基于SBA-15的表面增强拉曼基底的制备及对鸡肉和鸡饲料中恩诺沙星的检测

在氨基改性的多孔材料SBA-15表面修饰金纳米颗粒制备了表面增强拉曼(SERS)基底,以四巯基吡啶(4-Mpy)作为探针分子,对基底的SERS性能进行评价.结果显示,利用金纳米粒子在介孔材料中的有效负载形成的结构有利于SERS信号的增强,基底在保存5个月后信号降低幅度较小,稳定性好.将此基底应用于鸡肉和鸡饲料提取液中恩诺沙星的SERS检测,在0.1~1 mg/kg浓度范围内,特征峰的拉曼信号强度与恩诺沙星浓度具有良好线性关系(R~2分别等于0.98和0.99),检测限均达到0.1 mg/kg.该检测方法简单快速、灵敏度高、稳定性好,为SERS技术应用于抗生素的快速检测提供了新的途径.     

表面增强拉曼光谱快速检测蜂蜜中的金霉素残留

利用表面增强拉曼光谱(SERS)技术对蜂蜜中的金霉素(CTC)残留进行了快速、无损检测.以自制的金纳米粒子作金霉素的拉曼增强基底,对金纳米粒子与金霉素混合体积比及混合时间进行了讨论与优化,检测了不同浓度梯度的金霉素标准溶液,绘制了特征峰处浓度-拉曼信号强度的线性方程,对蜂蜜进行前处理后,运用加标回收法考察其回收率.结果表明,金霉素溶液在1450 cm-1处的特征峰可以作为蜂蜜中金霉素残留量检测的特征峰,金纳米基底和金霉素标准液的最佳混合体积比为1∶1,最佳混合时间为1 min.金霉素的浓度(X)在10~250 mg/L范围内与其在1450 cm-1处的SERS特征峰强度(Y)有着良好的线性关系,线性方程为Y=1×10-4X+0.0110(R2=0.9948).检测实际蜂蜜样品中金霉素含量的加标回收率均在80%~120%之间.该检测方法操作简单、快捷、准确度高,为检测食品中抗生素残留提供了新的思路和方法.     

用于低浓度三聚氰胺选择性检测的铝/银纳米传感器的组装及其SERS性能

通过置换法在铝板上快速制备了一种即插即用型的Al/Ag纳米表面增强拉曼光谱(SERS)活性基底。结果表明该SERS基底较好地解决了银纳米颗粒在支撑物质上的吸附问题,能够快速实现对三聚氰胺的检测,而且具有操作简单、成本低、无损伤检测等优点,最低检测浓度能达到10^-7 mol·L^-1,满足国家食品安全要求的最低标准。另外,Al/Ag活性基底对三聚氰胺检测具有较高的拉曼测试重现性,连续测定15 h的过程中拉曼强度波动不大;且该Al/Ag活性基底能够在三乙醇胺、N,N-二甲基甲酰胺和1,2-丙二胺等胺类物质中实现对三聚氰胺的选择性检测。     

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.     

基于疏水滤纸的金纳米花SERS 基底高灵敏检测牛奶中的三聚氰胺

将海胆状金纳米花(gold nanoflowers, GNFs)疏水滤纸基底和表面增强拉曼散射(surface-enhanced Raman scattering, SERS)技术相结合,实现了牛奶中三聚氰胺的高灵敏检测。由左旋多巴还原制备的GNFs拥有许多尖锐突起和尖端可激发强局部电磁场增强(electromagnetic enhancement, EM),产生大量的“热点”,提高SERS检测的灵敏度。采用疏水滤纸作为衬底,改进了纸基衬底上纳米材料分布不均匀的缺点。进而评估了SERS基底的灵敏度、稳定性和重现性。通过对加标牛奶中三聚氰胺的定量检测,在1×10_-3^~1×10_-9 ^mol/L范围内,牛奶中三聚氰胺的浓度对数与SERS强度呈良好的线性关系,检测限低至43 pmol/L,远低于同类检测方法。并且本方法检测实际样品结果与液相色谱法检测结果对比无显著性差异(p>0.05)。GNFs疏水滤纸SERS基底具有高灵敏度、稳定性、重现性和实用性的优点,为牛奶等其他食品中三聚氰胺的定量检测提供了参考价值。     

TiN-Ag@Ag SERS基底制备及其对腺嘌呤的检测性能与增强机制研究

该文制备了TiN@Ag溶胶、TiN-Ag薄膜、TiN-Ag@Ag溶胶3种复合基底对腺嘌呤进行表面增强拉曼光谱(SERS)检测,并对拉曼增强效应进行研究。结果显示,与理论峰位相比,腺嘌呤的SERS图峰位发生偏移,可能是腺嘌呤吸附在增强基底上时分子构型和偶极距发生了改变(理论计算中过多的电子和外部溶剂的参与也会引起峰位偏移)。研究发现TiN-Ag@Ag溶胶基底上腺嘌呤的信号最强,这是因为该基底不仅具有TiN薄膜与Ag纳米颗粒发生共振耦合出现的可使SERS活性明显提高的“热点”,还存在Ag纳米颗粒聚集在Ag纳米棒之间形成的纳米间隙产生的更多“热点”。利用TiN-Ag@Ag溶胶基底对腺嘌呤进行灵敏检测,检出限可达10^-5 mol/L。并通过紫外光电子能谱结合高斯软件中密度泛函理论和时域有限分差法,对各基底的增强机制进行了分析。     

