Abstract
This paper describes the preparation and characterization of a new type of core–shell nanoparticle in which the structure consists of a hydrogel core encapsulated within a porous silver shell. The thermo-responsive hydrogel cores were prepared by surfactant-free emulsion polymerization of a selected mixture of N-isopropylacrylamide (NIPAM) and acrylic acid (AAc). The hydrogel cores were then encased within either a porous or complete silver shell for which the localized surface plasmon resonance (LSPR) extends from visible to near-infrared (NIR) wavelengths (i.e., λmax varies from 550 to 1050 nm, depending on the porosity), allowing for reversible contraction and swelling of the hydrogel via photothermal heating of the surrounding silver shell. Given that NIR light can pass through tissue, and the silver shell is porous, this system can serve as a platform for the smart delivery of payloads stored within the hydrogel core. The morphology and composition of the composite nanoparticles were characterized by SEM, TEM, and FTIR, respectively. UV–vis spectroscopy was used to characterize the optical properties.
Highlights
Interest in the preparation and utilization of uniquely structured nanocomposites continues to expand due to their potential use in electronics, optics, magnetism, medicine, catalysis, and energy applications [1,2,3,4,5,6]
Scheme 1 depicts the strategy to prepare the silver nanocapsules with pNIPAM-co-acrylic acid (AAc) hydrogel cores
The steps include (i) synthesis of the pNIPAM-co-AAc hydrogel core, (ii) growth of tetrakis(hydroxymethyl)phosphonium chloride (THPC) gold seeds around the hydrogel core, and (iii) growth of the silver nanocapsule around the hydrogel core by the reduction of silver nitrate onto the gold seeds, which act as templates
Summary
Interest in the preparation and utilization of uniquely structured nanocomposites continues to expand due to their potential use in electronics, optics, magnetism, medicine, catalysis, and energy applications [1,2,3,4,5,6]. One typical structure is that of an exogenous spherical capsule containing various core materials [21,22,23,24]. Recent studies involving spherical capsules have introduced a variety of materials into the core such as DNA, antibiotics, fluorescent dyes, and metal nanoparticles [25,26,27,28,29,30]. These types of particles show great promise for Beilstein J.
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