New Design Of Merocyanine Fluorescent Probe And Its Application On The Analysis Study Of Bio-active Small Molecules

Chemical bio-sensing technology is able to transform important chemical biological information to signal able to be recognized by analytical instrument.It is of paramount importance to make these information digital to explore physiological and pathological processes.As a visual sensing method,fluorescent analysis method owns advantages such as high sensitivity,good reproducibility and low biological toxicity.Equipped with fluorescence imaging facilities,fluorescent probe could achieve sensing and imaging of analytes accurately,explicitly and sensitively.However,with the further development of science and technology research,the demand for chemical biological information becomes greater,and,of course,the requirement for fluorescent sensing method becomes higher.Although with a lot of progress gotten,intrinsic drawbacks of fluorescent probe are still highlighted when faced with practical conditions.It is urgent to improve optical characteristic of fluorescent probe to make it adapt to the high requirement of application research nowadays.Among them,cyanine-based fluorescent probes locates at near-infrared areas,endowing themselves with strong penetration capability and low interference from biological auto-fluorescence,and consequently they are commonly used in chemical biological analysis,especially in vivo imaging.However,cyanine fluorophores have shortcomings ranging from small stokes shift to low optical stability.This paper addresses the challenges and problems that cyanine fluorescent probes face w ith,aims to exalt their sensing and imaging performance,takes the job of design and development of new merocyanine derivates fluorescent probes,and applies them into the analytical research of crucial bio-active small molecules.It is anticipated that this paper could provide new idea and new method for the study and development of fluorescent probes.The detailed work are listed as below.(1)High resolution ratiometric near-Infrared fluorescent probe for monitoring pH changes in cell and in vivo.Based on hemicyanine skeleton,we designed and synthesized a series of near-infrared fluorescent probes NIR-Ratio.Signal is ratiometric in response to pH.Their emissions locate in near-infrared area,which is longer than 600nm,making it possible to sense pH in cell and more importantly,in vivo.In addition,The resolution of probes could be adjusted readily by linking different substituents to the same skeleton.Among the series,NIR-Ratio-BTZ modified with an electron-withdrawing substituent of benzothiazole exhibited the largest emission shift of about 76 nm.Meanwhile,its pK_a value is 7.2,locating right in the physiological pH range,so it is beneficial in seizing minor changes of pH near neutrality.(2)High selective fluorescent sensor for sensing GSH without interference from Cys and Hcy.Based on spiropyran-merocyanine switch,we designed and synthesized colorimetric molecule probe SP-1.Its good selectivity towards GSH could be ascribed to its special coordination effect with GSH.To enhance the sensitivity,we chose to combine SP-1 with fluorescent dye Rhodamine-6G to construct inner filter system,which helps us to successfully transform the absorbance method to fluorescent method.At the same time,when we change the ratio of SP-1 and Rhodamine-6G,the response concentration range changes correspondingly.That is to say,sensing in samples with different GSH concentrations could be accomplished.