Name: preparation of biopolymer aerogels using green solvents
Uploaded: 2016-07-04T14:00:00.000+00:00
Duration: 8 min 13 s
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从东风集团的资金支持（SM项目82 / 13-1）表示感谢。

1.酰胺化果胶原液的制备<ol><li>混合20克酰胺化果胶980克水（2.0重量％）。酰胺化的程度是25％（重量）。 </li><li>均质用高速搅拌器（10,000rpm下）的溶液2分钟以获得均匀的粘稠溶液。 </li><li>用pH条或pH计测量pH值。如果pH低于6.5，滴定用0.5M的NaOH以中和溶液（pH至7.0）。 </li><li>添加碳酸钙的每克干酰胺化果胶（Q = 1）的0.1825克的比率。 "Q"表示交联度。 </li><li> :每千克2.0％（重量）酰胺化果胶溶液，加入3.65克碳酸钙（Q = 1），7％20.0克干果胶。 </li><li>对于更大的交联，添加每克干酰胺化果胶（Q = 2）的0.3650克碳酸钙。 </li></ol> 2.生产的水凝胶<ol><li>使用高速均化器（10,000rpm下），以获得一个均匀的酰胺化果胶/碳酸钙混合物白色均匀分散。 </li><li>转移到悬挂开放聚丙烯模具或玻璃培养皿。 </li><li>放置模具在高压釜。密封该高压釜中。 </li><li>加压用气态CO 2的高压釜达到在RT 5兆帕。参阅Gurikov 等 7进一步的信息。维持24小时的压力。 </li><li>在0.2MPa /分钟慢慢减压高压釜中。 </li><li>打开高压釜并取出模具。通过把它们通过除去从模具的水凝胶。如果有必要，用刮刀。 </li></ol> 3.溶剂交换程序<ol><li>制备出10克10:90（重量/重量），每克水凝胶的乙醇/水混合物中。 </li><li>沉浸在10:90的水凝胶（W / W）12小时乙醇/水混合物中。 </li><li>继续增加的乙醇浓度， 即该方法中，从10:90（重量/重量）的乙醇/水混合物中以30:70（重量/重量）的乙醇/水混合物中。 12小时后，转移至5零点50（W / W）乙醇/水混合物中，然后至70:30（12小时），然后90:10（12小时），然后至100％的乙醇溶液（12小时）。 </li><li>进一步浸泡凝胶在纯乙醇使凝胶内的最终浓度为98％以上（重量/重量）。用密度计测量浓度。该醇凝胶现在准备超临界CO 2干燥。 </li></ol> 4.生产气凝胶的超临界CO 2干燥<ol><li>放置样品用于凝胶制剂相同的高压釜（见步骤2.3）。 </li><li>填用另外的乙醇（高压釜容积的2-10％）的高压釜，以防止过早溶剂蒸发从凝胶。不需要在溶剂凝胶完全浸没。 </li><li>密封该高压釜中。打开高压釜加热。设置高压釜工作温度至323 K.加压使用压缩机或泵的高压釜与二氧化碳12兆帕。 </li><li>定期更换的 CO 2高压釜10,11新鲜的CO 2保持压力恒定内。 6-7居住卷都必须经过一段6小时。参阅Gurikov 等 7进一步的信息。 </li><li>在0.2MPa /分钟慢慢减压高压釜中。 </li><li>打开高压釜，收集气凝胶。存储在一个exicator或密封容器中的气凝胶。 </li></ol>

