Fe₃O₄@SiO₂ Nanoparticles Functionalized with Gold and Poly(vinylpyrrolidone) for Bio-Separation and Sensing Applications

Abstract

Large Fe3O4@SiO2 nanoparticles (∼200 nm) functionalized with gold and poly­(vinylpyrrolidone) have been synthesized, characterized, and evaluated for bioseparation and sensing applications. The particles have been characterized using a combination of experimental techniques including ultraviolet visible spectroscopy, energy-dispersive spectroscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, electron microscopy, superconducting quantum interference device magnetrometry, and surface-enhanced Raman sensing (SERS) spectroscopy. The particles have a unique surface morphology comprised of roughened gold nodules. The surface coatings prevent oxidation and render the particles easy to functionalize in order to target a wide range of moieties. The gold coverage is not only uniform across the entire particle surface but also ultrathin so as to maintain a high percentage of the cores magnetic saturation (∼68%) when compared to that of bare magnetite. The gold nodules facilitate the generation of hot spots that enhance the electromagnetic field associated with the particle surface and are therefore useful in sensing applications like SERS, and the strong magnetic core allows for rapid separation (∼30 s) of target molecules from solution once they are bound to the particles.

RETRACTED: Multi‐Stimuli Nanocomposite Therapeutic: Docetaxel Targeted Delivery and Synergies in Treatment of Human Breast Cancer Tumor

“…To enhance the advantageous plasmonic properties of AuNPs, AuNP composites with other metals and metal oxides have been prepared and investigated in diverse applications. [39][40][41][42][43][44][45] The primary purpose of designing this composite is to enable the magnetic delivery of AuNPs to the target tissues, where PPTT can enhance the thermal release by the PVA network by incorporating AuNPs into nanocomposite materials with Fe 3 O 4 NPs via AuS bonding. [27] Herein, for the nanocomposite therapeutic design in this work, the PVA ability to incorporate and release DXL was combined with the functionalities of gold and iron oxide NPs to create Au/Fe 3 O 4 /PVA-10%DXL.…”

“…The composite system that has been studied the most for cancer treatment is one that integrates the gold and iron oxide. [39][40][41][42][43][44] In general, gold nanoparticles (AuNPs) represent an important class of anticancer agents due to their significant role in the inhibition of tumor metastasis, photodynamic [28] and plasmonic photothermal therapy (PPTT). [29,30] Specifically, unique plasmonic properties of AuNPs, that can be tailored in the designed nanocomposites, play an important role in controlling and modulating drug release inside the tumor cells.…”

Design of Magnetic‐Plasmonic Nanoparticle Assemblies via Interface Engineering of Plasmonic Shells for Targeted Cancer Cell Imaging and Separation

“…The estimated EF is comparable to other SERS probes exhibiting magnetic properties and is analogous to various plasmonic metal nanostructures despite the existence of the Fe 3 O 4 core. [ 21–23,49,50 ] Furthermore, the magnetic hysteresis loop of the S3 NPs displayed superparamagnetic‐like properties at RT with a saturation magnetization of 29.4 emu g −1 (Figure S9, Supporting Information). The decreased value of saturation magnetization was mainly due to the plasmonic part and the silica layer.…”

“…[ 17–19 ] In particular, MP NPs simultaneously exhibiting magnetic and surface‐enhanced Raman scattering (SERS) activities have been researched due to their synergistic properties in biomedical applications. [ 20–24 ] In detail, non‐destructive and sensitive analysis of the SERS technique and separating ability based on the magnetic properties could provide convenient and significant tools in sensing of target molecules or cells. [ 20–25 ] However, it is difficult to satisfy the designing criteria for high performances in bio‐applications: low remanence for preventing particle aggregation, maximized magnetic contents for high saturation magnetization, plasmonic coverage with abundant hotspots, and structural precision and uniformity for signal reproducibility.…”

“…[ 20–24 ] In detail, non‐destructive and sensitive analysis of the SERS technique and separating ability based on the magnetic properties could provide convenient and significant tools in sensing of target molecules or cells. [ 20–25 ] However, it is difficult to satisfy the designing criteria for high performances in bio‐applications: low remanence for preventing particle aggregation, maximized magnetic contents for high saturation magnetization, plasmonic coverage with abundant hotspots, and structural precision and uniformity for signal reproducibility. For achieving these criteria, this requires an increased level of synthetic sophistication with consideration of the size‐dependent properties of both magnetic and plasmonic nanostructures, the interfacial energy between dissimilar materials, and the role of surface ligands in the crystal growth.…”