Graphene oxide modulates inter-particle interactions in 3D printable soft nanocomposite hydrogels restoring magnetic hyperthermia responses

Srikanth Kolagatla,Jacek K. Wychowaniec,Cara Moloney,Sameer Shingte,Krystian Kowiorski,Liam Jowett,Katie McGarry,Esther Rani Aluri,Dermot F. Brougham,Eoin McKiernan,Brian J. Rodriguez,Krutika Singh,Edward Gannon

doi:10.1016/j.jcis.2021.12.048

Srikanth Kolagatla, Jacek K. Wychowaniec + Show 11 more

Open Access

https://doi.org/10.1016/j.jcis.2021.12.048

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Abstract

Hydrogels loaded with magnetic iron oxide nanoparticles that can be patterned and which controllably induce hyperthermic responses on AC-field stimulation are of interest as functional components of next-generation biomaterials. Formation of nanocomposite hydrogels is known to eliminate any Brownian contribution to hyperthermic response (reducing stimulated heating) while the Néel contribution can also be suppressed by inter-particle dipolar interactions arising from aggregation induced before or during gelation. We describe the ability of graphene oxide (GO) flakes to restore the hyperthermic efficiency of soft printable hydrogels formed using Pluronics F127 and PEGylated magnetic nanoflowers. Here, by varying the amount of GO in mixed nanocomposite suspensions and gels, we demonstrate GO-content dependent recovery of hyperthemic response in gels. This is due to progressively reduced inter-nanoflower interactions mediated by GO, which largely restore the dispersed-state Néel contribution to heating. We suggest that preferential association of GO with the hydrophobic F127 blocks increases the preponderance of cohesive interactions between the hydrophilic blocks and the PEGylated nanoflowers, promoting dispersion of the latter. Finally we demonstrate extrusion-based 3D printing with excellent print fidelity of the magnetically-responsive nanocomposites, for which the inclusion of GO provides significant improvement in the spatially-localized open-coil heating response, rendering the prints viable components for future cell stimulation and delivery applications.

Highlights

Magnetic nanoparticles (MNPs) are currently used and are under development for multiple biomedical applications including cancer treatment, as delivery/release agents in vitro and in vivo and as contrast agents for magnetic resonance imaging, due to their controlled responses to applied magnetic fields which are strongly dependent on the particles dispersion state [1,2,3,4,5]
Polyethylene glycol (PEG) chains of 8000 Da were grafted to the NF surfaces, following the protocol described by Studart et al [33] (Figure 1B and S1A-C), see Methods, forming PEGylated NF suspensions
The corresponding magnetic force microscopy (MFM) phase image recorded during lift-mode operation shows a phase shift associated with the resonance curve shift due to the long-range magnetic force gradient arising from PEGylated nanoflowers (PNFs) (Figure 1D)

Summary

Introduction

Magnetic nanoparticles (MNPs) are currently used and are under development for multiple biomedical applications including cancer treatment, as delivery/release agents in vitro and in vivo and as contrast agents for magnetic resonance imaging, due to their controlled responses to applied magnetic fields which are strongly dependent on the particles dispersion state [1,2,3,4,5]. Graphene and graphene oxide (GO) are being widely explored for liquid crystal [6] and electronics applications [7], and as composites [8] often for tissue engineering as they can provide functional responses and can modulate the aggregation state of other nanocomposite components [9, 10], providing means to control the final physical (e.g. mechanical or thermal) properties. Materials studied in this regard include hydrogels [11,12,13,14]. Pluronics provide a tuneable ‘soft’ shear-thinning matrix with is usually injectable or printable at room temperature, with

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Conclusion