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作者宣称，他们没有竞争的经济利益。

通过使用CO 2的诱导凝胶技术，可以消除对化学代用品（例如乙酸或葡糖酸-δ-内酯（GDL））用于诱导所述生物聚合物的交联所需的需要。该酰胺化果胶气凝胶的表面积在文献值5的较高范围，但是孔体积比在文献5中要高得多。较高的孔隙体积也由二氧化碳诱导凝胶7海藻酸钠制成气凝胶观察。但是，它仍然待验证此高孔体积（4-150纳米孔径范围）的原因是否是由于凝胶化技术或先前在文献中没有解决的生物聚合物的固有性质。果胶气凝胶已报道在文献具备superinsulating属性12和由该技术制备的藻气凝胶还具有在superinsulating范围的热导率3,7。因此，用这种技术生产的酰胺化果胶气凝胶也可以设想具有superinsulating属性。 减压的协议第2节的速率是在水凝胶制剂中的重要一步。快速减压，能够增加凝胶的大孔性。这个现象可应用于组织工程应用，其中与互联的材料的大孔性为细胞13,14的生长和增殖的重要特征。另外，在协议部分1的交联度起着脱水收缩的酰胺化果胶凝胶中的重要作用，溶胀性。这类似于海藻酸钠水凝胶的溶胀行为由交联剂浓度的影响，以及15。由此通过酰胺化果胶制成的气凝胶也可以被调谐至具有类似于那些报道的藻气凝胶16超吸收属性。 &lt;P类="jove_content"&gt;通过使用作为主系统的CO 2的诱导凝胶考虑酰胺化果胶（或藻），进一步分集可以通过引入不同交联剂和生物聚合物的组合掺入气凝胶。几个金属碳酸盐（ 例如，锌，镍，钴，铜，锶，钡）可用于交联3，其中阳离子可以通过pH值的水性介质中降低与加压的 CO 2（3-5兆帕）被释放。然而，其中一些阳离子的不溶盐可以不形成用于降低生物聚合物的浓度稳定的分散体，并且可以在底部导致不均匀的凝胶沉淀下来。这是与内部设定凝胶化方法，其包括CO 2的诱导凝胶3，由此，该技术的一个应用的可用性应到个案基础上进行评估的一般问题。 各种混合物使用水溶性生物制备聚合物，如淀粉，角叉菜胶，甲基和羧甲基纤维素，结冷胶，木质素，明胶及其他;水溶性合成聚合物，例如聚乙二醇（PEG），聚乙烯醇（PVA），聚醚的P-123及其他;和水溶性无机前体，如硅酸钠可以用酰胺化果胶以产生类似于藻酸盐2与调谐性能混合气凝胶可以还混合。 作为超临界二氧化碳干燥（SCCO 2干燥）是一个典型的步骤中气凝胶生产，预处理步骤，例如使用CO 2 7可以提供溶剂交换并干燥使用的 CO 2 17,18或凝胶化，溶剂交换并干燥的任何组合一个明确的处理优势。其优点是设想为集成一锅法:其中生物聚合物分散体可以被转换成以CO 2作为在单个高压釜主处理平台生物聚合物气凝胶。对于在使用CO 2作为处理介质的单个高压釜凝胶，溶剂交换，超临界干燥和活性成分装载5,19过程:某些药物应用，可以还想象到执行一个四步骤。后处理如在某些情况下药物加载气凝胶的保护涂层是必要的靶向药物释放20。 总之，目前的工作演示了基于酰胺化果胶体系的凝胶化利用加压的二氧化碳 。另外，作为用于前体产品转化为在一个单一的高压釜目标应用程序的通用平台使用加压的 CO 2的设想。

