血红蛋白在纳米孔径氧化铝膜修饰电极上的直接电化学

运用电化学包埋法成功将血红蛋白(Hb)固定于纳米孔阳极氧化铝膜(AAO)修饰的玻碳电极(GC)表面, 制得Hb/PPy/AAO/GC修饰电极, 并对Hb/PPy/AAO/GC修饰电极的制备条件进行了优化. 研究了Hb/PPy/AAO/GC修饰电极在磷酸缓冲液(pH＝6.8)中的电化学行为, 探讨了血红蛋白在AAO修饰电极表面的直接电子转移机理. 结果表明阳极氧化铝膜不仅保持了血红蛋白的生物活性, 而且通过它的纳米尺寸效应, 实现了Hb与电极之间的直接电子转移. 其研究内容对生命科学和临床医学有着重要意义.     

基于纳米银与有机多孔材料/纳米金修饰的甲胎蛋白免疫传感器研究

在金电极表面电沉积银为氧化还原探针,利用有机多孔材料(PTC-NH2)、纳米金(nano-Au)固载甲胎蛋白抗体(anti-AFP),制备出用于检测甲胎蛋白(AFP)的安培型免疫传感器。通过交流阻抗技术、循环伏安法研究了电极的电化学特性,考察了孵育时间、测试液pH值等实验条件对传感器性能的影响,并利用扫描电子显微镜(SEM)对电极的修饰过程进行了表征。该传感器对AFP有良好的电流响应,线性范围分别为1.0～20.0ng/mL和20.0～60.0 ng/mL,检测限为0.6 ng/mL。     

基于纳米金／壳聚糖掺杂碳纳米管修饰金电极非标记免疫传感器的研究

应用吸附法将羊抗人IgG抗体直接固定于纳米金(GNPs)/壳聚糖(Chit)掺杂碳纳米管(CNTs)修饰的金电极表面,制备了用于人IgG抗原检测的非标记电化学免疫传感器.利用循环伏安法和交流阻抗研究了修饰电极表面的电化学特性,用差分脉冲伏安法研究了测试底液的pH值对免疫传感器性能的影响.实验表明,在含不同浓度人IgG的...     

基于一维DNA组装磁性纳米探针的夹心型安培免疫传感器研究

采用Fe3O4(核)/ZrO2(壳)纳米磁珠(ZMPs)标记待测物识别抗体,并用HRP酶封闭和DNA链接,建立了一类新型的"珠链状"一维磁性纳米探针制备方法。将甲胎蛋白(AFP)一抗固定于纳米金修饰的玻碳电极表面,构建了免疫电极(GCE?AFP Ab1)。基于该电极和上述合成探针,通过双抗体夹心法测定免疫产物上HRP酶对过氧化脲(CP)氧化对苯二酚反应的催化电流,研制了一类基于一维纳米结构组装的夹心型安培免疫传感器。研究表明:此一维纳米结构探针不仅大大增加了酶在电极表面的富集量,成倍扩增了催化电流,显著提高了传感器的灵敏度,而且易于通过外磁场与背景液可控分离,简化了分析步骤,并提高了结果的重复性。此传感器对AFP检测的线性范围为0.01~25 mg/L;检出限达4 ng/L(3σ),并被用于人血清中痕量AFP的测定,结果满意。     

基于纳米四氧化三铁-二茂铁构建甲胎蛋白免疫传感器的研究

用对交联剂1-乙基-3-(3-二甲基氨苪基)-碳化二亚胺/N-羟基琥珀酰亚胺将壳聚糖中的氨基与二茂铁甲酸中的羧基交联,并将制备好的纳米四氧化三铁加入其中反应形成富含氨基和羧基的磁性纳米复合物。该纳米复合物修饰到金电极表面,通过氨基及静电作用,吸附纳米金溶胶及甲胎蛋白抗体(anti-AFP)含量,从而成功制得高灵敏电流型甲胎蛋白免疫传感器。通过循环伏安法考察了电极表面的电化学特性。研究了孵育时间、温度、pH对免疫传感器的影响。在最优实验条件下,甲胎蛋白(AFP)质量浓度在0.01~10 ng/mL和10~120 ng/mL范围内,该免疫传感器的还原峰电流值与AFP的质量浓度有良好的线性关系,检出限为3 pg/mL。     

基于HDT自组装金纳米粒子修饰电极的微囊藻毒素-LR电化学免疫传感器研究

构建了一种新型的基于金纳米粒子(Au NPs)修饰金电极的微囊藻毒素-亮氨酸-精氨酸(MCLR)电化学免疫传感器。采用柠檬酸钠还原法制备了Au NPs溶胶,分别用透射电子显微镜和紫外-可见吸收光谱对其进行表征。将Au NPs组装到1,6-己二硫醇(HDT)自组装单分子层修饰的金电极表面,再将MCLR抗体(anti-MCLR)固定于该修饰电极上,利用扫描探针显微镜法、循环伏安法和电化学交流阻抗法(EIS)表征了自制化学修饰电极表面的形貌特征和电化学免疫传感器的电化学特征。通过辣根过氧化物酶标记的MCLR(MCLR-HRP)与MCLR竞争结合抗体,建立了检测MCLR的差分脉冲伏安法(DPV)。在最佳实验条件下,用DPV对MCLR检测的线性范围为0.01~25μg/L,检出限为0.005μg/L。对构建的免疫传感器的重现性、稳定性和选择性进行了考察。该方法对实际水样中MCLR的加标回收率为100%~102%,测定结果与高效液相色谱法的测定结果一致。     

