Name: preparation of functional silica using a bioinspired method
Uploaded: 2018-08-01T14:45:00.000+00:00
Duration: 8 min 4 s
Description: Watch this Scientific Journal Video about Preparation of Functional Silica Using a Bioinspired Method at JoVE.com

作者感谢化学和生物工程系 (谢菲尔德大学) 和 EPSRC (EP/L017059/1 和 EP/P006892/1) 提供的财政支持。

1. 前体解决方案的编写 (和可选硅胶解决方案)
<ol><li>180毫升塑料容器, 测量1.5 毫摩尔硅酸钠五水合物 (318.2 毫克), 并溶解在20毫升的去离子水。</li>
	<li>同样, 在第二个容器中, 测量0.25 毫摩尔的五乌洛托品 (PEHA, 58.1 毫克) 和溶解在20毫升的去离子水。<ol>
<li>当使用替代的含胺化合物 (如diethylenetriamine (细节) 或 triethylenetetraamine (TETA) 时, 确保总硅: N 摩尔比保持恒定的 1 (即,对应于0.5 毫摩尔细节或0.375 毫摩尔 TETA 在被描述的做法)15。</li>
		<li>当使用聚合物胺添加剂例如,聚 (氮丙啶) (裴) 或聚 (烯丙胺) (多环芳烃), 保持浓度1毫克/毫升 (最终反应量)15。 注意: 只在通风罩内处理这些胺, 因为它们的纯净形式 (尤其是蒸气) 具有腐蚀性或毒性。</li>
	</ol>
</li>
	<li>在合成过程中进行原位封包, 在5毫升的去离子水中溶解预先确定的蛋白质 (50 毫克牛血清白蛋白, BSA)。将这一量的水从去离子水的容积中减去, 用于水合硅酸钠的溶解。<ol>
<li>为了缓解蛋白质溶解, 而不改变其结构, 一旦与去离子水混合, 瓶盖容器和贮存在4摄氏度。偶尔检查溶解进展, 最好不要搅拌。</li>
	</ol>
</li>
</ol>2. 硅胶合成
<ol><li>将硅酸钠和 PEHA 的溶液结合在180毫升容器中的一个, 加入足够的去离子水, 使最终溶液体积41毫升 (如果省略原位封装, 则为 46)。</li>
	<li>将新配制的硅酸钠和 PEHA 溶液放在搅拌器板的顶部, 加入搅拌器杆, 以提供一致的混合。</li>
	<li>进入此容器, 暂停 ph 探针并记录初始 ph 值。<ol>
<li>在这个阶段, 可以选择, 删除750µL 整除的起始混合物, 以后来确定的初始 [Si] 浓度使用钼蓝分光光度法, 如步骤8.1 所述。</li>
	</ol>
</li>
	<li>从图 1中添加预定数量的1米 HCl 开始合成, 观察浊度的立即演化 (见图 2)</li>
	<li>一旦酸添加结束, 尽快加入硅胶解决方案 (如果有的话)。 注: 给出的最终体积为50毫升的总反应混合物, 导致 Si 和 N 浓度为30mM。这可以根据需要缩放, 所有以上的数量乘以一个恒定的数量。</li>
	<li>记录5分钟后的 pH 值以确定反应完成;确保 pH 值为 7, 0.05。</li>
</ol>3. 材料的酸性洗脱
<ol><li>在反应达到完成后, 修改所生产二氧化硅的成分 (无论是作为制成的凝结, 还是通过 resuspending 以前合成的二氧化硅样品) 添加进一步的酸。</li>
	<li>如果 resuspending 二氧化硅, 在180毫升塑料容器中混合大约150毫克的 bioinspired 二氧化硅和100毫升的去离子水, 并放置在搅拌器板的顶部。</li>
	<li>一旦悬浮液混合良好, 在容器中悬浮 pH 探针。</li>
	<li>滴定在进一步 HCl, 直到期望 pH 值 (在7和2之间) 已经达到并且允许稳定为钙1分钟。</li>
	<li>再等5分钟, 确保系统完全平衡, 然后继续隔离实心二氧化硅。</li>
</ol>4. 硅胶的分离和干燥
<ol><li>醒酒将 bioinspired 硅悬浮液分为50毫升离心管。</li>
	<li>离心机悬浮在5000克为15分钟。</li>
	<li>离心后取出上清液并贮存进一步分析 (如布拉德福德化验, 见下文)。用去离子水将离心机管重新装满, 然后使用涡旋搅拌机将二氧化硅再悬浮。</li>
	<li>重复离心, 上清液储存, 并重新悬浮两次。</li>
	<li>最后离心后, 取出上清, 将二氧化硅刮成陶瓷坩埚。</li>
	<li>在烤箱里一夜之间干燥85摄氏度。<ol>
<li>如果封装已经发生, 使用冷冻干燥设施或在真空下操作的烤箱, 以避免蛋白质变性。</li>
	</ol>
</li>
</ol>5. 钼蓝试剂 (MBR) 的生产 [Si] 测定
<ol><li>到塑料 1 L 容积瓶, 在通风柜中添加8毫摩尔 (10 克) 钼酸铵四水合物。</li>
	<li>溶解在500毫升去离子水在搅拌。</li>
	<li>通过仔细添加60毫升的10米 HCl 溶液, 酸化解决方案。</li>
	<li>将最终音量调整为1升。</li>
</ol>6. 对氨基苯酚硫酸盐还原剂 (RA) 的生产 [Si] 测定
<ol><li>将一个500毫升的玻璃容积瓶放在水浴中, 环境温度在一个通风柜的搅拌器板上。</li>
	<li>添加111毫摩尔 (10 克) 的无水草酸, 19.5 毫摩尔 (3.35 克) 对氨基苯酚硫酸盐和16毫摩尔 (2 克) 亚硫酸钠, 并溶解在250毫升水。</li>
	<li>仔细和缓慢地添加92克 (50 毫升) 饱和硫酸, 同时搅拌和等待溶液冷却。</li>
	<li>最后, 用去离子水稀释到500毫升。</li>
</ol>7. 单体二氧化硅种类的硅钼酸测定
<ol><li>在5毫升塑料瓶, 稀释300µL MBR 生产的步骤5.4 与3毫升的去离子水。</li>
	<li>添加10µL 的硅酸试验溶液, 并摇动搅拌。 注意: 此解决方案将慢慢变黄。</li>
	<li>在完全15分钟后, 加入1.6 毫升的还原剂, 从6节中, 以减少黄硅钼复合物的蓝色异构体。</li>
	<li>允许蓝颜色至少发展 2, 但不超过24小时。</li>
	<li>测定紫外-可见光分光光度计中 810 nm 的样品吸光度, 并对校准曲线计算 [Si]。</li>
</ol>8. 硅钼酸法测定聚合物二氧化硅种类
<ol><li>用钼蓝法测定聚硅酸的浓度, 在离心管中, 将2米氢氧化钠溶液的750µL 与750µL 二氧化硅悬浮液相结合。</li>
	<li>密封和放置在一个离心浮动。<ol>
<li>确保足够的顶部留在管中, 以防止因压力积聚而爆裂。 注: 500 µL 的顶空通常足以避免这种情况。另外, 该程序可以在开放的小瓶, 只要蒸发的液体损失的核算。</li>
	</ol>
</li>
	<li>漂浮离心管在水浴加热了到80°c 并且留给它溶化为 1 h。</li>
	<li>经过1小时后, 取出离心管并擦拭外部干燥。</li>
	<li>一旦冷却, [Si] 可以确定如上所述, 如步骤7.2 至7.5 中所述。</li>
</ol>9. 布拉德福德测定二氧化硅中蛋白质浓度的方法
<ol><li>在每个指定的试管中插入预定数量的 (室温) 布拉德福德试剂和样品 (见表 1和表 2以了解具体的卷)。使用一次性吸管提示, 每试管, 以避免体积改变由于试剂的性质, 并重复每一个点。</li>
	<li>混合每试管3次, 并离开开发10分钟。</li>
	<li>以纯清液为空白, 测量 595 nm 的吸光度。</li>
	<li>计算每个试管的原始吸光度, 方法是从每种测量中减去对照样品的吸光度 (试管 0)。</li>
	<li>使用校准曲线计算未知样本的蛋白质浓度 (图 3)。在原样品稀释的情况下, 需要对稀释系数进行核算。<ol>
<li>为每组实验创建一个校准曲线, 方法是绘制对 BSA 浓度的测量吸光度, 以避免随机波动可能会影响化验的灵敏度。</li>
		<li>虽然这种蛋白质检测的目的是使用 BSA 作为一个标准, 以量化任何类型的蛋白质, 创建一个校准曲线, 为每个特定的蛋白质感兴趣, 以提高准确性。</li>
		<li>如果未知样品的蛋白质含量预期高于校准曲线的覆盖范围, 则根据需要稀释它。</li>
	</ol>
</li>
	<li>在重新悬浮过程中确定每个样品的蛋白质含量, 以监测可能的蛋白质损失。</li>
</ol>

