Design,Synthesis,Theoretical Calculation And Simulation Of The Fluorescent Probes For Albumin

In recent decades,because of its many advantages,fluorescent molecular probes have become effective detection tools in the field of life sciences,especially in the detection and imaging of biological macromolecules,such as proteins.However,Human serum albumin(HSA)is the most functional protein in human plasma and it plays an important role in maintaining osmotic pressure,internal and external transport of substances,and its abnormal content is related to the occurrence of various diseases related to liver and kidney.In addition,it is also related to the occurrence of some cardiovascular and cerebrovascular diseases.Abnormal serum albumin concentration in serum or urine is an important early biomarker for various medical conditions and diseases.Therefore,being able to accurately detect the HSA concentration in real biological samples is of great significance for clinical diagnosis and preventive medicine.Thus,it is an important research direction that the development of effective fluorescent probes for visual detection of serum albumin by using fluorescent probe technology.In this paper,we designed and synthesized six fluorescent probes for detecting human serum albumin based on Twisted Intramolecular Charge Transfer(TICT),Excited-State Intramolecular Proton Transfer(ESIPT)and Intramolecular Charge Transfer(ICT).The main contents of this work are as follows,Firstly,we designed six fluorescent probes,OBZ,OPH,GA,SA,SN and SCN,by reading a lot of literature,then the two probe molecules OBZ and OPH were synthesized and characterized,and the synthetic routes of the other four fluorescent probes were determined through preliminary experiments.In addition,the absorption spectra of OBZ and OPH were measured.The experimental results show that the maximum absorption of OBZ is at 340 nm,and that of OPH is at 421 nm.Then we use density functional theory(DFT)and time-dependent density functional theory(TDDFT)to optimize the structures of OBZ and OPH in ground state and excited state based on B3LYP/6-311G level.The corresponding infrared vibration frequency,absorption and emission spectra,molecular front-line orbits and potential energy curves were analyzed to investigate the luminescence mechanism of the fluorescent probe theoretically.According to the calculated absorption and emission spectra,the maximum absorption and emission of OBZ are located at 368 nm and 437 nm,respectively,and that of OPH are located at 467 nm and 540 nm,respectively.The calculated maximum absorption of these two probes is consistent with the actual maximum absorption,which indicates that the methods selected in this work are reasonable.The analysis of potential energy curve shows that TICT of OBZ will occur and ESIPT will occur in S₁ state of OPH,which is consistent with the original design principles of this work.And through analysis of the geometric structures,infrared vibration frequency and front molecular orbits,it is confirmed that OBZ is more conducive to the occurrence of TICT in the excited state,while OPH is more conducive to the occurrence of ESIPT in the excited state.Finally,in this paper,we dock the HSA with six fluorescent probe molecules based on Lamarckian Genetic Algorithm(LGA)by using software such as Py MOL,Auto Dock and Auto Dock Tools and so on.We selected the conformations with the lowest binding energy as the best conformations to analyze the binding sites and interactions between the six fluorescent probes and HSA.The results of molecular docking indicated that the probes OBZ,OPH,GA,and SA bound to HSA through hydrogen bonds and hydrophobic interactions.Among them,the probes OPH and SA bound to the Site?of HSA,while OBZ bound to the site nearby Site?and GA bound to Domain I.In addition,the probe SN bound to the domain I of HSA through hydrophobic interaction and electrostatic interaction,and the SCN bound to Site?of HSA through hydrophobic interaction.