Surface Functionalization by Stimuli-Sensitive Microgels for Effective Enzyme Uptake and Rational Design of Biosensor Setups

Abstract

We highlight microgel/enzyme thin films that were deposited onto solid interfaces via two sequential steps, the adsorption of temperature- and pH-sensitive microgels, followed by their complexation with the enzyme choline oxidase, ChO. Two kinds of functional (ionic) microgels were compared in this work in regard to their adsorptive behavior and interaction with ChO, that is, poly(N-isopropylacrylamide-co-N-(3-aminopropyl)methacrylamide), P(NIPAM-co-APMA), bearing primary amino groups, and poly(N-isopropylacrylamide-co-N-[3-(dimethylamino) propyl]methacrylamide), P(NIPAM-co-DMAPMA), bearing tertiary amino groups. The stimuli-sensitive properties of the microgels in the solution were characterized by potentiometric titration, dynamic light scattering (DLS), and laser microelectrophoresis. The peculiarities of the adsorptive behavior of both the microgels and the specific character of their interaction with ChO were revealed by a combination of surface characterization techniques. The surface charge was characterized by electrokinetic analysis (EKA) for the initial graphite surface and the same one after the subsequent deposition of the microgels and the enzyme under different adsorption regimes. The masses of wet microgel and microgel/enzyme films were determined by quartz crystal microbalance with dissipation monitoring (QCM-D) upon the subsequent deposition of the components under the same adsorption conditions, on a surface of gold-coated quartz crystals. Finally, the enzymatic responses of the microgel/enzyme films deposited on graphite electrodes to choline were tested amperometrically. The presence of functional primary amino groups in the P(NIPAM-co-APMA) microgel enables a covalent enzyme-to-microgel coupling via glutar aldehyde cross-linking, thereby resulting in a considerable improvement of the biosensor operational stability.

Highly Efficient Antimicrobial and Antifouling Surface Coatings with Triclosan-Loaded Nanogels

“…The introduced electrostatic repulsion of the charged DMAPMA comonomer leads to the altered thermosensitivity, which then affects the R h . 26 Additionally, the protonated DMAPMA amino segments are hydrophilic, leading to a stronger coordination of water molecules, and consequently, the VPTT is affected and the VPTT increase as compared to pure PNIPAM and the decrease in the hydrodynamic radius happen over a broader temperature range. 39 After quaternization with 1-bromo-dodecane, the thermoresponsiveness was altered compared to the N-nGel most likely because of the already collapsed network due to the intraparticle hydrophobic interactions of the dodecane chains that limit the swelling/deswelling process.…”

“… 20 − 22 Recently, our group reported the effect of nanogel size, mechanical properties, and coating thickness on the antifouling behavior toward bacterial adhesion. 13 So far, nanogel coatings have been used for antifouling purposes toward proteins, 23 macrophage adhesion, 24 antifogging and antifrosting performance, 25 enzyme uptake capability for biosensor design, 26 controlling the cell proliferation and cell adhesion, 27 , 28 and controlling antimicrobial and anti-inflammatory properties via peptide-loading. 29 The surface coating preparation with nanogel particles is a facile method and predominantly based on the electrostatic interactions of a pretreated surface and the nanogel surface charge that is induced by the synthesis method.…”

Hierarchy of Hybrid Materials—The Place of Inorganics-in-Organics in it, Their Composition and Applications

“…Functionalization by these molecules is relevant for all coatings, including hydrogels (Devolder and Kong, 2012). Enzymatic functionalization of coatings is another important property (Sigolaeva et al, 2018), because enzymes are also excellent candidates to create tissue-like extracellular matrices (Caliari et al, 2016) and can even be used to encapsulate cells to create pre-seeded scaffolds (Hoffman, 2012). Drug delivery vehicles or coatings can directly be modified by inorganic constituents, mostly by nanostructures for sensing, enhancing mechanical properties (also in drug delivery), or promoting cell-surface interaction.…”

Nanogels: A novel approach in antimicrobial delivery systems and antimicrobial coatings

“…More recently, increasing attention has been paid to enhance their biocompatibility as well as using them as antimicrobial and antifouling surface coatings. In this context, different approaches have recently been followed in the biomedical field; for example, the antifouling performance to inhibit protein, macrophage, and bacteria adhesion to the surface, the enzyme uptake capability for biosensors, the capacity to control the cell proliferation and cell adhesion of nanogel coatings have been investigated [ [27] , [28] , [29] , [30] , [31] , [32] ]. Their features such as size, charge, porosity, amphiphilicity, and softness can be tuned by changing the chemical composition during the synthesis or post-modification [ 33 ].…”