<ol>
	<li>Swaisgood, H. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+immobilized+enzymes+to+improve+functionality.">The use of immobilized enzymes to improve functionality.</a> Proteins Food Process. , 607-630 (2004).</li><li>Hartmann, M., Kostrov, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immobilization+of+enzymes+on+porous+silicas+-+benefits+and+challenges.">Immobilization of enzymes on porous silicas - benefits and challenges.</a> Chem Soc Rev. 42 (15), 6277 (2013).</li><li>Hudson, S., Cooney, J., Magner, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Proteins+in+Mesoporous+Silicates.">Proteins in Mesoporous Silicates.</a> Angew Chemie Int Ed. 47 (45), 8582-8594 (2008).</li><li>Hanefeld, U., Gardossi, L., Magner, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+enzyme+immobilisation.">Understanding enzyme immobilisation.</a> Chem Soc Rev. 38 (2), 453-468 (2009).</li><li>Magner, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immobilisation+of+enzymes+on+mesoporous+silicate+materials.">Immobilisation of enzymes on mesoporous silicate materials.</a> Chem Soc Rev. 42 (15), 6213-6222 (2013).</li><li>Rodrigues, R. C., Ortiz, C., Berenguer-Murcia, &. #. 1. 9. 3. ;., Torres, R., Fern&#225;ndez-Lafuente, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modifying+enzyme+activity+and+selectivity+by+immobilization.">Modifying enzyme activity and selectivity by immobilization.</a> Chem Soc Rev. 42 (15), 6290-6307 (2013).</li><li>Forsyth, C., Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Bio-Inspired Silicon-Based Materials. 5, (2014).</li><li>Luckarift, H. R., Spain, J. C., Naik, R. R., Stone, M. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzyme+immobilization+in+a+biomimetic+silica+support.">Enzyme immobilization in a biomimetic silica support.</a> Nat Biotechnol. 22 (2), 211-213 (2004).</li><li>Betancor, L., Luckarift, H. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioinspired+enzyme+encapsulation+for+biocatalysis.">Bioinspired enzyme encapsulation for biocatalysis.</a> Trends Biotechnol. 26 (10), 566-572 (2008).</li><li>Livage, J., Coradin, T., Roux, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Encapsulation+of+biomolecules+in+silica+gels.">Encapsulation of biomolecules in silica gels.</a> J Phys Condens Matter. 13 (33), R673-R691 (2001).</li><li>Hartmann, M., Jung, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biocatalysis+with+enzymes+immobilized+on+mesoporous+hosts:+the+status+quo+and+future+trends.">Biocatalysis with enzymes immobilized on mesoporous hosts: the status quo and future trends.</a> J Mater Chem. 20 (5), 844 (2010).</li><li>Carlsson, N., Gustafsson, H., Th&#246;rn, C., Olsson, L., Holmberg, K., &#197;kerman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enzymes+immobilized+in+mesoporous+silica:+A+physical-chemical+perspective.">Enzymes immobilized in mesoporous silica: A physical-chemical perspective.</a> Adv Colloid Interface Sci. 205, 339-360 (2014).</li><li>Manning, J. R. H., Yip, T. W. S., Centi, A., Jorge, M., Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Eco-Friendly,+Tunable+and+Scalable+Method+for+Producing+Porous+Functional+Nanomaterials+Designed+Using+Molecular+Interactions.">An Eco-Friendly, Tunable and Scalable Method for Producing Porous Functional Nanomaterials Designed Using Molecular Interactions.</a> ChemSusChem. 10 (8), 1683-1691 (2017).</li><li>Drummond, C., McCann, R., Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+feasibility+study+of+the+biologically+inspired+green+manufacturing+of+precipitated+silica.">A feasibility study of the biologically inspired green manufacturing of precipitated silica.</a> Chem Eng J. 244, 483-492 (2014).</li><li>Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomimetic+and+bioinspired+silica:+recent+developments+and+applications.">Biomimetic and bioinspired silica: recent developments and applications.</a> Chem Commun. 47 (27), 7567-7582 (2011).</li><li>Iler, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The Chemistry of Silica: Solubility, Polymerization, Colloid and Surface Properties and Biochemistry of Silica. , (1979).</li><li>Forsyth, C., Yip, T. W. S., Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CO2+sequestration+by+enzyme+immobilized+onto+bioinspired+silica.">CO2 sequestration by enzyme immobilized onto bioinspired silica.</a> Chem Commun (Camb). 49 (31), 3191-3193 (2013).</li><li>Forsyth, C., Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Controlling+performance+of+lipase+immobilised+on+bioinspired+silica.">Controlling performance of lipase immobilised on bioinspired silica.</a> J Mater Chem B. 1 (8), 1164 (2013).</li><li>Bradford, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+rapid+and+sensitive+method+for+the+quantitation+of+microgram+quantities+of+protein+utilizing+the+principle+of+protein-dye+binding.">A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding.</a> Anal Biochem. 72 (1-2), 248-254 (1976).</li><li>Ewlad-Ahmed, A. M., Morris, M. A., Patwardhan, S. V., Gibson, L. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Removal+of+formaldehyde+from+air+using+functionalized+silica+supports.">Removal of formaldehyde from air using functionalized silica supports.</a> Environ Sci Technol. 46, 13354-13360 (2012).</li><li>Yang, S. H., Ko, E. H., Jung, Y. H., Choi, I. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioinspired+functionalization+of+silica-encapsulated+yeast+cells.">Bioinspired functionalization of silica-encapsulated yeast cells.</a> Angew Chemie. 50 (27), 6239-6242 (2011).</li><li>Alotaibi, K. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Iron+supported+on+bioinspired+green+silica+for+water+remediation.">Iron supported on bioinspired green silica for water remediation.</a> Chem Sci. 8 (1), 567-576 (2017).</li><li>Davidson, S., Lamprou, D. A., Urquhart, A. J., Grant, M. H., Patwardhan, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bioinspired+Silica+Offers+a+Novel,+Green,+and+Biocompatible+Alternative+to+Traditional+Drug+Delivery+Systems.">Bioinspired Silica Offers a Novel, Green, and Biocompatible Alternative to Traditional Drug Delivery Systems.</a> ACS Biomater Sci Eng. 2 (9), 1493-1503 (2016).</li><li>Patwardhan, S. V., Perry, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+enzyme+and+quantum+dot+in+silica+by+combining+continuous+flow+and+bioinspired+routes.">Synthesis of enzyme and quantum dot in silica by combining continuous flow and bioinspired routes.</a> Silicon. 2 (1), 33-39 (2010).</li><li>Nozawa, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smart+control+of+monodisperse+st&#246;ber+silica+particles:+Effect+of+reactant+addition+rate+on+growth+process.">Smart control of monodisperse st&#246;ber silica particles: Effect of reactant addition rate on growth process.</a> Langmuir. 21 (4), 1516-1523 (2005).</li><li>Belton, D. J., Patwardhan, S. V., Annenkov, V. V., Danilovtseva, E. N., Perry, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=From+biosilicification+to+tailored+materials:+optimizing+hydrophobic+domains+and+resistance+to+protonation+of+polyamines.">From biosilicification to tailored materials: optimizing hydrophobic domains and resistance to protonation of polyamines.</a> Proc Natl Acad Sci U S A. 105 (16), 5963-5968 (2008).</li><li>de &#193;vila, S. G., Silva, L. C. C., Matos, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimisation+of+SBA-15+properties+using+Soxhlet+solvent+extraction+for+template+removal.">Optimisation of SBA-15 properties using Soxhlet solvent extraction for template removal.</a> Microporous Mesoporous Mater. 234, 277-286 (2016).</li><li>Cassiers, K., Van Der Voort, P., Vansant, E. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+stable+and+directly+usable+hexagonal+mesoporous+silica+by+efficient+amine+extraction+in+acidified+water.">Synthesis of stable and directly usable hexagonal mesoporous silica by efficient amine extraction in acidified water.</a> Chem Commun. (24), 2489-2490 (2000).</li><li>Tanev, P. T., Pinnavaia, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mesoporous+Silica+Molecular+Sieves+Prepared+by+Ionic+and+Neutral+Surfactant+Templating:+A+Comparison+of+Physical+Properties.">Mesoporous Silica Molecular Sieves Prepared by Ionic and Neutral Surfactant Templating: A Comparison of Physical Properties.</a> Chem Mater. 8 (8), 2068-2079 (1996).</li></ol>