气凝胶是一类的多孔材料，可以使用各种前体从无机（如二氧化硅，二氧化钛，氧化锆等），合成的（如间苯二酚甲醛，聚氨酯等）或生物聚合物（多糖，蛋白质和其他的制备）2。什么它们区别于传统的多孔材料是他们的能力，同时具有所有三个特点;即高表面积，超低密度和中孔的孔径分布（ 即从2-50纳米的孔径）。具有上述特性，气凝胶被广泛在绝缘，生物医药，催化，吸附和吸收的应用，药物和neutraceuticals 2领域的应用。考虑到上述可能性，生产生物聚合物凝胶系统及其随后的转化气凝胶开辟了向高价值的机会众多加入生物材料。这种努力溶于在这项研究中使用酰胺化果胶，例如， 气凝胶通常是由溶胶 - 凝胶技术产生的。凝胶是自由的以矩阵截留液系统，可以通过共价的，离子的，pH值诱发的，热或低温交联3来制备。对于这个特定的系统，我们利用离子交联， 即，二价阳离子（ 如钙），以生物聚合物链交联在一起。执行生物聚合物如酰胺化果胶或藻酸盐的可控离子交联，可以利用扩散法或内部设置方法4。在扩散方法中，凝胶化发生在第一外层，随后通过扩散传播，作为阳离子从外部解成酰胺化果胶或藻酸盐微滴或层4扩散。在内部设置的方法，所述交联剂的不溶形式被均匀地分散在该生物聚合物搜索解决方案n和阳离子通过启动pH变化4,5,6释放。然而，这两种技术面临板或整体形式制造时有关的最终凝胶的均匀性的问题。这项工作表明生产酰胺化果胶水凝胶藻酸盐凝胶3,7进一步对以前的作品建筑使用高压CO 2（5兆帕）的。简而言之，它是一个内部设定凝胶化技术，其利用加压的 CO 2来降低pH值，而不是弱酸，以产生均匀的凝胶。与增加的压力，二氧化碳在水中的溶解度增加伴随着pH值降低到3.0 8。这会导致碳酸钙溶解，释放出钙离子。钙离子与酰胺化果胶生物聚合物交联，得到水凝胶。稳定均匀的凝胶降到很低的生物聚合物的浓度（0.05重量％）可使用该技术7制备。 由于GELAT离子发生在含水介质中，溶剂交换的有机溶剂是必需的，由于在CO 2 /水系统中的溶解度间隙。典型的低分子量醇（甲醇/乙醇/异丙醇）和酮（丙酮）可被用于该溶剂交换过程。然而，与纯乙醇或其他有机溶剂的浴直接浸泡导致显著不可逆的收缩。为了避免这种缺点，逐步溶剂交换进行5,9。当凝胶内的溶剂浓度达到&gt; 98％时，有机溶剂与超临界的 CO 2（12兆帕），留下的气凝胶后面干燥。

<table><tbody><tr><td>&lt;strong&gt;Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Ultraturrax homogenizer</td><td>IKA, Germany</td><td>T 25 Digital</td><td></td></tr><tr><td>Polypropylene molds</td><td>TH. Geyer, Germany</td><td>9,033,201</td><td></td></tr><tr><td>High pressure autoclave&amp;nbsp;</td><td>Ernst Haage, Germany</td><td>custom made</td><td>Setup constuction done in-house</td></tr><tr><td>Compressor</td><td>Andreas Hofer</td><td>MKZ 185-40</td><td>Setup constuction done in-house</td></tr><tr><td>Nitrogen adsorption</td><td>Quantachrome</td><td>Nova 4000e</td><td></td></tr><tr><td>Density meter</td><td>Anton Paar</td><td>DMA 4000</td><td></td></tr><tr><td>&lt;strong&gt;Chemicals&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Amidated pectin</td><td>Herbstreith and Fox, Germany</td><td>CU 025</td><td>CAS # 56645-02-4; provided by company for research purposes</td></tr><tr><td>Sodium Hydroxide</td><td>Sigma Aldrich, Germany</td><td>S8045</td><td>CAS # 1310-73-2; required only in case the pectin solution needs to be neutralized to pH 6.5-7.5</td></tr><tr><td>Calcium carbonate</td><td>Magnesia GmbH, Germany</td><td>4421 Calcium carbonat, leicht, pr&amp;auml;zipitiert, EP, E170</td><td>CAS # 471-34-1</td></tr><tr><td>Ethanol, 99.8%</td><td>Sigma Aldrich, Germany</td><td>32205</td><td>CAS # 64-17-5</td></tr><tr><td>Carbon dioxide, 99.9%</td><td>AGA Gas GmbH, Germany</td><td></td><td>CAS # 124-38-9; in-house tank available (3 ton)</td></tr><tr><td>Deionised Water</td><td></td><td></td><td>CAS # 7732-18-5;&amp;nbsp; available in-house (6.4-7.0 pH)</td></tr></tbody></table>

preparation of biopolymer aerogels using green solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

