Recent advancements in analytical methods of phosphodiesterase 5 inhibitors and their metabolitesEI北大核心CSCD

磷酸二酯酶5抑制剂(PDE5i)用于治疗勃起功能障碍和肺动脉高压等疾病。因PDE5i类药物种类繁多,理化性质各异,在体内代谢迅速且具有多种代谢途径,故生物样本检验难度大。本文介绍了PDE5i类药物及其代谢物,总结了生物样本中该类物质的沉淀蛋白法、液-液萃取法、固相萃取法和固相微萃取法等前处理方法,综述了高效液相色谱法、液相色谱质谱联用法、荧光光谱法和电化学分析法等检测方法,展望了PDE5i及其代谢物分析的未来发展方向,以期为PDE5i的药物监测和法庭科学毒物检验提供参考。     

Unconventional detection methods for microfluidic devices

The direction of modern analytical techniques is to push for lower detection limits, improved selectivity and sensitivity, faster analysis time, higher throughput, and more inexpensive analysis systems with ever-decreasing sample volumes. These very ambitious goals are exacerbated by the need to reduce the overall size of the device and the instrumentation - the quest for functional micrototal analysis systems epitomizes this. Microfluidic devices fabricated in glass, and more recently, in a variety of polymers, brings us a step closer to being able to achieve these stringent goals and to realize the economical fabrication of sophisticated instrumentation. However, this places a significant burden on the detection systems associated with microchip-based analysis systems. There is a need for a universal detector that can efficiently detect sample analytes in real time and with minimal sample manipulation steps, such as lengthy labeling protocols. This review highlights the advances in uncommon or less frequently used detection methods associated with microfluidic devices. As a result, the three most common methods - LIF, electrochemical, and mass spectrometric techniques - are omitted in order to focus on the more esoteric detection methods reported in the literature over the last 2 years.     

Near-infrared quantum dots for deep tissue imaging

Developments in nanotechnology have paved the way for the early detection, treatment, and prevention of several tumors which affect mankind. In the past few years, near-infrared (NIR) fluorescence imaging techniques have emerged that enable the in vivo imaging of physiological, metabolic, and molecular function. The NIR window, also known as the diagnostic window (700–900 nm), can be explored for sensitive detection techniques. Nanoparticles, particularly semiconductor quantum dots (QDs), can be utilized for the purpose of optical imaging. These semiconductor QDs possess novel electronic, optical, magnetic, and structural properties which are quite different from those of bulk materials. NIR QDs with these unique properties can be utilized as contrast agents for optical imaging, particularly for deep tissue imaging. Deep tissue imaging provides more information about the pathological status of the disease, which makes the treatment more effective and efficient. In this review we highlight the importance of NIR QDs as probes for optical imaging. We describe the different types of NIR QDs, their synthesis, and their application for deep tissue imaging along with recently developed self-illuminating NIR QDs.     

Cancer detection using nanoparticle-based sensors

This tutorial review surveys the latest achievements in the use of nanoparticles to detect cancer biomarkers and cancer cells with a focus on optical and electrochemical techniques. Nanoparticle based cancer diagnostics are becoming an increasingly relevant alternative to traditional techniques. Although some drawbacks exist in relation to the obtained sensitivity the use of nanoparticle-based sensors in biomarker detection or cancer cell detection offers some advantages in comparison to conventional methods. The developed techniques can be interesting and relevant for their use in point-of-care of cancer diagnostics. The methods can be of low cost and in addition easy to be incorporated into user-friendly sensing platforms.     

基于石墨烯光子晶体光纤的流体传感器

与传统的传感器设备阵列相比,由于结构更为简单,具有广泛检测兼容性的光纤系统逐渐成为分布式监测的有力候选者。然而,受工作机制的限制,大多数光纤传感器仍局限于对折射率等物理参数进行探测,一种用于环境化学监测的全光纤分布式传感系统亟待研发。本工作中,我们向化学气相沉积法生长的石墨烯光子晶体光纤(Gr-PCF)中引入了一种化学传感机制。初步结果表明,石墨烯光子晶体光纤可以选择性地检测浓度为ppb级的二氧化氮气体,并在液体中表现出离子敏感性。石墨烯光子晶体光纤与光纤通信系统的波分、时分复用技术结合后,将为实现分布式光学传感环境问题提供巨大的潜力和机会。     

