Yu Shuai, Wang Zhen, Yao Tingfeng, Yuan Baohong
Ultrasound and Optical Imaging Laboratory, Department of Bioengineering, The University of Texas at Arlington, Arlington, TX 76019, USA.
Joint Biomedical Engineering Program, The University of Texas at Arlington and The University of Texas Southwestern Medical Center at Dallas, TX 75390, USA.
Quant Imaging Med Surg. 2021 Mar;11(3):1010-1022. doi: 10.21037/qims-20-797.
Near infrared (NIR) environment-sensitive fluorophores are highly desired for many biomedical applications because of its non-invasive operation, high sensitivity and specificity, non-ionizing radiation and deep penetration in biological tissue. When the fluorophores are appropriately encapsulated in or conjugated with some thermal-sensitive polymers, they could work as excellent temperature-sensing probes.
In this study, we synthesized and characterized a series of NIR temperature-switchable nanoparticles based on two series of NIR fluorophores aza-BODIPY (ADP is used for abbreviation in this work) and Zinc phthalocyanine (ZnPc) and four pluronic polymers (F127, F98, F68 and F38). Encapsulating the fluorophores in the polymers by sonication, we synthesized the nanoparticles that showed switch-like functions of the fluorescence intensity (and/or lifetime) as the temperature, with high switch on-to-off ratio. We also investigated various factors that might change the temperature thresholds (T) of the switch functions, in order to control T during synthesis.
These nanoparticles showed excellent temperature-switchable properties of fluorescence intensity and/or lifetime. Meanwhile, some factors (i.e., pluronic categories and nanoparticles' concentration) significantly affected the nanoparticles' Ts while other (i.e., fluorophore categories) that weakly affected Ts.
By selecting appropriate pluronic categories and adjusting the nanoparticle's concentration, we can synthesize the nanoparticles with a wide range of Ts. These temperature-switchable fluorescence nanoparticles can be used for biomedical imaging and tissue temperature sensing/imaging.
近红外（NIR）环境敏感型荧光团因其无创操作、高灵敏度和特异性、非电离辐射以及在生物组织中的深度穿透性，在许多生物医学应用中备受青睐。当荧光团适当地封装在某些热敏聚合物中或与它们共轭时，它们可以作为出色的温度传感探针。
在本研究中，我们基于两个系列的近红外荧光团氮杂硼二吡咯（在本工作中简称为ADP）和酞菁锌（ZnPc）以及四种普朗尼克聚合物（F127、F98、F68和F38）合成并表征了一系列近红外温度可切换纳米颗粒。通过超声处理将荧光团封装在聚合物中，我们合成了纳米颗粒，其荧光强度（和/或寿命）随温度呈现类似开关的功能，具有高开/关比。我们还研究了可能改变开关功能温度阈值（T）的各种因素，以便在合成过程中控制T。
这些纳米颗粒表现出优异的荧光强度和/或寿命的温度可切换特性。同时，一些因素（即普朗尼克聚合物种类和纳米颗粒浓度）对纳米颗粒的T有显著影响，而其他因素（即荧光团种类）对T的影响较弱。
通过选择合适的普朗尼克聚合物种类并调整纳米颗粒的浓度，我们可以合成具有广泛T值的纳米颗粒。这些温度可切换荧光纳米颗粒可用于生物医学成像和组织温度传感/成像。
