelihood of inactivation of the proteins. Proteins with a heparin-binding site adhere to dextran sulfate readily, and are, in turn, stabilized by the binding. These particles are also less inflammatory and toxic when delivered in vivo. In the protocol described below, SDF-1&#945; (Stromal cell-derived factor-1&#945;), a stem cell homing factor, is first mixed and incubated with dextran sulfate. Chitosan is added to the mixture to form polyelectrolyte complexes, followed by zinc sulfate to stabilize the complexes with zinc bridges. The resultant SDF-1&#945;-DS-CS particles are measured for size (diameter) and surface charge (zeta potential). The amount of the incorporated SDF-1&#945; is determined, followed by measurements of its in vitro release rate and its chemotactic activity in a particle-bound form.

所制备的SDF-1α-DS-CS粒子的大小和ζ电位均用颗粒分析仪确定的。 图1示出了尺寸测量的分析。从来自四个重复测量得到的累积的结果，所述SDF-1α-DS-CS颗粒的平均流体动力学直径是661±8.2（nm），而多分散性是0.23±0.02。 zeta电位的测量结果示于图2中 。在5次重复测量中，SDF-1α-DS-CS粒子的ζ电位为-24.8±0.5毫伏。如上所述，在SDF-1α-DS-CS粒子悬浮液的5％甘露糖醇的存在是为在一?...

Watch this Scientific Journal Video about Preparation and Characterization of SDF-1Î±-Chitosan-Dextran Sulfate Nanoparticles at JoVE.com

Preparation and Characterization of SDF-1&amp;#945;-Chitosan-Dextran Sulfate Nanoparticles

The objective of this protocol is to incorporate SDF-1&#945;, a stem cell homing factor, into dextran sulfate-chitosan nanoparticles. The resultant particles are measured for their size and zeta potential, as well as the content, activity, and in vitro release rate of SDF-1&#945; from the nanoparticles.

SDF-1α - 壳聚糖硫酸葡聚糖纳米粒子的制备与表征

Chitosan (CS) and dextran sulfate (DS) are charged polysaccharides (glycans), which form polyelectrolyte complex-based nanoparticles when mixed under ...

preparation-characterization-sdf-1-chitosan-dextran-sulfate

Research

JoVE Journal

Chemistry

Preparation and Characterization of SDF-1&#945;-Chitosan-Dextran Sulfate Nanoparticles

12.3K 次观看.  Brigham and Women's Hospital and Harvard Medical School. The objective of this protocol is to incorporate SDF-1α, a stem cell homing factor, into dextran sulfate-chitosan nanoparticles. The resultant particles are measured for their size and zeta potential, as well as the content, activity, and in vitro release rate of SDF-1α from the nanoparticles.

视频: Preparation and Characterization of SDF-1&#945;-Chitosan-Dextran Sulfate Nanoparticles

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

科研

化学

Preparation and Characterization of Individual and Multi-drug Loaded Physically Entrapped Polymeric Micelles

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar concentration forming hydrophobic cores surrounded by hydrophilic shells in aqueous environments. The core of these micelles can be utilized to load hydrophobic, poorly water soluble drugs like docetaxel (DTX) and everolimus (EVR). Systematic characterization of the micelle structure and drug loading capabilities are important before in vitro and in vivo studies can be conducted. The goal of the protocol described herein is to provide the necessary characterization steps to achieve standardized micellar products. DTX and EVR have intrinsic solubilities of 1.9 and 9.6 &#181;g/ml respectively Preparation of these micelles can be achieved through solvent casting which increases the aqueous solubility of DTX and EVR to 1.86 and 1.85 mg/ml, respectively. Drug stability in micelles evaluated at room temperature over 48 hr indicates that 97% or more of the drugs are retained in solution. Micelle size was assessed using dynamic light scattering and indicated that the size of these micelles was below 50 nm and depended on the molecular weight of the polymer. Drug release from the micelles was assessed using dialysis under sink conditions at pH 7.4 at 37 oC over 48 hr. Curve fitting results indicate that drug release is driven by a first order process indicating that it is diffusion driven.

