Multi stimuli-responsive hydrogel microfibers containing magnetite nanoparticles prepared using microcapillary devices

Abstract

Extensive research efforts have been devoted to the development of hydrogel microfibers for tissue engineering, because the vascular structure is related to the transport of nutrients and oxygen as well as the control of metabolic and mechanical functions in the human body. Even though stimuli-responsive properties would enhance the potential applicability of hydrogel microfibers for artificial tissue architectures, previous studies of their fabrication have not considered changes in the microfibers in response to external stimuli. In this work, we prepared temperature-responsive poly(N-isopropylacrylamide) (PNIPAm) microfibers with controlled shapes and sizes by the in situ photo-polymerization of aqueous monomers loaded in calcium alginate templates generated from microcapillary devices. We found that the shape and size of the hydrogel microfibers could be controlled by adjusting the injection positions of the solutions and varying the diameters of the inner capillary, respectively. We further fabricated light-responsive materials by incorporating photothermal magnetite nanoparticles (MNPs) within the temperature-responsive PNIPAm hydrogel microfibers. Because the MNPs incorporated into the PNIPAm microfibers generated heat upon the absorption of visible light, we could demonstrate volume changes in the microfibers triggered by both visible light irradiation and temperature.

Visible Light‐Triggered On‐Demand Drug Release from Hybrid Hydrogels and its Application in Transdermal Patches

“…MNP-containing copolymer and PNIPAm beads were found to show characteristic temperature-dependent volume phase transitions. In accordance with the previous study, [ 24,29 ] PNIPAm/ MNP beads exhibited a volume phase transition near 32 °C. As expected, p(NIPAm-co -VP)/MNP showed a higher LCST than PNIPAm/MNP due to the incorporation of hydrophilic VP into the PNIPAm backbone, and the temperature range for rapid volume decrease shifted to higher temperatures with increasing VP composition of the hydrogel ( Figure S1, Supporting Information).…”

“…[23][24][25]29 ] To demonstrate this point, selected p(NIPAm-co -VP)/MNP beads were irradiated with visible light of 47.5 mW cm −2 for 2 min. We found that only the beads in the irradiated area contracted, while the diameter change in nonirradiated areas was negligible (Figure 4 c,d).…”

“…Finally, 1 wt% aqueous calcium chloride solution was dropped into the alginate solution for gelation. [27][28][29] This procedure prevented direct contact of the rhodamine-loaded hydrogel beads when the PDMS patch was applied onto the skin. The top surface of the PDMS patch was covered with an additional 1 mm thick PDMS sheet to prevent drying of the alginate hydrogels.…”

“…Spherical beads of several hundred micrometers consisting of a PNIPAm-based hydrogel matrix and MNP were prepared by alginate templating [27][28][29] and spray injection. The hydrogel matrix was designed to induce sharp volume phase transition at…”

Nanoparticle–Polymer Synergies in Nanocomposite Hydrogels: From Design to Application

“…After modified with XYZ‐directions, composite hydrogel fibers could be obtained in purpose . In addition, the microfluidic strategy can be used to produce fibers with diverse morphologies and multiple components, such as hollow, thermosensitive, or magneto‐sensitive fibers, by the delicate design of microfluidic structures …”