Synthesis And Properties Of Fe²⁺ And Cys Fluorescent Probes Based On Naphthalimide Derivatives

In the human body,iron is not only an essential trace element,but also the most abundant transition metal element.Iron mainly exists in two forms of Fe²⁺and Fe³⁺,and is mainly distributed in various organs and tissues of the human body.In addition,iron can bind to hemoglobin in the human body.Not only can oxygen be transferred from the lungs to the cells,but it can also be used as part of cytochromes and respiratory enzymes to help transfer electrons and participate in breathing.In organisms,disorders of iron levels are accompanied by various diseases.Therefore,it is of great significance to design a fluorescent probe that can quickly detect ferrous ions in the body.Cysteine?Cys?is an essential small thiol-containing organic molecule that plays an important role in many physiological processes such as protein synthesis,detoxification and metabolism.This sulfhydryl amino acid can control redox homeostasis and transmit signals in cells,and it plays a role in protecting cells from oxidative damage.Excessive amounts of cysteine in living organisms can cause many diseases such as impaired hematopoietic function,psoriasis,neurotoxicity,edema and liver damage.Therefore,it is of great significance to design a probe with high sensitivity,high selectivity and rapid detection of biothiols in living organisms.?1?Design and synthesis of a ratiometric near-infrared fluorescent probe T1 for detecting Fe²⁺.Probe T1 is a nitrogen oxide?N-Oxide?formed based on a naphthalimide fluorophore derivative.This section aims to explore the mechanism of the reaction between probe T1 and Fe²⁺?ICT?and characterize its structure.The photophysical properties of probe T1 were studied in PBS:DMSO=2:8?0.01 M,pH 7.4?buffer solution.When saturated equivalent Fe²⁺was added,N-Oxide was reduced and the solution color changed from yellow to Fuchsia.Meanwhile,the minimum fluorescence emission at 510 nm,and the maximum fluorescence emission at 690 nm??ex=500 nm?,the fluorescence spectrum and Fe²⁺showed a good ratio change.The probe T1 has the characteristics of high selectivity,high sensitivity?detection limit of 5.9??44??,fast response,and good anti-interference.It has been successfully applied to Fluorescence imaging of Fe²⁺in living cells?HeLa cells?and C.elegans.?2?Design and synthesis of a ratiometric fluorescent probe T2 for detecting Cys.Probe T2 is based on naphthalimide derivatives.The mechanism of the reaction between probe T2 and Cys is explored and its structure is characterized.The photophysical properties of probe T2 were studied in PBS:DMF=3:7?0.01 M,pH7.4?buffer solution.When the saturation equivalent Cys is added,the fluorescence spectrum of the probe has obvious ratio change,and can realize the specificity recognition of Cys,and the detection limit is as low as 2.13??44?.More importantly,the probe has been successfully applied to Cys fluorescence imaging of C.elegans.