Gold and magnetic oxide/gold core/shell nanoparticles as bio-functional nanoprobes

Abstract

The ability to create bio-functional nanoprobes for the detection of biological reactivity is important for developing bioassay and diagnostic methods. This paper describes the findings of an investigation of the surface functionalization of gold (Au) and magnetic nanoparticles coated with gold shells (M/Au) by proteins and spectroscopic labels for the creation of nanoprobes for use in surface enhanced Raman scattering (SERS) assays. Highly monodispersed Au nanoparticles and M/Au nanoparticles with two types of magnetic nanoparticle cores (Fe(2)O(3) and MnZn ferrite) were studied as model systems for the bio-functionalization and Raman labeling. Comparison of the SERS intensities obtained with different particle sizes (30-100 nm) and samples in solution versus on solid substrates have revealed important information about the manipulation of the SERS signals. In contrast to the salt-induced uncontrollable and irreversible aggregation of nanoparticles, the ability to use a centrifugation method to control the formation of stable small clustering sizes of nanoparticles was shown to enhance SERS intensities for samples in solution as compared with samples on solid substrates. A simple method for labeling protein-capped Au nanoparticles with Raman-active molecules was also described. The functionalized Au and M/Au nanoparticles are shown to exhibit the desired functional properties for the detection of SERS signals in the magnetically separated reaction products. These results are discussed in terms of the interparticle distance dependence of 'hot-spot' SERS sites and the delineation of the parameters for controlling the core-shell reactivity of the magnetic functional nanocomposite materials in bio-separation and spectroscopic probing.

Recent advances in surface engineering of superparamagnetic iron oxide nanoparticles for biomedical applications

“…A mixture of the gold NPs encapsulated with the monolayer shell, olic-SPIONs or (oleyamine -SPIONs), and tetraocytylammonim bromide in tolune was prepared and heated at 149 °C for 1 h. The resulting NPs were found to be Fe 2 O 3 @Au and can be used for bio-separation. Lim et al [263] utilized these NPs as bio-functional nanoprobes for surface enhanced Ramman scattering assay.…”

“…Furthermore, the intracellular production of reactive oxygen species as well as oxidative stress is recognized as other toxicity mechanism of SPIONs. In order to relieve of these potential toxicity arising problems, SPIONs should be covered by rigid organic or inorganic coatings such as silica [29], gold [263,293] or crosslinked polymers [25].…”

In-situ immobilization of quantum dots in polysaccharide-based nanogels for integration of optical pH-sensing, tumor cell imaging, and drug delivery

“…The development of multifunctional nanomaterials combining diagnostic and therapeutic purpose has recently attracted intensive interests [1][2][3][4][5][6]. Semiconductor nanocrystals known as quantum dots (QDs) are particularly appealing for bioimaging and labeling probes due to their unique optical properties, including broad absorption with narrow photoluminescence (PL) spectra, high quantum yield, low photobleaching, and resistance to chemical degradation [2][3][4][5][6][7][8][9][10][11][12].…”

“…Semiconductor nanocrystals known as quantum dots (QDs) are particularly appealing for bioimaging and labeling probes due to their unique optical properties, including broad absorption with narrow photoluminescence (PL) spectra, high quantum yield, low photobleaching, and resistance to chemical degradation [2][3][4][5][6][7][8][9][10][11][12]. Typically, QDs are conjugated with biological and low-cytotoxic ligands, including antibodies, peptides, sugars, folic acid, and biopolymers for labeling and imaging applications.…”

Highly Sensitive Magnetic-SERS Dual-Function Silica Nanoprobes for Effective On-Site Organic Chemical Detection

“…They are usually exploited for the separation of cells [18] or small molecules [19] because NP's movement is easily controlled by applying an external magnetic field. Such a special modality could be combined with SERS to acquire a synergetic effect for on-site chemical detection.…”