基于QCM-D的天然多糖材料的蛋白吸附研究

采用QCM-D和AFM等技术研究比较了海藻酸钙和壳聚糖两种天然多糖材料经旋转成膜后的表面形貌、亲疏水性、水合过程及蛋白吸附和解吸行为.结果发现,海藻酸钙相比壳聚糖具有更好的亲水性,在生理环境中的水合过程达到平衡较快,且水合程度较高,这也影响材料的蛋白吸附性能.白蛋白吸附和洗脱实验表明,水舍程度较高的海藻酸钙初始吸附蛋白量较少,但海藻酸钙吸附的蛋白量在PBS洗脱后反而较大.而蛋白层|△D/△F|值在洗脱后减小,表明残留的蛋白层发生一定程度的构象变化,结构相对致密,其粘弹性变小.用3种动力学模型拟合蛋白吸附动力学过程发现Langmuir模型拟合度较高,且壳聚糖薄膜的蛋白吸附过程比海藻酸钙具有更小的速率常数k,达到吸附平衡较缓慢.     

金表面不同官能团自组装材料的生物性能研究

设计了一种特定的化学模型系统,将带有不同官能团(烷基、羧基、羟基、氨基)的硫醇分子自组装在金片表面,研究不同官能团分子对蛋白吸附的影响.实验结果表明,对于两种不同蛋白质牛血清蛋白(BSA)和碱性成纤维细胞生长因子(bFGF),带有疏水性官能团的烷基硫醇自组装膜对蛋白吸附量大于其他3种硫醇自组装膜,即亲疏水性是决定材料表面吸附蛋白的主要因素.另外,材料表面电荷性质也影响蛋白吸附,当表面官能团为带正电基团如氨基,则它对牛血清这类带负电的蛋白的吸附就大于带有羧基、羟基等这类带负电基团的分子,而后者对于正电蛋白的吸附更为明显.     

消息报道

我国制备出可控超疏水超亲水可逆转换薄膜在中国科学院、国家自然科学基金委和科技部的支持下,中国科学院化学研究所有机固体院重点实验室的研究人员成功制备出双响应可控超疏水与超亲水可逆转换材料。在前期工作中,该组研究人员在紫外响应超疏水-超亲水可逆“开关”研究中,利用水热法成功制备阵列的氧化锌纳米棒,实现了其超疏水表面的浸润性由超疏水向超亲水转变。同时通过表面原子转移自由基聚合方法,在基底上制备温度响应高分子的可逆开关(该项目已入选2004年度“中国十大科技进展新闻”)。在此基础上,该组研究人员成功制备了温度、pH值…     

超疏水聚丙烯表面的制备及血液相容性研究

将0.2g聚丙烯树脂在120℃溶于20ml二甲苯中,再滴涂在3片玻璃片上,然后分别在25、50和150℃条件下干燥,分别制得了具有低滚动角、高滚动角的超疏水表面和光滑的表面.血液相容性研究表明:具有低滚动角的超疏水表面具有良好的抗凝血性;超疏水聚丙烯表面没有血小板吸附,而光滑的聚丙烯薄膜表面则有明显的血小板吸附;超疏水聚丙烯和光滑聚丙烯薄膜表面的溶血率都低于5%且以具有低滚动角的超疏水聚丙烯表面的溶血率最低.     

金属锌表面超疏水薄膜的制备及其摩擦学性能

通过简单两步法在金属锌表面构筑超疏水薄膜, 锌片首先经N,N-二甲基甲酰胺(DMF)处理在表面构筑微纳结构薄膜, 然后在表面覆盖硬脂酸薄膜以实现超疏水. 采用扫描电子显微镜, 傅里叶红外光谱仪和接触角测量仪等手段表征了超疏水表面的形成机制和表面形貌, 并利用微纳米摩擦磨损试验机研究了超疏水薄膜的减摩耐磨特性. 研究结果发现, 在锌表面形成了一层纳米棒状结构的超疏水薄膜, 水的接触角可达155^o. 超疏水薄膜具有明显的减摩和耐磨特性, 这可归因于DMF处理导致的表面微织构化效应以及脂肪酸自组装薄膜的纳米润滑效应.     

