Alginate Hydrogel Beads with a Leakproof Gold Shell for Ultrasound-Triggered Release

<b>Background/Objectives:</b> Focused ultrasound has advantages as an external stimulus for drug delivery as it is non-invasive, has high precision and can penetrate deep into tissues. Here, we report a gold-plated alginate (ALG) hydrogel system that retains highly water-soluble small-mo...

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Main Authors: Marcus Flowers, Alex Paulsen, Claire R. W. Kaiser, Adam B. Tuma, Hubert H. Lim, Brenda M. Ogle, Chun Wang
Format: Article
Language:English
Published: MDPI AG 2025-01-01
Series:Pharmaceutics
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Online Access:https://www.mdpi.com/1999-4923/17/1/133
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Summary:<b>Background/Objectives:</b> Focused ultrasound has advantages as an external stimulus for drug delivery as it is non-invasive, has high precision and can penetrate deep into tissues. Here, we report a gold-plated alginate (ALG) hydrogel system that retains highly water-soluble small-molecule fluorescein for sharp off/on release after ultrasound exposure. <b>Methods:</b> The ALG is crosslinked into beads with calcium chloride and layered with a polycation to adjust the surface charge for the adsorption of catalytic platinum nanoparticles (Pt NPs). The coated bead is subject to electroless plating, forming a gold shell. Ultrasound is applied to the gold-plated ALG beads and the release of fluorescein with or without ultrasound stimulation is quantified. <b>Results:</b> Polyethylenimine (PEI), not poly-L-lysine (PLL), is able to facilitate Pt NP adsorption. Gold shell thickness is proportional to the duration of electroless plating and can be controlled. Gold-plated ALG beads are impermeable to the fluorescein cargo and have nearly zero leakage. Exposure to focused ultrasound initiated the release of fluorescein with full release achieved after 72 h. <b>Conclusions:</b> The gold-plated ALG hydrogel is a new material platform that can retain highly water-soluble molecules with a sharp off/on release initiated by focused ultrasound.
ISSN:1999-4923