Macro-/micro-environment-sensitive chemosensing and biological imaging

Abstract

Environment-related parameters, including viscosity, polarity, temperature, hypoxia, and pH, play pivotal roles in controlling the physical or chemical behaviors of local molecules. In particular, in a biological environment, such factors predominantly determine the biological properties of the local environment or reflect corresponding status alterations. Abnormal changes in these factors would cause cellular malfunction or become a hallmark of the occurrence of severe diseases. Therefore, in recent years, they have increasingly attracted research interest from the fields of chemistry and biological chemistry. With the emergence of fluorescence sensing and imaging technology, several fluorescent chemosensors have been designed to respond to such parameters and to further map their distributions and variations in vitro/in vivo. In this work, we have reviewed a number of various environment-responsive chemosensors related to fluorescent recognition of viscosity, polarity, temperature, hypoxia, and pH that have been reported thus far.

The benzo[b]quinolizinium ion as a water-soluble platform for the fluorimetric detection of biologically relevant analytes

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] It should be stressed, however, that most reported examples, such as the ones stated above, employ the rather conventional approach that one probe can be used only for one particular analyte. But in real samples several different analytes have to be detected at the same time.…”

“…128 To overcome the above mentioned shortcomings of probe 10 we turned our attention to crown-ether functionalities as receptor units, because it has been demonstrated already with numerous examples that the direct attachment of azacrown ether units to a fluorophore is a general design principle for the development of donor-acceptor based fluorescent probes that change emission wavelength upon complexation of a metal ion (Scheme 1c). [3][4][5][6][7][8][9][10][11][12][122][123][124][125][126][127] Nevertheless, most crown ether host molecules do not bind the analyte to significant extent in water, 129 so that the majority of probes can only operate in non-competitive organic solvents. Therefore, we focused our studies on the 1,4-dioxa-7,13-dithia-10-azacyclopentadecane receptor unit, that is known to bind Hg 2+ ions in water with high affinity.…”

“…It should be stressed that numerous other fluorescent dyes have been employed successfully for the development of chemosensors with remarkable properties. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] However, the overwhelming number of efficient and selective chemosensors, that have been explored and established during the past years, cannot be highlighted in this Account. With the intention to limit the extent of this Account to a reasonable size, a straight focus is kept on the class of benzo[b]quinolizinium ions.…”

“…2 The main principles of fluorescent sensing by organic chemosensors are well known and extensively described in recent reviews and monographs. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] In general, three different physical quantities may be determined from the emission of a molecule, namely emission energy, emission quantum yield and emission lifetime. 14,16 Therefore, essentially all fluorescent probes indicate a target analyte or a physical input (e.g.…”

“…The detection of analytes with fluorescent probes, also referred to as chemosensors, 1 is a useful and versatile technique in chemistry and biology as well as in their neighboring disciplines, [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] because it offers the advantages of fluorescence spectroscopy, e.g. high sensitivity and straightforward detection procedure, combined with the high potential of chemical synthesis to prepare a fluorophore with the required substitution pattern.…”