【作者】 程健；

【导师】 胡进明；

【作者基本信息】 中国科学技术大学 ， 高分子化学与物理， 2022， 博士

【摘要】 一氧化碳(CO)和一氧化氮(NO)气体信号分子在生物体内的调节作用对维持内环境平衡至关重要。CO在抗炎、抗凋亡、促进伤口修复等方面具有重要功能,NO具有在心血管、免疫和机体主动防御方面的应用;但CO/NO的这些功能有浓度依赖性。为了控制CO的浓度,发展了一系列CO释放分子,如金属羰基化合物和非金属CO供体。其中,金属羰基化合物已经被应用于研究CO的生理功能,但是由于含有金属离子及稳定性等问题,对研究CO的生理性质不利。尽管一些光响应非金属小分子供体可以原位可控递送CO,但仍然存在溶解性差、光照波长短等问题。因此有必要发展在水溶液中分散的长波长光照触发的非金属CO供体。为了清除生物体内产生的过量NO,以抑制高浓度NO带来的副作用,已经发展了胶束、凝胶等NO清除剂。基于以上背景,本论文在NO清除型高分子和光响应非金属CO释放高分子方面开展了系列工作,并围绕CO和NO的相关生理功能开展了促进小鼠伤口愈合、治疗风湿性关节炎及抗菌等方面的研究。具体内容可以分为以下三个部分:1.制备具有串联光化学反应性质的非金属CO释放胶束,在可见光照射下释放CO促进小鼠伤口愈合。发展CO释放聚合物(CORPs)可以增加材料的稳定性、优化药代动力学行为、降低小分子物质副作用。虽然通过直接聚合的方法可以获得结构明确的材料,然而目前所发展的CORPs基本上都通过后功能化的方式制备。我们通过直接聚合的方法合成了基于光响应性3-羟基黄酮(3-HF)衍生物的非金属CORPs,组装制备在水溶液中分散的胶束,在光照下从蓝色荧光转变为红色荧光再到无荧光,从而可以自报告CO的释放。将该CO释放胶束用于细胞及动物实验,发现在光照下该材料具有降低细胞炎症、促进小鼠全皮层伤口愈合的作用。2.制备具有清除NO和在可见光照射下释放CO的呼吸型胶束。呼吸过程中的气体交换在维持生物体的生理功能方面起着至关重要的作用。尽管人工制备的呼吸材料暴露在不同气体环境中表现出体积扩张和收缩,但能够调节气体信号分子的呼吸材料很少被探索。我们报道了一种可以吸入NO和呼出CO的呼吸型胶束材料(BM)。这种胶束可以同时清除体内过表达的NO并缓解脂多糖刺激的巨噬细胞产生的炎症因子。体内实验表明,BM治疗佐剂诱导类风湿性关节炎的疗效优于传统的非甾体抗炎药物地塞米松,这种效果可能来自于联合NO清除和CO介导的NO合酶活性抑制和血红素加氧酶激活。这项工作为研究呼吸型胶束在生物医学方面的应用提供了新策略。3.发展了通过红光触发CO释放的体系,可以选择性清除耐甲氧西林金黄色葡萄球菌(MRSA)感染。使用金属羰基化合物作为CO供体已经为阐述CO的生理功能提供了帮助,此类CO供体对细菌具有广谱的杀灭性质,然而对于杀菌性能来自于金属离子还是释放的CO还不明确。在此,利用3-HF衍生物的光氧化机制开发了非金属CO释放胶束,可以在650nm光照下释放CO。和金属羰基化合物可以和革兰氏阴性和阳性菌作用不同,这种胶束只能和金黄色葡萄球菌选择性作用,而对大肠杆菌没有影响,表现出选择性杀菌的能力。此外,这种CO释放胶束还可以治疗MRSA感染的伤口,加速伤口的愈合。更多还原

