Thermoresponsive and Active Functional Fiber Mats for Cultured Cell Recovery

Abstract

Thermoresponsive and active functional fiber mats were prepared from random copolymer of poly(pentafluorophenyl acrylate-co-N-isopropylacrylamide) (P(PFPA-co-NIPAM)), which was synthesized by a controlled radical polymerization process based on reversible addition-fragmentation chain transfer (RAFT). As reactive sites, pentafluorophenyl ester (PFP) groups were incorporated in the copolymer to allow for a multiple post-polymerization modification. UV-cross-linkable moieties were first introduced by partially reacting PFP groups in the copolymer with ortho-nitrobenzyl (ONB)-protected diamine. Electrospinning the resulting ONB-containing P(PFPA-co-NIPAM), followed by UV-induced cross-linking, yielded stable cross-linked thermoresponsive PNIPAM-based fiber mats. The remaining PFP active groups on the surface of copolymer fiber mats allowed for further conjugation with an H-Gly-Arg-Gly-Asp-Ser-OH (GRGDS) peptide, a well-known cell adhesive peptide sequence that was selected as a model in order to promote cell growth. At 37 °C, fibroblast cells were found to attach, spread, and proliferate well on the GRGDS-immobilized cross-linked (CL) fiber mat, as opposed to those on the GRGDS-immobilized un-cross-linked (UCL) fiber mat. By decreasing the temperature down to 20 °C, i.e. below the lower critical solution temperature (LCST) of thermoresponsive PNIPAM, cultured cells could easily be released from both GRGDS-immobilized CL and UCL fiber mats, whereas no cells were detached from tissue culture polystyrene (TCPS). These results suggest that the thermosensitive and active functional fiber mat obtained in this research represent an attractive and versatile platform for cultured cell recovery, which is beneficial for tissue engineering applications.

Cross-linking electrospinning

“…35 In 2017, a poly( pentafluorophenyl acrylate-co-N-isopropylacrylamide) [P(PFPA-co-NIPAM)] fiber mat with thermo-responsive properties was fabricated via cross-linking e-spinning. 36 Due to the presence of pentafluorophenyl ester (PFP) groups (reactive sites), the copolymer could easily introduce orthonitrobenzyl (ONB)-protected diamine (UV-cross-linkable moieties), thus exhibiting photo-cross-linking capability. Around the same time, de Oliveira et al first produced unsaturated aliphatic polyglobalide (PGl) fibers with dichloromethane (DCM) as the solvent by e-spinning, and then by introducing dithiol as the cross-linking agent, achieved the preparation of crosslinked fiber mats under UV irradiation.…”

Manipulating cell fate: dynamic control of cell behaviors on functional platforms

“…Using a similar strategy, crosslinked thermo-responsive fiber mats were developed for the culture and recovery of fibroblast cells. 135 Besides PNIPAAm and its derivatives, other different classes of materials have been applied to design temperature-responsive platforms for cell regulation. For example, a gelatin-based layer-bylayer nanocoating was built on PDMS surfaces for CTC capture (Fig.…”

“…Using a similar strategy, cross-linked thermo-responsive fiber mats were developed for the culture and recovery of fibroblast cells. 135…”

Smart polymers for cell therapy and precision medicine

“…When the temperature is above LCST, PNiPAAm becomes hydrophobic since water molecules are expelled from the hydrophilic region of PNiPAAm [29, 30]. With the thermoresponsiveness between room temperature and physiological temperatures, PNiPAAm has been employed to design a variety of smart biomaterials, such as drug or cell delivery vehicles, imaging or sensing, fiber mats for cell recovery, and strain sensors [32, 62].…”