Design,synthesis And Application Of Fluorescent Probes For The Detection Of β-lactamase

β-lactam antibiotics occupied the important position in the treatment of various bacterial infectious diseases.Due to their exceptional antibacterial activity,wide spectrum,and low toxicity,antibiotics in the clinic has increased dramatically.As a result of continuous evolution,the bacteria gradually developed resistance to antibiotics.Nowadays,drug resistance was too common to prevent antibiotics from achieving the expected therapeutic effects,which brought great challenges to the treatment of infectious diseases.Therefore,rapid and accurate detection of drug-resistant bacteria was very important.β-Lactamase,which could efficiently hydrolyze theβ-lactam ring and made theβ-lactam antibiotic ineffective,was the primary cause for bacterial resistance.In this thesis,β-lactamase was used as the detection target,then three kinds ofβ-lactamase fluorescent probes were designed and synthesized,and it was confirmed that these probes were effective in the detection ofβ-lactamase or evaluating the antibiotic activity.The main content was divided into three parts:（1）Through structural modification on theβ-lactam ring,new fluorescent probes CDC-559 and CDP-560 were designed by connecting theβ-lactam ring with the fluorophore through C=C bond and synthesized.CDC-559 and CDP-560 could be used to specifically detect Amp C Bla.When these two probes were used as substrates,the IC₅₀value of sulbactam sodium or tazobactam acid were proportional to those previously reported in the literature,indicating that CDC-559 and CDP-560 could be expected to replace cephalosporin in screeningβ-lactamase inhibitors.The bacteria test results showed that the probe could distinguish the sensitivity of strains to antibiotics and specifically identify Amp C Bla-producing resistant bacteria simultaneously.In addition,the bacteriostatic zone experiment showed that CDC-559 had strong antibacterial activity against two sensitive strains,providing a new idea for the development of antibiotics.（2）Indirect probes IP-1 and IP-2 were non-fluorescent,but an obvious fluorescence emission peak appeared at 575 nm once they reacted withβ-lactamase through the bridge"cefazolin sodium".IP-1 and IP-2 could be used to detectβ-lactamase and Amp C Bla-producing strains.Besides,they could also be used to assess the ability of antibiotics to resist resistant bacteria.（3）The probe TDA-34 was designed and synthesized based on the skeleton of cefazolin sodium.The TDA-34 was weak fluorescence,but the fluorescence intensity decreased rapidly when Amp C Bla was added.Additionally,the TDA-34 presented the same antibacterial effect on both ATCC 25923 and ATCC 29213 as cefazolin sodium.TDA-23,an isomer of compound TDA-34,could also be used to detect Amp C Bla.The fluorescence intensity of TDA-23 could increase approximately three times after interacting with Amp C Bla,which was the first time that cephalosporin isomers had been found to be sensitive to cephalosporin antibiotics..