【Abstract】 Recent evidences have established the major roles for Carbon monoxide(CO)and Nitric oxide(NO)as gasotransmitters.They are essential for maintaining a balance between physiological and pathological functions in mammalian tissues.CO displays many physiological functions including anti-inflammatory,anti-apoptotic and accelerating wound healing.NO shares several common properties including cardioprotective and immune systems.They are beneficial at low concentrations but hazardous in higher amounts.A variety of CO-releasing molecules(CORMs)have been developed,which are primarily categorized into metal carbonyls and nonmetallic CORMs.Metal carbonyls have been the most extensively investigated CORMs,while recent studies discovered that they are unstable in PBS buffer and cell culture media.Notably,nonmetallic CORMs are receiving increasing attention.Most of CORMs are sensitive to ultraviolet(UV)irradiation,so it would be necessary to activate photoCORMs under long-wavelength illumination with decreased phototoxicity.Overproduction of NO has been associated with several diseases,and a reasonable treatment is to scavenge excess NO,for which a few NO scavenger molecules have been developed.In this paper,we focus on preparation of NO scavenger polymer material and photoresponsive CO-releasing polymers.The biological applications of these materials include accelerating wound healing,treatment of rheumatoid arthritis and antibacterial been clarified.The specific content can be divided into the following three parts:(1)Metal-free carbon monoxide-releasing micelles undergoing tandem photochemical reactions were developed for cutaneous wound healing.The development of carbon monoxide(CO)-releasing polymers(CORPs)can increase the stability,optimize pharmacokinetic behavior,and reduce the side effects of small molecule precursors.We fabricated metal-free CO releasing polymers based on photoresponsive 3-hydroxyflavone(3-HF)derivatives in a direct polymerization strategy.Such CO releasing amphiphiles self-assemble into micelles,having excellent water-dispersity.Photo-triggered tandem photochemical reactions confer successive fluorescence transitions from blue-to-red-to-colorless,enabling self-reporting CO release in vitro and in vivo.More importantly,the localized CO delivery of CORPs by taking advantage of the spatiotemporal control of light stimulus outperformed conventional metal carbonyls such as CORMs in terms of anti-inflammation and cutaneous wound healing.This work opens a novel avenue toward metal-free CORPs for potential biomedical applications.(2)Fabricated breathing micelles for combinatorial treatment of rheumatoid arthritis.Breathing process involves inhalation and exhalation of different gases in animals.The gas exchange of the breathing process plays a critical role in maintaining the physiological functions of living organisms.Although artificial breathing materials exhibiting volume expansion and contraction upon alternate exposuring to different gases have been well explored,those being able to realize the gas exchange remain elusive.Herein,we report breathing micelles(BM)capable of inhaling nitric oxide(NO)and exhaling carbon monoxide(CO),both of which are endogenous gaseous signaling molecules.We demonstrate that BM can simultaneously scavenge overproduced NO and attenuate proinflammatory cytokines in lipopolysaccharide(LPS)-challenged macrophage cells.In vivo studies revealed that BM outperformed conventional nonsteroidal anti-inflammatory drugs such as dexamethasone(Dexa)in treatment of rheumatoid arthritis(RA)in adjuvant-induced arthritis(AIA)rats,likely due to the combinatorial effect of NO depletion,CO-mediated deactivation of inducible NO synthase(iNOS)and activation of heme oxygenase-1(HO-1).This work provides new insights into artificial BM for potential biomedical applications.(3)Red light-triggered carbon monoxide releasing system was developed for selective eradication of Methicillin-resistant Staphylococcus aureus(MRSA)infection.The use of metal carbonyls CO-releasing molecules enables the elucidation of the pleiotropic functions of CO.Although metal carbonyls show a broadspectrum antimicrobial activity,it remains unclear whether the bactericidal property originates from the transition metals or the released CO.Here,we develop nonmetallic COreleasing micelles via a photooxygenation mechanism of 3-hydroxyflavone derivatives,enabling CO release under 650 nm irradiation.Unlike metal carbonyls that nonspecifically internalize into both Gram-positive and Gram-negative bacteria,the nonmetallic micelles are selectively taken up by S.aureus instead of E.coli cells,exerting a selective bactericidal effect.Further,we demonstrate that the CO-releasing micelles can cure MRSA infected wounds,simultaneously eradicating MRSA pathogens and accelerating wound healing.更多还原