Concept for a new generation of sensors: Mechanosensitive polymer brush systems enable high-resolution detection

Polymer brushes have been the subject of much research in recent decades due to their potential for creating switchable or sensory surface properties. Polymer brush surface coatings consist of polymer chains with one end attached to an anchoring surface. Influencing factors such as temperature, pH value, solvents or soluble substances in the ambient medium quickly and reversibly change the conformation of the chains, e.g. the chains stretch away from the surface or contract. This switching behaviour has already been used many times for sensor applications, but the possibilities of detecting the conformational transitions - and thus the stimuli - in a spatially resolved manner have been severely limited until now. Atomic force microscopy or spectroscopic ellipsometry could usually only be used to read the height of the rarest stimuli. The resolution was very low (height typically averaged over a range of 10 x 10 micrometres); detection did not work at complex interfaces and in some methods the sample surfaces were irreversibly destroyed.

In his work, Quinn Besford has developed a completely new concept with which the conformational bridges of polymer brushes can be detected quickly, spatially in four dimensions (2 x lateral, perpendicular and with time) and in complex architectures, i.e. not only on planar substrates, using fluorescence microscopy.
For this purpose, fluorophores are integrated into specific polymer architectures in such a way that the fluorescence properties reflect the mechanical conformation of the chains. This is realised using the so-called FRET mechanism (distance-dependent energy transfer from an excited donor to an acceptor). Special complex diblock copolymer brushes had to be synthesised for this purpose. In addition, Quinn Besford found an additional and simpler method for the spatial resolution of the bristle conformation, which is based on integrated self-solubilisation effects, i.e. the fact that the fluorophores lose their fluorescence properties depending on their concentration in a solution.

Both approaches were investigated experimentally, but also by simulations (cooperation with IPF Institute Theory of Polymers: Prof. Jens-Uwe Somme and Dr Holger Merlitz).

The award ceremony took place on 20 April 2023, 5 p.m., as part of the IPF's annual reception in the Great Hall of the Deutsches Hygiene-Museum Dresden.

Dr Quinn A. Besford received his doctorate in theoretical/physical chemistry (2016) from the University of Melbourne (UoM), Australia, with a focus on statistical mechanics. He then worked in the ARC Centre of Excellence in Bio-Nano Science and Technology at the UoM, where he specialised in the development of novel nanomaterials for therapeutic applications, including work on an industry-funded project to treat type 1 diabetes using glucose-responsive nanoparticles. In 2019, he came to the IPF in Dresden as an Alexander von Humboldt Research Fellow (Ludwig Leichhardt Fellowship). He has headed an independent junior research group here since May 202. His team focuses on the development of functional polymer materials for sensor technology using fluorescence methods, as well as on the development of nanoparticle and hydrogel systems for therapeutic applications and their interactions in blood contact.

Press release of the "idw - Informationsdienst Wissenschaft" from 20 April 2023