High-Speed AFM Reveals the Detailed Mechanism of Dynamic Protein Adsorption Onto Individual Hydrogel Microspheres

Abstract

Hydrogel microspheres, i.e., microgels have both colloidal and hydrogel properties, which are composed of cross-linked hydrophilic polymer network. Due to the colloidal size property and biocompatibility, microgels are promising for advanced bio-nanomaterials such as protein drug delivery vehicles [1]. In order to establish the design concept of such protein carrier, understanding the dynamic interaction between the protein and microgels is essential. Up to now, the dynamic interaction between protein and microgels is well characterize by means of scattering, spectroscopy, and sensor [2]. However, to the best of our knowledge, there are no study that direct visualization during protein adsorption to individual microgels at nanoscale in real-time. Against this background, we visualized individual microgels during protein adsorption onto the microgels at nanoscale in real-time for the first time [3]. This approach, which enabled us to monitor the moment of protein adsorption to individual microgels, was realized by high-speed atomic force microscopy (HS-AFM) [4]. This method allows the direct visualization of the dynamics of biological molecules in action, without significantly disturbing the physiological function of the molecules [5]. We have already monitored the dynamic adsorption behavior of microgels onto solid/liquid interface [6]. The microgels were synthesized through aqueous free-radical precipitation polymerization of N-isopropyl acrylamide, the cross-linker N,N'-methylenebis (acrylamide), and acrylic acid with different content. In this presentation, the effect of protein interaction on the microgels’ dynamics will be discussed. Partially reproduced with permission from [6] Copyright (2017) John Wiley and Sons.