【作者】 刘伟；

【导师】 董彪；

【作者基本信息】 吉林大学 ， 生物医学工程， 2024， 硕士

【摘要】 细菌感染会对人类健康造成严重威胁,感染后会给机体造成脓肿、牙周炎、眼内炎等,延迟伤口的愈合。抗生素是目前对抗细菌感染的主要疗法,但由于不当使用和滥用导致细菌出现耐药性,使疾病产生了难治性。近年来,抗菌光动力疗法（aPDT）逐渐成为抗菌领域的研究热点。光敏剂在光激发下,通过aPDT过程产生活性氧（ROS）,可获得杀灭细菌效果。然而,在aPDT进一步临床应用还需要解决一些问题:以牙周炎为例,在牙周袋组织内的aPDT过程还存在乏氧,而且激发光难以穿透组织。围绕如何在aPDT过程实现氧气供应和深部组织有效光激发是目前抗菌光动力学亟待解决的关键科学问题。本论文开展了如下工作:1.研究设计并合成了多功能复合材料UCNPs-Ce6-Mn（CO）₅Br@Silane（简称UCM@Si）,复合材料由上转化纳米粒子(UCNPs:Na Er F₄:Tm³⁺@Na YF₄:Yb³⁺),二氢卟吩e6（Ce6）和五羰基溴化锰（Mn（CO）₅Br）构成。在硅烷修饰作用下,材料具有良好生物相容性;复合材料在近红外光（980 nm）下,可以获得强上转换红光;而且Ce6出现了吸收红移现象,与上转换红光有效重叠,时,在红光激发下,Ce6分子可以有效产生活性氧（ROS）、同时ROS破坏Mn（CO）₅Br结构,产生一氧化碳（CO）和锰离子(Mn²⁺);而则通过催化过氧化氢分解产生氧气,进而解决深部组织的乏氧难题,提升aPDT性能。2.利用上转换荧光激发的aPDT性能和产氧性能,实现了对aPDT过程中细菌的生长抑制、通过细胞和动物水平实验验证了复合材料的抗菌性能,200μg/m L的复合材料可以抑制87.4%的大肠杆菌,85.9%的金黄色葡萄球菌;促进抗菌光动力学的正向进行、促进由细菌感染所导致的伤口愈合的同时也能避免细菌产生耐药性。同时,通过上转换荧光触发了CO分子释放,实现了基于CO气体小分子的炎症调节,研究了通过释放CO分子来抑制NF-κB信号通路。NF-κB是一种信号通路,受细菌脂多糖LPS的刺激活化后,能调控促炎因子的生成。在这其中PI3K的作用是控制NF-κB亚基p65磷酸化,亚基磷酸化之后会与DNA结合,结合后会产生促炎因子,而CO会抑制PI3K活性,使NF-κB亚基p65不能磷酸化,从而不能与DNA结合、产生促炎因子,就达到了抑制炎症的目的,实现炎症有效调节,复合材料能将大部分LPS极化的巨噬细胞从M1表型转换到M2表型。本论文同步实现了近红外光触发的深组织杀菌,利用aPDT自供氧设计,不但增强了光动力学性能,还通过提高受影响微环境中的氧气水平来对抗细菌感染,具有潜在的临床应用价值。更多还原

【Abstract】 Bacterial infection poses a serious threat to human health.After infection,the body will cause abscess,periodontitis,endophthalmitis,etc.,delaying the healing of wounds.Antibiotics are the main treatment against bacterial infection at present,but due to improper use and abuse,bacterial resistance occurs,making the disease intractable.In recent years,antibacterial photodynamic therapy（aPDT）has gradually become a research hotspot in the field of antibacterial.The photosensitizer can produce ROS through aPDT process under light excitation,and the bactericidal effect can be obtained.However,further clinical application of aPDT still needs to solve some problems:taking periodontitis as an example,the aPDT process in the periodontal pocket tissue is still oxygen-poor,and the excitation light is difficult to penetrate the tissue.How to achieve oxygen supply and deep tissue aPDT photoexcitation in the aPDT process is an urgent problem to be solved by antimicrobial photodynamics at present.Based on this,this paper completed the following work:1.Material design:We designed a multifunctional composite UCNPs-Ce6-Mn（CO）₅Br@Silane（UCM@Si for short）,which is converted from up to up nanoparticles(UCNPs:Na Er F₄:Tm³⁺@Na YF₄:Yb³⁺),chlorin e6（Ce6）and pentacarbonyl manganese bromide（Mn（CO）₅Br）.Under Silane modification,the material has good biocompatibility.Under near-infrared light（980 nm）,the composite can obtain strong upconversion red light.In addition,Ce6 has the phenomenon of absorption redshift,which overlaps effectively with upconverted red light.Under the excitation of red light,Ce6 molecules can effectively produce reactive oxygen species（ROS）,while ROS damages the structure of Mn（CO）₅Br,producing carbon monoxide（CO）and manganese ion(Mn²⁺).By catalyzing the decomposition of hydrogen peroxide to produce oxygen,it can solve the problem of oxygen deficiency in deep tissues and improve the performance of aPDT.2.The upconversion fluorescence stimulated aPDT performance and oxygen production performance were used to realize the growth inhibition of bacteria during aPDT process.The antibacterial performance of the composite was verified by cell and animal experiments.200μg/m L of the composite material could inhibit 87.4%of Escherichia coli and 85.9%of Staphylococcus aureus.Promote the forward progress of antibacterial photodynamics,promote wound healing caused by bacterial infection,and avoid bacterial resistance.At the same time,the up-conversion fluorescence triggers the release of CO molecules,which realizes the regulation of inflammation based on CO gas small molecules,and studies the inhibition of NF-κB signaling pathway by releasing CO molecules.NF-κB is a signaling pathway that can regulate the production of proinflammatory factors after activation by bacterial lipopolysaccharide LPS.Among them,the role of PI3K is to control the phosphorylation of NF-κB subunit p65,which will bind to DNA after phosphorylation and produce pro-inflammatory factors,while CO will inhibit the activity of PI3K,so that NF-κB subunit p65 cannot be phosphorylated,so that it cannot bind to DNA and produce pro-inflammatory factors,thus achieving the purpose of inhibiting inflammation.To achieve effective regulation of inflammation,the composite material can switch most of the LPS-polarized macrophages from M1 to M2.Through the composite material,this paper synchronously realizes the near-infrared light-triggered deep tissue sterilization.The aPDT self-oxygenated design not only enhances the photodynamic performance,but also fights bacterial infection by improving the oxygen level in the affected microenvironment,which has potential clinical application value.更多还原