纳米多孔银的制备及其表面增强拉曼散射特性研究

表面增强拉曼散射(SERS)因其具有高达单分子检测量级的灵敏度，在医学诊断、食品安全、环境监测等领域有着较大的应用前景。制备具有高密度“热点”的SERS基底是这项技术走向实际应用的关键。双连续结构的纳米多孔金属由于近邻纳米结构之间的耦合效应，所以具有很好的SERS增强特性。采用溅射方法制备了银锌合金前驱体，采用自由脱合金工艺和电化学脱合金工艺制备了具有纳米多孔结构的银基底，通过调制脱合金参数，获得了具有高增强因子的SERS基底。所制备的纳米多孔银基底对结晶紫的检测极限达到了10^-12 mol/L，可应用于超灵敏检测。     

金铜双金属表面增强拉曼散射基底的制备及应用

双金属材料结合了两种金属的特性从而获得远超单一金属的性能,因而在材料应用领域获得了广泛关注。如何以低成本获得高性能功能性材料是双金属推广应用的关键。以Cu₃₀Mn₇₀合金片材为前驱体,采用自由腐蚀和化学电镀两步法制备了金包铜纳米多孔基底(Au@NPC)。金包覆层在有效抑制铜在空气中氧化的同时,减小了韧带间孔径距离,进一步增大了紧邻韧带间的电磁耦合效应, 使Au@NPC具有更强的局域电磁场增强特性,表现出优于纳米多孔铜的表面增强拉曼散射活性。金铜双金属材料可用作表面拉曼增强散射基底,具有优异的稳定性和较低的成本。     

基于纳米锥森林的三维SERS基底检测miRNA

表面增强拉曼散射(SERS)是一种从存在于不同化学或生物环境中的分子中获取振动信息的强大技术。本文提出了一种基于纳米锥森林结构的三维SERS基底。制备基板采用等离子体处理技术,这项技术是一种简单、快速和高通量的方法。制备的基于纳米锥森林的SERS基底具有很高的灵敏度。实验表明,该基底可以检测到浓度低至10-10 M的miRNA。同时,所制备的SERS基底在大面积上表现出高度的均匀性。这些实验结果表明该3D SERS基底在广泛应用中的巨大潜力。     

基于纳米锥森林的三维SERS基底检测miRNA（英文）

表面增强拉曼散射(SERS)是一种从存在于不同化学或生物环境中的分子中获取振动信息的强大技术。本文提出了一种基于纳米锥森林结构的三维SERS基底。制备基板采用等离子体处理技术,这项技术是一种简单、快速和高通量的方法。制备的基于纳米锥森林的SERS基底具有很高的灵敏度。实验表明,该基底可以检测到浓度低至10~(-10) M的miRNA。同时,所制备的SERS基底在大面积上表现出高度的均匀性。这些实验结果表明该3D SERS基底在广泛应用中的巨大潜力。     

热处理对金纳米颗粒活性衬底的影响

利用退火工艺对拉曼增强衬底进行热处理,得到粒径和密度不同的金纳米颗粒拉曼增强衬底,并且此工艺不引入杂质离子。通过用生物大分子龙胆紫作为探针分子,对金纳米颗粒表面的表面增强拉曼散射(SERS)和表面增强荧光(SEF)进行研究发现,拉曼和荧光强度存在相同的变化趋势。研究结果表明:热处理可以优化SERS和SEF增强效果,为高效率、低成本的基于SERS和SEF效应生物化学传感器件的研究提供参考。     

激光辐照制备银纳米基底及其用于葡萄糖检测

通过激光辐照的方法制备银纳米条纹表面增强拉曼散射基底,该基底具有制备方法简单、均匀性好、重复性强的优点。用巯基吡啶(4-MPY)作为探针分子,葡萄糖和葡萄糖氧化酶产生的过氧化氢会改变银纳米条纹的形貌,进而影响探针分子的表面增强拉曼光谱强度,从而实现葡萄糖的间接检测。得到的探针分子的表面增强拉曼光谱的强度与葡萄糖溶液的浓度具有较好的线性关系。实验结果表明,该基底在葡萄糖的检测及定量分析方面具有良好的应用前景。     