Electrokinetic techniques applied to electrochemical DNA biosensors

Electrokinetic techniques are contact-free methods currently used in many applications, where precise handling of biological entities, such as cells, bacteria or nucleic acids, is needed. These techniques are based on the effect of electric fields on molecules suspended in a fluid, and the corresponding induced motion, which can be tuned according to some known physical laws and observed behaviours. Increasing interest on the application of such strategies in order to improve the detection of DNA strands has appeared during the recent decades. Classical electrode-based DNA electrochemical biosensors with combined electrokinetic techniques present the advantage of being able to improve the working electrode's bioactive part during their fabrication and also the hybridization yield during the sensor detection phase. This can be achieved by selectively manipulating, driving and directing the molecules towards the electrodes increasing the speed and yield of the floating DNA strands attached to them. On the other hand, this technique can be also used in order to make biosensors reusable, or reconfigurable, by simply inverting its working principle and pulling DNA strands away from the electrodes. Finally, the combination of these techniques with nanostructures, such as nanopores or nanochannels, has recently boosted the appearance of new types of electrochemical sensors that exploit the time-varying position of DNA strands in order to continuously scan these molecules and to detect their properties. This review gives an insight into the main forces involved in DNA electrokinetics and discusses the state of the art and uses of these techniques in recent years.     

Advances in Optical Single‐Molecule Detection: En Route to Supersensitive Bioaffinity Assays

The ability to detect low concentrations of analytes and in particular low‐abundance biomarkers is of fundamental importance, e.g., for early‐stage disease diagnosis. The prospect of reaching the ultimate limit of detection has driven the development of single‐molecule bioaffinity assays. While many review articles have highlighted the potentials of single‐molecule technologies for analytical and diagnostic applications, these technologies are not as widespread in real‐world applications as one should expect. This Review provides a theoretical background on single‐molecule—or better digital—assays to critically assess their potential compared to traditional analog assays. Selected examples from the literature include bioaffinity assays for the detection of biomolecules such as proteins, nucleic acids, and viruses. The structure of the Review highlights the versatility of optical single‐molecule labeling techniques, including enzymatic amplification, molecular labels, and innovative nanomaterials.     

Considerations on contactless conductivity detection in capillary electrophoresis

Nearly all analyses by capillary electrophoresis (CE) are performed using optical detection, utilizing either absorbance or (laser-induced) fluorescence. Though adequate for many analytical problems, in a large number of cases, e.g., involving non-UV-absorbing compounds, these optical detection methods fall short. Indirect optical detection can then still provide an acceptable means of detection, however, with a strongly reduced sensitivity. During the past few years, contactless conductivity detection (CCD) has been presented as a valuable extension to optical detection techniques. It has been demonstrated that with CCD detection limits comparable, or even superior, to (indirect) optical detection can be obtained. Additionally, construction of the CCD around the CE capillary is straightforward and robust operation is easily obtained. Unfortunately, in the literature a large variety of designs and operating conditions for CCD were described. In this contribution, several important parameters of CCD are identified and their influence on, e.g., detectability and peak shape is described. An optimized setup based on a well-defined detection cell with three detection electrodes is presented. Additionally, simple and commercially available read-out electronics are described. The performance of the CCD-CE system was demonstrated for the analysis of peptides. Detection limits at the microM level were obtained in combination with good peak shapes and an overall good performance and stability.     

Precision of Raman depolarization and optical attenuation measurements of sound tooth enamel

The demineralization of enamel that is associated with early caries formation affects the optical properties of the enamel. Polarized Raman spectroscopy and optical coherence tomography have been used to detect these changes and potentially offer a means to detect and monitor early caries development. The total optical attenuation coefficient as measured by optical coherence tomography and the polarization anisotropy of the Raman peak arising from the symmetric ν₁ vibration of at approximately 959 cm⁻¹ have been demonstrated as being sensitive markers of early caries. This ex vivo study on extracted human teeth demonstrates that these measurements can be made with reasonable precision with concomitantly good repeatability and reproducibility in sound enamel. Such reliability is crucial for these techniques to have a practical clinical value.     

Recent trends in the detection of freshwater cyanotoxins with a critical note on their occurrence in Asia

Cyanobacteria are highly prevalent in slow-moving and nutrient-rich water bodies due to changing climatic conditions, eutrophication, and anthropogenic activities. Toxins of cyanobacterial blooms, i.e., cyanotoxins are also increasing at alarming rates in freshwater. Several efforts are being taken to detect cyanotoxins using molecular and analytical techniques to understand their occurrence and distribution, however, these studies are discrete and localized. The detection of cyanotoxins within water bodies is a long-established challenge. In this article, conventional methods of detection and the recently used nanostructure based immuno-sensors are described. Several studies are considered where aptamers are utilised as the biorecognition probe and we have discussed their use in colorimetric, electrochemical and optical sensors for the detection of cyanotoxins. Furthermore, this article also reviews the current field deployable diagnostics for the real-time monitoring of cyanotoxins. Future work on fundamental studies, development of highly specific aptamers for recognising different congeners of cyanotoxins and the integration of sensors into portable or lab-on-a-chip devices could be interesting and useful research. Moreover, several studies related to the occurrence and distribution of cyanotoxins in the freshwater bodies of Asia are reviewed, with potential threats identified. This article also adds a note on the geographical distribution and detection of cyanotoxins in Asia. Thus, we have provided an overview of various evolving detection systems that could be employed in identified problematic underdeveloped regions to improve management strategies to monitor and control cyanotoxins.     

