Preparation And Application Of Cucurbit[6]uril Polymer Nanoparticles

Polymer nanoparticles have attracted much attention because of their high stability,controllable size,non-toxicity and designability.In practical application,it can have some specific physical and chemical properties by introducing different functional monomers and adjusting the ratio of each monomer.Cucurbit[n]uril（CB[n]）is a host compound derived from glycide with high selectivity and affinity for guest molecules,By introducing CB[n]into the side chain structure of polymer nanoparticles,it can not only form a stimulus responsive host-guest inclusion complex with guest molecules through hydrophobic and electrostatic interaction,but also retain the excellent inherent properties of polymer nanoparticles,which can be used to establish the specific analysis and detection of target guest molecules and adsorption removal methods.Spermine is a common polyamine in organisms,mainly involved in metabolic regulation,intestinal mucosal regeneration,wound healing and other processes.The alteration of spermine levels in urine serves as a reliable biomarker,which is important to establish a highly selective and sensitive method for the detection of spermine in urine.Endotoxin,also known as Lipopolysaccharide（LPS）,is the cell wall component of Gram-negative bacteria,which is released after the death or lysis of bacteria.It can cause immune,inflammatory reaction,even sepsis and other life-threatening diseases through drinking water,air,hemodialysis and other ways into the human body.Because endotoxin usually exists as aggregates,it is considered to be the most difficult pollutant to remove from medical water.Therefore,it is of great significance to develop a kind of adsorbent with high efficiency to remove endotoxin.In this study,a variety of polymer nanoparticles with different surface chemical properties were synthesized using cucurbit[6]uril（CB[6]）containing double bond as the functional monomer.A polymer nanoparticles with the specific recognition ability for spermine and LPS was screened from this synthetic polymer nanoparticles.This interaction between host-guest establishes a specific detection method for spermine in urine and provides a potential affinity adsorption material for the removal of endotoxin.The main research work and results are as follows:1.The 12-hydroxyl CB[6](（OH）₁₂CB[6])intermediate was synthesized by the strong oxidation of CB[6],by potassium persulfate,which was further reacted with acryloyl chloride to obtain Acryloyloxycucurbit[6]uril（（AO）n CB[6]）monomer.A series of polymer nanoparticles（（AO）n CB[6]-NPs）with CB[6]side chain were prepared by precipitation polymerization by adjusting the ratio of（AO）n CB[6],N-tert-butylacrylamide（TBAm）and N-isopropylacrylamide（NIPAm）.At the same time,CB[6]polymer nanoparticles(（AO）₁₂CB[6]-NPs)with similar structure were synthesized by using commercial Perallyloxycucurbit[6]uril potassiumsulfate(（AO）₁₂CB[6])as functional monomer.It was found that the yield of polymer nanoparticles decreased with the increase of the ratio of CB[6],which was mainly attributed to the steric hindrance effect caused by the larger molecular size of CB[6]and the shorter spacer arms.In addition,the synthesis yield of（AO）n CB[6]-NPs was lower than that of（AO）₁₂CB[6]-NPs due to the low amount of acryloxy introduced into the CB[6]monomer synthesized in our laboratory.2.¹H NMR analysis confirmed that CB[6]had an obvious host-guest interaction withspermineanddyemolecule trans-4-[4-（Dimethylamino）styryl]-methylpyridinium iodide（Object A）,but the subsequent detection of spermine was difficult due to the absence of chromogenic groups in the ultraviolet visible range.Uv-vis spectrum analysis showed that the adsorption effect of CB[6]on object A was weaker than that of spermine,When CB[6]was combined with object A,the binding object A could be released by introducing different concentrations of spermine.The above results laid a foundation for the subsequent establishment of an indirect UV-vis spectrophotometric method of spermine based on CB[6]polymer nanoparticles.3.NP14（12%（AO）nCB[6],86%NIPAm,and 2%BIS）with strong interaction of host-guest but low nonspecific adsorption were screened from the polymer nanoparticles library to establish a high-throughput indirect UV-vis spectrophotometric method for spermine.The method has high sensitivity and wide linear range（0～14.71μg/m L）for spermine detection.In addition,the method also has high selectivity.Compared with several common amino acids and biological amines the replacement rate of spermine to object A is nearly 100%,the replacement rate of arginine,cadhistamine and histamine is less than 25%,and the replacement rate of other amino acids is almost no response.Therefore,these possible interferences have little influence on the detection of spermine.The accuracy of the method for spermine detection was also high,and the standard recovery of spermine in urine was close to90%,which was comparable to the traditional Dansyl chloride derivation-HPLC method.Compared with the traditional method,this method has the characteristics of fast detection speed,simple method and low instrument dependence.4.NP11（12%（AO）nCB[6],40%TBAm,46%NIPAm,2%BIS）with the highest adsorption performance for LPS were screened from the polymer nanoparticle library as the endotoxin affinity adsorption material.The optimum adsorption condition was p H 9.0 10 mmol/L PBS buffer solution.Adsorption kinetics experiments showed that the adsorption rate of polymer nanoparticles based on CB[6]to LPS was very fast,and the adsorption equilibrium could be reached at 10 minutes.The isothermal adsorption experiments showed that the maximum adsorption capacity of NP11 to LPS could reach 11.23 mg/g.These results indicate that the polymer nanoparticles based on CB[6]can be used for the adsorption and removal of endotoxin in water,and the specific capture ability was mainly attributed to the binding between the host-guest compound of CB[6]on side chain and the fatty acid long chain of LPS lipid A.