Design of a High-Sensitivity Dimeric G-Quadruplex/Hemin DNAzyme Biosensor for Norovirus Detection

G-quadruplexes can bind with hemin to form peroxidase-like DNAzymes that are widely used in the design of biosensors. However, the catalytic activity of G-quadruplex/hemin DNAzyme is relatively low compared with natural peroxidase, which hampers its sensitivity and, thus, its application in the detection of nucleic acids. In this study, we developed a high-sensitivity biosensor targeting norovirus nucleic acids through rationally introducing a dimeric G-quadruplex structure into the DNAzyme. In this strategy, two separate molecular beacons each having a G-quadruplex-forming sequence embedded in the stem structure are brought together through hybridization with a target DNA strand, and thus forms a three-way junction architecture and allows a dimeric G-quadruplex to form, which, upon binding with hemin, has a synergistic enhancement of catalytic activities. This provides a high-sensitivity colorimetric readout by the catalyzing H₂O₂-mediated oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline -6-sulfonic acid) diammonium salt (ABTS). Up to 10 nM of target DNA can be detected through colorimetric observation with the naked eye using our strategy. Hence, our approach provides a non-amplifying, non-labeling, simple-operating, cost-effective colorimetric biosensing method for target nucleic acids, such as norovirus-conserved sequence detection, and highlights the further implication of higher-order multimerized G-quadruplex structures in the design of high-sensitivity biosensors.     

Creating Complex Polyacrylamide Hydrogel Structures Using 3D Printing with Applications to Mechanobiology

Due to its favorable physical and chemical properties, including chemical inertness, low fouling by biological molecules, high porosity and permeability, optical transparency, and adjustable elasticity, polyacrylamide has found a wide range of biomedical and non‐biomedical applications. To further increase its versatility, this communication describes a simple method, using readily available reagents and equipment, for 3D printing polyacrylamide hydrogels at a resolution of 100–150 μm to create complex structures. As a demonstration of the application, the method is used for creating a lab‐on‐a‐chip cell culture surface with micropatterned stiffness, which then leads to the discovery of stiffness‐guided collective cell segregation distinct from durotaxis. The present technology is expected to unleash new applications such as the construction of biocompatible elastic medical devices and artificial organs.     

化学发光色谱柱后检测技术及其应用

化学发光(chemiluminescence,CL)检测的最大特点是设备简单、分析速度快及灵敏度高,是一种有效的微量和痕量分析手段,已在环境科学、临床检验、药学、工业分析等领域得到广泛的应用[1～3]。但是,化学发光分析法也存在着选择性差的问题,从而限制了这一方法的应用范围。高灵敏度的CL检测手段与高分辨的高效液相色谱(HPLC)、毛细管电泳(CE)和微流控芯片等分离技术相结合,成为一种理想的分离分析方法,得到人们的广泛重视。20世纪80年代的毛细管电泳和90年代初微流控芯片的出现、分析仪器的微型化和进样量少的要求向科研人员提出了要解决…     

Enhanced Immunosensor Using a Handheld pH Meter for the Point-of-Care,Sensitive Detection of Prostate Specific Antigen

An enhanced handheld pH meter based immunosensor was proposed for point-of-care, quantitative determination of prostate specific antigen (PSA). Monoclonal antibody-functionalized magnetic beads (MB-Ab₁) were prepared to capture PSA in sample, and subsequently bond to polyclonal antibody-immobilized gold nanoparticles-polyamide-amine dendrite-lead ion (GO-PAMAM-Pb²⁺) and dispersed in H₂S solution. Based on negative Gibbs free energy of formation, PbS (solubility product constant K_sp=8.0×10⁻²⁸ was formed by reaction of Pb²⁺ and H₂S. Hence, the pH of solution increased due to the H⁺ appeared, and the resulting pH value was monitored by a handheld pH meter.     