可见光控亲/疏水可逆转换纳米N-TiO2-CTMS薄膜的制备及研究

以普通玻璃片为基材,钛酸丁酯为前驱体,通过氮掺杂可见光改性和三甲基氯硅烷疏水化修饰的方法,制备出一种新颖的表面浸润性受可见光控可逆转换的纳米TiO2薄膜材料(N-TiO2-CTMS)。采用UV-Vis、FE-SEM、接触角测试等方法对样品进行了表征和分析。研究结果显示掺氮量存在最佳值,20%的样品(20%N-TiO2)在可见光下降解甲基橙活性最高。对20%N-TiO2膜进行疏水化修饰后,接触角达到95°,可见光照射5h产生相对亲水表面(45°),置于黑暗处5h恢复相对疏水(90°),如此转换可于同一样品多次重复,说明样品具有一定的可见光控亲/疏水可逆转换功能。并对上述现象进行了初步的机理探讨。     

还原氧化石墨烯/聚丙烯熔喷布复合薄膜的制备与性能

石墨烯材料因其优异的导电、抗菌、防紫外、阻燃、疏水等性能吸引人们的广泛关注。为了让石墨烯稳固而均匀地负载于聚丙烯(PP)纺织品上，实验跟踪研究了从PP熔喷布到还原氧化石墨烯(rGO)负载改性PP功能薄膜整个过程。利用多巴胺的自聚成膜性对PP熔喷布进行预处理改性，使其在纤维表面引入氨基、酚羟基等官能团。随后，再在其表面负载氧化石墨烯(GO),并通过水合肼还原得到rGO/PP改性薄膜。实验通过扫描电镜(SEM)、红外光谱(FT-IR)、电阻率测试仪、接触角测试仪对改性过程中薄膜的表面形貌、表面组成、导电性能、亲水性能等进行测试和表征。结果表明：多巴胺改性后可在PP纤维表面形成均匀的聚多巴胺薄膜，后期GO的稳固负载提供活性位点。经GO负载改性，薄膜的初始水接触角由138.8°降为37.6°,实现从表面高疏水性到高亲水性的转变。经两次水合肼还原，薄膜表面负载的GO绝大部分转变为rGO,薄膜对应的电阻率直接降为1.10×10²Ω·m,展现出优异的导电性。同时，对大豆油的饱和吸附率由原来的12.8g/g增加至23.4g/g。     

银靶电流及溅射偏压对溅射沉积Cu/Ag薄膜导电性能的影响研究

磁控溅射技术制备有望作为电接触材料的Cu-Ag薄膜的工艺探索。利用方块电阻仪测试薄膜电阻,借助白光干涉仪和扫描电镜分析不同电流和不同偏压下粗糙度、薄膜厚度、Ag含量及微观结构对薄膜电阻影响规律。结果表明:不同银靶溅射电流下,Ag含量及微观结构为影响薄膜面电阻的主要因素,Ag含量低于18.13%(原子比)时膜中Cu-Ag固溶体相占比增大,这可能是引起薄膜面电阻增大的主要原因,柱状晶的贯穿程度越高电阻越小。不同偏压下,薄膜致密性和粗糙度对面电阻的影响较为明显,薄膜致密性越好,缺陷越少,电阻越小,而致密性相差不大时薄膜表面越光滑面电阻越小。     

多壁碳纳米管超疏水涂层的制备和性能

以硬脂酸钠(SST)和多壁碳纳米管(MWCNT)为原料,采用溶液混合法制备了碳纳米管超疏水涂层。首先将硬脂酸钠与碳纳米管制备成分散溶液,然后过滤。硬脂酸钠可以和乙酸反应生成硬脂酸(STA),使得碳纳米管的表面附着上硬脂酸这种疏水物质。通过扫描电镜(SEM)观察发现薄膜表面有类似于荷叶结构的微小凸起,通过接触角测试仪测得薄膜的接触角为162°,表现出良好的超疏水效果。这种制备超疏水材料的方法简单易行,可重复性好,在需要大面积使用超疏水涂层的领域具有广阔的应用前景。     