The goal of this protocol is to describe the preparation and characterization of physically entrapped, poorly water soluble drugs in micellar drug delivery systems composed of amphiphilic block copolymers.

制备及个体表征和多载药物理截留聚合物胶束

Amphiphilic block copolymers like polyethyleneglycol-block-polylactic acid (PEG-b-PLA) can self-assemble into micelles above their critical micellar ...

Synthesis, Characterization, and Functionalization of Hybrid Au/CdS and Au/ZnS Core/Shell Nanoparticles

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large extinction coefficients which can be tuned across the visible spectrum. Research into the plasmonic enhancement of optical transitions has become popular, due to the possibility of altering and in some cases improving photo-absorption or emission properties of nearby chromophores such as molecular dyes or quantum dots. The electric field of the plasmon can couple with the excitation dipole of a chromophore, perturbing the electronic states involved in the transition and leading to increased absorption and emission rates. These enhancements can also be negated at close distances by energy transfer mechanism, making the spatial arrangement of the two species critical. Ultimately, enhancement of light harvesting efficiency in plasmonic solar cells could lead to thinner and, therefore, lower cost devices. The development of hybrid core/shell particles could offer a solution to this issue. The addition of a dielectric spacer between a gold nanoparticles and a chromophore is the proposed method to control the exciton plasmon coupling strength and thereby balance losses with the plasmonic gains. A detailed procedure for the coating of gold nanoparticles with CdS and ZnS semiconductor shells is presented. The nanoparticles show high uniformity with size control in both the core gold particles and shell species allowing for a more accurate investigation into the plasmonic enhancement of external chromophores.

The synthesis of uniform gold nanoparticles coated with semiconductor shells of CdS or ZnS is performed. The semiconductor coating is conducted by first depositing a silver sulfide shell and exchanging the silver cations for zinc or cadmium cations.

合成，表征和混合金/硫化镉和Au / ZnS核/壳纳米颗粒功能化

Plasmonic nanoparticles are an attractive material for light harvesting applications due to their easily modified surface, high surface area and large ...

Synthesis and Characterization of Supramolecular Colloids

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical properties for applications in photonics, drug delivery and coating technology. Here we present a new family of colloidal building blocks, coined supramolecular colloids, whose self-assembly is controlled through surface-functionalization with a benzene-1,3,5-tricarboxamide (BTA) derived supramolecular moiety. Such BTAs interact via directional, strong, yet reversible hydrogen-bonds with other identical BTAs. Herein, a protocol is presented that describes how to couple these BTAs to colloids and how to quantify the number of coupling sites, which determines the multivalency of the supramolecular colloids. Light scattering measurements show that the refractive index of the colloids is almost matched with that of the solvent, which strongly reduces the van der Waals forces between the colloids. Before photo-activation, the colloids remain well dispersed, as the BTAs are equipped with a photo-labile group that blocks the formation of hydrogen-bonds. Controlled deprotection with UV-light activates the short-range hydrogen-bonds between the BTAs, which triggers the colloidal self-assembly. The evolution from the dispersed state to the clustered state is monitored by confocal microscopy. These results are further quantified by image analysis with simple routines using ImageJ and Matlab. This merger of supramolecular chemistry and colloidal science offers a direct route towards light- and thermo-responsive colloidal assembly encoded in the surface-grafted monolayer.

A protocol for the synthesis and characterization of colloids coated with supramolecular moieties is described. These supramolecular colloids undergo self-assembly upon the activation of the hydrogen-bonds between the surface-anchored molecules by UV-light.

超分子胶体的合成与表征

Control over colloidal assembly is of utmost importance for the development of functional colloidal materials with tailored structural and mechanical ...