Recent advances in microchip-based methods for the detection of pathogenic bacteria

Pathogenic bacteria pose a global threat to public health and attract considerable attention in terms of food safety. Rapid and highly sensitive strategies for detecting pathogenic bacteria must be urgently developed to ensure food safety and public health. Microchips offer significant advantages for pathogenic bacterial detection in terms of speed and sensitivity compared with those of traditional techniques. Microfluidic devices, in particular, have attracted significant attention for the dete...     

Versatile Metalloporphyrin-Based Electrochemical Sensing Applications: From Small Gasotransmitters to Macromolecules

At the beginning of his youthful sixth decade, this work is dedicated to Prof. Dr. Fabio Doctorovich. He is distinctive in organometallic chemistry. During his successful career, he has been studying the reactivity and application of metalloporphyrins. Metalloporphyrins are organometallic complexes that exhibit, through synthetic modifications, the ability to tune their optical and electrochemical properties and their selectivity towards a particular molecule or ion. For this reason, they are systems extremely useful as electrochemical sensors to detect and quantify a wide variety of analytes with high selectivity, even in real samples such as food, water, biological fluids, or pharmaceutical compounds. This review presents an up-to-date list of reports in which metalloporphyrins are used as electrochemical sensors. In addition to compiling a comprehensive and up-to-date list of reported sensors that utilize metalloporphyrins, this work aims to provide an overview of currently available tools and techniques for the detection of various chemical species through similar approaches, which are constantly being developed.     

Lectin sensitized anisotropic silver nanoparticles for detection of some bacteria

A method of bacteria detection by sensitized anisotropic silver nanoparticles is presented. Anisotropic silver nanoparticles with two bands of surface plasmon resonance (SPR) are prepared and sensitized with potato lectin. These nanoparticles are able to detect three bacterial species: Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The interaction of these bacteria with such nanoparticles induces drastic changes in optical spectra of nanoparticles that are correlated with bacteria titer. The maximal sensitivity is observed for S. aureus (up to 1.5 × 10⁴ mL⁻¹).     

Optical waveguide sensors in analytical chemistry: today’s instrumentation, applications and trends for future development

Current concepts for chemical and biochemical sensing based on detection with optical waveguides are reviewed. The goals are to provide a framework for classifying such sensors and to assist a designer in selecting the most suitable detection techniques and waveguide arrangements. Sensor designs are categorized on the basis of the five parameters that completely describe a light wave: its amplitude, wavelength, phase, polarization state and time-dependent waveform. In the fabrication of a successful sensor, the physical or chemical property of the determined species and the particular light wave parameter to detect it should be selected with care since they jointly dictate the sensitivity, stability, selectivity and accuracy of the eventual measurement. The principle of operation, the nature or the detected optical signal, instrumental requirements for practical applications, and associated problems are analyzed for each category of sensors. Two sorts of sensors are considered: those based on direct spectroscopic detection of the analyte, and those in which the analyte is determined indirectly through use of an analyte-sensitive reagent. Key areas of recent study, useful practical applications, and trends in future development of optical waveguide chemical and biochemical sensors are considered.     

Rapid bioanalysis with chemical sensors: novel strategies for devices and artificial recognition membranes

The increasing importance of biological analytes in chemistry has triggered the development of a vast number of techniques for rapidly assessing them. Aside from microbiological test methods, a wide range of analytical sensor and detection methods are being developed. Within this article, we review the literature on this topic from the last five years, stressing two main aspects of method development. The first aspect is the design of novel analytical strategies and transducers to generate signals more sensitively, more rapidly and more efficiently. Most of the progress in this field has focused on electrochemical detection, although novel approaches to optical and mass-sensitive measurements have been reported. Second, we provide an overview of two main approaches to creating artificial interaction layers for sensors based on tailored interaction sites in polymeric or biomimetic systems. The most prominent of these approaches is (molecular) imprinting, where selectivity is achieved by directly templating a polymer material with the target analyte or a model compound, thus achieving biomimetic interaction sites within both thin films and particles.     

