| Polyethylene glycol（PEG,the formula:HO-（CH2CH2O）n-H）is a linear polymer without any double bonds in the molecular chains,and the only electron-rich heteroatom is oxygen.PEG is easily soluble in water and common organic solvents.It is well known for its good biocompatibility,thermal stability and non-toxicity,and widely used in bioengineering,cosmetics,pharmaceutical and food industries.PEG is a new type of fluorescent polymer and a member of non-traditional intrinsic luminescence（NTIL）.Recent research has found that PEG fluoresces effectively in both solid state and its aqueous solution.NTIL members are only composed of heteroatoms（O,N,S,etc.）,have no conjugated structure,do not emit light at low concentration,but have strong fluorescence emission in solid and high concentration solution.Their emission is usually concentration dependent.Being in generally environmentally friendly,NTIL materials have been used in biological imaging,optoelectronic devices and chemical synthesis applications due to their high hydrophilicity,wide availability and simple preparation.Tetracyclines are a well-known class of antibiotics,widely used in the treatment of various bacterial infections.Their monitoring and detection have been an important issue.Therefore,a large number of methods for their detection and monitoring have been developed.Among the many established methods,fluorescence sensing is one of the most reported methods.However,most of the reported sensor materials are made of transition metals,and their preparation processes are sophisticated.However,there are few reports on polymers as sensor materials,especially biocompatible polymers.In this study,the aqueous solution of PEG,a biocompatible polymer,was shown to emit at 340 nm under excitation at 280 nm,while the selected tetracycline drug solutions,namely doxycycline（DOX）and tetracycline（TC）,were not emission under the same conditions.In the binary solution of PEG-DOX and PEG-TC,the luminescence of PEG is dramatically quenched,that is to say,DOX and TC are highly sensitive and selective to the quenching of PEG fluorescence.Compared with those reported in the literature,PEG has significantly better performance as a sensor for the detection of DOX and TC in aqueous solution.By infrared spectroscopy（FTIR）and nuclear magnetic resonance（NMR）analysis,it was shown that DOX quenching mechanism of PEG luminescence is caused by the interaction between O atoms in PEG clusters and specific heteroatoms on DOX molecules.Pyrimidines,especially uracil（UL）and 5-fluorouracil（5FU）,are widely used as anticancer drugs in the treatment of various cancers.A major concern is its monitoring and testing in order to adequately control its dose and minimize its health risks.As for the tetracyclines above,many methods have been developed for pyrimidines monitoring and detection,and fluorescence sensing is one of the common methods because of its advantages of high precision,simple operation and intuitiveness.In this work,PEG was also used as the sensor probe to detect pyrimidines.Although the selected pyrimidine solutions,i.e.UL and5FU,do not emit under excitation at 280 nm,their addition to the PEG solution produces a significant,concentration-dependent quenching of PEG emission.Therefore,PEG can be used as an efficient sensor for detecting UL and 5FU in water.The detection using the standard addition method was also done in one of the pyrimidines,5FU,in tap water,milk and artificial urine for recovery experiment.The results confirmed that in all of these cases,the recovery rate of 5FU was nearly 100%.The hydrogen bond interaction between PEG clusters and pyrimidine heteroatoms was confirmed to be the cause of fluorescence quenching,which was analyzed by NMR,FTIR and DLS analysis.Therefore,this work provides a new protocol for the detection of tetracyclines and pyrimidines,which can be characterized by its environmental friendleness,simple operation,and low cost,opening up new potential applications for PEG. |
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