Probing Temperature-Responsivity of Microgels by Superresolution Microscopy

The ability to observe microgel morphologies at nanometer scale and its response to temperature changes opens exciting opportunities to design and precisely control the behavior of microgels for various applications [1]. In this context, super resolution microscopy is a well-established tool used to investigate colloidal systems e.g. poly(N-isopropylacrylamide) (pNIPAM) microgels [2]. An important role when performing advanced microscopy experiments on such particles plays the interface where the microgels are established, as they have to be fixed during the experiment. We use super resolution microscopy and molecular dynamic (MD) simulations to investigate how individual microgels anchored on hydrophilic and hydrophobic surfaces change morphology with temperature. Super resolved images of individual microgel particles at different collapsing stages are analyzed and their density profiles are obtained. The results suggest that the anchoring parts of the microgel stick to the surface as the temperature is increased. For these surfaces the experimental data and the MD simulations are in very good agreement. Such study is relevant to establish a technique for the investigation of more complex systems along lower critical solution temperature (LCST), where molecules of interest can be incapsulated in the microgel network and controllably released with temperature.<br/><br/>References<br/>[1] Scheffold, F. Nat Commun 2020, 11, 4315.<br/>[2] Conley, G. M., Nöjd, S., Braibanti, M., Schurtenberger, P., & Scheffold, F. Physicochemical and Engineering Aspects 2016, 499, 18–23.