Analysis of nerve agents using capillary electrophoresis and laboratory-on-a-chip technology

The nerve agents belong among the most toxic compounds produced by human kind. While they have been used very sporadically until now, typically in local conflicts or by local terrorists groups, the global increase in terrorist activity in the recent years has generated tremendous demand for innovative tools capable of detecting nerve agents. Fast, sensitive and reliable detection of nerve agents in the field is very important issue in present days. Capillary electrophoresis (CE) offers great possibilities for sensitive detection of these harmful compounds as well as incorporation in mobile laboratory and it proved to have capability to detect nerve agent breakdown products in real environmental samples. Laboratory-on-a-chip format offers great possibilities to create portable, field deployable, rapidly responding and potentially disposable device, allowing security forces to make the important decision regarding the safety of civilians. This article overviews the conventional capillary electrophoretic and laboratory-on-a-chip techniques for analysis of degradation products of G-type and V-type nerve agents. It discusses diverse strategies of detection of different nerve agents breakdown products, which are corresponding to their parental nerve agents. It also overviews possibilities and challenges for analysis of the real samples.     

Multifunctional modified silver nanoparticles as ion and pH sensors in aqueous solution

Silver nanoparticles capped with mercaptoacetic acid and 2-aminoethanethiol short-chain alkanethiols were prepared by a one-step method in aqueous solution for monitoring pH and a range of heavy metal ions. The mode of transduction is optical, based on the change in aggregation of the nanoparticles in solution. Because of the different ionic interactions between the modified nanoparticles, these nanoparticle sensors can rapidly detect Pb(2+), Cu(2+) and Fe(2+), with detection limits as low as 1 × 10(-5) M, 5 × 10(-7) M and 5 × 10(-5) M respectively, as well as having the ability to detect Cu(2+) ions from Pb(2+) and Fe(2+). Furthermore, the same functionalised nanoparticles are also sensitive to pH; exhibiting a good linear dynamic response between pH 1 and 10.     

检测硫酸氢根离子光化学探针分子研究进展

酸氢根离子(HSO4)在生命、环境科学中发挥着非常重要的作用,进入环境后会污染环境,对人体造成危害.因此,选择性和高灵敏识别检测生物与环境样品中HSO4具有非常重要的意义.在众多的分析检测手段中,基于分子识别理念发展起来的光化学传感分子(探针)具有独特的优势.阴离子光化学传感体系以其选择性好、灵敏度高、易于实现在线分析,特别是可通过目视比色识别和原位检测等特点成为目前研究的热点.本文根据探针分子与HSO4之间的作用机理, 对近年来HSO4的光化学探针分子进行分类和总结,综述了HSO4光化学探针的研究进展,并对其应用前景与发展趋势进行了展望.     

Development of bacteria-based bioassays for arsenic detection in natural waters

Arsenic contamination of natural waters is a worldwide concern, as the drinking water supplies for large populations can have high concentrations of arsenic. Traditional techniques to detect arsenic in natural water samples can be costly and time-consuming; therefore, robust and inexpensive methods to detect arsenic in water are highly desirable. Additionally, methods for detecting arsenic in the field have been greatly sought after. This article focuses on the use of bacteria-based assays as an emerging method that is both robust and inexpensive for the detection of arsenic in groundwater both in the field and in the laboratory. The arsenic detection elements in bacteria-based bioassays are biosensor–reporter strains; genetically modified strains of, e.g., Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Rhodopseudomonas palustris. In response to the presence of arsenic, such bacteria produce a reporter protein, the amount or activity of which is measured in the bioassay. Some of these bacterial biosensor–reporters have been successfully utilized for comparative in-field analyses through the use of simple solution-based assays, but future methods may concentrate on miniaturization using fiberoptics or microfluidics platforms. Additionally, there are other potential emerging bioassays for the detection of arsenic in natural waters including nematodes and clams.     

Ultrasensitive Detection of Salmonella and Listeria monocytogenes by Small‐Molecule Chemiluminescence Probes

Detection of Salmonella and L. monocytogenes in food samples by current diagnostic methods requires relatively long time to results (2–6 days). Furthermore, the ability to perform environmental monitoring at the factory site for these pathogens is limited due to the need for laboratory facilities. Herein, we report new chemiluminescence probes for the ultrasensitive direct detection of viable pathogenic bacteria. The probes are composed of a bright phenoxy‐dioxetane luminophore masked by triggering group, which is activated by a specific bacterial enzyme, and could detect their corresponding bacteria with an LOD value of about 600‐fold lower than that of fluorescent probes. Moreover, we were able to detect a minimum of 10 Salmonella cells within 6 h incubation. The assay allows for bacterial enrichment and detection in one test tube without further sample preparation. We anticipate that this design strategy will be used to prepare analogous chemiluminescence probes for other enzymes relevant to specific bacteria detection and point‐of‐care diagnostics.