Nanostructuring the Interior of Stimuli-Responsive Microgels by N-Vinylimidazoles Quaternized with Hydrophobic Alkyl Chains

Fibrin Hydrogels Reinforced by Reactive Microgels for Stimulus-Triggered Drug Administration

Tissue engineering is a steadily growing field of research due to its wide-ranging applicability in the field of regenerative medicine. Application-dependent mechanical properties of a scaffold material as well as its biocompatibility and tailored functionality represent particular challenges. Here the properties of fibrin-based hydrogels reinforced by functional cytocompatible poly(N-vinylcaprolactam)-based (PVCL) microgels are studied and evaluated. The employment of temperature-responsive microgels decorated by epoxy groups for covalent binding to the fibrin is studied as a function of cross-linking degree within the microgels, microgel concentration, as well as temperature. Rheology reveals a strong correlation between the mechanical properties of the reinforced fibrin-based hydrogels and the microgel rigidity and concentration. The incorporated microgels serve as cross-links, which enable temperature-responsive behavior of the hydrogels, and slow down the hydrogel degradation. Microgels can be additionally used as carriers for active drugs, as demonstrated for dexamethasone. The microgels' temperature-responsiveness allows for triggered release of payload, which is monitored using a bioassay. The cytocompatibility of the microgel-reinforced fibrin-based hydrogels is demonstrated by LIVE/DEAD staining experiments using human mesenchymal stem cells. The microgel-reinforced hydrogels are a promising material for tissue engineering, owing to their superior mechanical performance and stability, possibility of drug release, and retained biocompatibility.

Soft Actuators and Actuation: Design, Synthesis, and Applications

Soft actuators are one of the most promising technological advancements with potential solutions to diverse fields' day-to-day challenges. Soft actuators derived from hydrogel materials possess unique features such as flexibility, responsiveness to stimuli, and intricate deformations, making them ideal for soft robotics, artificial muscles, and biomedical applications. This review provides an overview of material composition and design techniques for hydrogel actuators, exploring 3D printing, photopolymerization, cross-linking, and microfabrication methods for improved actuation. It examines applications of hydrogel actuators in biomedical, soft robotics, bioinspired systems, microfluidics, lab-on-a-chip devices, and environmental, and energy systems. Finally, it discusses challenges, opportunities, advancements, and regulatory aspects related to hydrogel actuators.

Selective Extraction and Quantification of Hemoglobin Based on a Novel Molecularly Imprinted Nanopolymeric Structure of Poly(acrylamide-vinyl imidazole)

Imbalances in hemoglobin (Hb) levels can lead to conditions such as anemia or polycythemia, emphasizing the importance of precise Hb extraction from blood. To address this, a novel synthetic imprinted polymer was meticulously developed for capturing and separating Hb. Poly(acrylamide-vinylimidazole) nanopolymer (poly(AAm-VIM)) was synthesized using acrylamide and vinyl imidazole as functional monomers through surfactant-free emulsion polymerization. Characterization using FTIR, particle size, zeta potential, and SEM ensured the polymer's structure. The Hb-imprinted nanopolymer (Hb-poly(AAm-VIM)) demonstrated notable specificity, with a calculated Hb-specific adsorption value (Qmax) of 3.7377 mg/g in a medium containing 2.5 mg/mL Hb. The molecularly imprinted polymer (MIP) exhibited approximately 5 times higher Hb adsorption than the nonimprinted polymer (NIP). Under the same conditions, the imprinted nanopolymer displayed 2.39 and 2.17 times greater selectivity for Hb over competing proteins such as bovine serum albumin (BSA) and lysozyme (Lys), respectively. Also, SDS-PAGE analysis results confirmed the purification of Hb by the molecularly imprinted nanopolymer. These results underscore the heightened specificity and efficacy of the molecularly imprinted nanopolymer in selectively targeting Hb atoms among other proteins. Incorporating such polymers is justified by their notable affinity, cost-effectiveness, and facile production. This research contributes valuable insights into optimizing synthetic imprinted polymers for efficient Hb extraction, with potential in medical diagnostics and treatment applications.

Multiresponsive Core-Shell Microgels Functionalized by Nitrilotriacetic Acid

Stimuli-responsive microgels with ionizable functional groups offer versatile applications, e.g., by the uptake of oppositely charged metal ions or guest molecules such as drugs, dyes, or proteins. Furthermore, the incorporation of carboxylic groups enhances mucoadhesive properties, crucial for various drug delivery applications. In this work, we successfully synthesized poly{N-vinylcaprolactam-2,2'-[(5-acrylamido-1-carboxypentyl)azanediyl]diacetic acid} [p(VCL/NTAaa)] microgels containing varying amounts of nitrilotriacetic acid (NTA) using precipitation polymerization. We performed fundamental characterization by infrared (IR) spectroscopy and dynamic and electrophoretic light scattering. Despite their potential multiresponsiveness, prior studies on NTA-functionalized microgels lack in-depth analysis of their stimuli-responsive behavior. This work addresses this gap by assessing the microgel responsiveness to temperature, ionic strength, and pH. Morphological investigations were performed via NMR relaxometry, nanoscale imaging (AFM and SEM), and reaction calorimetry. Finally, we explored the potential application of the microgels by conducting cytocompatibility experiments and demonstrating the immobilization of the model protein cytochrome c in the microgels.

Pre- and post-functionalization of thermoresponsive cationic microgels with ionic liquid moieties carrying different counterions

We investigate the effect of different anions on the temperature-dependent solution properties of poly(N-vinylcaprolactam) microgels carrying alkylated ionic liquid vinylimidazolium moieties synthesized by a pre- and post-functionalization approach.