聚酯表面类金刚石薄膜的制备及疏水性能

采用线性离子束技术在PET基材表面制备类金刚石薄膜,分析薄膜结构、性能随离子束电流的演变规律并研究了薄膜润湿特性与表面形貌、结构、表面能的作用关系。结果表明:沉积在PET表面的类金刚石薄膜具有典型的非晶碳膜结构特征,随着离子束电流的增大sp~2/sp~3比值由0.774增加到1.622,薄膜表面的石墨化程度提高;改性后的PET材料接触角从63.51°增大到103.7°。进一步分析发现,疏水性能的提高归因于材料表面能的降低,表面石墨化程度的提高和微-纳结构的形成是表面能降低的根本原因。此外,疏水的PET材料在500~760 nm可见光范围内具有一定的増透效果,透过率达到88.5%以上。用线性离子束沉积碳膜及刻蚀技术能得到合适的微观形貌和表面化学结构,可在保持基体材料透明性的同时提高PET柔性聚合物材料的疏水性能。     

Stable permanently hydrophilic protein-resistant thin-film coatings on poly(dimethylsiloxane) substrates by electrostatic self-assembly and chemical cross-linking

Poly(dimethylsiloxane) (PDMS) is a biomaterial that presents serious surface instability characterized by hydrophobicity recovery. Permanently hydrophilic PDMS surfaces were created using electrostatic self-assembly of polyethyleneimine and poly(acrylic acid) on top of a hydrolyzed poly(styrene-alt-maleic anhydride) base layer adsorbed on PDMS. Cross-linking of the polyelectrolyte multilayers (PEMS) by carbodiimide coupling and covalent attachment of poly(ethylene glycol) (PEG) chains to the PEMS produced stable, hydrophilic, protein-resistant coatings, which resisted hydrophobicity recovery in air. Attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy revealed that the thin films had excellent chemical stability and resisted hydrophobicity recovery in air over 77 days of measurement. The spectra also showed a dense coverage for PEG dialdehyde and excellent resistance to protein adsorption from undiluted rat serum. Atomic force microscopy revealed dense coverage with PEG dialdehyde and PEG diamine. Contact angle measurements showed that all films were hydrophilic and that the PEG dialdehyde-topped thin film had a virtually constant contact angle (approximately 20 degrees ) over the five months of the study. Electrokinetic analysis of the coatings in microchannels always exposed to air also gave good protein separation and constant electroosmotic flow during the five months that the measurements were done. We expect that the stable, hydrophilic, protein-resistant thin-film coatings will be useful for many applications that require long-term surface stability.     

Conformational changes during protein adsorption. FT-IR spectroscopic imaging of adsorbed fibrinogen layers

The influence of hydrophobicity of the substrate surface on structural changes during protein adsorption was investigated. Plasma fibrinogen was chosen to model this effect as it is the most important protein in the body that adsorbs to foreign surfaces. Only conformations of adsorbed fibrinogen similar to that of the protein in solution do not activate the process of blood coagulation. Small spots on the substrate surface with conformational changes within the adsorbed protein are already sufficient to deteriorate biocompatibility. Mid-infrared hyperspectral imaging permits the identification of coagulated spots down to a few micrometers in size. The spectra of the FT-IR images that were assessed to be of suitable quality were clustered by a fuzzy c-means algorithm. The determination of the appropriate number of clusters was based on cluster variance. Subsequent evaluation of the centroid spectra of each cluster showed that their amide I band was separated into contributions from different structural units, with the alpha-helix content always being dominant. Significant differences between hydrophobic and hydrophilic surfaces were observed for turn and sheet contributions. Lower sheet/turn ratios appear to indicate inferior biocompatibility. Spots on hydrophilic surfaces could be identified, which exhibit structural changes similar to those on hydrophobic surfaces.     