Aligning Text and Phonemes for Speech Technology Applications Using an EM-Like Algorithm

A common requirement in speech technology is to align two different symbolic representations of the same linguistic ‘message’. For instance, we often need to align letters of words listed in a dictionary with the corresponding phonemes specifying their pronunciation. As dictionaries become ever bigger, manual alignment becomes less and less tenable yet automatic alignment is a hard problem for a language like English. In this paper, we describe the use of a form of the expectation-maximization (EM) algorithm to learn alignments of English text and phonemes, starting from a variety of initializations. We use the British English Example Pronunciation (BEEP) dictionary of almost 200,000 words in this work. The quality of alignment is difficult to determine quantitatively since no ‘gold standard’ correct alignment exists. We evaluate the success of our algorithm indirectly from the performance of a pronunciation by analogy system using the aligned dictionary data as a knowledge base for inferring pronunciations. We find excellent performance—the best so far reported in the literature. There is very little dependence on the start point for alignment, indicating that the EM search space is strongly convex. Since the aligned BEEP dictionary is a potentially valuable resource, it is made freely available for research use.     

G-四链体的构型、热稳定性测试及其在钾离子定量检测中的应用

G-四链体是由具有连续鸟嘌呤(G)序列的DNA或RNA形成的一种特殊的核酸二级结构,由于有望形成G-四链体结构的序列广泛地分布于人类基因组的许多重要区域,有关G-四链体的研究已经成为国际上的一个研究热点。本文对G-四链体构型的多态性、G-四链体热稳定性的测试手段及G-四链体在K+定量检测方面的应用研究进行了简单的介绍和评述。     

液相色谱–质谱联用技术在水产品兽药残留检测中的应用

液相色谱–质谱联用技术逐渐成为水产品中兽药残留检测的重要手段。从技术原理、样品处理方法的改进和新方法的应用,以及多兽药残留同时分析等方面论述了液相色谱–质谱联用技术在水产品兽药残留检测中的应用与进展。     

Assessing the Progression of Early Atherosclerosis Mice Using a Fluorescence Nanosensor for the Simultaneous Detection and Imaging of pH and Phosphorylation

The inflammatory microenvironment involves changes in pH and protein phosphorylation state and is closely related to the occurrence and development of atherosclerosis (AS). Herein, we constructed a dual-detection fluorescence nanosensor PCN-NP-HPZ based on post modification of MOFs, which realized the simultaneous detection and imaging of pH and phosphorylation through the pH-sensitive group piperazine and the Zr^IV node of the MOFs. The sensors were used to monitor changes in blood pH and phosphate levels at different time stages during atherosclerotic plaque formation. Two-photon fluorescence imaging was also performed in the vascular endothelium. Blood tests combined with two-photon fluorescence images indicated that in the early stage of AS, blood and tissue pH levels were lower than that of the normal mice, while phosphate and tissue phosphorylation levels were higher than that of the normal mice. The present study provides a new analysis method for the assessment of early atherosclerotic disease.     

Batch Injection Analysis with Amperometric Detection for DNA Biosensing Applications

In this work, batch injection analysis with the amperometric detection (BIA‐AD), employing a detection cell designed to adapt a screen‐printed carbon electrode (SPCE) was used for the first time as a robust electroanalytical system for DNA biosensing applications. The sensitive amperometric detection was used to evaluate the structural changes in double‐stranded DNA (dsDNA) after UV‐C irradiation of its solution for a given time. Batching of DNA samples was performed by precise electronic pipette microinjection of an irradiated sample aliquot onto the unmodified activated SPCE surface incorporated in the BIA‐AD system. Using the optimized experimental conditions (40 μL of 1 mg mL^?1 dsDNA in a 0.1 M phosphate buffer of pH 7.4 sampled at the injection speed degree of 6 and detected at the potential of +1.5 V vs silver pseudo‐reference electrode), a time‐dependent response (gradual decrease of amperometric signal up to 58 % after 10 min of the irradiation) was found for the detection of damage to low molecular weight salmon sperm dsDNA. The advantages of this low‐dimensional and cost‐effective measuring system can be utilized not only for the quantification of DNA damage/degradation by UV irradiation, but they are also promising for studying other types of DNA interactions.     