作者声明没有竞争的财政利益。

在目前的工作中, 我们提出了一种快速沉淀 bioinspired 二氧化硅材料和在其中的生物分子封装的方法。我们展示了过程中的关键步骤, 即要添加反应启动酸的量, 以及加入分子硅胶的时间。我们展示了酸添加量对反应进展和产量的影响 (分别为图 4和图 5), 并展示了一种严格控制合成条件的方法, 尽管这种敏感性可以保持一致性。关于活性物种的封装, 虽然在程序方面是直截了当的, 但封装被证明对实验条件 (添加顺序、添加 pH 值、环境条件) 敏感, 但是, 材料的一致性属性又可以实现。
合成条件可以通过使用不同的添加剂进行修改, 其中许多已在别处发表,15提供了一系列的形貌和孔隙度。此外, 还报告了 bioinspired 硅材料的改质和化学修饰后的合成技术, 如温和纯化13和表面胺装饰。20最后, 由于合成的温和, 水的性质,原位封装是可能的更广泛的基质比这里所展示的, 范围从酶17,18到全细胞,21金属盐,22种活性药物成分,23和量子点。24
与其他有机介导的二氧化硅合成 (如 MCM-41 或 SBA-15 系列材料) 不同, bioinspired 添加剂的多功能性质不能产生有序孔隙结构, 也不能形成高度单分散粒度分布。Stöber 型二氧化硅的特点。25这是由于缺乏定义良好的 micellization 行为的 bioinspired 添加剂 (在特殊情况下)26加上其催化活性超过单官能度胺类添加剂。26
另一方面, 这种多功能添加剂的性质, 使使用较短的反应时间和温和的温度 & 压力相比, 其他有机介导二氧化硅合成。这也导致了室温添加剂洗脱的可能性如上所述, 这还有待实现的其他二氧化硅家庭由于其表面化学的细节。27,28,29因此, bioinspired 二氧化硅材料被证明是更经济和实用的生产在更大的规模, 导致更容易的商业化和发展。14
总之, bioinspired 二氧化硅合成是一种快速, 简便的方法来生产活性的物种支持或气体吸附剂介质。通过对反应过程中的 pH 值的严格控制, 可以合成多种不同性质的二氧化硅胺复合材料, 进一步补充了在原位封装各种有机物的可能性,无机或生物有机材料。虽然尚未实现对 bioinspired 添加剂和硅胶浓度的独立后合成改性, 但这些方法是迈向环境良性化学过程的一个有希望的步骤。