Hydrophobic but hygroscopic polymer films--identifying interfacial species and understanding water ingress behavior

The hydrophobic but hygroscopic nature of polydimethylsiloxane (PDMS) with quaternary ammonium cationic side chains adsorbed on a SiO(2) surface was investigated with sum frequency generation vibration spectroscopy (SFG) and attenuated total reflectance infrared spectroscopy (ATR-IR). PDMS with cationic side chains, named cationic polymer lubricant (CPL), forms a self-healing boundary lubrication film on SiO(2). It is interesting that CPL films are externally hydrophobic but internally hydrophilic. The comparison of SFG and ATR-IR data revealed that the methyl groups of the PDMS backbone are exposed at the film/air interface and the cationic side groups and counterions are embedded within the film. The hydrophobicity must originate from the surface CH(3) groups, while the ionic groups inside the film must be responsible for water uptake. The surface hydrophobicity can alleviate the capillary adhesion while the hygroscopic property enhances the mobility and self-healing capability of the CPL boundary lubrication film.     

微细蒙脱石颗粒界面疏水改性机理研究

采用密度泛函理论方法计算了不同甲基取代程度的甲基胺类(伯胺、仲胺、叔胺和季铵)的分子形式和离子形式在蒙脱石(001)表面上的吸附能、吸附平衡构型和差分电子密度,并测试了药剂作用后蒙脱石悬浮液上清液透光率、表面对药剂的吸附量和表面接触角。结果表明:甲基胺类离子形式在蒙脱石表面的吸附能比分子形式的大很多,可以稳定吸附在表面上;烷基胺中N原子上的甲基对H原子的取代程度越高,吸附能越小,对蒙脱石表面的疏水改性能力越差;甲基胺类阳离子主要通过静电作用和氢键作用吸附到蒙脱石表面上;药剂作用后蒙脱石悬浮液的上清液透光率、表面对药剂吸附量和表面接触角的试验结果与模拟结果相一致。     

Proving the existence of nanobubbles produced by hydrodynamic cavitation and their significant effects in powder flotation

Selective attachment of nanobubles (NBs) generated in different conditions on the surface of valuable minerals during flotation separation was a challenge that needs to be addressed. This investigation filled this gap and proved the existence of NBs on the target mineral's surface and their selective effectiveness through the process. The bubble size analysis results showed that the mean diameter of bubbles was between 60 and 70 nm; thus, they could be correctly called “nanobubbles”. Flotation test results showed a significant increase in the flotation recovery (by 37%) and grade (more than 1%) of fine phosphate ore sample (d₈₀: 37 µm) using NBs that generated in the presence of collector. Interestingly, surface analyses of flotation products showed that the amounts of flotation collector adsorbed onto the surface of floated particles was decreased in the presence of NBs compared with their absence. The change in the particle surface (zeta) potential in the presence of NBs also provides additional evidence of NBs “adsorbed” (i.e., the surface NBs) onto the particle surface. These results indicated that NBs produced by hydrodynamic cavitation could adsorb onto the target mineral particles. This adsorption could change their surface properties, improve their hydrophobicity and surface potentials, and enhanced the bubble-particle attachment in flotation.     

Influence of functional silanes on hydrophobicity of MCM-41 synthesized from rice husk

Mesoporous molecular sieve MCM-41 was synthesized from rice husk and rice husk ash, called RH-MCM-41 and RHA-MCM-41. The sol–gel mixtures were prepared with molar composition of 1.0 SiO₂: 1.1 NaOH: 0.13 CTAB: 0.12 H₂O. After calcination, the polarity of MCM-41 still remained on its surface due to the existence of some silanol groups. In this study, both RH-MCM-41 and RHA-MCM-41 were silylated with two different functional silanes trimethylchlorosilane (TMCS) and phenyldimethylchlorosilane (PDMS) in order to reduce the surface polarity. The efficiency of silylation was determined based on the amount of moisture adsorbed using thermogravimetric analysis (TGA). The structure of silylating agents and silica templates were found to be important parameters affecting the hydrophobic property of the MCM-41 surface. The post-grafting silylation with aliphatic silane can decrease the surface polarity better than that with aromatic silane, probably due to less sterric hindrance effect. Thus, the surface hydrophobicity of MCM-41 can be improved by the silylation of small molecular silane on RH-MCM-41.     

