TBA-Pb2＋-hemin模拟酶催化显色法测定水中痕量铅

在pH 7.5的Tris-HC1缓冲液中,凝血酶适体（TBA）与Pb2＋形成复合物,再与氯化血红素（hemin）配位结合,形成辣根过氧化物模拟酶,能催化H2O2氧化2,2＇-连氮-双（3-乙基苯并噻唑-6-磺酸）（ABTS）,生成蓝绿色自由基产物,导致体系在415 nm处吸光度值增加,且在1.07 × 10-10～6.01 ×l0-7 mol/L范围内△A值与pb2浓度有良好线性关系,其回归方程为△A=0.409 c（×10-9 mol/L）＋40.7,相关系数r=0.996 6,检出限为3.21×10-11 mol/L,相对标准偏差在0.67％～3.45％.用于环境水样测定,回收率在98.2％～102.7％.该方法特异性好、灵敏度高.     

Advances in riboswitch-based biosensor as food samples detection tool

Food safety has always been a hot issue of social concern, and biosensing has been widely used in the field of food safety detection. Compared with traditional aptamer-based biosensors, aptamer-based riboswitch biosensing represents higher precision and programmability. A riboswitch is an elegant example of controlling gene expression, where the target is coupled to the aptamer domain, resulting in a conformational change in the downstream expression domain and determining the signal output. Riboswitch-based biosensing can be extensively applied to the portable real-time detection of food samples. The numerous key features of riboswitch-based biosensing emphasize their sustainability, renewable, and testing, which promises to transform engineering applications in the field of food safety. This review covers recent developments in riboswitch-based biosensors. The brief history, definition, and modular design (regulatory mode, reporter, and expression platform) of riboswitch-based biosensors are explained for better insight into the design and construction. We summarize recent advances in various riboswitch-based biosensors involving theophylline, malachite green, tetracycline, neomycin, fluoride, thrombin, naringenin, ciprofloxacin, and paromomycin, aiming to provide general guidance for the design of riboswitch-based biosensors. Finally, the challenges and prospects are also summarized as a way forward stratagem and signs of progress.     

高灵敏的线形一体化探针用于癌细胞的快速检测

利用DNA自组装原理合成了一种高灵敏的线形一体化细胞探针,用于快速、高灵敏以及高特异性的癌细胞定量分析。该探针采用了功能元件一体化的设计,以DNA纳米线为载体,将磁分离元件、识别元件以及信号元件集中于一体。该探针与电化学检测手段相结合,实现了对人B淋巴瘤细胞(Ramos细胞)的快速定量分析,检测时间仅需30min,检测限可达到200个细胞。通过选择性实验证明了该方法不仅具有高的灵敏度,还具有良好的特异性,因此,具有潜在的应用价值。     

基于纳米金非标记化学发光分析测定K^＋

将核酸识体分子识别模式与纳米金催化发光特性相结合,建立了一种简单、灵敏测定K^＋的新方法。该方法测定K＋的线性范围为7．4×10^-8～7．4×10^-5mol／L,其检出限为2．9×10^8mol／L。并对浓度为5．6×10^-7mol／L的K^＋重复测定6次,相对标准偏差为3．6％。同时,考察了K’的适配体对K^＋结合的特异性,结果表明,该：方法对于K^＋的测定具有很好的选择性。     

Identification and Engineering of Aptamers for Theranostic Application in Human Health and Disorders

An aptamer is a short sequence of synthetic oligonucleotides which bind to their cognate target, specifically while maintaining similar or higher sensitivity compared to an antibody. The in-vitro selection of an aptamer, applying a conjoining approach of chemistry and molecular biology, is referred as Systematic Evolution of Ligands by Exponential enrichment (SELEX). These initial products of SELEX are further modified chemically in an attempt to make them stable in biofluid, avoiding nuclease digestion and renal clearance. While the modification is incorporated, enough care should be taken to maintain its sensitivity and specificity. These modifications and several improvisations have widened the window frame of aptamer applications that are currently not only restricted to in-vitro systems, but have also been used in molecular imaging for disease pathology and treatment. In the food industry, it has been used as sensor for detection of different diseases and fungal infections. In this review, we have discussed a brief history of its journey, along with applications where its role as a therapeutic plus diagnostic (theranostic) tool has been demonstrated. We have also highlighted the potential aptamer-mediated strategies for molecular targeting of COVID-19. Finally, the review focused on its future prospective in immunotherapy, as well as in identification of novel biomarkers in stem cells and also in single cell proteomics (scProteomics) to study intra or inter-tumor heterogeneity at the protein level. Small size, chemical synthesis, low batch variation, cost effectiveness, long shelf life and low immunogenicity provide advantages to the aptamer over the antibody. These physical and chemical properties of aptamers render them as a strong biomedical tool for theranostic purposes over the existing ones. The significance of aptamers in human health was the key finding of this review.     

Aptamers for Anti-Viral Therapeutics and Diagnostics

Viral infections cause a host of fatal diseases and seriously affect every form of life from bacteria to humans. Although most viral infections can receive appropriate treatment thereby limiting damage to life and livelihood with modern medicine and early diagnosis, new types of viral infections are continuously emerging that need to be properly and timely treated. As time is the most important factor in the progress of many deadly viral diseases, early detection becomes of paramount importance for effective treatment. Aptamers are small oligonucleotide molecules made by the systematic evolution of ligands by exponential enrichment (SELEX). Aptamers are characterized by being able to specifically bind to a target, much like antibodies. However, unlike antibodies, aptamers are easily synthesized, modified, and are able to target a wider range of substances, including proteins and carbohydrates. With these advantages in mind, many studies on aptamer-based viral diagnosis and treatments are currently in progress. The use of aptamers for viral diagnosis requires a system that recognizes the binding of viral molecules to aptamers in samples of blood, serum, plasma, or in virus-infected cells. From a therapeutic perspective, aptamers target viral particles or host cell receptors to prevent the interaction between the virus and host cells or target intracellular viral proteins to interrupt the life cycle of the virus within infected cells. In this paper, we review recent attempts to use aptamers for the diagnosis and treatment of various viral infections.     

Molecular Aptamer Beacons and Their Applications in Sensing,Imaging, and Diagnostics

The ability to monitor types, concentrations, and activities of different biomolecules is essential to obtain information about the molecular processes within cells. Successful monitoring requires a sensitive and selective tool that can respond to these molecular changes. Molecular aptamer beacon (MAB) is a molecular imaging and detection tool that enables visualization of small or large molecules by combining the selectivity and sensitivity of molecular beacon and aptamer technologies. MAB design leverages structure switching and specific recognition to yield an optical on/off switch in the presence of the target. Various donor–quencher pairs such as fluorescent dyes, quantum dots, carbon‐based materials, and metallic nanoparticles have been employed in the design of MABs. In this work, the diverse biomedical applications of MAB technology are focused on. Different conjugation strategies for the energy donor–acceptor pairs are addressed, and the overall sensitivities of each detection system are discussed. The future potential of this technology in the fields of biomedical research and diagnostics is also highlighted.