Construction And Application Of Fluorescent Probes Based On Dipeptides

Fluorescence analysis is a method which converts the identification of a test substance into a detectable fluorescent signal by a specific transformation mechanism to achieve measurement or function evaluation of the substance to be tested.Fluorescence analysis,which has been widely applied in many fields,such as chemistry,electrochemistry,biology,medicine,has promoted the development of scientific research.Fluorescent probes are one of the important roles in fluorescence analysis,and their performance determines the sensitivity and reliability of analytical results.Since most of the fluorescent probes are external substances,the environment is also polluted while achieving the purpose of detection.Therefore,it is necessary to construct a simple and environmentally friendly fluorescent probe.Because of many advantages,such as easy construction,adjustable morphology,good biocompatibility,etc.,peptide molecules and their nanomaterials are widely used in the construction of energy storage devices,displays and light-emitting devices,piezoelectric elements,metal-organic frameworks,ultra-sensitive sensors,drug delivery and substance testing.Based on the many advantages of peptide materials,two fluorescent probes based on dipeptide molecules were constructed in this paper.The detection performance was investigated and their applications in detection and fluorescence imaging analysis were explored.Based on the above content,in this dissertation,two fluorescent probes based on dipeptide molecules were constructed.The detection performance was investigated and their applications in detection and fluorescence imaging analysis were explored.The detailed contents are summarized as follows:1.Aromatic amino acids were used to construct a series of molecular fluorescent probes and the tryptophan-phenylalanine dipeptide(Trp-Phe)was screened as a copper ion(Cu2+)responsive molecule fluorescent probe by studying the optical interaction between aromatic amino acids and their dipeptides and metal ions.While Cu2+ is absent,Trp-Phe will produce strong fluorescence intensity with a excitation wavelength at 280 nm;While Cu2+ is present,the amide group of Trp-Phe will coordinate with Cu2+,which makes photoinduced electron transfer occur,resulting in fluorescence quenching of Trp-Phe.This probe can be used for detection of Cu2+ in actual samples and screening of Cu2+ antidote with good biocompatibility,high selectivity and sensitivity.2.A dipeptide/nucleic acid nano-fluorescent probe for detecting cytochrome C gene was constructed with a hairpin DNA and a cationic dipeptide nanoparticle(CDPNP).The hairpin DNA was modified with a fluorophore and a quenching group at both ends as the signal unit and its neck as the recognition unit.The CDPNP act as carrier was formed by self-assembly of a cationic diphenylalanine dipeptide.CDPNP which has a positive charge,can adsorb negatively charged hpDNA through electrostatic interaction.Since there is no optical conversion between CDPNP and the fluorophore,the fluorescence of the modified fluorophore on hpDNA is not quenched,and its fluorescence intensity is only related to its distance from the quenching group.When c-myc DNA is added,the loop of the hpDNA will be complementary to the c-myc DNA,and the hairpin structure will open,leaving the fluorophore and the quenching group away,and the fluorescence of the fluorophore will recover.Compared with nano-fluorescent probes based on traditional nanocarriers,CDPNP/hpDNA nano-fluorescent probe has higher fluorescence signal intensity,and can successfully overcome the false-negative signal.In addition,the nanoprobe can enter cells to achieve fluorescence imaging analysis of intracellular c-myc RNA.