Biosensors

Two decades of research into biosensors has been accelerated recently by the commercial potential offered by biotechnology. New developments in biosensor technology in which a biologically sensitive material is immobilized in intimate contact with a suitable potentiometric, amperometric, optical or other transducer are described. It is expected that some of these devices will be commercialized in 1984.     

Biosensors

Biosensors are analytical devices that respond selectively to analytes in an appropriate sample and convert their concentration into an electrical signal via a combination of a biological recognition system and an electrochemical, optical or other transducer. Such devices will find application in medicine, agriculture, environmental monitoring and the bioprocessing industries. The last few years have seen great advances in the design of sensor architectures, the marriage of biological systems with monolithic silicon and optical technologies, the development of effective electron-transfer systems and the configuration of direct immunosensors. Recent progress in these areas has already led to the introduction of new-generation biosensors into the competitive diagnostics market place.     

Aptamer-based molecular imaging

Molecular imaging has greatly advanced basic biology and translational medicine through visualization and quantification of single/multiple molecular events temporally and spatially in a cellular context and in living organisms. Aptamers, short single-stranded nucleic acids selected in vitro to bind a broad range of target molecules avidly and specifically, are ideal molecular recognition elements for probe development in molecular imaging. This review summarizes the current state of aptamer-based biosensor development (probe design and imaging modalities) and their application in imaging small molecules, nucleic acids and proteins mostly in a cellular context with some animal studies. The article is concluded with a brief discussion on the perspective of aptamer-based molecular imaging.     

Biosensors and bioelectrochemistry

This review describes recent developments in the field of biosensors and bioelectrochemistry. Nanoparticles have been used to improve sensor performance and to develop biosensors based on new detection principles. Their use has extended into all areas of biosensor and bioelectrochemistry research. Other active areas of biosensor development include DNA sensing, immunosensing, direct electron transfer between an electrode and a redox protein or enzyme, and in vivo sensors.     

压电生物传感

本文提出：压电生物传感器应分为两大类型,即质量响应型和非质量响应型。探讨了这两类生物传感器的理论基础。叙述了它们在酶学、免疫学、微生物学、ＤＮＡ杂化、内毒素检测、气相传感、仿生学和血液流变学中的应用。     

Targeted molecular imaging agents for cellular-scale bimodal imaging

Molecular imaging is a powerful tool that has the ability to elucidate biochemical mechanisms and signal the early onset of disease. Overexpression of the peripheral benzodiazepine receptor (PBR) has been observed in a variety disease states, including glioblastoma, breast cancer, and Alzheimer's disease. Thus, the PBR could be an attractive target for molecular imaging. In this paper, the authors report cellular uptake and multimodal (MRI and fluorescence) imaging of PBR-overexpressing C6 glioblastoma (brain cancer) cells using a cocktail administration approach and a new PBR targeted lanthanide chelate molecular imaging agent.     

Protein scaffold-based molecular probes for cancer molecular imaging

Protein scaffold molecules are powerful reagents for targeting various cell signal receptors, enzymes, cytokines and other cancer-related molecules. They belong to the peptide and small protein platform with distinct properties. For the purpose of development of new generation molecular probes, various protein scaffold molecules have been labeled with imaging moieties and evaluated both in vitro and in vivo. Among the evaluated probes Affibody molecules and analogs, cystine knot peptides, and nanobodies have shown especially good characteristics as protein scaffold platforms for development of in vivo molecular probes. Quantitative data obtained from positron emission tomography, single photon emission computed tomography/CT, and optical imaging together with biodistribution studies have shown high tumor uptakes and high tumor-to-blood ratios for these probes. High tumor contrast imaging has been obtained within 1 h after injection. The success of those molecular probes demonstrates the adequacy of protein scaffold strategy as a general approach in molecular probe development.     

In vivo molecular and single cell imaging

Molecular imaging is used to improve the disease diagnosis, prognosis, monitoring of treatment in living subjects. Numerous molecular targets have been developed for various cellular and molecular processes in genetic, metabolic, proteomic, and cellular biologic level. Molecular imaging modalities such as Optical Imaging, Magnetic Resonance Imaging (MRI), Positron Emission Tomography (PET), Single Photon Emission Computed Tomography (SPECT), and Computed Tomography (CT) can be used to visualize anatomic, genetic, biochemical, and physiologic changes in vivo. For in vivo cell imaging, certain cells such as cancer cells, immune cells, stem cells could be labeled by direct and indirect labeling methods to monitor cell migration, cell activity, and cell effects in cell-based therapy. In case of cancer, it could be used to investigate biological processes such as cancer metastasis and to analyze the drug treatment process. In addition, transplanted stem cells and immune cells in cell-based therapy could be visualized and tracked to confirm the fate, activity, and function of cells. In conventional molecular imaging, cells can be monitored in vivo in bulk non-invasively with optical imaging, MRI, PET, and SPECT imaging. However, single cell imaging in vivo has been a great challenge due to an extremely high sensitive detection of single cell. Recently, there has been great attention for in vivo single cell imaging due to the development of single cell study. In vivo single imaging could analyze the survival or death, movement direction, and characteristics of a single cell in live subjects. In this article, we reviewed basic principle of in vivo molecular imaging and introduced recent studies for in vivo single cell imaging based on the concept of in vivo molecular imaging.     

生物传感器的应用研究进展

生物传感器是一门由生物、化学、物理、医学、电子技术等多种学科互相渗透成长起来的高新技术 ,是一种将生物感应元件的专一性与一个能够产生和待测物浓度成比例的信号传导器结合起来的分析装置。由于其具有选择性好、灵敏度高、分析速度快、成本低、能在复杂体系中进行在线连续监测的特点 ,已在生物、医学、环境监测、食品、医药、及军事医学等领域显示出广阔的应用前景 ,引起了世界各国的极大关注。综述了生物传感器的基本原理、分类、特点及在环境监测、食品分析、生物医学和军事上的应用 ,并对其发展前景进行了展望。     

生物芯片、生物传感器和生物信息学

近年来,在生物技术和医学研究领域涌现出了许多新技术平台,其中就包括生物芯片技术和生物传感器技术。生物芯片和生物传感器的构建都必须以生物信息学为基础,而两种技术平台应用所得出的数据和结果又反过来大大丰富和充实了生物信息学本身。本分析概述了生物芯片和生物传感器两种技术平台以及生物信息学,对三之间的相互关系进行了讨论。     

Peptide heterodimers for molecular imaging

One main issue with peptide-based molecular imaging probes is their relatively low tumor affinity and short retention time. To improve peptide binding affinity, multivalency approach has been introduced. Traditionally, this approach involves the use of peptide homodimers or homomultimers in which peptide ligands of the same type are constructed with suitable linkers. Recently, a new approach using peptide heterodimers has emerged as a promising method for targeting multi-receptor over-expressed tumor cells. Significant affinity enhancements have been observed with peptide heterodimers compared with their parent peptide monomers. In a peptide heterodimer, two different peptide ligands capable of targeting two different receptors are covalently linked. The binding modes of peptide heterodimers can be monovalent or bivalent depending on whether simultaneous binding of two ligands can be achieved. Increased local ligand concentration and improved binding kinetics contribute to enhanced binding in both monovalent- and bivalent binding modes, while multivalency effect also plays an important role in bivalent binding mode. As many tumors overexpress multiple receptors, more peptide heterodimer-based molecular imaging probes are expected to be developed in future. This review article will discuss the peptide homodimers and heterodimers for molecular imaging with special emphasis on peptide heterodimers.