基于普鲁士蓝/二氧化钛纳米管修饰碳糊电极的电流传感器检测偏二甲肼的研究

以TiO_2纳米管(TNTs)作为普鲁士蓝(PB)的载体,制备了PB/TNTs修饰碳糊电极(PB/TNTs/CPE),考察了偏二甲肼(UDMH)在该电极上的电化学行为,评估PB/TNTs/CPE测定UDMH的可靠性。结果表明,PB可以作为促进UDMH氧化的催化剂,利用TNTs作为PB的载体,可以提高电子的转移效率和速率。通过电流测定法得出测定UDMH的线性范围为0.3~100mg·L~(-1),检测限为2.6×10~(-5) g·L~(-1)。相比PB修饰的碳糊电极,本文基于PB/TNTs修饰碳糊电极所制备的电流传感器具有更高的灵敏度。     

普鲁士蓝@石墨烯-壳聚糖纳米复合物用于构建microRNA电化学传感器的研究

制备了基于普鲁士蓝(PB)、石墨烯(GN)、壳聚糖(Chi)的纳米复合物(PB@GN-Chi),并将其修饰在玻碳电极表面制得microRNA电化学传感器。实验发现,GN可有效提高敏感膜的导电性能和比表面积,增强PB在电极表面的稳定性和传感器的重现性。通过戊二醛的交联作用,将氨基化的捕获探针(ssDNA)固载在PB@GN-Chi修饰的电极表面,并用于miR-21的检测。以透射电子显微镜对纳米复合物的形态进行表征,采用循环伏安法、示差脉冲伏安法对传感器的电化学特性进行研究。实验结果表明,该传感器具有良好的稳定性和重现性,在2.8~2.8×10~4pmol/L浓度范围内,响应电流与miR-21浓度的对数呈线性关系,检出限为0.87 pmol/L,可用于miR-21的检测。     

高灵敏甲胎蛋白夹心免疫传感器的制备

构建了新型甲胎蛋白(AFP)夹心免疫传感器.采用金纳米粒子-氧化石墨烯-普鲁士蓝纳米立方体(AuNP-GO-PBNCs)纳米复合材料标记甲胎蛋白(AFP)二抗,将制备的金-聚多巴胺-四氧化三铁(Au-PDA-Fe3O4)磁性纳米复合物固定在自制的磁性电极表面,通过吸附作用固定AFP一抗,用牛血清白蛋白(BSA)封闭电极上的非特异性吸附位点.在37℃下与AFP抗原溶液孵育50 min,最后将电极放入AuNP-GO-PBNCs纳米复合材料标记的二抗溶液中孵育,基于此建立了采用普鲁士蓝(PB)标记的的夹心免疫传感器检测AFP的方法.在最佳实验条件下,PB催化H2O2氧化的响应电流与AFP的浓度表现出两段线性关系,线性范围分别为0.005~1.000 ng/mL和1~20 ng/mL, 检出限(LOD, S/N=3)为1.0 pg/mL.本方法具有灵敏度高、选择性好的特点.     

基于双醛基功能化离子液体构建电化学免疫传感器

合成了含双醛基的离子液体,此离子液体一端的醛基与修饰在电极表面的氨基发生共价键作用,将离子液体修饰在电极表面,另一端的醛基可用来固定抗体,构建电化学免疫传感器,实现对心肌肌钙蛋白I(cTnI)的检测。离子液体通过共价键作用固定在电极表面,不仅减少了从电极表面向检测溶液的渗透,提高传感器的稳定性,而且还可以直接固定抗体,不需要使用其他交联试剂;同时,离子液体可增强传感界面的导电性,提高传感器的灵敏度。在优化的实验条件下,传感器的线性范围为0.1~40 ng/mL,检出限为0.06 ng/mL。     

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.     

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.     

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.     

Catalyst free,visible-light promoted photoaddition reactions between C60 and N-trimethylsilylmethyl-substituted tertiary amines for synthesis of aminomethyl-1,2-dihydrofullerenes

An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C₆₀ and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C₆₀, followed by SET from the amine to the triplet excited state of C₆₀. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C₆₀ radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared.     

Highly efficient and stereoselective cycloaddition of nitrones to indolyl- and pyrrolylacrylates

The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities.     

Transition metal-free direct amination of benzoxazoles using formamides as nitrogen sources

A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields.     

l-Proline-catalyzed five-component domino reaction leading to multifunctionalized 1,2,3,4-tetrahydropyridines

Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl₃-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction.     

Exploring the scope of the Gewald reaction: Expansion to a four-component process

An efficient four-component reaction was developed to take advantage of the reactivity of the 2-aminothiophene-3-carbonitrile functionality, which is obtained during the classical three-component Gewald reaction. Various α-methylene bearing ketones were reacted with malononitrile, elemental sulfur, and aryl/heteroarylnitrile derivatives in t-BuOH/NaOH to afford 2-arylthieno[2,3-d]pyrimidin-4-amines in high yields. Preliminary studies revealed the photophysical properties of the products and their potential for use as metal sensors.