光致电化学鸟嘌呤传感器的制备及其应用

将硫堇电聚合在光透电极的表面,再利用壳聚糖将黄嘌呤氧化酶固定在具有光电活性的聚硫堇光透电极的表面上制备了光致电化学鸟嘌呤传感器.基于同时具有光敏和电子受体功能的聚硫堇光电界面,该传感器能与黄嘌呤氧化酶催化鸟嘌呤氧化而产生的电子供体(过氧化氢)产生光致电化学响应,通过测量光致电化学反应产生的光电流实现了对鸟嘌呤的检测.文中探讨了传感器的光致电化学响应机理,讨论了偏压、酶量、电解质溶液pH对传感器测定鸟嘌呤的影响.在优化的实验条件下,该传感器对鸟嘌呤的测定范围为1.00～200μmol/L,检出限为0.55μmol/L,9次测定的相对标准偏差小于3.92%.应用该传感器对酸解DNA脱出的鸟嘌呤基和药品阿昔洛韦进行的检测实验显示,相对标准偏差小于5.37%,加标回收率为96.8%～106%.该传感器的制备和对鸟嘌呤的检测不需要过氧化物酶,不需要除氧,有经济、简便等优点.     

氧化石墨烯修饰碳离子液体电极同时测定鸟嘌呤和腺嘌呤

以离子液体1-丁基-3-甲基咪唑六氟磷酸盐为粘合剂制备了碳糊电极,然后将氧化石墨烯滴涂到碳糊电极表面制成了一种新型的氧化石墨烯修饰碳离子液体电极。研究了鸟嘌呤和腺嘌呤在修饰电极上的电化学行为。实验结果表明,在0.1 mol/L醋酸盐缓冲溶液中(pH4.5),鸟嘌呤和腺嘌呤在该修饰电极上具有良好的电化学行为,在2.0×10-7～1.5×10-5mol/L浓度范围内鸟嘌呤和腺嘌呤的浓度在该电极上与电化学响应信号呈良好的线性关系,相关系数分别为为0.992和0.996。信噪比为3时,检出限为1.0×10-8mol/L。     

Detection of Wild-Type Hypoxanthine Guanine Phosphoribosyl Transferase of Lymphocytes in Gamma-Irradiated Mice with Surface Plasmon Resonance

A quick and sensitive detection of the wild-type hypoxanthine guanine phosphoribosyl transferase (HPRT), which is known as a biomarker for radiation exposure, was developed. The conventional HPRT measurement technique is to detect the mutant HPRT, which is time-consuming and has low sensitivity. In this study, the wild-type HPRT was detected as a gamma radiation biomarker using a surface plasmon resonance (SPR) biosensor with 6-thioguanine (6-TG) as a probe and the anti-HPRT antibody as a signal amplification factor. First, we used this system to measure the wild-type HPRT dissolved in PBS. Six-TG immobilized on the surface can specifically detect the wild-type HPRT, and the anti-HPRT antibody enhances about 10 times the primary signal produced by the binding of the wild-type HPRT with 6-TG. A linear relationship (r = 0.991) was obtained between the concentration of the wild-type HPRT and the enhanced signal. The low detection limit (LDL) is 2.1 ng/mL. The regeneration using glycine-HCl was also investigated. Six-TG immobilized on the surface can be used in 9 injection-regeneration cycles. The relative standard deviation (RSD) of baseline changes after regenerations is 2.8%. The applicability of the method to real samples has been demonstrated with comparative analyses of lymphocyte extracts in gamma irradiated and unirradiated mice. The irradiated sample displays a significantly lower level of the wild-type HPRT compared to that in the unirradiated sample. The single sample detection only needs about 20 min. Thus, the SPR biosensor could potentially serve as an attractive technique for rapid and sensitive detection of the wild-type HPRT, a gamma radiation biomarker.     

Multifunctional G‐Quadruplex Aptamers and Their Application to Protein Detection

Two significant G‐quadruplex aptamers named AGRO100 and T30695 are identified as multifunctional aptamers that can bind the protein ligands nucleolin or HIV‐1 integrase and hemin. Besides their strong binding to target proteins, both AGRO100 and T30695 exhibit high hemin‐binding affinities comparable to that of the known aptamer (termed PS2M) selected by the in vitro evolution process. Most importantly, their corresponding hemin–DNA complexes reveal excellent peroxidase‐like activities, higher than that of the reported hemin–PS2M DNAzyme. This enables these multifunctional aptamers to be applied to the sensitive detection of proteins, which is demonstrated by applying AGRO100 to the chemiluminescence detection of nucleolin expressed at the surface of HeLa cells. Based on the specific AGRO100–nucleolin interaction, the surface‐expressed nucleolin of HeLa cells is labeled in situ with the hemin–AGRO100 DNAzyme, and then determined in the luminol–H₂O₂ system. Through this approach, the sensitive detection of total nucleolin expressed at the surface of about 6000 HeLa cells is accomplished. Our results suggest that exploiting new functions of existing aptamers will help to extend their potential applications in the biochemical field.     