（如在协议部分2指示）在图1中示出具有更高的交联度（Q = 2）凝胶化步骤后得到的典型水凝胶。将样品在左侧（样品A和B）是2重量％和1％（重量）用CO 2诱导凝胶获得果胶凝胶。通过降低生物聚合物浓度（0.5％（重量）或更低），凝胶变得透明（样品C）。在生物聚合物的浓度（0.25％重量）进一步减少也产生稳定的水凝胶（样品D），但这些凝胶非常脆弱，操作时可以打破。当溶解的CO 2离开，由于在CO 2的溶解性降低凝胶的水系统中的水凝胶内观察到的气泡被减压期间创建的。 该酰胺化果胶气凝胶特性在表1中。将所得的气凝胶的超多孔低巢穴<html>减到（低至0.013克/厘米3）作为气凝胶和其体积的质量之间的比率。表面积通过氮吸附测定的。为果胶气凝胶，它产生了350之间的比表面积- 400米2 /克。在4-150纳米范围内的孔径的细孔容积是通过使用氮（BJH法）孔隙填充的Kelvin模型测定。细孔容积为酰胺化的果胶气凝胶是3之间-第7 毫升 /克4和150纳米之间的孔尺寸。 <img alt="图1" src="/files/ftp_upload/54116/54116fig1.jpg" /> 图1.酰胺化果胶的水凝胶具有较高的交联度（Q = 2）左上:2％（重量）（样品A）。右上:1％（重量）（样品B）;左下:0.5％（重量）（样品C）;右下:0.25％（重量）（样品D）。凝胶成为透明的生物聚合物降低浓度。气泡是二氧化碳减压过程中产生的。https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/54116/54116fig1large.jpg"目标="_空白"&gt;点击此处查看该图的放大版本。 <table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody><tr><td> 果胶含量[重量％] </td><td> 交联度q </td><td> 堆积密度[克/厘米3] </td><td> 比表面积[米2 /克] </td><td> 比孔体积[厘米3 / g 的 ] </td><td> 平均孔尺寸（直径）[nm]的 </td></tr><tr><td> 2.00 </td><td> 1 </td><td> 0.081 </td><td> 502 </td><td> 4.1 </td><td> 14 </td></tr><tr><td> 1.00 </td><td> 1 </td><td> 0.044 </td><td> 491 </td><td> 7.1 </td><td> 27 </td></tr><tr><td> 0.50 </td><td> 1 </td><td> 0.035 </td><td> 357 </td><td> 3.8 </td><td> 27 </td></tr><tr><td> 0.25 </td><td> 1 </tD&gt; <td> 0.013 </td><td> 335 </td><td> 4.9 </td><td> 41 </td></tr><tr><td> 2.00 </td><td> 2 </td><td> 0.069 </td><td> 447 </td><td> 3.1 </td><td> 13 </td></tr><tr><td> 1.00 </td><td> 2 </td><td> 0.048 </td><td> 441 </td><td> 3.6 </td><td> 26 </td></tr><tr><td> 0.50 </td><td> 2 </td><td> 0.030 </td><td> 429 </td><td> 5.8 </td><td> 25 </td></tr><tr><td> 0.25 </td><td> 2 </td><td> 0.017 </td><td> 347 </td><td> 5 </td><td> 24 </td></tr></tbody></table> 表1.酰胺化果胶气凝胶的特点。

Watch this Scientific Journal Video about Preparation of Biopolymer Aerogels Using Green Solvents at JoVE.com

Preparation of Biopolymer Aerogels Using Green Solvents

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

生物聚合物气凝胶制备使用绿色溶剂

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

preparation-of-biopolymer-aerogels-using-green-solvents

Nanyang Technological University

Research

JoVE Journal

Chemistry

17.6K 次观看.  Hamburg University of Technology. A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

视频: Preparation of Biopolymer Aerogels Using Green Solvents

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 ...

