China
Africa
Explore chapters and articles related to this topic
Nanoparticle Contrast Agents for Medical Imaging
Published in Alok Dhawan, Sanjay Singh, Ashutosh Kumar, Rishi Shanker, Nanobiotechnology, 2018
Rabee Cheheltani, Johoon Kim, Pratap C. Naha, David P. Cormode
Nanoparticle contrast agents of many different forms are used together with several imaging modalities. In this chapter, contrast agents for computed tomography (CT), magnetic resonance imaging, fluorescence imaging, nuclear imaging, and photoacoustic imaging will be discussed in detail, as they are the most widely used imaging modalities for which nanoparticles are relevant. Nanoparticle contrast agents in CT have been based on many heavy elements, such as iodine, gold, bismuth, bromine, and tantalum, to name a few. Most of the studies in MRI contrast agents are done with different types of gadolinium chelate-labeled nanoparticles or iron oxide-based nanoparticles. Fluorescence imaging uses a wide variety of quantum dots, such as Ag2S, CdTe, or CdSe, as well as gold and carbon-based nanostructures and fluorophore tagged polymer-based nanoparticles. Nuclear imaging utilizes different radioisotopes embedded in structures of nanoparticles. 99mTc, 111In, 125I for SPECT and 18F-FDG, 64Cu, 67Ga, and 89Zr for PET imaging are few of the frequently used radioisotopes. For photoacoustic imaging, gold and silver nanoparticles, and dye-embedded nanoparticles (e.g., Prussian blue), are most commonly used.
Smart Analytical Lab
Published in Shampa Sen, Leonid Datta, Sayak Mitra, Machine Learning and IoT, 2018
Subhrodeep Saha, Sourish Sen, Bharti Singh, Shampa Sen
Fluorescence imaging is the process of visualizing molecular and cellular structures by labeling them with fluorescent dyes or markers. This technique has various applications in the fields of biotechnology, organic chemistry, and medicine because of easy implementation, innate sensitivity, inert nature, nonintrusiveness, and the commercial availability of many well-developed fluorescence dyes and labeling schemes for biological studies. A few cases of across the board use of fluorescence imaging are enzyme assays, capillary electrophoresis (CE), antibody detection and screening, bead-based immunoassays, DNA sequencing and fragment sizing or extraction, protein detection, food assay, cellular microscopy, and imaging detection.
Laser-Induced Fluorescence Imaging
Published in Helmut H. Telle, Ángel González Ureña, Laser Spectroscopy and Laser Imaging, 2018
Helmut H. Telle, Ángel González Ureña
Fluorescence imaging is the visualization of fluorescence radiation emitted at different wavelengths by molecules present in a given sample that has been illuminated by incident photons. Thus, the color image of the fluorescence radiation obtained with a sufficient resolution provides a map of fluorophore distribution within the investigated object. There are two main criteria for classifying fluorescence imaging methods: the first one is the size of the object to be imaged and the second one is based on the contrast mechanism employed to obtain the image.
Bioimaging of metals in environmental toxicological studies: Linking localization and functionality
Published in Critical Reviews in Environmental Science and Technology, 2022
Identification of metal ions in biological systems should certainly be linked with their functionality in organisms, and there is a real need to develop various biosensors capable of detecting the functions of other molecules in organisms. There are various commercially available probes for cellular localization and function (e.g., lysosome trackers, mitochondria trackers, pH, membrane potentials, RNA, among many others). The applications of AIE, which emit fluorescence when molecules are aggregated, are particularly powerful for the visualization of various cellular structures, functions, and movements. There is also a variety of bioprobes available for the investigation of subcellular structures and processes of cells based on the AIEgens. These AIEgens have shown their biocompatibility and photostability as compared to many commercially available bioprobes which have aggregation-caused quenching (ACQ) efforts and are unstable. Song et al. (2021) recently summarized the different AIEgens available for the imaging of various subcellular structures such as nuclei, membranes, lipid droplets, endoplasmic reticulum (ER), mitochondria, lysosomes, and cytoplasm. Of particular importance for metals are a few organelles such as mitochondria (targeted metal toxic site) and lysosomes (targeted metal detoxification site). Lipid droplets may be important for metal handling and the formation of lipofuscin. ER is an important site for protein and lipid synthesis, and Golgi bodies are important in protein transport. Fluorescence imaging allows the visualization of these subcellular structures as well as the processes associated with them. Table 4 summarizes some of these AIEgens that may be potentially used for environmental toxicological studies of metals. It should be noted that this field is expanding rapidly, and it is a matter whether they are assessible for use by toxicologists.
Recent advances in nuclear and hybrid detection modalities for image-guided surgery
Published in Expert Review of Medical Devices, 2019
Matthias N. Van Oosterom, Daphne D.D. Rietbergen, Mick M. Welling, Henk G. Van Der Poel, Tobias Maurer, Fijs W.B. Van Leeuwen
Fluorescence imaging is an optical method that exploits the nature of fluorescent dyes: under excitation with a dye specific wavelength of light (typically between 400 and 800 nm), these substances emit light with a lower energy themselves (typically between 500 and 900 nm). Due to this shift in energy, optical filters can be used to separate excitation from emission light, allowing for precise visual localization of the fluorescent pharmaceutical. Of all the hybrid detection systems described for radioguided surgery, the combination of γ and fluorescence is the one most addressed in clinical literature. The optonuclear probe is a hybrid version of the traditional γ probe (see Figure 4(a–d)), providing both low-to-mid energy γ tracing and ICG fluorescence tracing in a single device [220–222]. This functionality is achieved by extending a γ probe design with two optical fibers, one coupled to an ICG excitation laser and the other coupled to an optically filtered (>810 nm) PMT. It has been used during both open and laparoscopic surgery for SN procedures in head and neck cancers, penile cancer, breast cancer, melanoma and cervical cancer [220–222]. Recently, it was shown that an integration of this hybrid detection probe with a surgical navigation system was even capable of producing 3D fluorescence tomography reconstructions (i.e. freehand Fluorescence scans) in addition to the above described fhSPECT modality [258]. This hybrid imaging and navigation technology was evaluated in ex vivo prostate cancer samples using ICG-99mTc-nanocolloid. KleinJan et al. investigated the use of image-based hybrid modalities in vivo (i.e. penile cancer SN procedure), by using a tailored bracket to physically connect either a γ probe or portable γ camera to a fluorescence camera system [154]. Here, the in-depth information of radioguidance provided the ability to more accurately position the fluorescence camera. A portable and fully integrated hybrid γ and fluorescence camera has only been studied in preclinical evaluations [223]. In this system, γ and fluorescent emissions are both collected at the front of the device, but in the camera are separated through an angled mirror (45°) to allow for separate detection. With an innovative wavelength division-based multiplexing method, Kang et al. propose an integrated hybrid laparoscope for simultaneous γ and fluorescence imaging in a laparoscopic setting [107]. In this system, γ, white light and fluorescent emissions are all collected through the same tungsten pinhole collimator. Subsequently, all emissions are passed through a gadolinium oxyorthosilicate (GSO) scintillator, converting only the γ rays to visible blue light (~400–500 nm). Hereafter all emissions are transported via de laparoscope imaging fiber bundle and collected with three different cameras based on wavelength. However, usability of this system still has to be determined.