Immobilization of olfactory receptors onto gold electrodes for electrical biosensor

We investigate the immobilization of native nanovesicles containing functional olfactory receptors onto gold electrodes by means of atomic force microscopy in liquid. We show that nanovesicles can be adsorbed without disrupting them presenting sizes once immobilized ranging from 50 nm to 200 nm in diameter. The size of the nanovesicles shows no dependence on the electrode hydrophobicity being constant in a height/width ratio close to 1:3. Nevertheless, electrode hydrophobicity does affect the surface coverage, the surface coverage is five times higher in hydrophilic electrodes than on hydrophobic ones. Surface coverage is also affected by nanovesicles dimensions in suspension, the size homogenization to around 50 nm yields a further five fold increment in surface coverage achieving a coverage of about 50% close to the hard spheres jamming limit (54.7%). A single layer of nanovesicles is always formed with no particle overlap. Present results provide insights into the immobilization on electrodes of olfactory receptors for further olfactory electrical biosensor development.     

氟化活性炭纤维的制备及其憎水性

将活性炭纤维（ACF）和氟气反应制备了氟化活性炭纤维（FACF）。XPS的研究结果表明FACF的碳原子是以sp^3杂化轨道同氟原子形成共价键。αs图分析氮吸附等温线的结果表明，ACF氟化后其比表面积和微孔容积显著降低、微孔宽度基本不变。FACF对水的吸附量极小，微孔表面具有完美的憎水性和高稳定性。     

ζ-potential characterization of collagen and bovine serum albumin modified silica nanoparticles: a comparative study

In this study, bovine serum albumin (BSA) and collagen (COLL) were adsorbed independent of one another, onto the surface of silica nanoparticles (SNPs) at pH’s where the ζ-potential of the proteins were equal in magnitude, but opposite to the SNP surface to ascertain the differences in surface coverage and conformation in the adsorbed layer. In both systems, increasing the concentration of free protein resulted in an increase in protein surface coverage and ζ values, with ζ values approaching that of native protein at high surface coverage. However, a lower critical charge reversal concentration range was measured for COLL relative to BSA (COLL: 0–25 μg/mL, BSA: 25–90 μg/mL). Additionally, a considerable difference in ζ for adsorbed protein versus free protein was observed. These results when interpreted in terms of the theory of Ottewill and Watanabe indicate a higher Gibbs energy of association for COLL versus BSA on SNP surfaces, accompanied by perturbation in protein structure.     

Surface-modified mesoporous silicas as recyclable adsorbents of an endocrine disrupter, bisphenol A

Surface-modified mesoporous silicas (MSs) were investigated for recyclable adsorption of an endocrine disrupter, bisphenol A (BPA). Surface-modified MSs were prepared by (i) post-synthesis surface modification of MSs using surface hydroxyl groups and organosilanes (m-MS) and by (ii) co-condensation of tetraethoxysilane and the corresponding organosilanes (d-MS). Infrared measurements indicated that organic groups mainly existed on the surface of m-MS, which resulted in a surface characterized by high hydrophobicity. Both organic groups and isolated hydroxyl groups existed on the surface of d-MS, resulting in both hydrophobicity and hydrophilicity on the surface. The amount of BPA adsorbed on surface-modified MSs per organic group was similar for m-MS and d-MS, however, the d-MS established equilibrium for BPA adsorption faster than m-MS, as measured by UV-vis spectra. A larger amount of BPA per surface area could be adsorbed on carbon materials than on the surface-modified MSs, however, the regeneration of carbon materials by washing could not be done easily. The surface-modified MSs retain adsorption capacity for BPA after several regeneration cycles, demonstrating that the surface-modified MSs are effective recyclable adsorbents of the endocrine disrupter, bisphenol A.