Sulfate Separation by Selective Crystallization with a Bis-iminoguanidinium Ligand

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, 1,4-benzene-bis(iminoguanidinium) (BBIG), is demonstrated. The ligand is synthesized as the chloride salt (BBIG-Cl) by in situ imine condensation of terephthalaldehyde with aminoguanidinium chloride in water, followed by crystallization as the sulfate salt (BBIG-SO4). Alternatively, BBIG-Cl is synthesized ex situ in larger scale from ethanol. The sulfate separation ability of the BBIG ligand is demonstrated by selective and quantitative crystallization of sulfate from seawater. The ligand can be recycled by neutralization of BBIG-SO4 with aqueous NaOH and crystallization of the neutral bis-iminoguanidine, which can be converted back into BBIG-Cl with aqueous HCl and reused in another separation cycle. Finally, 35S-labeled sulfate and &#946; liquid scintillation counting are employed for monitoring the sulfate concentration in solution. Overall, this protocol will instruct the user in the necessary skills to synthesize a ligand, employ it in the selective crystallization of sulfate from aqueous solutions, and quantify the separation efficiency.

A protocol for in situ aqueous synthesis of a bis(iminoguanidinium) ligand and its utilization in selective separation of sulfate is presented.

分离硫酸选择性结晶用双 -  iminoguanidinium配体

A simple and effective method for selective sulfate separation from aqueous solutions by crystallization with a bis-guanidinium ligand, ...

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance imaging (MRI). Their purpose is to enhance the relaxation rate of water protons in tissue, thus increasing the MR image contrast and the specificity of the MRI measurements. Current clinically approved contrast agents are low molecular weight molecules that are rapidly cleared from the body. The use of dendrimers as carriers of paramagnetic chelators can play an important role in the future development of more efficient MRI contrast agents. Specifically, the increase in local concentration of the paramagnetic species results in a higher signal contrast. Furthermore, this CA provides a longer tissue retention time due to its high molecular weight and size. Here, we demonstrate a convenient procedure for the preparation of macromolecular MRI contrast agents based on poly(amidoamine) (PAMAM) dendrimers with monomacrocyclic DOTA-type chelators (DOTA &#8211; 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate). The chelating unit was appended by exploiting the reactivity of the isothiocyanate (NCS) group towards the amine surface groups of the PAMAM dendrimer to form thiourea bridges. Dendrimeric products were purified and analyzed by means of nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis. Finally, high resolution MR images were recorded and the signal contrasts obtained from the prepared dendrimeric and the commercially available monomeric agents were compared.

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

This protocol describes the preparation and characterization of a dendrimeric magnetic resonance imaging (MRI) contrast agent that carries cyclen-based macrocyclic chelates coordinating paramagnetic gadolinium ions. In a series of MRI experiments in vitro, this agent produced an amplified MRI signal when compared to the commercially available monomeric analogue.

制备及<em&gt;体外</em&gt;磁共振成像基于树状大分子造影剂的表征

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance ...

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We present methods for depositing and passively manipulating C60 molecules on rippled graphene that advance the pursuit of realizing applications involving 1D C60/graphene hybrid structures. The techniques applied in this exposition are geared towards high vacuum systems with preparation areas capable of supporting molecular deposition as well as thermal annealing of the samples. We focus on C60 deposition at low pressure using a homemade Knudsen cell connected to a scanning tunneling microscopy (STM) system. The number of molecules deposited is regulated by controlling the temperature of the Knudsen cell and the deposition time. One-dimensional (1D) C60 chain structures with widths of two to three molecules can be prepared via tuning of the experimental conditions. The surface mobility of the C60 molecules increases with annealing temperature allowing them to move within the periodic potential of the rippled graphene. Using this mechanism, it is possible to control the transition of 1D C60 chain structures to a hexagonal close packed quasi-1D stripe structure.

Preparation and Characterization of C60/Graphene Hybrid Nanostructures

Here we present a protocol for the fabrication of C60/graphene hybrid nanostructures by physical thermal evaporation. Particularly, the proper manipulation of deposition and annealing conditions allow the control over the creation of 1D and quasi 1D C60 structures on rippled graphene.

C 型60/石墨烯混合纳米结构的制备与表征

Physical thermal deposition in a high vacuum environment is a clean and controllable method for fabricating novel molecular nanostructures on graphene. We ...

