Hybrid Magnetic–Plasmonic Nanoparticle Probes for Multimodal Bioimaging

Abstract

Multimodal contrast agents, which take advantage of different imaging modalities, have emerged as an interesting approach to overcome the technical limitations of individual techniques. We developed hybrid nanoparticles comprising an iron oxide core and an outer gold spiky layer, stabilized by a biocompatible polymeric shell. The combined magnetic and optical properties of the different components provide the required functionalities for magnetic resonance imaging (MRI), surface-enhanced Raman scattering (SERS), and fluorescence imaging. The fabrication of such hybrid nanoprobes comprised the adsorption of small gold nanoparticles onto premade iron oxide cores, followed by controlled growth of spiky gold shells. The gold layer thickness and branching degree (tip sharpness) can be controlled by modifying both the density of Au nanoparticle seeds on the iron oxide cores and the subsequent nanostar growth conditions. We additionally demonstrated the performance of these hybrid multifunctional nanoparticles as multimodal contrast agents for correlative imaging of in vitro cell models and ex vivo tissues.

Hybrid core–shell nanoparticles for cell-specific magnetic separation and photothermal heating

“…4 Indeed, not only can multiple imaging modalities be combined ( i.e. MRI and SERS), 6 but also diagnostic and therapeutic applications, resulting in the commonly used term of theranostics. 7 Finally, the elemental components of such hybrid NPs offer a wide range of supplementary applications, such as magnetically controlled cell separation 8,9 or heat-induced drug delivery, 3 both of which could be included to achieve a truly multimodal hybrid NP system.…”

Accurate Quantification and Imaging of Cellular Uptake Using Single-Particle Surface-Enhanced Raman Scattering

“…This method of particle counting is a different approach to digital SERS in cells, enabling scalable and high-resolution particle quantification. This complements digital SERS approaches that rely on heavily undersampling and determining the percentage of spectra with detectable signal, which are useful for the analysis of larger volumes such as whole cells. ,, This method is suitable for applications of particle counting in small volumes and subcellular regions limited by the confocal volume typically used in point mapping. spICP-MS provided insight into NP agglomeration in cells, which may be useful for understanding important application-dependent parameters related to drug release from mesoporous silica or the effective lifetime of a biosensor in cells.…”

Biphasic Approach for the Synthesis of Au Nanoparticles via Diffusional Release of Gallic Acid from Supramolecular Hydrogels to Aqueous Solutions: Implications for Biomedical Applications

“…Plasmonic nanoparticles (NPs) such as gold (Au NPs) and silver nanoparticles (Ag NPs) are unique nanomaterials mainly due to their optical and electronic properties given by localized surface plasmon resonance (LSPR). − These NPs have demonstrated potential applications in catalysis, nanomedicine, sensing, optoelectronics, and bioimaging, among others. − In this sense, using different metallic NPs for catalytic reaction-based therapy or disease diagnosis has been highlighted recently. − Basically, the designed nanomaterial catalyzes the generation of a reaction product suitable for therapeutic or diagnostic purposes in a specific environment. This therapy, known as nanocatalytic therapy, could be used for cancer treatments, taking full advantage of the physiological differences between tumoral and normal tissues for triggering a specific reaction, such as low pH, overproduction of H 2 O 2 , and glutathione concentration, among others .…”