微接触印刷技术转移Au纳米粒子及氧化石墨烯复合图案及其性质研究

通过改良的“Hummers方法”制得氧化石墨烯,利用聚二甲基硅氧烷（PDMS）弹性印章的微接触印刷技术,以Au膜和氧化石墨烯溶液为“墨水”,通过二次印章转移,分别将Au纳米粒子和氧化石墨烯（Graphene Oxide,GO）转移至修饰了(3-氨基丙基)三乙氧基硅烷（APTES）的ITO基底（APTES/ITO）表面. 利用场发射扫描电子显微镜（FE-SEM）、原子力显微镜（AFM）等表征图案,结果表明转移的AuNPs和GO组成的复合图案均匀,致密性较好. 利用表面电势显微镜（Surface Potential Microscope,SEPM,KFM）测定了各部分的表面电势,以APTES/ITO基底表面为表面电势零点,各部分表面电势大小为：APTES/ITO > GO > Au（0,-11.6,-44.2 mV）.     

SERS结合光谱法研究正壬酸香草酰胺与人血清白蛋白的相互作用

在模拟生理条件下,以金纳米颗粒(AuNPs)作为增强基底,归属正壬酸香草酰胺分子(OC)的表面增强拉曼光谱(SERS)特征峰,确定了其在基底表面的吸附方式.通过对比与人血清白蛋白(HSA)识别前后OC分子SERS光谱的变化情况,推测OC分子通过甲氧基与HSA进行结合,在AuNPs基底上的吸附方式也由垂直吸附转为倾斜吸附...     

PDMS-Au复合基底上多环芳烃分子的表面增强拉曼光谱

利用聚二甲基硅氧烷(PDMS)对有机物的富集功能,通过在金纳米粒子单层膜(Au MLF)表面旋涂薄层PDMS膜制备PDMS-Au MLF复合表面增强拉曼光谱(SERS)基底.研究了SERS增强性能与旋涂液浓度及稀释溶剂间的关系,考察了复合基底增强活性的均匀性.研究发现,采用叔丁醇为稀释溶剂,浓度为2%(质量分数)的旋涂液时所得复合基底表面多环芳烃(PAHs)的SERS信号强度最高,且此基底SERS信号强度偏差小于10%.分别以PDMS-Au MLF复合材料和Au MLF作为基底,对比研究了对萘、蒽、菲和芘4种多环芳烃的SERS检测能力.结果表明,PDMS-Au MLF复合基底对以上4种有机物的检出限分别为10~(-6),10~(-7),10~(-8)及10~(-7)mol/L,相比于单一Au MLF基底,其检测限至少降低了1个数量级,这主要源自于PDMS对PAHs的富集作用,且此类复合基底可用于多种多环芳烃混合物的特征识别.     

基于双面透明胶带/AuNPs基底的表面增强拉曼光谱检测烟草中仲丁灵

通过粘贴和剥离手段,将金纳米（AuNPs）溶胶固定在透明双面胶带表面,用于柔性表面增强拉曼光谱（SERS）基底的制备。结合便携式拉曼光谱仪,利用仲丁灵在AuNPs溶胶表面的吸附放大其拉曼信号,实现了仲丁灵的高灵敏检测。结合分散液液微萃取技术处理烟草样品,在消除干扰的同时,提升仲丁灵的检测灵敏度。结果表明,SERS技术对烟草中仲丁灵的检出限为20μg/kg。方法可实现烟草中仲丁灵农药残留的快速测定。     