利用二氧化硅作为工业催化剂的结构支撑, 使催化剂活性、稳定性和加工性得到改进,1因此有可能降低操作成本。在酶固定化的情况下, 这些好处是复合的, 因为在硅胶孔隙系统中储存可以在其自由对应的酶寿命上带来显著的好处。因此, 在寻找将酶与二氧化硅种结合的最佳方法方面已经付出了很大的努力, 并通过多种方法对硅固支的不同固定方式进行比较研究。2,3,4
酶通常通过储或共价键连接, 除了在多孔材料内的封装。5然而, 每种方法都有很大的缺点: 储依赖二氧化硅和分子之间的瞬态表面相互作用, 这可以很容易地被反应条件所削弱, 导致无法接受的酶浸出。由于活性物种构象自由的减少, 共价键通常会导致更低的活动。由于酶的不容易或扩散的限制, 封装可能导致活动减少。6
最近在温和 (经常被称为 ' bioinspired ') 二氧化硅合成领域的发展已经建立了在物质合成过程中生物分子和其他活性物种的原位封装。7,8,9这种方法否定了传统固定化的许多缺点--不像吸附的方法, 分子的构象自由是通过使用较弱的 noncovalent 相互作用维持的, 但随着孔隙的形成围绕分子, 浸出仍然被防止。事实上, 封装已被证明为一系列的生物分子, 甚至整个细胞,10和通过封装 bioinspired 二氧化硅效应, 如失活由于苛刻的工艺条件可以避免。7,11
本文所描述的方法的目的是在环境条件下, 使用 bioinspired 有机添加剂, 制备具有可控性能的多孔二氧化硅。该方法可以很容易地修改, 包括无机或生物分子的封装, 其中的选择应显示。我们进一步展示了一种简便的方法来修改合成材料, 以达到预期的散装性能和纯化, 通过去除有机模板, 通过酸洗脱。
与传统的模板化多孔二氧化硅支架的合成相比 (例如,通过超分子表面活性剂组件 (如 MCM-41 或 SBA-15) 来模板化的二氧化硅材料)12这种方法明显更快、更温和, 使量身定做,就地封装, 无需大量的固定步骤和费力的净化。此外, 使用酸性洗脱而不是煅烧打开了有机表面功能化的可能性。
这种方法非常适用于那些在活性物种固定化, 发现储或共价键固定无效的人。与传统模板化二氧化硅材料相比, bioinspired 合成在工业化中具有独特的定位作用, 对于那些研究过程的扩展也很有用。13,14本方法不适用于需要在材料中有有序排列的孔隙 (如光子学) 的应用, 因为尽管散装物的任何相似性, 材料结构是无序的。

<table><tbody><tr><td>&lt;strong&gt;Silica synthesis&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Sodium silicate pentahydrate</td><td>Fisher scientific</td><td>10070470</td><td></td></tr><tr><td>Pentaethylene hexamine (PEHA)</td><td>Sigma-Aldrich</td><td>292753</td><td></td></tr><tr><td>Diethylenetriamine (DETA)</td><td>Sigma-Aldrich</td><td>D93856</td><td>Toxic</td></tr><tr><td>Triethylenetetraamine (TETA)</td><td>Sigma-Aldrich</td><td>90460</td><td></td></tr><tr><td>Poly(ethyleneimine) (PEI)</td><td>Polysciences</td><td>6088</td><td>1.2K MW</td></tr><tr><td>Poly(allylamine hydrochloride) (PAH)</td><td>Sigma-Aldrich</td><td>283215</td><td>17.5k MW</td></tr><tr><td>Bovine Serum Albumin (BSA)</td><td>Sigma-Aldrich</td><td>A2153</td><td></td></tr><tr><td>Hydrochloric acid (HCl) 1M</td><td>Fisher Scientific</td><td>10487830</td><td></td></tr><tr><td>&lt;strong&gt;Silicomolybdic acid assay&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Ammonium molybdate tetrahydrate</td><td>Sigma-Aldrich</td><td>A7302</td><td>Product replaced by M1019</td></tr><tr><td>Hydrochloric acid (HCl) 37.0%wt</td><td>Fluka Analytical</td><td>84436</td><td></td></tr><tr><td>Anhydrous oxalic acid</td><td>Sigma-Aldrich</td><td>75688</td><td></td></tr><tr><td>Para-aminophenol sulphate</td><td>Fisher Scientific</td><td>10446880</td><td></td></tr><tr><td>Sodium sulphite</td><td>Fisher Scientific</td><td>10234400</td><td></td></tr><tr><td>Sulphuric acid</td><td>Sigma-Aldrich</td><td>84727</td><td></td></tr><tr><td>&lt;strong&gt;Bradford assay&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Bradford reagent</td><td>Sigma-Aldrich</td><td>B6916</td><td></td></tr><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Autotitrator Titrando 902</td><td>Metrohm</td><td>2.902.0010</td><td></td></tr><tr><td>801 magnetic stirrer plate</td><td>Metrohm</td><td>2.801.0040</td><td>For use with above</td></tr><tr><td>800 Dosino</td><td>Metrohm</td><td>2.800.0010</td><td>For use with above</td></tr><tr><td>Aquatrode Plus</td><td>Metrohm</td><td>6.0253.100</td><td>For use with above</td></tr><tr><td>Centrifuge Sorvall ST16</td><td>Thermo Scientific</td><td>11814243</td><td>Code is for Fisher scientific</td></tr><tr><td>UV-Vis spectrophotometer Genesys 10A</td><td>Thermo scientific</td><td>12104972</td><td>Code is for Fisher scientific</td></tr></tbody></table>

preparation of functional silica using a bioinspired method

本文所描述的协议的目标是合成 bioinspired 二氧化硅材料, 在其中执行酶封装, 并部分或完全净化相同的酸性洗脱。通过将硅酸钠与多功能 bioinspired 添加剂相结合, 在中和后的环境条件下, 二氧化硅迅速形成。
研究了中和率和分子添加点对硅产量的影响, 并对不同添加点的分子固定效率进行了报道。与其他多孔二氧化硅合成方法相比, 表明 bioinspired 二氧化硅合成所需的温和条件完全符合精细生物分子的封装。此外, 在所有的合成和修改步骤中使用温和的条件, 使 bioinspired 二氧化硅成为一个有希望的目标, 扩大和商业化作为一个裸露的材料和积极的支持介质。
合成被证明是高度敏感的条件,即中和率和最终合成 pH 值, 但严格控制这些参数是通过使用自动滴定方法, 导致高重现性反应进展途径和产量。
因此, bioinspired 二氧化硅是一个优秀的积极材料支持的选择, 显示多用途, 对许多目前的应用, 不仅限于在这里演示, 并在未来的应用效力。