基于磁控溅射制备铜基表面增强拉曼散射基底

为了提高拉曼光谱仪的探测灵敏度,设计了铜基表面增强拉曼散射(surface enhanced Raman scattering, SERS)薄膜基底。以Cu_(40)Ti_(60)合金为靶材,通过控制磁控溅射参数获得了一系列铜钛合金薄膜,采用脱合金法进一步获得了不同结构的铜基薄膜,系统地研究了不同溅射参数对铜基薄膜的SERS特性的影响,确定了制备SERS基底的最佳溅射参数。脱合金后所得铜膜具有多孔结构,能形成高强度局域电磁场,即SERS"热点"(hotspots),从而表现出优异的SERS增强性能。该基底制备成本低,重复性好,能用于灵敏检测且SERS增强因子可达1.8×10~7,具有较好的应用前景。     

基于Fe3O4/SiO2/Au-MNPs磁性SERS基底的特布他林超灵敏检测

为了快速灵敏地检测特布他林(terbutaline,TB),制备核?卫星纳米结构的Fe3O4/SiO2/Au-MNPs磁性基底对其进行表面增强拉曼光谱(SERS)检测。通过磁性分离、调节体系pH的方法考察特布他林浓度与拉曼光谱强度之间的线性关系并绘制校准曲线。实验结果表明,该纳米卫星结构的磁性SERS基底对TB的检测限为3.77×10^?10 mol/L,同时在5×10?5~5×10^?9 mol/L范围内,TB的SERS信号与其浓度呈线性关系,利用最小二乘法拟合得到的线性相关系数R2为0.996。该复合材料制备方法简便易行,为合成其他纳米复合材料提供了参考。     

紫外-可见光双通道拉曼光谱仪光学设计

紫外拉曼光谱技术具有高强度拉曼散射、无荧光干扰的特点;可见光拉曼光谱技术可实现低波数、高分辨率探测。为兼具两种激发波长的优势,设计了一款对称分布的双Czerny-Turner光路聚焦于一个探测器的双通道拉曼光谱仪。通过元器件的选型和初始结构的计算,在不增加多余元器件的情况下,对弧矢方向像散进行补偿,避免了像面上的能量损失。配合Zemax软件对双通道光谱分别进行建模优化,最终实现了对400~5000 cm^-1（266 nm激发）和50~3500 cm^-1（633 nm激发）两段光谱的同时探测。均方根半径、点列图和调制传递函数等评价指标有效验证了设计的合理性和可行性。结果表明,两套拉曼光谱仪分别可达8 cm^-1和5 cm^-1分辨率,本设计具有高分辨率、低波数、多波长激发、集成化等优势。     

基于纳米修饰透射式光纤传感测试

基于金属纳米颗粒结构的光学特性,结合光纤传感技术,对金属纳米颗粒的光纤传感特性进行了研究.实验中采用种子溶液生长法合成了粒径在60～80 nm的星形纳米金颗粒,以此作为光纤传感敏感部分的修饰体,修饰到锥形光纤表面作为表面拉曼增强基底.最后选取了不同浓度的酒精溶液对其进行了透射谱和拉曼谱测试,结果表明金属纳米颗粒的激发谱对周围介质特性非常敏感,同时对基于金属纳米颗粒锥形SERS基底的拉曼谱存在非常高的增强.     

激光刻蚀金银合金胶体的制备及其SERS应用

金属胶体是一种新兴的表面增强拉曼散射(SERS)活性衬底,利用激光液相刻蚀技术制备了金银合金胶体,并通过透射电镜、吸收光谱、表面增强拉曼散射光谱等手段对其特性进行表征。结果表明,合金粒子多数为球形颗粒,颗粒大小在5nm左右,并且有很好的分散性,等离子体共振吸收峰位于428nm。此外,该胶体表现出很好的表面增强拉曼散射活性,且性能稳定可在室温下长时间保存。     

Label‐free identification of antibiotic resistant isolates of living Escherichia coli: Pilot study

