Angelw: CO2 responsive vesicle micelle reversible AIE polymer
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Last Update: 2019-06-14
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Source: Internet
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Author: User
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In recent years, stimulus responsive polymer vesicles have attracted much attention in drug delivery and nanoreactors CO 2 is a non-toxic, mild, cheap and abundant stimulus source, and has good biocompatibility and cell membrane permeability When aerobic organisms metabolize carbohydrates and lipids, they will produce CO2 However, studies have shown that the disorder of CO2 metabolism is related to a variety of metabolic diseases Therefore, many research and development of CO2 responsive polymer vesicles can change the morphology under the stimulation of CO2 Based on previous studies, min Hui Li, Professor of Paris University of Arts and Sciences and Beijing University of chemical technology, in cooperation with researchers of Curie Research Institute in Paris, developed the first polymer system (peg-b-p (DEAEMA Co tpema)) with reversible CO 2 response, which also has the characteristics of aggregation induced luminescence (AIE) Relevant research results were recently published on angelw Chem Int ed (DOI: 10.1002 / anie 201905089) (image source: angelw Chem Int ed.) the polymer is formed by random copolymerization of 2 - (diethylamino) ethyl methacrylate (DEAEMA) and tetraphenylethylene modified methacrylate (tpema) initiated by macromolecular initiator mpeg-cta under the catalysis of AIBN It can be formed in tetrahydrofuran / water or dioxane by nanoprecipitation method/ The polymer vesicles (scheme 1) were formed by self-assembly in the mixed solution of water The size and morphology of the polymer vesicles were characterized by cryo-EM and DLS The results showed that the size of the vesicles (421 nm, DLS) formed in THF / water was smaller than that of the vesicles (1009 nm, DLS) formed in dioxane / water, but the thickness of the films was the same, both at 14.7 nm The length of the hydrophobic chains is less than 25.4 nm, indicating that the hydrophobic chains are intertwined in the hydrophobic bimolecular layer At the same time, these vesicles have the characteristics of AIE, which can emit blue light, and the quantum yield is 6% (Figure 1) (picture source: angelw Chem Int ed.) (picture source: angelw Chem Int ed.) the author next studied the CO 2 response of polymer vesicles The author tested the conductivity, pH, transparency, fluorescence intensity, morphology and size change of solution (dioxane / water) respectively (Figure 2) The conductivity (k) of the vesicle solution increased from 5.3 to 50.4 μ s / cm in 6 minutes, and remained stable after reaching 50.7 μ s / cm The pH value also decreased from 7.9 to 4.7, which means that the DEAEMA block will undergo protonation The transparency of the solution increased to 97% (Figure 3) The fluorescence intensity decreased by 30% It is assumed that this is due to the change of hydrophilicity and hydrophobicity of polymer after protonation and the transformation of vesicles into small particles The authors verified their conjecture by cryo EM and DLS: due to the existence of hydrophobic tpema, the vesicles were transformed into small micelles of about 12 nm; however, due to the different degree of assembly, the intramolecular rotational freedom of TPE was higher, so the fluorescence intensity was reduced (image source: angelw Chem Int ed.) after CO 2 for 20 minutes, the solution was changed to AR, and the conductivity, pH and transparency of the solution were restored Cryo EM characterization showed that the polymer was reassembled into vesicles with different morphology (Figure 4) This shows that the polymer can realize reversible transformation between vesicles and micelles under the repeated action of CO 2 and ar This is mainly due to the change of the hydrophilicity and hydrophobicity of the polymer caused by the protonation and deplasmization of DEAEMA block, and the change of the interfacial tension, thus realizing this reversible change (image source: angelw Chem Int ed.) in this study, the author reported the first polymer system that can realize the reversible transformation of vesicle micelle in response to CO 2, and studied its transformation process in detail (after CO 2 is introduced, it changes from large vesicle to small micelle, and then into ar) The reason of the change was analyzed (the change of hydrophilicity and hydrophobicity resulted in the change of interfacial tension) Because the polymer has TPE group and AIE characteristic, the author thinks that the fluorescent polymer may be used in the fields of CO2 related biosensors and real-time monitoring of drug delivery in vivo.
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