FRET‐Integrated Polymer Brushes for Spatially Resolved Sensing of Changes in Polymer Conformation

• Published in: Angewandte Chemie International Edition Vol. 60; no. 30; pp. 16600 - 16606
• Main Authors: Besford, Quinn A., Yong, Huaisong, Merlitz, Holger, Christofferson, Andrew J., Sommer, Jens‐Uwe, Uhlmann, Petra, Fery, Andreas
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 19.07.2021; John Wiley and Sons Inc
• Edition: International ed. in English
• Subjects: Brushes; Chemical stimuli; chemosensing; Composition; Conformation; fluorescence; Fluorescence resonance energy transfer; FRET; Interfaces; Micrometers; Physical properties; Polyisopropyl acrylamide; polymer brushes; polymer dynamics; Polymers; Spatial discrimination; Spatial resolution; Stimuli; Chemosensing; FRET; Polymer Brush; fluorescence; Polymer Dynamics
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202104204

Polymer brush surfaces that alter their physical properties in response to chemical stimuli have the capacity to be used as new surface‐based sensing materials. For such surfaces, detecting the polymer conformation is key to their sensing capabilities. Herein, we report on FRET‐integrated ultrathin (<70 nm) polymer brush surfaces that exhibit stimuli‐dependent FRET with changing brush conformation. Poly(N‐isopropylacrylamide) polymers were chosen due their exceptional sensitivity to liquid mixture compositions and their ability to be assembled into well‐defined polymer brushes. The brush transitions were used to optically sense changes in liquid mixture compositions with high spatial resolution (tens of micrometers), where the FRET coupling allowed for noninvasive observation of brush transitions around complex interfaces with real‐time sensing of the liquid environment. Our methods have the potential to be leveraged towards greater surface‐based sensing capabilities at intricate interfaces. FRET chemistry was integrated within stimuli‐responsive polymer brush layers on planar substrates for spatial sensing of changing polymer conformations. Sensing was demonstrated for a variety of liquid mixture compositions, including high‐resolution observation of lateral differences in polymer conformation at immiscible liquid interfaces (see picture), thus offering great potential to be leveraged for new surface‐based sensing devices.