基于自组装纳米金单层膜的全内反射SERS研究

采用静电自组装技术分别在玻璃基片和30 nm厚的金膜表面固定一层金纳米粒子(GNP)制得两种表面增强拉曼散射(SERS)基底,然后通过棱镜全内反射(TIR)激励和背向收集模式分别测试了两种基底上吸附的染料单分子层SERS光谱.实验结果表明两种SERS基底的拉曼增强效果均高度依赖于入射激光的偏振状态,对于玻璃/纳米金SERS基底,s光全内反射导致的拉曼增强因子是线偏振光(p)光的2-5倍,说明该基底上的"热点"位于纳米金单层膜内相邻粒子之间;对于玻璃/金膜/纳米金SERS基底,只有采用p光在特定的全内反射角下才能激发SERS信号,而且测得的SERS信号比玻璃/纳米金基底增强了近30倍.究其原因是p光在金膜表面共振激发的传播表面等离子体与纳米金局域表面等离子体耦合,进而导致显著场增强.实验结果指出在背向收集模式下,由p光激发的SERS信号是非偏振光,包含强度几乎相等的s和p成分.利用玻璃/金膜/纳米金基底还实现了拉曼光定向发射和收集,测得的SERS信号是p光.     

SERS标记的金纳米棒探针用于免疫检测

报道了基于金纳米棒表面增强拉曼散射(SERS)的免疫检测. 将拉曼活性分子对巯基苯甲酸吸附于金纳米棒表面, 制备出SERS标记的金纳米棒探针. 该探针和蛋白抗体结合形成SERS标记抗体. 通过SERS标记抗体、待测抗原和俘获抗体(固体基底上修饰的抗体, 即俘获抗体)之间的免疫应答反应, 将金纳米棒探针组装到固体基底上, 形成SERS标记抗体-抗原-俘获抗体 “三明治”夹心复合体. 待测抗原浓度越大, 固体基底上俘获的金纳米棒探针的数目越多, 从而可通过SERS信号的强弱来检测待测抗原的浓度. 由于金纳米棒的表面等离子体共振(SPR)峰位置可以在较宽的范围内调控, 可通过激发光和SPR的耦合来提高SERS信号, 从而提高免疫检测的灵敏度. 单组分抗原可检出的浓度范围高于1×10－8 mg/mL.     

介孔SiO2薄膜与金银合金薄膜相结合的大面积、高性能SERS基底

通过对涂布在金银合金薄膜表面的硅基凝胶膜进行高温热处理首次制备出均匀的大面积表面增强拉曼散射(Surface Enhanced Raman Scattering, SERS)基底. 利用扫描电子显微镜观测到由硅基凝胶膜经高温脱模形成的介孔二氧化硅薄膜具有表面开口结构, 基底的X射线能量色散(EDX)谱揭示了高温热处理引起金银合金薄膜中的银原子流失, 从而导致薄膜的纳米构造. 通过测试基底对Nile blue (NB)和Crystal violet (CV)拉曼活性分子的SERS光谱, 观测到在玻璃衬底与50 nm厚的金银合金薄膜之间插入20 nm厚金薄膜能够显著提高基底的SERS增强因子. 测试了基底在水溶液样品(50 nmol·L^-1 CV)中的浸渍时间对SERS信号的影响, 结果指出SERS信号随浸渍时间的增加而增强并在30 min后达到稳定, 15 min浸渍时间对应的SERS信号强度达到其稳定值的85%. 比对实验指出CV的SERS光谱与其溶液的常规拉曼光谱的峰位完全一致, 揭示了介孔二氧化硅薄膜能够有效阻止SERS基底的金属成份对待测分子拉曼指纹谱的干扰. 实验还证明了这种新型SERS基底对水溶液中NB的探测下限可达1 nmol·L^-1.     

基于自组装纳米金单层膜的全内反射SERS研究

采用静电自组装技术分别在玻璃基片和30 nm厚的金膜表面固定一层金纳米粒子（GNP）制得两种表面增强拉曼散射（SERS）基底,然后通过棱镜全内反射（TIR）激励和背向收集模式分别测试了两种基底上吸附的染料单分子层SERS光谱. 实验结果表明两种SERS基底的拉曼增强效果均高度依赖于入射激光的偏振状态,对于玻璃/纳米金SERS基底,s 光全内反射导致的拉曼增强因子是线偏振光（p）光的2-5 倍,说明该基底上的“热点”位于纳米金单层膜内相邻粒子之间;对于玻璃/金膜/纳米金SERS基底,只有采用p光在特定的全内反射角下才能激发SERS信号,而且测得的SERS信号比玻璃/纳米金基底增强了近30 倍. 究其原因是p 光在金膜表面共振激发的传播表面等离子体与纳米金局域表面等离子体耦合,进而导致显著场增强. 实验结果指出在背向收集模式下,由p 光激发的SERS信号是非偏振光,包含强度几乎相等的s 和p 成分. 利用玻璃/金膜/纳米金基底还实现了拉曼光定向发射和收集,测得的SERS信号是p光.     