科研

化学

Synthesis and Functionalization of 3D Nano-graphene Materials: Graphene Aerogels and Graphene Macro Assemblies

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. Additionally, most reported graphene assemblies are held together through physical interactions (e.g., van der Waals forces) rather than chemical bonds, which limit their mechanical strength and conductivity. This video method details recently developed strategies to fabricate mass-producible, graphene-based bulk materials derived from either polymer foams or single layer graphene oxide. These materials consist primarily of individual graphene sheets connected through covalently bound carbon linkers. They maintain the favorable properties of graphene such as high surface area and high electrical and thermal conductivity, combined with tunable pore morphology and exceptional mechanical strength and elasticity. This flexible synthetic method can be extended to the fabrication of polymer/carbon nanotube (CNT) and polymer/graphene oxide (GO) composite materials. Furthermore, additional post-synthetic functionalization with anthraquinone is described, which enables a dramatic increase in charge storage performance in supercapacitor applications.

This video method describes the synthesis of high surface area, monolithic 3D graphene-based materials derived from polymer precursors as well as single layer graphene oxide.

合成和3D纳米石墨烯材料的功能化:石墨烯气凝胶和石墨烯宏组件

Efforts to assemble graphene into three-dimensional monolithic structures have been hampered by the high cost and poor processability of graphene. ...

工程学

Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three preparation methods are described: (a) the incorporation of metal salts into silica or alumina wet gels using an impregnation method; (b) the incorporation of metal salts into alumina wet gels using a co-precursor method; and (c) the addition of metal nanoparticles directly into a silica aerogel precursor mixture. The methods utilize a hydraulic hot press, which allows for rapid (&#60;6 h) supercritical extraction and results in aerogels of low density (0.10 g/mL) and high surface area (200-800 m2/g). While the work presented here focuses on the use of copper salts and copper nanoparticles, the approach can be implemented using other metal salts and nanoparticles. A protocol for testing the three-way catalytic ability of these aerogels for automotive pollution mitigation is also presented. This technique uses custom-built equipment, the Union Catalytic Testbed (UCAT), in which a simulated exhaust mixture is passed over an aerogel sample at a controlled temperature and flow rate. The system is capable of measuring the ability of the catalytic aerogels, under both oxidizing and reducing conditions, to convert CO, NO and unburned hydrocarbons (HCs) to less harmful species (CO2, H2O and N2). Example catalytic results are presented for the aerogels described.

Here we present protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms. Methods for preparing materials using copper salts and copper-containing nanoparticles are featured. Catalytic testing protocols demonstrate the effectiveness of these aerogels for three-way catalysis applications.

快速超临界萃取制备催化气凝胶的制备与试验研究

Protocols for preparing and testing catalytic aerogels by incorporating metal species into silica and alumina aerogel platforms are presented. Three ...

A Rapid Synthesis Method for Au, Pd, and Pt Aerogels Via Direct Solution-Based Reduction

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various precursor noble metal ions with reducing agents in a 1:1 (v/v) ratio results in the formation of metal gels within seconds to minutes compared to much longer synthesis times for other techniques such as sol-gel. Conducting the reduction step in a microcentrifuge tube or small volume conical tube facilitates a proposed nucleation, growth, densification, fusion, equilibration model for gel formation, with final gel geometry smaller than the initial reaction volume. This method takes advantage of the vigorous hydrogen gas evolution as a by-product of the reduction step, and as a consequence of reagent concentrations. The solvent accessible specific surface area is determined with both electrochemical impedance spectroscopy and cyclic voltammetry. After rinsing and freeze drying, the resulting aerogel structure is examined with scanning electron microscopy, X-ray diffractometry, and nitrogen gas adsorption. The synthesis method and characterization techniques result in a close correspondence of aerogel ligament sizes. This synthesis method for noble metal aerogels demonstrates that high specific surface area monoliths may be achieved with a rapid and direct reduction approach.

