Multifunctional Silver‐Embedded Magnetic Nanoparticles as SERS Nanoprobes and Their Applications

Abstract

In this study, surface-enhanced Raman spectroscopy (SERS)-encoded magnetic nanoparticles (NPs) are prepared and utilized as a multifunctional tagging material for cancer-cell targeting and separation. First, silver-embedded magnetic NPs are prepared, composed of an 18-nm magnetic core and a 16-nm-thick silica shell with silver NPs formed on the surface. After simple aromatic compounds are adsorbed on the silver-embedded magnetic NPs, they are coated with silica to provide them with chemical and physical stability. The resulting silica-encapsulated magnetic NPs (M-SERS dots) produce strong SERS signals and have magnetic properties. In a model application as a tagging material, the M-SERS dots are successfully utilized for targeting breast-cancer cells (SKBR3) and floating leukemia cells (SP2/O). The targeted cancer cells can be easily separated from the untargeted cells using an external magnetic field. The separated targeted cancer cells exhibit a Raman signal originating from the M-SERS dots. This system proves to be an efficient tool for separating targeted cells. Additionally, the magnetic-field-induced hot spots, which can provide a 1000-times-stronger SERS intensity due to aggregation of the NPs, are studied.

Multifunctional Au‐Coated TiO2 Nanotube Arrays as Recyclable SERS Substrates for Multifold Organic Pollutants Detection

“…[ 19 ] Similarly, multifunctional silver-embedded magnetic nanoparticles as SERS probes for cancer-cell targeting and separation have been reported by Lee and co-workers. [ 20 ] Conversely, there are few reports about a renewable SERS substrate that can reverse the problem of facing only one-time detection. Recently, two research groups prepared renewable SERS substrates by cyclic depositing a string of silver shells and by using silverloaded agarose gels, respectively.…”

Nanoparticles in biomedical applications

“…Silver nanoparticles have unique physicochemical properties such as high electrical conductivity, thermal conductivity, chemical stability, catalytic activity, antibacterial and enhanced optical properties [131,132]. These properties have led to the use of silver nanoparticles in electronic, photonic, antimicrobial and disinfectant applications [133][134][135][136][137][138][139][140][141][142][143]. Because of silver nanoparticles extraordinary antimicrobial activity it is mainly used in the medical industry for textiles, wound dressings and device coatings.…”

“…Because of silver nanoparticles extraordinary antimicrobial activity it is mainly used in the medical industry for textiles, wound dressings and device coatings. However, the use of silver nanoparticles in biomedical applications such as biosensors [133][134][135] photothermal therapy and drug delivery [144][145][146][147][148][149][150][151][152][153][154] is increasing and will be discussed in Section 4.…”

Phase transformation of iron oxide–silica coreshell structure during differential scanning calorimetry and pulsed electric current sintering processes: A comparison

“…The SiO 2 surface layer, in addition to maintaining the stability and protecting the magnetic particles against oxidation or erosion by acids or base, also provides an active surface for attachment of noble metals and functional groups [3]. Furthermore, the SiO 2 matrix also can act as either an anti-oxidation or reduction agent for magnetic core particles especially the iron oxide (magnetite, Fe 3 O 4 and maghemite, g-Fe 2 O 3 ) during thermal heating, its effectiveness depending on the atmosphere, temperature and the content of magnetic particles [2].…”