QSense
User Day
26th of November 2024

Project has proposed a novel smart wound healing device based on conducting polymers, which is expected to combine drug delivery and electrical stimulation in one system, controlled by a clean, simple, and efficient electrochemical method. The platform is also expected to achieve attachment-release of wound-healing drugs with different structures and investigate this platform for advanced wound regeneration. The key technology of the platform was based on a functionalized CP monomer EDOT-thioacetate (EDOTSAc) reported by our group, which was used to provide a thiol functionality that is capable of electrochemical and reversible conjugation of various (bio)molecules. This has enabled the capture and release of small and biomolecules, such as 2-mercaptoethanol (2ME) and DNA drugs, as well as larger bio entities. To realize the interaction between the drug molecules and the deposited CP layers, we are utilizing QCM-D to monitor the whole attachment-release process. Moreover, the QCM-D was used to test the anti-fouling performance of wound-healing devices.

Stabilization of liquid therapeutic protein formulations with non-ionic surfactants is imperative to avoid critical loss of the active pharmaceutical ingredient by aggregation or adsorption onto different types of interfaces. 

In the present work, we have characterized the interfacial activity of different surfactants – alone and in competition with antibodies, by applying a comprehensive suite of experimental techniques including tensiometry, interfacial rheology and quartz-crystal microbalance with dissipation monitoring (QCM-D). 

The obtained data show important differences between the surfactants as well as a clear influence of the type of interface considered on the observed behavior. We have linked these physicochemical results to the performance of the surfactants in stabilization of antibodies. 

Our findings and the broad spectrum of tests described in this work are instructive towards a better understanding of protein stabilization in distinct primary packaging systems through surfactants in aqueous formulations. 

In recent years, the development of proton exchange membrane fuel cells has been greatly accelerated due to the increasingly evident climate change, as they represent an efficient alternative for the conversion of green hydrogen into electricity. Despite the rapid progress in this field, not all problems have been solved yet. For example, corrosion on the electrodes of fuel cells remains an ongoing challenge, which still has a major impact on the durability and therefore also the commercial application of this technology. To date, not much is known about the interplay during the corrosion processes between ionomer and the platinum catalyst material. Consequently, in this study the interaction of platinum surfaces and Nafion as an ionomer material is analysed using EQCM-D. With this method, mass changes as well as structural changes on the surface of the electrode can be tracked with high precision and subsequently correlated to the corresponding electrochemical processes. Thus, we were able to observe a significant loss of mass during potential cycling for a pure polycrystalline platinum surface, while the same surface coated with a thin layer of Nafion demonstrated contrary behaviour. Instead, a significant increase in mass on the electrode surface and an increase in dissipation were observed. However, this effect could not be observed for surfaces of other materials such as gold and carbon. Therefore, we conclude that the cyclic oxidation and reduction of the platinum surface during potential cycling leads to an increase of the water content in the Nafion layer. In this context, it is assumed that the osmotic drag force of the ions involved in the oxidation and reduction reaction is primarily responsible for the observed effect. 

Soft interfaces formed by polymer materials are important interfaces for biological systems (biointerfaces). Controlling the chemical and physical structures of the interfaces at the nanometer level plays a pivotal role in understanding the mechanism of functioning and its applications. To this end, the polymer brush surfaces prepared by controlled radical polymerization is suitable to investigate the relationship between the interfacial structure and the functions.　In this study, a cationic poly(2-(methacryloyloxy)ethyl) trimethylammonium chloride) (PMTAC) brush surfaces were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP), and their properties were systematically investigated to discuss the factors affecting their bactericidal abilities and interactions with proteins. The bactericidal ability for S. aureus of the high-graft-density polymer brush (0.45 chains nm-2) was higher than that of the low-graft-density polymer brush (0.06 chains nm-2). To discuss the effect of polymer brush structure on bactericidal ability in the view of molecular interactions, we focused on dissipation change (ΔD) of QCM-D measurement to consider the adsorption state. For the protein adsorption, BSA was likewise adsorbed when the brush structure was changed; however, the negative ΔD indicated the BSA-adsorbed, high-graft-density PMTAC brush became a rigid state. Moreover, for S. aureus adhesion after incubating in a growth media, a small slope of ΔD/ΔF plots considered initial adsorption of bacteria on the high-graft-density polymer brush strongly interacted compared to that of low-graft-density polymer brush. The value of the slope of ΔD/ΔF on the high-graft-density polymer brush was considered due to the dead bacteria in between the bacteria and the polymer brush interface. These investigations for structure-controlled cationic polymer brush will contribute to the design of anti-bacterial surfaces. (T. Masuda* et al., Langmuir 2023, 39, 16522–16531.)