Synthesis and Characterization of a Micelle-Based pH Nanosensor with an Unprecedented Broad Measurement Range
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- 作者：Pramod Kumar E.K. ; Lise N. Feldborg ; Kristoffer Almdal ; Thomas L. Andresen
- 刊名：Chemistry of Materials
- 出版年：2013
- 出版时间：May 14, 2013
- 年：2013
- 卷：25
- 期：9
- 页码：1496-1501
- 全文大小：357K
- 年卷期：v.25,no.9(May 14, 2013)
- ISSN：1520-5002
文摘
A new cross-linked micelle pH nanosensor design was investigated. The nanosensor synthesis was based on self-assembly of an amphiphilic triblock copolymer, poly(ethylene glycol)-b-poly(2-amino ethyl methacrylate)-b-poly(coumarin methacrylate) (PEG-b-PAEMA-b-PCMA), which was synthesized by isolated macroinitiator atom transfer radical polymerization. Micelles were formed by PEG-b-PAEMA-b-PCMA self-assembly in water, giving micelles with an average diameter of 45 nm. The PCMA core was employed to utilize coumarin-based photoinduced cross-linking in the core of the micelles, which was performed by UV irradiation (320 nm < 位 < 500 nm), and the progress of the cross-linking was monitored by UV spectroscopy. The formed cross-linked core鈥搒hell鈥揷orona micelle was converted into ratiometric pH nanosensors by binding the pH-sensitive fluorophores oregon green 488 and 2鈥?7鈥?bis-(2-carboxyethyl)-5-(and-6) carboxyfluorescein and a reference fluorophore Alexa 633 to the PAEMA shell region of the micelles. Fluorescence measurements show that these pH nanosensors are sensitive in a surprisingly broad pH range of 3.4鈥?.0, which is hypothesized to be due to small differences in the individual fluorophores鈥?local environement. It was found that the utilization of self-organization principles to form the nanoparticles, followed by cross-linking to ensure sensor integrity, provides a fast and highly flexible method that can be utilized in a broad range of nanosensor designs.