Preparation Of A DCM-based Ratiometric Fluorescent Probe And Its Application Of The Carboxylesterase Detection

Carboxylesterases(CaE)are widely distributed enzymes in the human body that catalyze hydrolysis of various endogenous and exogenous substrates.They are directly linked to drug metabolisms and steatosis.CaE hydrolyze various prodrugs,including the oseltamivir,clopidogrel,and esmolol.The hydrolytic activity of CaE has important roles in drug protection and metabolism.Abnormal regulation or deficiency of CaE is directly related to human diseases such as hyperlipidemia,atherosclerosis,and cancer etc.Therefore,the researches on detecting CaE are important issues in pharmacological and clinical application.Compared with other detection methods,fluorescence detection techniques have been widely used in areas including biology,chemistry medical and materials sciences,due to its simple,specific selectivity,high sensitivity and non-destructive for biological samples.In this paper,a new ratiometric two-photon fluorescent probe for detecting CaE has been designed.Dicyanomethylene-4H-pyran chromophores(DCM)is selected as the fluorophore and acetic acid-4-benzyl methoxyl group is fluorescence quenching agent.In the presence of carboxylesterases,the ICT-based probe can be rapidly hydrolysed and formed a metabolite with hydroxyl.Naked hydroxyl spontaneously trigger the 1,6-elimination reaction of the metabolite,which recovered ICT process of the probe molecule.The translation can provide rationmetric analysis of CaE activity.The main contents and the results of this paper are as follows:(1)The ratiometric two-photon fluorescent probe DCM-CE based on intramolecular charge transfer(ICT)was successfully synthesized.Then,we made sure the chemical structure of intermediate products and the final product through 1H-NMR and MS.(2)The light spectrum tests show that a fluorescence emission band with a maximum value at 606 nm upon excitation at 470 nm in the mixture of PBS buffer(10 mM,pH= 7.4)and DMSO(v/v,4: 1).Upon addition of CaE,fluorescent intensity of the probe increases at 666 nm and has a 60 nm red shift.Correspondingly,the reaction mixture emits dual emission fluorescence signal at 606 nm and at 666 nm,and displayed a change the solution from light yellow to colourless,which can be clearly distinguished by “naked eyes”.In addition,the probe has a rapid response towards CEs with 30 min,stability to pH in 3.0-10.0,good selectivity,and anti-interference performance of other ions or compounds,which is an effective tool for monitoring CaE activities at subcellular level.(3)The tests results in vivo show that the probe has excellent cell membrane permeability,good cell uptake,and low cytotoxicity.The probe not only can be successfully applied to single-photon and two-photon fluorescent imaging in cell(He La),but also monitors CaE activities in real-time.So,the probe has potential application in biomedical research,including studies of steatosis and drug developments.