上面描述的技术能够始终如一地重现性沉淀二氧化硅。这是最容易确定的反应釜内混浊的迅速开始, 在停止搅拌将自发地沉淀成一个厚凝结沉淀二氧化硅 (图 2)。通过测量分离后的凝结质量, 可以确定反应的程度和产量, 通常为 58 6.5% (图 4, 黄色)。
通过对钼蓝光谱法进行调整, 以检测反应单体硅酸盐物种的数量以及那些对形成 polysilicates 或 "寡聚物" 有反应的物种, 可以进一步了解反应进展, 但没有达到足够的大小凝聚 (图 4, 红色和蓝色分别)。
当比较不同的滴定效率对沉淀反应-即最终反应 pH 值和达到的速率对单体二氧化硅聚合的影响时, 这种特定的二氧化硅形态数据特别感兴趣。"寡聚物" 及其随后凝固成固体二氧化硅。通过修改2.4 级的加酸量, 可以进行反应混合物的下或过滴定 (图 5)。通过对这两种情况再次测量二氧化硅的形态, 在反应完成过程中可以看到明显的差异 (图 4), 尽管反应的滴定剖面变化不大 (图 5)。
虽然三反应 (剩余 29-33%) 的单体种的消耗量之间没有差异, 但在每种情况下沉淀的寡聚二氧化硅的数量有明显的差异。这与传统的溶胶-凝胶二氧化硅理论一致--在 ' 低于 ' 的情况下, pH 值更长, 允许单个粒子生长, 从而帮助高效凝固;在 "超调" 的情况下, 由于快速滴定法, 凝血的诱导速度快得多, 因此, 很少的二氧化硅物种生长到足够的大小来凝聚并滞留在胶体相中。16
考虑到滴定对二氧化硅形成的重要性, 对适当滴定量的先验知识是必不可少的。虽然由于胺类添加剂的复杂质子行为和硅表面酸度的变化而无法从反应化学成分中萃取, 但系统含量、浓度和很容易产生滴度量 (图 1)。
一旦凝固完成, 材料表面可以通过使用酸性洗脱, 容易地修改, 正如作者最近报告的其他地方。13这允许对材料性质 (如成分、孔隙度和添加剂的化学活性) 进行微调 (图 6a 和 b)。
在这项研究中, BSA 被用作范例硅胶酶, 但是, 这里描述的技术可以用于多种酶17,18。蛋白质检测所遵循的过程是布拉德福德检测协议,19使用从每个离心循环中存储的上清液。在上清液中蛋白质的含量是用已知数量的 BSA 在样品中的上清液中溶解的标准曲线 (对照样品) 计算出来的。上清液中所检测到的蛋白质的减法将由添加的蛋白质初始量来计算。化验所需的唯一试剂是布拉德福德试剂 (根据标准配方采购或制作)。
有三种类型的化验格式, 取决于样本量, 预期的蛋白质量和使用的测量方法。在这里, 为分光光度计指定了遵循的格式, 需要一次性小试管的宏观和微小的大小, 可以检测从10µg/毫升的蛋白质1.4 毫克/毫升。
在图 7中, 每次洗涤后检测到的蛋白质量 (步骤 4.3) 显示为最初蛋白质量 (50 毫克) 的%。在第一次离心后上清液中检测到50% 的 BSA, 与50% 的固定效率有关。由于没有检测到在下列洗涤中的 bsa, bsa (或任何其他酶) 可以安全地封装在二氧化硅合成没有浸出-这是一个很大的优势, 这种方法。为了确定白蛋白在硅中的存在, 对傅里叶变换红外光谱分析进行了研究。1500/厘米和 1650/厘米 (图 8) 中的酰胺 I 和 II 的特征带存在于 bsa 的样本中, 但在对照样品 (无 bsa) 中, 证实了 bsa 在固体中的存在。
除了上文所述的酶加法方法外 (bsa 在反应混合物中和过程中增加), 还有其他可能的变化,例如,在混合硅酸盐和添加剂溶液中的 bsa 加入, 在中和之前或酶添加到硅酸盐或添加剂溶液之前, 他们的混合和中和。进一步探讨了其中的一些可能性, 并测定了固定化效率 (bsa 的质量固定为在反应系统中添加的酶的百分比, 根据布拉德福德测定结果计算) 和最终二氧化硅中 bsa 的含量 (白蛋白在二氧化硅中的浓度占总复合重量的百分比, 见图 9)。很明显, 当 bsa 被添加到反应试剂 (如图 9中的情况下) 时, 其固定化效率和 bsa 在合成物中的含量并无显著差异。然而, 当在硅胶形成期间添加 BSA (如图9所示), 固定效率和 bsa 在最终产品中的数量都显著降低。尽管存在这些差异, 但所生产的二氧化硅的平均含量仍保持不变 (介于85-90 毫克之间)。这些观测可以根据 BSA、硅酸盐/二氧化硅和添加剂的电离 (或等电点) 来解释。不同的加法方法允许酶和二氧化硅前体之间的不同的相互作用。随着 pH 值的增加, 酶的变化, 每个物种的电离将决定分子间的相互作用, 这反过来将控制固定效率。
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody>
<tr>
<td>试管没有</td>
			<td>血清白蛋白浓度 (毫克/毫升)</td>
			<td>布拉德福德试剂 (毫升)</td>
			<td>样品 (mL)</td>
		</tr>
<tr>
<td>0</td>
			<td>0 (控制)</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>1</td>
			<td>0。1</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>2</td>
			<td>0.25</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>3</td>
			<td>0。5</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>4</td>
			<td>0.75</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>5</td>
			<td>1</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>6</td>
			<td>1.25</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
<tr>
<td>7</td>
			<td>未知示例 (X)</td>
			<td>1。5</td>
			<td>0.05</td>
		</tr>
</tbody></table>表 1: 宏布拉德福德检测的设置和计算的分量卷.有效的确定范围 0.1-1.4mg/毫升 (容量为1复制)
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody>
<tr>
<td>试管没有</td>
			<td>血清白蛋白浓度 (ug/毫升)</td>
			<td>布拉德福德试剂 (毫升)</td>
			<td>样品 (mL)</td>
		</tr>
<tr>
<td>0</td>
			<td>0 (控制)</td>
			<td>1</td>
			<td>1</td>
		</tr>
<tr>
<td>1</td>
			<td>1</td>
			<td>1</td>
			<td>1</td>
		</tr>
<tr>
<td>2</td>
			<td>2。5</td>
			<td>1</td>
			<td>1</td>
		</tr>
<tr>
<td>3</td>
			<td>5</td>
			<td>1</td>
			<td>1</td>
		</tr>
<tr>
<td>4</td>
			<td>7。5</td>
			<td>1</td>
			<td>1</td>
		</tr>
<tr>
<td>5</td>
			<td>10</td>
			<td>1</td>
			<td>1</td>
		</tr>
<tr>
<td>6</td>
			<td>未知示例 (X)</td>
			<td>1</td>
			<td>1</td>
		</tr>
</tbody></table>表 2:微布拉德福德测定法的建立和计算组分体积.有效的确定范围1-10 µg/毫升 (卷为1复制)
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57730/57730fig1.jpg"> 图 1: 使用细节或 PEHA 作为添加剂的反应系统的硅浓度所需的效价量。在不同浓度下合成二氧化硅, 同时保持 [N]: [Si] 比为两种不同的添加剂化学物质的1。误差线是平均值附近的一个标准偏差。
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57730/57730fig2.jpg"> 图 2:在反应容器 (a) 和 (b) 搅拌后的二氧化硅凝结的照片, 表明溶液混浊和沉淀, 表明了最佳反应.  
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57730/57730fig3.jpg"> 图 3: 布拉德福德宏观测定的范例校准曲线.无 BSA 的 bioinspired 二氧化硅合成中清液与已知量的蛋白质混合, 之后根据步骤9.1 的说明进行布拉德福德分析。
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57730/57730fig4.jpg"> 图 4: 不同反应条件下二氧化硅的最终聚合态.二氧化硅的合成使用最佳 (基线) 条件, 以及过度或低于滴定, 之后, 相对二氧化硅浓度是量化的单体或二聚体硅酸盐 (红色), 聚硅酸 ' 寡聚物 ' (蓝色) 和不稳定凝固二氧化硅 (黄色)。
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57730/57730fig5.jpg"> 图 5:pH 值通过反应系统的进展作为初始效价量的函数.酸被立即加药后, 38s 的混合, 导致 pH 值迅速下降到低于8。随后, 进一步的酸量自动加药量, 使 pH 值为 7.0, 0.05 300s 后, 初始添加。在过度滴定的情况下, 这是无法实现的, 因为初始剂量足以降低 ph 值低于 7, 达到 ph 值6.65 后300s。为 "低于"、"基线" 和 "超调" 添加的初始 HCl 体积分别为6.90、7.05 和7.20mL。
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/57730/57730fig6.jpg"> 图 6:凝固硅材料酸化后的代表性性能变化.(a) 在 ph 值方面, 添加剂浓度的变化, (b) 硅的孔隙度与 ph 值的变化有关。从曼宁等复制。13在创作共同性执照之下。 
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/57730/57730fig7.jpg"> 图 7: BSA 在 bioinspired 二氧化硅合成上清液中的含量。对离心后的反应上清液进行了布拉德福德测定, 确定了剩余的相对量 (因此从合成二氧化硅中遮挡)。
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/57730/57730fig8.jpg"> 图 8: bioinspired 二氧化硅的红外光谱分析与无活性种的封装。光谱显示: 黑线: bioinspired 二氧化硅, 灰色线: 纯 bsa, 蓝线: bioinspired 二氧化硅载有 BSA。垂直虚线表示有特性的酰胺带。
<img alt="Figure 9" class="xfigimg" src="/files/ftp_upload/57730/57730fig9.jpg"> 图 9:用 PEHA 生产二氧化硅的固定化效率和 BSA 含量.在 PEHA 溶液与硅酸盐混合之前, (B)在硅酸盐溶液中加入 PEHA 前, ( C)在 PEHA 和硅酸盐溶液的初始混合后, ( D)混合 PEHA 和硅酸盐后添加 BSA解决方案和中和。效率的测量 as% bsa 封装从反应混合物中的比例总 bsa 添加, 而 bsa 在二氧化硅 signifies% 浓度的白蛋白在最终二氧化硅复合材料的质量。误差线是平均值附近的一个标准偏差。