基于超强拉曼增强金纳米粒子修饰的过渡金属双硫属化合物纳米片的分子检测（英文）

本文报道用不同尺寸的金纳米粒子(AuNPs)来修饰单层WS_2和MoS_2纳米片,通过表面增强拉曼散射(SERS)技术检测微量的罗丹明6G染料,并对比了它们在不同波长的激光激发下的等离子体特性。AuNPs在WS_2和MoS_2纳米片上的均匀沉积是通过种子介导的生长方法还原HAuCl_4来实现的。我们进一步使用扫描电子显微镜和拉曼光谱对所制备的异质结构进行了表征。几种优化结构的拉曼增强因子接近10~8,几乎达到检测单分子需要的灵敏度。我们的研究结果表明,通过贵金属纳米粒子对超薄过渡金属双硫属元素化合物进行可控修饰是完全可行的。这个策略也适合于制备高效且灵活的基底,用在新一代基于表面增强拉曼散射的化学传感器和生物传感器上。     

Ag/ZIF-90自组装薄膜的制备及SERS活性研究

合成了金属有机框架化合物沸石咪唑框架-90(ZIF-90)溶胶和ZIF-90晶体薄膜,分别以这2种材料为基底,制备出了Ag@ZIF-90复合材料和Ag/ZIF-90自组装薄膜.通过傅里叶变换红外(FT-IR),X射线衍射(XRD),扫描电子显微镜(SEM)对产物进行表征,分析了它们的形貌和结构特征.以罗丹明6G(R 6G)作为检测分子,对所制备材料的表面增强拉曼散射(SERS)性能进行测试.结果表明制备出的Ag/ZIF-90自组装薄膜具有好的SERS性能,而ZIF-90本身的拉曼峰并不会对Ag/ZIF-90自组装薄膜的SERS检测效果产生影响.这种材料可以作为一种较好的表面增强拉曼(SERS)活性基底,在农药残留检测方面具有很好的应用前景.     

ITO基底上ZnO薄膜的制备以及刻蚀图形的扫描电化学显微镜表征

在氧化铟锡(ITO)导电玻璃的衬底上,利用直接电沉积方法制备了ZnO纳米线或ZnO薄膜.然后利用存储有HCI刻蚀剂的琼脂糖微图案印章对其进行了化学刻蚀以形成不同的图形.利用扫描电子显微镜(SEM)、X射线衍射(XRD)和扫描电化学显微镜(SECM)分别对ITO衬底上的ZnO薄膜的结构、形貌和电化学性质进行表征.     

Green synthesis of Au nanoparticles immobilized on halloysite nanotubes for surface-enhanced Raman scattering substrates

A facile and green route was introduced to synthesize Au nanoparticles immobilized on halloysite nanotubes (AuNPs/HNTs) used for surface-enhanced Raman scattering substrates. The naturally occurring HNTs were firstly functionalized with a large amount of -NH(2) groups by N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane (AEAPTES), which possesses one lone electron pair and will "anchor" Au ions to form a chelate complex. Then, with the addition of tea polyphenols (TP), the Au ions were reduced on the surface of the previously formed Au-NH(2) chelate complex to form AuNPs. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM) observations indicate that a large amount of AuNPs were synthesized on HNTs. The AuNPs are irregularly spherical and densely dispersed on HNTs and the diameter of the nanoparticles varies from 20 to 40 nm. The interactions between AuNPs and -NH(2) groups were verified by X-ray photoelectron spectroscopy (XPS) and the results showed that the functional groups can "anchor" AuNPs through the chelating effect. The as-prepared AuNPs/HNTs nanomaterials with several nanometers gaps among nanoparticles were used as a unique surface-enhanced Raman scattering substrate, which possessed strong and distinctive Raman signals for R6G, indicating the remarkable enhancement effect of the AuNPs/HNTs.     

