Detection Of Photosensitive Antibiotics And Its Application In Killing Pathogenic Bacteria And Tumor Cells

The threat of pathogen infection and cancer to human life and health has become the focus of attention of scientists around the world.Antibiotics,as the most important antibacterial drugs,play an important role in human anti-infection treatment.The development of antitumor antibiotics also provides a new way for antitumor therapy.However,the unreasonable use or even abuse of antibiotics by humans has spawned more and more drug-resistant pathogens,resulting in the decline or even failure of the efficacy of various antibiotics.The existing antibiotics have many types,large quantities,low prices and clear antibacterial mechanisms.Therefore,further research and development of new functions of existing antibiotics to expand their application has attracted much attention.In this paper,by screening photosensitive antibiotics and based on their inherent characteristics,a new,rapid,simple,and sensitive method for antibiotics detection was developed.By combining with the excellent optical properties of conjugated polymer nanomaterials,antibiotic-modified multifunctional conjugated polymer nanoparticles were constructed,and their applications in killing pathogenic bacteria and tumor cells were studied.The specific contents are as follows:1.Six traditional antibiotics,including polymyxin B（PMB）,sulfamethizole（SMT）,norfloxacin（Norf）,teicoplanin（Teic）,ampicillin（AMP）and kanamycin（Kana）were selected to investigate their ability to generate reactive oxygen species（ROS）upon excitation by a white light source.First,antibiotics that can generate ROS were screened by non-specific ROS dye（2′,7′-dichlorodihydrofluorescein diacetate）.Then,ROS-specific dyes（3′-（phydroxyphenyl）fluorescein and hydroxyfluorescein）and electron paramagnetic resonance spectroscopy were used to explore the types of ROS produced by antibiotics.The results show that PMB and Norf can produce·OH,SMT can produce·OH and ¹O₂,and Teic can produce·O^2-.And fluorescence imaging was used to verify the fact that PMB can generate ROS in Escherichia coli（E.coli）under light conditions.The results can provide new ideas for the detection of photosensitive antibiotics and their application in antibacterial and antitumor therapy.2.A simple,light-assisted and non-competitive immunoassay for demethyltetracycline（DMCO）and polymyxin B（PMB）was developed based on the ROS-generating properties of DMCO and PMB under certain light irradiation.The targeted antibiotics can be captured by specific antibodies immobilized on a 96-well plate,and then the captured antibiotics can generate ROS when exposed to the blue light.At the same time,the generated ROS can directly oxidize the added DCFH dye to DCF,thereby releasing a fluorescent signal to realize the detection of antibiotics.The detection limits of DMCO and PMB were 2 ng/m L and 58ng/m L,respectively.This method is simple,sensitive and economical and provides a general technique for photosensitive antibiotics detection.3.A PMB-modified multifunctional conjugated oligomer nanoparticle（PMB-CON）was prepared based on nanoprecipitation and click chemistry.In PMB-CON,the surface of CON can selectively bind to gram-negative bacteria.Based on the strong fluorescence emission performance of CON,the fluorescence imaging of Escherichia coli（E.coli）was realized.In addition,both PMB and CON can generate ROS under white light irradiation,which can be used to synergistically enhance the photodynamic antibacterial effect of kanamycin-resistant E.coli.PMB-CON integrates target recognition,fluorescence imaging and synergistic photodynamic antibacterial therapy,which provides a new idea for expanding the application of PMB and the development of multifunctional antibacterial nanomaterials.4.Based on the excellent photothermal properties of conjugated polymer nanoparticles（F8IC）and the photodynamic activity of PMB,a multifunctional nanoparticle（F8IC-PMB）integrating photodynamic therapy（PDT）and photothermal therapy（PTT）was prepared.The PMB on the surface of F8IC can bind to the surface of gram-negative bacteria.In addition,PMB and F8IC can generate ROS and photothermal under near-infrared light illumination,respectively,so the combined antibacterial PDT-PTT was achieved.The studied photosensitive antibiotic-modified multifunctional nanoparticle strategy broadens the application of photosensitive antibiotics,and provides a new strategy for combating bacterial resistance and enhancing photodynamic antibacterial therapy.5.A folic acid（FA）-modified nanoparticle（F8DTBT-FA）was prepared based on the photodynamic activity of PMB and the excellent fluorescence properties of the polymer（F8-DTBT）.And PMB was modified to the surface of F8DTBT-FA by chemical coupling reaction to abtain a multifunctional polymer nanoparticle（PMB@F8DTBT-FA）.Through the specific binding of FA in PMB@F8DTBT-FA to the folate receptor overexpressed on the surface of MCF-7 cancer cells,the fluorescence imaging of MCF-7 cancer cells was realized based on the superior fluorescence properties of F8-DTBT.Based on the fact that PMB can generate ROS under the excitation of 808 nm infrared light,the photodynamic killing of cancer cells is realized.This method may provide a new idea for the application of photosensitive antibiotics in antitumor therapy.