基于便携式表面增强拉曼光谱仪检测血红蛋白

本研究以纳米Au溶胶为增强试剂,利用便携式拉曼光谱仪,建立了一种血红蛋白的快速无标记检测方法。测定了系列浓度梯度的不同粒径纳米Au溶胶对血红蛋白表面增强拉曼光谱(SERS)信号的增强效果,并进行了重复性验证。结果表明,与血红蛋白溶液的普通拉曼测试效果相比,血红蛋白与纳米Au溶胶混合后,拉曼信号得到显著增强,且粒径为50±15 nm的纳米Au溶胶对血红蛋白拉曼信号的增强效果最好;血红蛋白的拉曼特征峰强度I_(1531)与其质量浓度间具有较好的线性关系,线性范围是5～30 mg/L,相关系数R~2=0.9223;不同批次、相同质量浓度的血红蛋白与纳米Au溶胶混合测定的实验结果重现性好,且与共聚焦显微拉曼光谱仪测定血红蛋白的SERS结果相一致。该方法检测耗时短、设备操作简便且具有较好的重现性。     

Ag_2W_2O_7@Au纳米带对亚甲基蓝的选择性SERS检测

利用水热法调控Na_2WO_4·2H_2O和Ag NO_3混合溶液的p H,制备了Ag_2W_2O_7纳米带,再用离子束溅射法制备了Ag_2W_2O_7@Au复合材料。以Ag_2W_2O_7@Au作为拉曼活性基底,对亚甲基蓝(M B)等6种低浓度有机染料进行检测。实验表明,其对MB分子的表面增强拉曼散射效应(SERS)有显著的增强,M B的检测限(LOD)为82.8 pmol/L,增强因子1.08!10~6。选择浓度均为1.0 nmol/L的以上染料分子的混合溶液为探针分子,发现在Ag_2W_2O_7@Au基底上只能检测到M B的特征拉曼峰。最后对M B浓度为10 nmol/L的15个同一基底不同测试点的SERS测试揭示其增强效应的相对标准偏差(RSD)均低于15%。说明Ag_2W_2O_7@Au基底是可选择性检测M B的有效SERS活性基底。     

应用表面增强拉曼光谱法快速检测鸭肉中呋喃它酮代谢物残留

采用表面增强拉曼光谱(SERS)技术建立了鸭肉中呋喃它酮代谢物(AMOZ)残留检测的方法。研究以纳米金胶和NaCl作为SERS增强基底,并利用自适应迭代重加权惩罚最小二乘法(air-PLS)扣除光谱中的背景信号,确定了拉曼位移为801 cm~(-1)处的特征峰可作为鸭肉中AMOZ的特征峰。利用单因素分析法得出试验中纳米金胶、待测样品及Na Cl的最佳加入量分别为1.2 m L,35μL及100μL,且最佳吸附时间为1 min。并在此基础上建立了鸭肉提取液中AMOZ质量浓度范围为0.5~12 mg/L时特征峰强度Y与鸭肉提取液中AMOZ质量浓度X之间的线性关系,得到其线性方程为Y=224.99X+718.83,决定系数(R2)为0.9961,最低检测限为0.5 mg/L,并得到其预测集样本中回收率的范围为97.2%~119.1%。结果表明,该方法线性关系良好,可用于鸭肉中AMOZ残留的快速检测。     

超疏水性三维银纳米树SERS基底的制备及用于阿奇霉素检测

制备了一种超疏水性三维银纳米树表面增强拉曼散射(SERS)基底，利用扫描电子显微镜(SEM)、能量色散X射线光谱(EDS)及X射线衍射(XRD)对三维银纳米树进行表征，利用接触角(CA)分析其疏水性能。以罗丹明B(RB)为拉曼探针进行条件优化，并考察阿奇霉素(AZM)在该基底上的SERS性能，发现该SERS基底对AZM具有较强的拉曼增强效应，在1.0×10^-11～1.0×10^-9 mol/L范围内，AZM浓度的对数值与拉曼峰强度I_SERS呈良好的线性关系，线性拟合方程为I_SERS=4098logc+47769(R²=0.987)，检出限为4 pmol/L。使用该方法检测AZM分散片、人血清及猪血清中的AZM，加标回收率在91.2%～118.1%之间，相对标准偏差为1.1%～6.2%。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.