We introduce a label‐free spectroscopic method to classify subtypes of quinolone‐nonsusceptible Escherichia coli (E. coli ) isolates obtained from human blood cultures. Raman spectroscopy with a 30‐nm gold‐deposited, surface‐enhanced Raman scattering (SERS) substrate was used to evaluate three multilocus sequencing typing (MLST)‐predefined groups including E . coli ATCC25922, E . coli ST131:O75, and E . coli ST1193:O25b. Although there was a coffee‐ring effect, the ring zone was selected at the ideal position to screen E. coli isolates. Strong Raman peaks were present at 1001–1004 cm^?1 (C? C aromatic ring breathing stretching vibrational mode of phenylalanine), 1447–1448 cm^?1 (C? H₂ scissoring deformation vibrational mode), and 1667 cm^?1 (amide I α‐helix). Although the three MLST‐predefined E . coli isolates had similar Raman spectral patterns, a support vector machine (SVM) learning algorithm‐assisted principal component analysis (PCA) analysis had superior performance in detecting the presence of quinolone‐nonsusceptible E. coli isolates as well as classifying similar microbes, such as quinolone‐nonsusceptible E . coli ST131:O75 and E . coli ST1193:O25b isolates. Therefore, this label‐free and nondestructive technique is likely to be useful for clinically diagnosing quinolone‐nonsusceptible E. coli isolates with the MLST method.     

Label‐free monitoring of inflammatory tissue conditions using a carrageenan‐induced acute inflammation rat model

Although the confirmation of inflammatory changes within tissues at the onset of various diseases is critical for the early detection of disease and selection of appropriate treatment, most therapies are based on complex and time‐consuming diagnostic procedures. Raman spectroscopy has the ability to provide non‐invasive, real‐time, chemical bonding analysis through the inelastic scattering of photons. In this study, we evaluate the feasibility of Raman spectroscopy as a new, easy, fast, and accurate diagnostic method to support diagnostic decisions. The molecular changes in carrageenan‐induced acute inflammation rat tissues were assessed by Raman spectroscopy. Volumes of 0 (control), 100, 150, and 200 µL of 1% carrageenan were administered to rat hind paws to control the degree of inflammation. The prominent peaks at [1,062, 1,131] cm^?1 and [2,847, 2,881] cm^?1 were selected as characteristic measurements corresponding to the C–C stretching vibrational modes and the symmetric and asymmetric C–H (CH₂) stretching vibrational modes, respectively. Principal component analysis of the inflammatory Raman spectra enabled graphical representation of the degree of inflammation through principal component loading profiles of inflammatory tissues on a two‐dimensional plot. Therefore, Raman spectroscopy with multivariate statistical analysis represents a promising method for detecting biomolecular responses based on different types of inflammatory tissues.     

Varying SiO2 thickness of core–shell noble-grains on a gradient sensing plate to enhance field Raman scattering

This study demonstrates a strong surface-enhanced Raman scattering (SERS) of crystal violet (CV) dye by using SiO₂ shell/Ag core nanoparticle in gradient-size surface plate. The excitation of CV dye can be enhanced by the localized surface plasmons of Ag core/shell SiO₂ grains due to electromagnetic (EM) enhancement induced. For SERS resonance, the change of dielectric environment of grains results in red shift and magnification of spectra in varying SiO₂ thickness. Herein, the enhanced SERS conducted the core/shell grain with an SiO₂ thickness of 8.7 nm to magnify the intensity about 83 %-fold that is a direct evidence in enhanced charge transport and mutative dielectric environment.

Influence of target grit count and sintering temperature on pulsed laser deposition of SiC thin films

A pulsed laser deposition (PLD) technique for depositing SiC on Si(100) substrates using Nd³⁺:YAG laser at 355 nm is studied. The influence of substrate temperature, ambient pressure, and SiC powder grit size on both structure and morphology of SiC thin film is investigated. Further, the influence of the target preparation on the reduction of droplet formation during Nd³⁺:YAG laser-assisted pulsed laser deposition of SiC thin films is investigated. Experimental studies show that multicrystalline SiC film can be obtained with temperature ranging from 600 to 700 °C and at an ambient pressure of about 5.5 × 10^?3 Pa. Further, droplet formation on the deposited film was reduced significantly by selecting the grit count of SiC powder 500 and the pressure of 2 × 10^?2 Pa. SiC target sintered at 1,600 °C showed a reduced wear during the laser ablation. The X-ray diffraction (XRD) and the Raman spectroscopy studies on deposited films clearly show the multicrystalline (combined 3C-SiC and 4H-SiC) nature of SiC films. I-V characteristics of deposited SiC film on n-type c-Si substrate also indicated that SiC thin film possesses P-type semiconductor properties.