Construction Of Small Molecule Fluorescent Probe And Its Application In The Analysis Of Biological Signaling Molecules

The abnormal expression of certain biological signaling molecules is closely related to the occurrence and progression of disease.With the rapidly increasing demands for ultrasensitive biodetection,owing to the distinctive characteristics of simplicity,high selectivity,quick reaction time and sensitivity,whilst being non-invasive,optical probes have shown enormous potential in the diagnosis of disease and in real-time analysis of living systems with high signal-to-noise ratios.In this article,three types of new multifunctional fluorescent probes were innovatively constructed,achieved high sensitivity and selective detection of bioactive molecules with minimal perturbation to living systems.The main research contents are as follows:(1)Inorganic phosphate(Pi)is an essential nutrient for the maintenance of cells.Mitochondrion plays a crucial role in ATP synthesis and directly affects energy balance.In addition,at the cellular level,the viscosity of mitochondria is much greater than that of cytoplasm.Herein,we construct a dual-functional fluorescence probe(Mito-VP)that is designed via the molecular rotor strategy and a unique Pi induced hydrolytic reaction.Probe Mito-VP shows excellently spectral responses to Pi in viscous systems with high sensitivity and selectivity.The cationic probe can selectively cluster in mitochondria and was successfully utilized to sense Pi in living Hep G2 cells and zebrafish through fluorescence imaging.What's more,Mito-VP was used to monitor changing behavior of energy metabolism during cell division,and may be expected to be used in the study of Pi detection in more viscous biosystems.(2)Accurate detection of human serum albumin(HSA)in biological samples is quite meaningful for early disease diagnosis and treatment.Herein,a novel fluorescent probe 1-ethyl-4-[2-[4-(diethylamino)-2-hydroxyphenyl]ethenyl]]-pyridinium salt(DEHP)was developed for HSA determination.The inherent fluorescence of DEHP is essentially negligible at physiological conditions assigned to the well-developed twisted intramolecular charge transfer(TICT)protocol.An intriguing fluorescence light up is triggered as the addition of HSA,on account of the inhibited TICT procedure when DEHP enters the hydrophobic cavity of protein HSA.This combination leads to a turn on fluorescent response for HSA with a detection limit of 4.8 nM.After an overall investigation,it has been proved that the strong binding between DEHP and HSA is specific-site-related.In additional,the probe is suitable for the usage in actual serum detection.Cell imaging also shows that the probe is expected to monitor HSA production process at cell level.(3)Acetylcholinesterase(AChE)is a vital cholinesterase for neural transmission accounting for several nervous diseases.Upon an elegant integration of the aggregation-based response strategy and the intrinsic property of MnO₂ nanosheets(NSs)in morphology and oxidizability,a composite receptor PBM@MnO₂ NSs for AChE was developed in this work.The electrostatic interaction between the positive PBM and negative MnO₂ NSs is responsible for the self-assembly of PBM monomers onto MnO₂NSs,accompanied by the fluorescence quenching arising from PBM aggregation.By virtue of the specific enzymatic interaction induced by AChE with positive thiocholine(TCh)as product to degrade MnO₂ NSs and release PBM monomers.In addition,this work examined the bio-imaging in cells and zebrafish,and in-depth study found out that this imaging platform is capable of discriminating cells at apoptosis from the living cells.