A rapid, direct solution-based reduction synthesis method to obtain Au, Pd, and Pt aerogels is presented.

直接溶液还原法快速合成金、钯、铂气凝胶的研究

Here, a method to synthesize gold, palladium, and platinum aerogels via a rapid, direct solution-based reduction is presented. The combination of various ...

Synthesis Method for Cellulose Nanofiber Biotemplated Palladium Composite Aerogels

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often result in fragile aerogels with poor shape control. The use of carboxymethylated cellulose nanofibers (CNFs) to form a covalently bonded hydrogel allows for the reduction of metal ions such as palladium on the CNFs with control over both nanostructure and macroscopic aerogel monolith shape after supercritical drying. Crosslinking the carboxymethylated cellulose nanofibers is achieved using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) in the presence of ethylenediamine. The CNF hydrogels maintain their shape throughout synthesis steps including covalent crosslinking, equilibration with precursor ions, metal reduction with high concentration reducing agent, rinsing in water, ethanol solvent exchange, and CO2 supercritical drying. Varying the precursor palladium ion concentration allows for control over the metal content in the final aerogel composite through a direct ion chemical reduction rather than relying on the relatively slow coalescence of pre-formed nanoparticles used in other sol-gel techniques. With diffusion as the basis to introduce and remove chemical species into and out of the hydrogel, this method is suitable for smaller bulk geometries and thin films. Characterization of the cellulose nanofiber-palladium composite aerogels with scanning electron microscopy, X-ray diffractometry, thermal gravimetric analysis, nitrogen gas adsorption, electrochemical impedance spectroscopy, and cyclic voltammetry indicates a high surface area, metallized palladium porous structure.

A synthesis method for cellulose nanofiber biotemplated palladium composite aerogels is presented.The resulting composite aerogel materials offer potential for catalysis, sensing, and hydrogen gas storage applications.

纤维素纳米纤维生物模板复合气凝胶的合成方法

Here, a method to synthesize cellulose nanofiber biotemplated palladium composite aerogels is presented. Noble metal aerogel synthesis methods often ...

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol&#8211;gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO2) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development.

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

This procedure describes how to encapsulate cytochrome c (cyt. c) in silica (SiO2) sol-gels, process these gels to form bioaerogels, and use these bioaerogels to rapidly recognize nitric oxide (NO) through a gas-phase reaction. This type of protocol may aid in the future development of biosensors or other bioanalytical devices.

细胞色素封装<em&gt;ç</em&gt;在二氧化硅气凝胶Nanoarchitectures没有金属纳米粒子，同时保持气相生物活性

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are ...

生物工程

Forming Giant-sized Polymersomes Using Gel-assisted Rehydration

Polymer vesicles, or polymersomes, are being widely explored as synthetic analogs of lipid vesicles based on their stability, robustness, barrier properties, chemical versatility and tunable physical characteristics. Typical methods used to prepare giant-sized (&gt; 4 &#181;m) vesicles, however, are both time and labor intensive, yielding low numbers of intact polymersomes. Here, we present for the first time the use of gel-assisted rehydration for the rapid and high-yielding formation of giant (&gt;4 &#181;m) polymer vesicles (polymersomes). Using this method, polymersomes can be formed from a wide array of rehydration solutions including several different physiologically-compatible buffers and full cell culture media, making them readily useful for biomimicry studies. This technique is also capable of reliably producing polymersomes from different polymer compositions with far better yields and much less difficulty than traditional methods. Polymersome size is readily tunable by altering temperature during rehydration or adding membrane fluidizers to the polymer membrane, generating giant-sized polymersomes (&gt;100 &#181;m).