尿素与鸟嘌呤相互作用的DFT研究

采用B3LYP／6—311＋G^＋方法对鸟嘌呤-尿素复合物氢键相互作朋体系进行了研究,并对该复合物的几何构型及结合能（BSSE）进行了计算．此外,采用从静电势导出原子净电荷的chelpg方法分析了体系中的电荷转移和利用分子中的原子理论（AIM）方法对相互作用的本质进行了分析．结果一共得到五个稳定的复合物构型,其中A5是最稳定的,结合能为-73．95kJ／mol．     

铁氰化钆修饰电极对鸟嘌呤的电催化氧化及应用

用电化学沉积法制备了稀土铁氰化钆修饰玻碳电极(GdHCF/GC/CME),考察了该电极对鸟嘌呤的电催化氧化性能,同时根据Fenton反应产生的羟基自由基对鸟嘌呤的氧化作用和修饰电极氧化作用之间的竞争机理,对抗坏血酸清除羟基自由基进行了初步评价.实验结果表明,修饰电极对鸟嘌呤具有很好的电催化氧化性能.在HAc-NaAc缓冲液(pH=5.1)中,鸟嘌呤在1.0×10-6～4.6×10-5 mol/L浓度范围内与其氧化峰电流呈良好的线性关系,其线性回归方程为Ip(μA)=0.1112C 2.8715,r=0.9889;检出限为3.3×10-7 mol/L.以此电极评价抗坏血酸对羟基自由基的清除作用,取得了较好的效果,为羟基自由基清除剂的筛选提供了一种新的方法.     

基于碳纳米管修饰电极/鸟嘌呤电化学体系的固体电位型pH传感器

根据鸟嘌呤在短单壁碳纳米管修饰玻碳电极(S-SWCNT/GCE)上发生的电催化氧化特性,及其氧化电位对支持电解质溶液的pH值具有灵敏的响应,制备了以鸟嘌呤为指示剂的固体电位型pH传感器。在优化各种影响因素后,其电位在pH2.0~12.0范围内具有线性响应,回归方程为Epa(V)=-0.0497pH 0.8931。该传感器制备简单,使用方便,响应时间<20 s。在pH响应范围内待测液中离子强度对测定没有影响。酸碱滴定终点具有明显的突跃。对Na 、K 和Ca2 的选择性系数小。已成功地应用于实际样品的测定。     

Geometry dependence of spin-spin couplings in cyanamide by DFT analysis.

There have been numerous theoretical and experimental investigations examining NMR parameters related to non-amino N-H...N H-bonded moieties in both biological and chemical contexts. In contrast, little information on the geometry dependence of NMR parameters related to the biologically important H-bond donor amino group is available. Herein, the geometric dependencies of the one-bond amino N-H spin-spin coupling constants [(1)J(NH)] in the cyanamide monomer and dimer have been computed with B3LYP and the aug-cc-pVTZ-su0 basis set. In an isolated planar cyanamide molecule, the |(1)J(NH)| couplings were found to increase as the N-H bond lengthened. In contrast, in the planar cyanamide dimer the size of the H-bonded amino N-H coupling (|(1)J(N(d)H(d))|) decreased with increasing N(d)H(d) bond length. The |(1)J(N(d)H(d))| coupling was larger than the |(1)J(N(d)H(free))| coupling for N(d)H(d) distances up to 1.18 A (for a fixed N(d)H(free) distance of 1.006 A). Hence, the decrease of |(1)J(NH)| with increasing N-H distance, as well as the larger value of |(1)J(N(d)H(d))| compared to |(1)J(N(d)H(free))|, were only observed for situations where the amino group is involved in an H-bonding interaction. This is attributed to electron redistribution induced by the presence of the second cyanamide molecule. Similar electron-redistribution effects are thought to be responsible for the observed distance dependence of computed (1)J(NH) couplings of H-bonded amino groups in near-planar G-quartet structures. Here, the |(1)J(NH)| couplings of the amino N-H bonds decreased with increasing N-H bond length whereas the |(1)J(N(d)H(d))| couplings are approximately 7 Hz larger than the |(1)J(N(d)H(free))| couplings, despite the longer N(d)-H(d) bond length.     

Cu(bpy)2+2与鸟嘌呤及鸟苷相互作用的研究

在中性磷酸盐缓溶冲液中，用电化学和荧光光谱法研究了Cu(bpy)²⁺₂与鸟嘌呤和鸟苷的相互作用。结果表明鸟嘌呤和鸟苷与Cu(bpy)²⁺₂的配位比均为1∶1，配位常数分别为4.62×10⁴ L/mol和1.96×10⁴ L/mol。紫外光谱电化学实验进一步表明，鸟嘌呤或鸟苷与Cu(bpy)²⁺₂发生了相互作用。