Multifunctional superparamagnetic nanoshells: combining two-photon luminescence imaging, surface-enhanced Raman scattering and magnetic separation

Abstract

With the increasing need for multi-purpose analysis in the biomedical field, traditional single diagnosis methods cannot meet the requirements. Therefore new multifunctional technologies and materials for the integration of sample collection, sensing and imaging are in great demand. Core-shell nanoparticles offer a unique platform to combine multifunctions in a single particle. In this work, we have constructed a novel type of core-shell superparamagnetic nanoshell (Fe₃O₄@SiO₂@Au), composed of a Fe₃O₄ cluster core, a thin Au shell and a SiO₂ layer in between. The obtained multifunctional nanoparticles combine the magnetic properties and plasmonic optical properties effectively, which were well investigated by a number of experimental characterization methods and theoretical simulations. We have demonstrated that Fe₃O₄@SiO₂@Au nanoparticles can be utilized for two-photon luminescence (TPL) imaging, near-infrared surface-enhanced Raman scattering (NIR SERS) and cell collection by magnetic separation. The TPL intensity could be further greatly enhanced through the plasmon coupling effect in the self-assembled nanoparticle chains, which were triggered by an external magnetic field. In addition, Fe₃O₄@SiO₂@Au nanoparticles may have great potential applications such as enhanced magnetic resonance imaging (MRI) and photo-thermotherapy. Successful combination of multifunctions including magnetic response, biosensing and bioimaging in single nanoparticles allows further manipulation, real-time tracking, and intracellular molecule analysis of live cells at a single-cell level.

Versatile design and synthesis of nano-barcodes

“…The uptake of barcodes by human umbilical vein endothelial cells showed their imaging ability at the single cell level with the potential to be used for real-time monitoring of cellular events. 252 SERS encoded hollow nanospheres conjugated with antibodies on the surface were used for multiplex imaging of the epidermal growth factor (EGF), ErbB2, and insulin-like growth factor-1 (IGF-1) for three human breast cancer cell lines MDA-MB-468, KPL4 and SK-BR-3. 253 Multiple codes generated by encoding different SERS reporter molecules to gold nanostars have also demonstrated the multiplex imaging of five different types of breast cancer cells present in a cell coculture.…”

Multimodal Magnetic-Plasmonic Nanoparticles for Biomedical Applications

“…Gelatin was used as a mediator as it can be degraded by a subclass of matrix metalloproteinases, and superparamagnetic Fe3O4 nanoparticles have been shown to be biodegradable in vivo. A similar approach was used by Jin et al-except in this case an APTES functionalised silica coating is used in place of gelatin, and THPC is also used to reduce a layer of gold onto the Fe3O4 nanoparticles [50]. An interesting method of obtaining concave magneto-plasmonic core-shell supraparticles is used by Lee et al [51].…”

Plasmonic nanoshells enhanced laser desorption/ionization mass spectrometry for detection of serum metabolites

“…Au nanoshells NPs were fabricated by following previous reports [42,43]. Briefly, silica particles were synthesized following a St€ ober process by mixing ammonia and absolute ethanol, followed by adding TEOS dropwise.…”

“…A subsequent 10 min reduction in an overnight-aged mixture of HAuCl 4 (3 mL, 1%) and K 2 CO 3 (100 mL, 3.6 mM) in the presence of formaldehyde (5 mL) resulted in a continuous Au shell on the silica surface. The nanoparticles were centrifuged after reaction and re-dispersed in water to form a stable suspension [18,43]. The averaged dimension of obtained Au nanoshells was a 100 nm core in diameter and a 33 nm Au shell in thickness (an outer diameter of 166 nm).…”