We present a protocol to rapidly form giant polymer vesicles (pGVs). Briefly, polymer solutions are dehydrated on dried agarose films adhered to coverslips. Rehydration of the polymer films results in rapid formation of pGVs. This method greatly advances the preparation of synthetic giant vesicles for direct applications in biomimetic studies.

形成用凝胶辅助补液巨型的聚合物囊泡

Polymer vesicles, or polymersomes, are being widely explored as synthetic analogs of lipid vesicles based on their stability, robustness, barrier ...

Aesthetically Enhanced Silica Aerogel Via Incorporation of Laser Etching and Dyes

A procedure for aesthetically enhancing silica aerogel monoliths by laser etching and incorporation of dyes is described in this manuscript. Using a rapid supercritical extraction method, large silica aerogel monolith (10 cm x 11 cm x 1.5 cm) can be fabricated in about 10 h. Dyes incorporated into the precursor mixture result in yellow-, pink- and orange-tinged aerogels. Text, patterns, and images can be etched onto the surface (or surfaces) of the aerogel monolith without damaging the bulk structure. The laser engraver can be used to cut shapes from the aerogel and form colorful mosaics.

This protocol describes a method for etching text, patterns, and images onto the surface of silica aerogel monoliths in native and dyed form and assembling the aerogels into mosaic designs.

通过将激光蚀刻和染料结合，美学增强硅气凝胶

A procedure for aesthetically enhancing silica aerogel monoliths by laser etching and incorporation of dyes is described in this manuscript. Using a rapid ...

Designed for Molecular Recycling: A Lignin-Derived Semi-aromatic Biobased Polymer

The development of chemically recyclable biopolymers offers opportunities within the pursuit of a circular economy. Chemically recyclable biopolymers make a positive effort to solve the issue of polymer materials in the disposal phase after the use phase. In this paper, the production of biobased semi-aromatic polyesters, which can be extracted entirely from biomass such as lignin, is described and visualized. The polymer poly-S described in this paper has thermal properties similar to certain commonly used plastics, such as PET. We developed a Green Knoevenagel reaction, which can efficiently produce monomers from aromatic aldehydes and malonic acid. This reaction has been proven to be scalable and has a remarkably low calculated E-factor. These polyesters with ligno-phytochemicals as a starting point show an efficient molecular recycling with minimal losses. The polyester poly(dihydrosinapinic acid) (poly-S) is presented as an example of these semi-aromatic polyesters, and the polymerization, depolymerization, and re-polymerization are described.

An example of a closed-loop approach towards a circular materials economy is described here. A whole sustainable cycle is presented where biobased semi-aromatic polyesters are designed by polymerization, depolymerization, and then re-polymerized with only slight changes in their yields or final properties.

专为分子回收而设计:一种褐宁衍生的半芳烃生物基聚合物

The development of chemically recyclable biopolymers offers opportunities within the pursuit of a circular economy. Chemically recyclable biopolymers make ...

Synthesis of Hydrogels with Antifouling Properties As Membranes for Water Purification

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and thus achieving stable water permeability through membranes over time. Here, we report a facile method to prepare hydrogels based on zwitterions for membrane applications. Freestanding films can be prepared from sulfobetaine methacrylate (SBMA) with a crosslinker of poly(ethylene glycol) diacrylate (PEGDA) via photopolymerization. The hydrogels can also be prepared by impregnation into hydrophobic porous supports to enhance the mechanical strength. These films can be characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to determine the degree of conversion of the (meth)acrylate groups, using goniometers for hydrophilicity and differential scanning calorimetry (DSC) for polymer chain dynamics. We also report protocols to determine the water permeability in dead-end filtration systems and the effect of foulants (bovine serum albumin, BSA) on membrane performance.

This paper reports practical methods to prepare hydrogels in freestanding films and impregnated membranes and to characterize their physical properties, including water transport properties.

水凝胶的合成与防污性能作为膜的净水

Hydrogels have been widely utilized to enhance the surface hydrophilicity of membranes for water purification, increasing the antifouling properties and ...