Crosslinked Poly( N ‐Isopropylacrylamide)‐Based Microfibers as Cell Manipulation Materials with Prompt Cell Detachment

A surface-grafted hydrogel demonstrating thermoresponsive adhesive strength change

Here, we designed a surface-grafted hydrogel (SG gel) that exhibits thermoresponsive changes in surface properties. Quantitative measurements using a self-made device showed that the adhesive strength between the SG gel surface and a Bakelite plate due to hydrophobic interaction changed significantly with temperature.

Reversible Adsorption and Detachment of Saccharomyces cerevisiae on Thermoresponsive Poly(N-isopropylacrylamide)-Grafted Fibers for Continuous Immobilized Fermentation

Biofilm-mediated continuous fermentation with cells immobilized has gained much attention in recent years. In this study, thermoresponsive poly(N-isopropylacrylamide)-grafted cotton fibers (PNIPAM-CF) were prepared via an improved surface-initiated atom transfer radical polymerization. The modification process imparted switchable wettability to the surface while maintaining the thermal stability and biocompatibility of the CF. During the ethanol transformation, the rapid, reversible cell adsorption and detachment of Saccharomyces cerevisiae were performed through the modulation of wettability, displaying the enhancement of immobilized biomass and immobilization efficiency from 2.20 g/L and 59.43% to 2.81 g/L and 93.32%, respectively. Moreover, the biofilm adsorption matched well with the Freundlich model, indicating that multilayer adhesion was the main mode of biofilm formation. Based on the accumulation of the biofilm, the fabrication and utilization of PNIPAM-CF improved the efficiency of continuous immobilized fermentation, making the ethanol production reach 26.34 g/L in the sixth batch of fermentation. Meanwhile, wettability regulation further enhanced the reusability of the carrier. Therefore, the findings of this study revealed that the application of smart materials in cell immobilization systems had broad prospects for achieving sustainable and continuous catalysis.

Synthetic Thermo-Responsive Terpolymers as Tunable Scaffolds for Cell Culture Applications

The use of tailored synthetic hydrogels for in vitro tissue culture and biomanufacturing provides the advantage of mimicking the cell microenvironment without issues of batch-to-batch variability. To that end, this work focused on the design, characterization, and preliminary evaluation of thermo-responsive, transparent synthetic terpolymers based on N-isopropylacrylamide, vinylphenylboronic acid, and polyethylene glycol for cell manufacturing and in vitro culture applications. Polymer physical properties were characterized by FT-IR, ¹H-NMR, DLS, rheology, and thermal-gravimetric analysis. Tested combinations provided polymers with a lower critical solution temperature (LCST) between 30 and 45 °C. Terpolymer elastic/shear modulus varied between 0.3 and 19.1 kPa at 37 °C. Cellular characterization indicated low cell cytotoxicity on NIH-3T3. Experiments with the ovarian cancer model SKOV-3 and Jurkat T cells showed the terpolymers’ capacity for cell encapsulation without interfering with staining or imaging protocols. In addition, cell growth and high levels of pluripotency demonstrated the capability of terpolymer to culture iPSCs. Characterization results confirmed a promising use of terpolymers as a tunable scaffold for cell culture applications.

Thermo-responsive, Mechanically-robust and 3D Printable Supramolecular Hydrogels

In this work, poly(N-isopropylacrylamide) (PNIPAm) grafted and multi-urea linkage segmented linear polyurethane-urea (PUU) copolymers were synthesized using α-dihydroxyl terminated PNIPAm as chain extender and water as an indirect chain extender,respectively....

Thermoresponsive interfaces obtained using poly(N-isopropylacrylamide)-based copolymer for bioseparation and tissue engineering applications

Poly(N-isopropylacrylamide) (PNIPAAm) is the most well-known and widely used stimuli-responsive polymer in the biomedical field owing to its ability to undergo temperature-dependent hydration and dehydration with temperature variations, causing hydrophilic and hydrophobic alterations. This temperature-dependent property of PNIPAAm provides functionality to interfaces containing PNIPAAm. Notably, the hydrophilic and hydrophobic alterations caused by the change in the temperature-responsive property of PNIPAAm-modified interfaces induce temperature-modulated interactions with biomolecules, proteins, and cells. This intrinsic property of PNIPAAm can be effectively used in various biomedical applications, particularly in bioseparation and tissue engineering applications, owing to the functionality of PNIPAAm-modified interfaces based on the temperature modulation of the interaction between PNIPAAm-modified interfaces and biomolecules and cells. This review focuses on PNIPAAm-modified interfaces in terms of preparation method, properties, and their applications. Advances in PNIPAAm-modified interfaces for existing and developing applications are also summarized.