Watch this Scientific Journal Video about Preparation of Functional Silica Using a Bioinspired Method at JoVE.com

Preparation of Functional Silica Using a Bioinspired Method

在这里, 我们提出了合成 bioinspired 二氧化硅材料和固定酶在其中的协议。硅胶是通过将硅酸钠和胺 ' 添加剂 ' 结合在一起合成的, 在控制速率下中和。材料性能和功能可以通过原位酶固定或后合成酸洗脱的封装添加剂来改变。

用 Bioinspired 法制备功能性二氧化硅

The goal of the protocols described herein is to synthesize bioinspired silica materials, perform enzyme encapsulation therein, and partially or totally ...

preparation-of-functional-silica-using-a-bioinspired-method

Research

JoVE Journal

Chemistry

17.1K 次观看.  University of Sheffield. 在这里, 我们提出了合成 bioinspired 二氧化硅材料和固定酶在其中的协议。硅胶是通过将硅酸钠和胺 ' 添加剂 ' 结合在一起合成的, 在控制速率下中和。材料性能和功能可以通过原位酶固定或后合成酸洗脱的封装添加剂来改变。

视频: Preparation of Functional Silica Using a Bioinspired Method

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

Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The procedure requires 15-20 min of preparation time, during which a liquid precursor mixture is prepared and poured into wells of a metal mold that is placed between the platens of a hydraulic hot press, followed by several hours of processing within the hot press. The precursor solution consists of a 1.0:12.0:3.6:3.5 x 10-3 molar ratio of tetramethylorthosilicate (TMOS):methanol:water:ammonia. In each well of the mold, a porous silica sol-gel matrix forms. As the temperature of the mold and its contents is increased, the pressure within the mold rises. After the temperature/pressure conditions surpass the supercritical point for the solvent within the pores of the matrix (in this case, a methanol/water mixture), the supercritical fluid is released, and monolithic aerogel remains within the wells of the mold. With the mold used in this procedure, cylindrical monoliths of 2.2 cm diameter and 1.9 cm height are produced. Aerogels formed by this rapid method have comparable properties (low bulk and skeletal density, high surface area, mesoporous morphology) to those prepared by other methods that involve either additional reaction steps or solvent extractions (lengthier processes that generate more chemical waste).The rapid supercritical extraction method can also be applied to the fabrication of aerogels based on other precursor recipes.

