Temperature-Responsive Hydrogel-Coated Gold Nanoshells

Abstract

Abstract:Gold nanoshells (~160 nm in diameter) were encapsulated within a shell of temperature-responsive poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-co-AA)) using a surface-bound rationally-designed free radical initiator in water for the development of a photothermally-induced drug-delivery system. The morphologies of the resultant hydrogel-coated nanoshells were analyzed by scanning electron microscopy (SEM), while the temperature-responsive behavior of the nanoparticles was characterized by dynamic light scattering (DLS). The diameter of the P(NIPAM-co-AA) encapsulated nanoshells decreased as the solution temperature was increased, indicating a collapse of the hydrogel layer with increasing temperatures. In addition, the optical properties of the composite nanoshells were studied by UV-visible spectroscopy. The surface plasmon resonance (SPR) peak of the hydrogel-coated nanoshells appeared at~800 nm, which lies within the tissue-transparent range that is important for biomedical applications. Furthermore, the periphery of the particles was conjugated with the model protein avidin to modify the hydrogel-coated nanoshells with a fluorescent-tagged biotin, biotin-4-fluorescein (biotin-4-FITC), for colorimetric imaging/monitoring.

Polymeric Nanogels as Versatile Nanoplatforms for Biomedical Applications

“…The formulation of core-shell NGs is a very critical process depending upon several parameters such as size, core-shell density, and inclusion of functional groups in core-shell compartments. Journal of Nanomaterials nanorods are available in the market and are applied in different temperature-sensitive therapies [43,44]. Amphoteric core-shell NGs provide important information relevant to specific properties of core-shell NG.…”

Synthetic Methodologies to Gold Nanoshells: An Overview

“…Besides, DLS studies can be carried out at controlled temperatures, which makes it suitable to study temperature based surface modification. As shown in Figure 21 , bare gold nanoshells showed no change in hydrodynamic diameter in a temperature range, while it varied for hydrogel coated gold nanoshells based on temperature [ 142 ]. One of the limitations of DLS is that it assumes the particles to be spheres, which makes it impractical for size determination of nonspherical nanomaterials [ 143 ].…”

“…XPS offers information related to elemental composition, electronic structure and oxidation states of elements. In addition, it can be used to monitor ligand-gold nanoshell chemistry [ 142 ]. As shown in Figure 23 , the Au-S covalent bond formation was confirmed by XPS in the thiol-PEG functionalized gold nanoshells [ 142 ].…”

“…In addition, it can be used to monitor ligand-gold nanoshell chemistry [ 142 ]. As shown in Figure 23 , the Au-S covalent bond formation was confirmed by XPS in the thiol-PEG functionalized gold nanoshells [ 142 ]. The binding energy for 2p 3/2 electron in a free thiol is ~164 eV, while for the bound thiol on to gold, it is 162 eV [ 152 ].…”

“… Variation of the hydrodynamic diameter of bare and hydrogel-coated gold nanoshells as a function of temperature, determined using Dynamic Light Scattering (DLS) [ 142 ]. …”