Copper-based reactions in analyte-responsive fluorescent probes for biological applications

Abstract

Copper chemistry has been capitalized on in a wide spectrum of biological events. The central importance of copper in biology lies in the diverse chemical reactivity of the redox-active transition metal ranging from electron transfer, small molecule binding and activation, to catalysis. In addition to its many different roles in natural biological systems, the diverse chemical reactivity of copper also represents a rich opportunity and resource to develop synthetic bioanalytical tools for the study of biologically important species and molecules. In this mini-review, fluorescent probes featuring a specific copper-based chemical reaction to selectively detect a biologically relevant analyte will be discussed. In particular, fluorescent probes for sensing labile copper ions, amino acids and small reactive species will be highlighted. The chemical principles, advantages and limitations of the different types of copper-mediated chemical reactions in these fluorescent probes will be emphasized.

Selective catecholamine detection in living cells by a copper-mediated oxidative bond cleavage

“…Of note, developing an activity-based recognition that targets both amine and diol while avoiding cross reactivity is non-trivial because these functional groups are also widely present in a biological matrix. Because of the necessity of the C–O bond cleavage for the fluorescence response, CAP differentiates catecholamines from other competitive species that react with the N 3 S–Cu II complex differently 55–59. In fact, synthetic copper complexes supported by ligands with primary N 3 S donors have been intensively studied as models of DβH and PHM 52,60,61.…”

Activity‐Based Sensing of Ascorbate by Using Copper‐Mediated Oxidative Bond Cleavage

“…This key difference provides the necessary ascorbate selectivity by preventing false positive via simple Cu 2+ reduction, competitive ligand exchange or other non-bond cleavage-leading reactions. [21] On the other hand, because of the irreversible nature of the bond cleavage, the cleaved fluorophore can be accumulated to result in a fluorescent signal despite potential competitive binding to the copper by other molecules, which further distinguishes the current design from other metal-based probes that produce a fluorescent response via a simple reversible binding with the target analyte.…”

Emerging analytical tools for the detection of the third gasotransmitter H2S, a comprehensive review

“…However, Cu (II) containing probes, turn-on via CuS precipitation may be interfered by other biological reducing species such as NO, HNO, which occur via metal displacement by His and Cys, reduction of Cu(II) to Cu(I), or hampered by other competitive pathways to remove the metal quencher [87] . Though, a more selective or even specific chemical reaction may be needed to overcome the interfering endogenous similar chemical species or other competitive pathways.…”