Ditopic boronic acid and imine-based naphthalimide fluorescence sensor for copper(II).

Meng Li,Weihong Zhu,Vincenzo Mirabello,Rory L Arrowsmith,Tony D James,Haobo Ge,Sofia I Pascu,Stanley W Botchway

doi:10.1039/c4cc03453h

Abstract

Copper ions are essential for many biological processes. However, high concentrations of copper can be detrimental to the cell or organism. A novel naphthalimide derivative bearing a monoboronic acid group (BNP) was investigated as a Cu(2+) selective fluorescent sensor in living cells. This derivative is one of the rare examples of reversible fluorescent chemosensors for Cu(2+) which uses a boronic acid group for a binding site. Moreover, the adduct BNP-Cu(2+) displays a fluorescence enhancement with fructose. The uptake of this novel compound in HeLa cancer cells was imaged using confocal fluorescence microscopy techniques including two-photon fluorescence lifetime imaging microscopy.

Highlights

The adduct bearing a monoboronic acid group (BNP)–Cu2+ displays a fluorescence enhancement with fructose. The uptake of this novel compound in HeLa cancer cells was imaged using confocal fluorescence microscopy techniques including two-photon fluorescence lifetime imaging microscopy
The complex BNP– Cu2+ is obtained and displays a fluorescence enhancement with fructose, which can be considered as a fluorescence based INHIBIT logic gate
Upon increasing the concentration of Cu2+ (0–300 mM), an absorption enhancement could be observed with a red-shift to 465 nm in the absorption maximum which indicated the formation of an adduct between BNP and Cu2+

Summary

Introduction

Fluorescent sensors have been widely investigated in both environmental and biological systems due to their simplicity and high detection limit.[1,2] Copper(II), the third most abundant transition metal ions in the human body after iron(III) and zinc(II),[3] plays a crucial role in biological, environmental and chemical systems.[4,5] Both excess and deficiency in Cu(II) may lead to severe diseases, such as Alzheimer’s and Wilson’s diseases and haematological manifestations.[6,7,8,9,10,11,12] The average normal concentration range of blood copper is 100–150 mg dLÀ1 (15.7–23.6 mM).[13]. James et al Ditopic boronic acid and imine-based naphthalimide fluorescence sensor for copper(II) Ditopic boronic acid and imine-based naphthalimide fluorescence sensor for copper(II)† A novel naphthalimide derivative bearing a monoboronic acid group (BNP) was investigated as a Cu2+ selective fluorescent sensor in living cells.

Results

Conclusion