Microscale plasma-initiated patterning (muPIP)

A novel technique to create biomolecular micropatterns of varying complexity on several types of polymer substrates is presented. This method uses a patterned PDMS stamp to preferentially expose or protect areas of an underlying polymer substrate from oxygen plasma. Following plasma treatment, the substrate is immersed in a biomolecular ink, whereby molecules preferentially adsorb to either the plasma-exposed or plasma-protected substrate regions, depending on the particular substrate/ink combination. Using this method, polyethylene (PE), polystyrene (PS), poly(methyl methacrylate) (PMMA), poly(dimethylsiloxane) (PDMS), and poly(hydroxybutyrate/hydroxyvalerate) (PHBV) were micropatterned with different aqueous-based biomolecular inks (i.e., goat anti-rabbit immunoglobulin G, poly-l-lysine, and bovine serum albumin (BSA)). Water contact angle measurements performed on substrates after oxygen plasma exposure showed that the hydrophilicity of substrate areas exposed to plasma was significantly greater than that of areas protected from plasma by the PDMS stamp. In addition, scanning electron microscopy results demonstrated that substrate areas exposed to plasma were physically modified (e.g., roughened) compared to adjacent, protected areas. Areas in contact with a patterned PDMS stamp during plasma exposure were found to be physically unaffected by plasma treatment, and exhibited spatial features/dimensions consistent with the corresponding features of the patterned stamp. Last, protein patterns of BSA on the polymer substrates were stable and distinct after 4 weeks of incubation at 37 degrees C.     

Pattern Formation in Thin Polymer Films Containing Conducting Polyaniline

Summary: In the present work knowledge the authors tried to direct the phase separation process in a thin polymer composite film to manufacture a polymer pattern via self organisation of the blend components. The Au substrate was modified by applying with a PDMS stamp a pattern of alternating stripes of a self-assembled monolayer. This in turn influenced the microstructure of the blend, allowing for the production of elongated domains repeating the pattern of the substrate. The blends studied in this work contained conducting polyaniline doped with camphorsulfonic acid or diphenyl phosphate and polystyrene. The role of the dopant was to induce electrical conductivity in polyaniline as well as to improve its solubility in common organic solvents. The microstructure of thin films was analysed using atomic force microscopy (AFM), dynamic secondary ion mass spectroscopy (dSIMS) and optical microscopy.     

Creating patterned carbon nanotube catalysts through the microcontact printing of block copolymer micellar thin films

We report a route for synthesizing patterned carbon nanotube (CNT) catalysts through the microcontact printing of iron-loaded poly(styrene-block-acrylic acid) (PS-b-PAA) micellar solutions onto silicon wafers coated with thin aluminum oxide (Al(2)O(3)) layers. The amphiphilic block copolymer, PS-b-PAA, forms spherical micelles in toluene that can form quasi-hexagonal arrays of spherical PAA domains within a PS matrix when deposited onto a substrate. In this report, we dip a poly(dimethylsiloxane) (PDMS) molded stamp into an iron-loaded micellar solution to create a thin film on the PDMS features. The PDMS stamp is then put in contact with a substrate, and uniaxial compressive stress is applied to transfer the micellar thin film from the PDMS stamp onto the substrate in a defined pattern. The polymer is then removed by oxygen plasma etching to leave a patterned iron oxide nanocluster array on the substrate. Using these catalysts, we achieve patterned vertical growth of multiwalled CNTs, where the CNTs maintain the fidelity of the patterned catalyst, forming high-aspect-ratio standing structures.     

Light stamping lithography: microcontact printing without inks

We report a new patterning method, called light-stamping lithography (LSL), that uses UV-induced adhesion of poly(dimethylsiloxane) (PDMS). LSL is based on the direct transfer of the contact surface of the PDMS stamp to a substrate via a UV (254 nm)-induced surface bonding between the stamp and the substrate. This procedure can be adopted in automated printing machines that generate patterns with a wide range of feature sizes on diverse substrates. To demonstrate its usefulness, the LSL method was applied to prepare several PDMS patterns on a variety of substrates. The PDMS patterns were then used as templates for selective deposition of TiO2 thin film using atomic layer deposition as well as resists for selective wet etching.     