This article describes a rapid supercritical extraction method for fabricating silica aerogels. By utilizing a confined mold and hydraulic hot press, monolithic aerogels can be made in eight hours or less.

通过快速超临界萃取法制备二氧化硅气凝胶巨石

A procedure for the fabrication of monolithic silica aerogels in eight hours or less via a rapid supercritical extraction process is described. The ...

Synthesis and Catalytic Performance of Gold Intercalated in the Walls of Mesoporous Silica

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties of the materials were investigated. We used a one pot sol-gel approach to intercalate gold nano particles in the walls of mesoporous silica. To start with the synthesis, P123 was used as template to form micelles. Then TESPTS was used as a surface modification agent to intercalate gold nano particles. Following this process, TEOS was added in as a silica source which underwent a polymerization process in acid environment. After hydrothermal processing and calcination, the final product was acquired. Several techniques were utilized to characterize the porosity, morphology and structure of the gold intercalated mesoporous silica. The results showed a stable structure of mesoporous silica after gold intercalation. Through the oxidation of benzyl alcohol as a benchmark reaction, the GMS materials showed high selectivity and recyclability.

Here, we present a protocol with a sol-gel process to synthesize gold intercalated in the walls of mesoporous materials (GMS), which is confirmed to possess a mesoporous matrix with gold intercalated in the walls imparting great stability and recyclability.

合成和金插在介孔二氧化硅的墙壁催化性能

As a promising catalytically active nano reactor, gold nanoparticles intercalated in mesoporous silica (GMS) were successfully synthesized and properties ...

Real-time Monitoring of Reactions Performed Using Continuous-flow Processing: The Preparation of 3-Acetylcoumarin as an Example

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible to ensure consistent product quality over time using this technique. We here show how to interface a commercially available flow unit with a Raman spectrometer. The Raman flow cell is placed after the back-pressure regulator, meaning that it can be operated at atmospheric pressure. In addition, the fact that the product stream passes through a length of tubing before entering the flow cell means that the material is at RT. It is important that the spectra are acquired under isothermal conditions since Raman signal intensity is temperature dependent. Having assembled the apparatus, we then show how to monitor a chemical reaction, the piperidine-catalyzed synthesis of 3-acetylcoumarin from salicylaldehyde and ethyl acetoacetate being used as an example. The reaction can be performed over a range of flow rates and temperatures, the in-situ monitoring tool being used to optimize conditions simply and easily.

Real-time monitoring allows for fast optimization of reactions performed using continuous-flow processing. Here the preparation of 3-acetylcoumarin is used as an example. The apparatus for performing in-situ Raman monitoring is described, as are the steps required to optimize the reaction.

反应执行使用连续流处理的实时监控:3  - 乙酰基香豆素的制备为例

By using inline monitoring, it is possible to optimize reactions performed using continuous-flow processing in a simple and rapid way. It is also possible ...

Attaching Biological Probes to Silica Optical Biosensors Using Silane Coupling Agents

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) technique), make use of various surface modification techniques, that can, for example, prevent surface fouling, tune the hydrophobicity / hydrophilicity of the surface, adapt to a variety of electronic environments, and most frequently, induce specificity towards a target of interest.1-5 These techniques extend the functionality of otherwise highly sensitive biosensors to real-world applications in complex environments, such as blood, urine, and wastewater analysis.2,6-7 While commercial biosensing platforms, such as Biacore, have well-understood, standard techniques for performing such surface modifications, these techniques have not been translated in a standardized fashion to other label-free biosensing platforms, such as Whispering Gallery Mode (WGM) optical resonators.8-9
WGM optical resonators represent a promising technology for performing label-free detection of a wide variety of species at ultra-low concentrations.6,10-12 The high sensitivity of these platforms is a result of their unique geometric optics: WGM optical resonators confine circulating light at specific, integral resonance frequencies.13 Like the SPR platforms, the optical field is not totally confined to the sensor device, but evanesces; this "evanescent tail" can then interact with species in the surrounding environment. This interaction causes the effective refractive index of the optical field to change, resulting in a slight, but detectable, shift in the resonance frequency of the device. Because the optical field circulates, it can interact many times with the environment, resulting in an inherent amplification of the signal, and very high sensitivities to minor changes in the environment.2,14-15
To perform targeted detection in complex environments, these platforms must be paired with a probe molecule (usually one half of a binding pair, e.g. antibodies / antigens) through surface modification.2 Although WGM optical resonators can be fabricated in several geometries from a variety of material systems, the silica microsphere is the most common. These microspheres are generally fabricated on the end of an optical fiber, which provides a "stem" by which the microspheres can be handled during functionalization and detection experiments. Silica surface chemistries may be applied to attach probe molecules to their surfaces; however, traditional techniques generated for planar substrates are often not adequate for these three-dimensional structures, as any changes to the surface of the microspheres (dust, contamination, surface defects, and uneven coatings) can have severe, negative consequences on their detection capabilities. Here, we demonstrate a facile approach for the surface functionalization of silica microsphere WGM optical resonators using silane coupling agents to bridge the inorganic surface and the biological environment, by attaching biotin to the silica surface.8,16 Although we use silica microsphere WGM resonators as the sensor system in this report, the protocols are general and can be used to functionalize the surface of any silica device with biotin.

Biosensors interface with complex, biological environments and perform targeted detection by combining highly sensitive sensors with highly specific probes attached to the sensor via surface modification. Here, we demonstrate the surface functionalization of silica optical sensors with biotin using silane coupling agents to bridge the sensor and the biological environment.

将生物探针使用硅烷偶联剂的硅光学生物传感器

In order to interface with biological environments, biosensor platforms, such as the popular Biacore system (based on the Surface Plasmon Resonance (SPR) ...

生物工程

Layer-by-layer Synthesis and Transfer of Freestanding Conjugated Microporous Polymer Nanomembranes

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in combination with their outstanding thermal and chemical stability, and low densities. However, their insoluble nature causes problems in their processing since usually applied techniques such as spin coating are not available. Especially for membrane applications, where the processing of CMP as thin films is desirable, the processing problems have hindered their commercial application.
Here we describe the interfacial synthesis of CMP thin films on functionalized substrates via molecular layer-by-layer (l-b-l) synthesis. This process allows the preparation of films with desired thickness and composition and even desired composition gradients.
The use of sacrificial supports allows the preparation of freestanding membranes by dissolution of the support after the synthesis. To handle such ultra-thin freestanding membranes the protection with sacrificial coatings showed great promise, to avoid rupture of the nanomembranes. To transfer the nanomembranes to the desired substrate, the coated membranes are upfloated at the air-liquid interface and then transferred via dip coating.

