摘要
生物体内氧化还原状态的平衡是机体正常生理代谢活动稳定运行的基本保障,氧化还原平衡的异常通常与诸多疾病的发生有关.对于氧化还原过程的可逆监测,可以用于监控疾病的发生、进展以及修复情况.本文中设计构建了一个新型氧化还原可逆的近红外二区(NIR-Ⅱ)荧光纳米探针.该探针利用带正电的聚乙烯亚胺(PEI),将带负电的 NIR-Ⅱ发光金纳米簇(Au NCs)和钼基多金属氧酸盐(POM),通过静电相互作用吸附在一起.由于 POM 在 Au NCs的激发光处具有较强的吸收,其可通过内滤效应有效猝灭 Au NCs的发光.当体系有 ROS存在时,ROS能够氧化 POM,破坏内滤效应,使得 Au NCs的荧光恢复,且荧光的恢复程度与 ROS 的浓度线性相关;当体系有还原性物质谷胱甘肽(GSH)存在时,氧化的 POM 能够被GSH还原,使得Au NCs的荧光又被猝灭,且荧光的猝灭程度与GSH的浓度线性相关.本工作构建的 NIR-Ⅱ荧光纳米探针,能够对 ROS/GSH 进行可逆响应,具有较好的灵敏度、良好的选择性和稳定性,有望为体内氧化还原过程的追踪,疾病的发生和发展过程的实时、动态成像监测提供一种有效的技术手段.
Abstract
The balance of redox state in organisms is the basic guarantee for normal physiological metabolic activities.The abnormal balance of redox is usually related to the occurrence of various diseases.The reversible monitoring of redox process can be used to monitor the occurrence,progress and recovery of diseases.In this paper,we designed and constructed a novel redox-reversible second near-infrared(NIR-Ⅱ)fluorescent nanoprobe.The nanoprobes were formed by using positively charged polyethylenimide(PEI)to adsorb negatively charged NIR-Ⅱ luminescent Au nanoclusters(Au NCs)and molybdo-based polyoxometalate clusters(POM)through electrostatic interaction.Due to the strong absorption of POM at the excitation wavelength of Au NCs,it could effectively quench the luminescence of Au NCs via the internal filtration effect.When ROS was present,ROS could oxidize POM,thereby induced the weakening of the internal filtration effect between POM and Au NCs and the fluorescence recovery of Au NCs.The degree of fluorescence recovery was linearly related to the concentration of ROS.When there were reducing substances such as glutathione(GSH)in the system,the oxidized POM could be reduced by GSH,making the quenching of the fluorescence of Au NCs.The quenching degree of the fluorescence was linearly related to the concentration of GSH.The as-constructed NIR-Ⅱ fluorescent nanoprobe is capable of reversible response towards ROS/GSH with good sensitivity,selectivity and stability.Benefiting from these salient merits,the nanoprobe is expected to provide an effective technical mean for tracing the redox process in vivo,and real-time and dynamic imaging monitoring of the occurrence and development of diseases.
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