A Simple Method for Fabricating Patterned Curvilinear Microstructures in Poly(dimethylsiloxane) by Selective Wetting

The fabrication of patterned microstructures in poly(dimethylsiloxane) (PDMS) is a prerequisite for soft lithography. Herein, curvilinear surface relief microstructures in PDMS are fabricated through a simple three‐stage approach combining microcontact printing (μCP), selective surface wetting/dewetting and replica molding (REM). First, using an original PDMS stamp (first‐generation stamp) with linear relief features, a chemical pattern on gold substrate is generated by μCP using hexadecanethiol (HDT) as an ink. Then, by a dip‐coating process, an ordered polyethylene glycol (PEG) polymer‐dot array forms on the HDT‐patterned gold substrate. Finally, based on a REM process, the PEG‐dot array on gold substrate is used to fabricate a second‐generation PDMS stamp with microcavity array, and the second‐generation PDMS stamp is used to generate third‐generation PDMS stamp with microbump array. These fabricated new‐generation stamps are utilized in μCP and in micromolding in capillaries (MIMIC), allowing the generation of surface micropatterns which cannot be obtained using the original PDMS stamp. The method will be useful in producing new‐generation PDMS stamps, especially for those who want to use soft lithography in their studies but have no access to the microfabrication facilities.     

Self-assembly and encoding of polymer-stabilized gold nanoparticles with surface-enhanced Raman reporter molecules

Polymer-stabilized gold nanoparticles (AuNPs) were prepared and encoded with a range of surface-enhanced Raman reporter molecules. A range of as-synthesized polymers produced by reversible addition fragmentation chain transfer (RAFT) polymerization were demonstrated to self-assemble at the surface of AuNPs dispersed in water. The method involved the coprecipitation of polymer-gold conjugates by the addition of polymer dissolved in a water-miscible solvent to gold AuNPs dispersed in water. This method represents a simplification of the preparation of polymer-stabilized AuNPs compared with other published methods, in that the AuNPs do not need to be first transferred to an organic solvent. The process enabled the polymer stabilized AuNPs to be easily recovered by filtration or by phase transfer of the AuNPs to an organic solvent in which the RAFT polymer was soluble. The polymer-stabilized AuNPs were characterized by a range of methods including UV-visible spectrophotometry, transmission electron microscopy, thermogravimetric analysis, dynamic light scattering, and attenuated total reflection Fourier transform infrared spectroscopy. Furthermore, 1H pulsed field gradient spin echo NMR was utilized to characterize the self-diffusion of the polymer-stabilized AuNPs. Finally, we then demonstrated that these polymer-stabilized AuNPs maintained their ability to be encoded with surface-enhanced Raman spectroscopy reporter molecules.     

Printing biomacromolecules on a bovine serum albumin precursor layer

Various biomacromolecules including proteins and polysaccharides are printed on a substrate capped with a bovine serum albumin (BSA) precursor layer to create clear co-patterns of these molecules. Characterizations by confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) demonstrate the successful production and clear boundaries of the co-patterns. Rinsing the BSA-adsorbed substrate and the biomacromolecules-inked stamp before microcontact printing (microCP) is crucial for the creation of clear and stable co-patterns. The patterns are mainly stabilized by electrostatic interactions and van der Waals forces. Characterizations by ellipsometry, UV-Vis and fluorescence spectroscopy reveal that printing by a flat PDMS stamp yields a denser layered structure of proteins with a higher amount than that of adsorbed proteins. By printing, however, a lower enzymatic catalytic activity for horseradish peroxidase (HRP) or binding capability for avidin (both normalized to amount) is determined. A conformational transition from alpha-helix to beta-sheet of HRP is observed by ATR-IR. By contrast, a BSA precursor layer can effectively improve the functionality of the printed HRP or avidin and preserve the original conformation of the proteins, although the absolute transferred amount of these proteins is decreased.