液相色谱–质谱联用仪在畜禽产品质量安全检测中的应用

液相色谱–质谱联用技术逐渐成为畜禽产品质量安全检测的重要手段。从β-兴奋剂、磺胺类药物、喹诺酮类和β-内酰胺类等抗生素类药物和其它添加剂、药物以及多组分同时分析方面综述了液相色谱–质谱联用仪在畜禽产品质量安全检测中的应用,并展望了今后的发展趋势。     

An Update of Nucleic Acids Aptamers Theranostic Integration with CRISPR/Cas Technology

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas system is best known for its role in genomic editing. It has also demonstrated great potential in nucleic acid biosensing. However, the specificity limitation in CRISPR/Cas has created a hurdle for its advancement. More recently, nucleic acid aptamers known for their high affinity and specificity properties for their targets have been integrated into CRISPR/Cas systems. This review article gives a brief overview of the aptamer and CRISPR/Cas technology and provides an updated summary and discussion on how the two distinctive nucleic acid technologies are being integrated into modern diagnostic and therapeutic applications     

牛血清白蛋白模板法制备的金属复合纳米材料在生物检测中的应用

随着纳米科技的快速发展,纳米材料得到广泛应用,其功能也得到全面的研究。由于蛋白质外壳和金属内核,以牛血清白蛋白为模板制备的金属复合纳米材料拥有很好的稳定性、高荧光特性、优良的催化活性、环保的制备过程和潜在的多功能特性。本文综述了近年来牛血清白蛋白-金属复合纳米材料的相关研究,包括已开发的种类、制备方法、性能、生物检测及临床相关应用。     

液相色谱/光电二极管阵列检测/质谱联用技术在中药分析中的应用

建立了基于液相色谱/光电二极管阵列检测/质谱(LC/DAD/MS)技术的中药分析基本方法。检出了丹参水溶性成分中的丹参素、原儿茶醛、咖啡酸、紫草酸、丹参酸丙和丹酚酸C等;在银杏内酯提取物中,鉴定和发现了白果内酯,银杏内酯A、B、C和一些新化合物,其中经结构确证的两个新化合物分别被命名为银杏内酯K和L;在苦参生物碱中鉴定了苦参碱、氧化苦参碱、槐果碱或异槐果碱、N-氧化槐果碱和槐花醇N-氧化物。     

Synthesis of MnO2/MWNTs Nanocomposites Using a Sonochemical Method and Application for Hydrazine Detection

A sonochemical method has been successfully used to synthesize MnO₂/MWNTs nanocomposites. The structure and nature of the resulting MnO₂/MWNTs composite were characterized by scanning electron microscopy (SEM), energy‐dispersive X‐ray diffraction (EDX), X‐ray photoelectron spectroscopy (XPS).The results show that the sonochemically synthesized MnO₂ nanoparticles were homogeneously dispersed on the modified MWNT surfaces. The performance of the MnO₂/MWNTs nanocomposites modified electrode was characterized using cyclic voltammetry (CV) and Nyquist plots. The electrode exhibits efficient electron transfer ability and high electrochemical response towards hydrazine. This may be attributed to the small particle size, high dispersion of MnO₂ particles. The fabricated hydrazine sensor showed a wide linear range of 5.0×10^?7–1.0×10^?3 M with a response time less than 5 s and a detection limit of 0.2 μM. Taking the advantage of the unique properties of both MWNTs and MnO₂, it would greatly broaden the applications of MWNTs and MnO₂.     

