Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo 060-0810, Japan.
Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo 060-0810, Japan.
Anal Chem. 2021 Feb 16;93(6):3202-3208. doi: 10.1021/acs.analchem.0c04673. Epub 2021 Feb 4.
We report photothermal phase separation of aqueous poly(-isopropylacrylamide) (PNIPAM)/1-butanol (BuOH) solutions by focused 1064 nm laser irradiation and subsequent single microparticle formation in the solution. The single microparticle [diameter = ∼10 μm and volume = ∼picoliter (pL)] produced by laser irradiation was optically trapped by the incident 1064 nm laser beam, and this enabled us Raman/fluorescence microspectroscopies of the particle. Raman spectroscopy demonstrated that the particle produced by laser irradiation was composed of PNIPAM and BuOH. In the presence of rhodamine B (RhB) in the solution, RhB was distributed from the water phase to the PNIPAM/BuOH microparticle produced by laser irradiation, as confirmed by fluorescence microspectroscopy. Laser-induced distribution/extraction of RhB to a single PNIPAM/BuOH microparticle was shown to be possible at the RhB concentration as low as 10 mol/dm, where the RhB fluorescence intensity from the particle showed a step-by-step increase by every ∼3 min laser irradiation. This is the first demonstration of laser-induced simultaneous extraction and detection of single RhB molecules in solution.
我们报告了通过聚焦 1064nm 激光辐照实现水相聚异丙基丙烯酰胺（PNIPAM）/1-丁醇（BuOH）溶液的光热相分离，以及随后在溶液中单颗粒的形成。由激光辐照产生的单颗粒[直径约为 10μm，体积约为皮升（pL）]被入射的 1064nm 激光束光学捕获，这使得我们能够对颗粒进行拉曼/荧光微光谱分析。拉曼光谱表明，由激光辐照产生的颗粒由 PNIPAM 和 BuOH 组成。在溶液中存在罗丹明 B（RhB）的情况下，通过荧光微光谱证实，RhB 从水相分布到由激光辐照产生的 PNIPAM/BuOH 微颗粒中。在 RhB 浓度低至 10mol/dm 的情况下，已经证明可以对单个 PNIPAM/BuOH 微颗粒进行激光诱导的 RhB 分配/提取，其中来自颗粒的 RhB 荧光强度通过每次约 3 分钟的激光辐照呈现逐步增加。这是首次在溶液中单分子 RhB 的激光诱导同时提取和检测的证明。