Ligand-Mediated Nucleation and Growth of Palladium Metal Nanoparticles

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution of capping ligands during the synthesis reaction, their role in regulating the nucleation and growth rates of colloidal nanoparticles is not well understood. In this work, we demonstrate a mechanistic investigation of the role of trioctylphosphine (TOP) in Pd nanoparticles in different solvents (toluene and pyridine) using in situ SAXS and ligand-based kinetic modeling. Our results under different synthetic conditions reveal the overlap of nucleation and growth of Pd nanoparticles during the reaction, which contradicts the LaMer-type nucleation and growth model. The model accounts for the kinetics of Pd-TOP binding for both, the precursor and the particle surface, which is essential to capture the size evolution as well as the concentration of particles in situ. In addition, we illustrate the predictive power of our ligand-based model through designing the synthetic conditions to obtain nanoparticles with desired sizes. The proposed methodology can be applied to other synthesis systems and therefore serves as an effective strategy for predictive synthesis of colloidal nanoparticles.

The main goal of this work is to elucidate the role of capping agents in regulating the size of palladium nanoparticles by combining in situ small angle x-ray scattering (SAXS) and ligand-based kinetic modeling.

配体介导成核与钯金属纳米粒子的生长

The size, size distribution and stability of colloidal nanoparticles are greatly affected by the presence of capping ligands. Despite the key contribution ...

High Resolution Physical Characterization of Single Metallic Nanoparticles

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single nanometer-scale pore. The signal is characteristic of the molecule&#39;s physicochemical properties and its interactions with the pore. We demonstrate that the nanopore formed by the bacterial protein exotoxin Staphylococcus aureus alpha hemolysin (&#945;HL) can detect polyoxometalates (POMs, anionic metal oxygen clusters), at the single molecule limit. Moreover, multiple degradation products of 12-phosphotungstic acid POM (PTA, H3PW12O40) in solution are simultaneously measured. The single molecule sensitivity of the nanopore method allows for POMs to be characterized at significantly lower concentrations than required for nuclear magnetic resonance (NMR) spectroscopy. This technique could serve as a new tool for chemists to study the molecular properties of polyoxometalates or other metallic clusters, to better understand POM synthetic processes, and possibly improve their yield. Hypothetically, the location of a given atom, or the rotation of a fragment in the molecule, and the metal oxidation state could be investigated with this method. In addition, this new technique has the advantage of allowing the real-time monitoring of molecules in solution.&#160;

Here, we present a protocol to detect discrete metal oxygen clusters, polyoxometalates (POMs), at the single molecule limit using a biological nanopore-based electronic platform. The method provides a complementary approach to traditional analytical chemistry tools used in the study of these molecules.

单金属纳米粒子的高分辨率物理特性

Individual molecules can be detected and characterized by measuring the degree by which they reduce the ionic current flowing through a single ...

Synthesis and Characterization of Amphiphilic Gold Nanoparticles

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of their interactions with cell membranes, lipid bilayers, and viruses. The hydrophilic ligands make these particles colloidally stable in aqueous solutions and the combination with hydrophobic ligands creates an amphiphilic particle that can be loaded with hydrophobic drugs, fuse with the lipid membranes, and resist nonspecific protein adsorption. Many of these properties depend on nanoparticle size and the composition of the ligand shell. It is, therefore, crucial to have a reproducible synthetic method and reliable characterization techniques that allow the determination of nanoparticle properties and the ligand shell composition. Here, a one-phase chemical reduction, followed by a thorough purification to synthesize these nanoparticles with diameters below 5 nm, is presented. The ratio between the two ligands on the surface of the nanoparticle can be tuned through their stoichiometric ratio used during synthesis. We demonstrate how various routine techniques, such as transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), and ultraviolet-visible (UV-Vis) spectrometry, are combined to comprehensively characterize the physicochemical parameters of the nanoparticles.

Amphiphilic gold nanoparticles can be used in many biological applications. A protocol to synthesize gold nanoparticles coated by a binary mixture of ligands and a detailed characterization of these particles is presented.

两栖金纳米粒子的合成与表征

Gold nanoparticles covered with a mixture of 1-octanethiol (OT) and 11-mercapto-1-undecane sulfonic acid (MUS) have been extensively studied because of ...