In this paper we describe the interfacial synthesis of conjugated microporous polymers (CMP) on sacrificial substrates, and the dissolution of the substrate for the preparation of freestanding CMP nanomembranes. In addition, we will describe how the fragile nanomembranes can be transferred to other substrates.

层 - 层的合成和独立式共轭微孔聚合物纳米薄膜的转移

CMP as large surface area materials have attracted growing interest recently, due to their high variability in the incorporation of functional groups in ...

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 ...

Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) with a 4.6 nm pore size, and ordered silica porous matrix, SBA-15, with a 5.3 nm pore size. This work describes the surface properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the differently ordered porous materials with similar pore sizes. For this purpose, OMC and SBA-15 with highly ordered nanoporous structures are synthesized via impregnation of the silica matrix by applying a carbon precursor and by the sol-gel method, respectively. The porous structure of investigated systems is characterized by an N2 adsorption-desorption analysis at 77 K. To determine the electrochemical character of the surface of synthesized materials, potentiometric titration measurements are conducted; the obtained results for OMC shows a significant pHpzc shift toward the higher values of pH, relative to SBA-15. This suggests that investigated OMC has surface properties related to oxygen-based functional groups. To describe the surface properties of the materials, the contact angles of liquids penetrating the studied porous beds are also determined. The capillary rise method has confirmed the increased wettability of the silica walls relative to the carbon walls and an influence of the pore roughness on the fluid/wall interactions, which is much more pronounced for silica than for carbon mesopores. We have also studied the melting behavior of D2O confined in OMC and SBA-15 by applying the dielectric method. The results show that the depression of the melting temperature of D2O in the pores of OMC is about 15 K higher relative to the depression of the melting temperature in SBA-15 pores with a comparable 5 nm size. This is caused by the influence of adsorbate/adsorbent interactions of the studied matrices.

Here we report the synthesis and characterization of ordered nanoporous carbon (with a 4.6 nm pore size) and SBA-15 (with a 5.3 nm pore size). The work describes the surface and textural properties of nanoporous molecular sieves, their wettability, and the melting behavior of D2O confined in the materials.

合成纳米碳和二氧化硅矩阵的表面性能

In this work, we report the synthesis and characterization of ordered nanoporous carbon material (also called ordered mesoporous carbon material [OMC]) ...

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared according to the methodology developed by surface organometallic chemistry (SOMC). In this framework, catalytic cycles can be determined by isolating crucial intermediates. All air-sensitive materials are handled under inert atmosphere (using gloveboxes or a Schlenk line) or high vacuum lines (HVLs, &#60;10-5 mbar). The preparation of SiO2-700 (silica dehydroxylated at 700 &#176;C) and subsequent applications (the grafting of complexes and catalytic runs) requires the use of HVLs and double-Schlenk techniques. Several well-known characterization methods are used, such as Fourier-transform infrared spectroscopy (FTIR), elemental microanalysis, solid-state nuclear magnetic resonance spectroscopy (SSNMR), and state-of-the-art dynamic nuclear polarization surface enhanced NMR spectroscopy (DNP-SENS). FTIR and elemental microanalysis permit scientists to establish the grafting and its stoichiometry. 1H and 13C SSNMR allows the structural determination of the hydrocarbon ligands coordination sphere. DNP SENS is an emerging powerful technique in solid characterization for the detection of poorly sensitive nuclei (15N, in our case). SiO2-700 is treated with about one equivalent of the metal precursor compared to the amount of surface silanol (0.30 mmol&#183;g-1) in pentane at room temperature. Then, volatiles are removed, and the powder samples are dried under dynamic high vacuum to afford the desired materials [(&#8801;Si-O-)Hf(&#951;2&#960;-MeNCH2)(&#951;1-NMe2)(&#951;1-HNMe2)]. After a thermal treatment under high vacuum, the grafted complex is converted into metal imido silica complex [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)]. [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] effectively promotes the metathesis of imines, using the combination of two imine substrates, N-(4-phenylbenzylidene)benzylamine, or N-(4-fluorobenzylidene)-4-fluoroaniline, with N-benzylidenetert-butylamine as substrates. A significantly lower conversion is observed with the blank runs; thus, the presence of the imido group in [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is correlated to the catalytic performance.

A new group IV metal catalyst for imine metathesis is prepared by grafting amine metal complex onto dehydroxylated silica. Surface metal fragments are characterized using FT-IR, elemental microanalysis, and solid-state NMR spectroscopy. Further dynamic nuclear polarization surface enhanced NMR spectroscopy experiments complement the determination of the coordination sphere.

利用表面有机金属化学方法，利用硅支持的催化剂进行Imine金属分析

With this protocol, a well-defined singlesite silica-supported heterogeneous catalyst [(&#8801;Si-O-)Hf(=NMe)(&#951;1-NMe2)] is designed and prepared ...

胺化化合物的浸渍和接枝到二氧化硅基材上

A Synthetic Methodology for Preparing Impregnated and Grafted Amine-Based Silica Composites for Carbon Capture

Recently, there has been a significant effort towards reducing or mitigating CO2 emissions through the use of carbon capture materials for point source or direct air capture (DAC) methods. This work focuses on amine-functionalized CO2 adsorbents for DAC. These materials show promise for CO2 removal because they have low regeneration energy consumption and high adsorption capacity. The incorporation of amine species into a porous substrate combines the advantages of the amine species&#39; affinity to CO2 with the large pore volumes and surface areas of the porous substrate. There are three methods commonly used to prepare amine-based CO2 sorbents, depending on the selection of the amine species, material support, and preparation method. These methods are impregnation, grafting, or chemical synthesis. Silica is a prevalent choice of substrate material because of its adjustable pore size, moisture tolerance, temperature stability, and ability to adsorb CO2 in low concentrations for DAC applications. Typical synthetic procedures and primary attributes of both impregnated and grafted amine-silica composites are described herein.

作者聚焦:胺基二氧化硅复合材料作为直接空气捕获的 CO2 吸附剂的标准化开发 

This work aims to facilitate the development of standardized techniques for impregnating or grafting aminated compounds onto silica substrates, which are often broadly described in the literature. Specific amounts of solvent, substrate, amines, and the values of other important experimental parameters will be discussed in detail.

一种制备浸渍接枝胺基二氧化硅复合材料的合成方法

Recently, there has been a significant effort towards reducing or mitigating CO2 emissions through the use of carbon capture materials for point source or ...