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Issue 24, 2019, Issue in Progress
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Polydopamine functionalized hydrogel beads as magnetically separable antibacterial materials

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Abstract

In the present study, magnetically separable hydrogel beads of ionically cross-linked alginate were functionalized with polydopamine (PDA). The rationale behind this was to enhance the structural stability and antibacterial profile of PDA/Alg/Fe3O4 beads (K3). Incorporation of superparamagnetic magnetite (Fe3O4) nanoparticles endowed the hydrogel beads with magnetism. X-ray diffraction (XRD) analysis revealed the successful formation of pure Alg/Fe3O4 nanoparticles having an inverse spinel structure. Vibrating sample magnetometry (VSM) confirmed their superparamagnetic behaviour with Ms values of 36.18 and 30.46 emu g−1 at 5 and 300 K, respectively. High resolution-transmission electron microscopy (HR-TEM) images showed alginate capping and the size of the Alg/Fe3O4 nanoparticles (∼8 nm). The successful deposition of PDA granules on the K3 bead surface was verified by field emission-scanning electron microscopy (FE-SEM). The PDA functionalization was further justified by VSM, XRD and Fourier-transform infrared spectroscopy (FT-IR). During swelling experiments, K3 beads displayed appreciable structural stability compared to bare/non-functionalized beads. Wettability studies revealed K3 beads to be hydrophilic with a contact angle of ∼55°. Rheological parameters including storage modulus (G′) and shear viscosity of K3 increased upon PDA functionalization. During antibacterial tests, K3 strongly inhibited E. coli, S. typhi, S. aureus and L. monocytogenes in a concentration and time dependent manner. Fluorescence staining experiments showed that K3 could greatly alter the bacterial membrane integrity. Reusability experiments with K3 beads substantiated their effective broad-spectrum antibacterial performance for three consecutive cycles.

Graphical abstract: Polydopamine functionalized hydrogel beads as magnetically separable antibacterial materials

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Publication details

The article was received on 24 Jan 2019, accepted on 18 Apr 2019 and first published on 01 May 2019


Article type: Paper
DOI: 10.1039/C9RA00623K
RSC Adv., 2019,9, 13444-13457
  • Open access: Creative Commons BY-NC license
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    Polydopamine functionalized hydrogel beads as magnetically separable antibacterial materials

    I. Matai, M. Garg, K. Rana and S. Singh, RSC Adv., 2019, 9, 13444
    DOI: 10.1039/C9RA00623K

    This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. Material from this article can be used in other publications provided that the correct acknowledgement is given with the reproduced material and it is not used for commercial purposes.

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