光波导共振技术结合比色法检测葡萄糖溶液的浓度

利用比色法结合双面金属包覆波导构建了一种高灵敏度的光波导振荡场传感器. 将葡萄糖溶液与氧化酶试剂混合, 使葡萄糖溶液显色并注入波导结构, 采用波长为650 nm的激光入射于波导表面, 经角度扫描产生衰减全反射(ATR)吸收峰, 通过ATR吸收峰的极小值来检测葡萄糖溶液的浓度变化. 实验结果表明, 该技术对葡萄糖溶液浓度的分辨率达到111 nmol/mL, 其灵敏度高于分光光度计.     

Aptamer-based Biosensor for Detection of Phenylalanine at Physiological pH

A simple, sensitive aptamer-based biosensor for the detection of phenylalanine is developed using the electrochemical transduction method. For this proposed aptasensor, a 5-thiol-terminated aptamer is covalently attached onto a gold electrode. At the first time, the electrode was evaluated as an electrochemical aptasensor for determination of phenylalanine in aqueous solutions. This sensor was tested in a Tris–HCl buffer with physiological pH?=?7.4 by cyclic voltammetry and differential pulse voltammetry. The detection limit and sensitivity of the modified electrode toward phenylalanine were estimated to be 1 nM (S/N?=?3) and 0.367 μA nM^?1, respectively. The linear range of the signal was observed between 1 and 10 nM of phenylalanine with 0.9914 correlation factor. The herein-described approach is expected to promote the exploitation of aptamer-based biosensors for protein assays in biochemical and biomedical studies.     

荧光纳米探针用于细胞器pH检测的研究进展

pH稳态对于维持活细胞细胞器的正常功能具有重要作用.细胞器内pH稳态被打破会导致细胞器功能的紊乱,进而引发癌症、神经退行性疾病等相关疾病.因此,在活细胞水平上定量测定pH并对其波动进行实时监测对于理解相关疾病的发生机制非常重要.基于非侵入、高时空分辨率成像的优势,荧光探针非常适合用于活细胞内pH的检测.本综述总结了近些年利用不同种类荧光纳米探针对不同细胞器进行pH成像的研究工作,并对荧光纳米探针应用面临的机遇与挑战进行了展望.     

磁性固相萃取在食品安全检测中的应用进展

本文介绍了磁性固相萃取技术,综述了近5年来磁性固相萃取技术在食品中重金属、农药、兽药、合成色素及其他有机污染物残留检测中的应用进展,并展望了磁性固相萃取技术的发展方向(引用文献56篇)。     

纳米铂-石墨烯修饰电极电化学检测1-羟基芘

该文以氧化石墨烯和氯铂酸混合液为前驱体,采用一步电沉积法制备了纳米铂/还原氧化石墨烯修饰电极(Pt/E-rGO/GCE),通过差分脉冲伏安法对1-羟基芘进行原位富集检测。结果表明,当溶液pH 2.0,制备Pt/E-rGO/GCE的电沉积圈数为5圈时,在50～700 nmol/L范围内,1-羟基芘浓度与还原峰电流呈线性关系,相关系数(r)为0.976,检出限(S/N=3)为12.1 nmol/L。该方法的稳定性、重现性及抗干扰能力良好,将其应用于尿样的检测,回收率为99.7%～108%,相对标准偏差为3.2%～4.2%。Pt/E-rGO/GCE的良好性能对电化学传感器的构建具有一定的实用价值。     

化学教育与现代信息技术的整合

21世纪 ,人类正迎来信息时代。目前以多媒体和国际互联网为代表的当代信息技术迅猛发展 ,已正在改变着人们的生活、学习方式 ,这种影响已开始深入到大、中学课堂。在化学课堂上 ,教师越来越多地使用现代信息技术 ,因此越来越多的关于如何在化学课堂中使用现代信息技术的问题需要化学教师和化学教育研究者去研究。笔者认为 ,在这些问题中 ,如何将化学教育与现代信息技术整合是首先要研究的问题。教师要在课堂上使用现代信息技术进行教学 ,那么他 (她 )必须要解决 2个大问题 ,即硬件问题 ,如电脑、投影仪 ,甚至需要网络 (包括局域网或因特网 )…