Magnetic Nanodiamonds Research Articles

Multifunctional ferromagnetic nanodiamond for dual-mode fluorescence imaging and magnetic drug targeting

The use of nanoparticles as drug delivery vehicles has been receiving much attention in recent years, especially for cancer treatment, with high hope to develop nanocarriers that can deliver therapeutic compounds to the target sites more efficiently. Magnetic drug targeting can be an effective way to deliver drugs to specific areas controlled by magnetic fields at the tumor area; possible to guide and transport anticancer drugs bound to magnetic materials to the tumor site. In this study, magnetic nanodiamond (MND) particles are used as an efficient drug delivery vehicle which can be targeted and imaged simultaneously. A protein Human serum albumin (HSA) is conjugated to MND to improve dispersion in biological medium and to facilitate controlled release of the drug. The particle loaded with clinical drug doxorubicin (DOX) and the effectiveness of the therapy against the cancer cells in-vitro was studied. The DOX-loaded MNDa-HSA remained stable for a prolonged period, rendering its ability to penetrate and release its drug into cells. When nanodiamond-DOX complexes are exposed to magnetic field (MF), their IC50 values are reduced significantly lower than those of free DOX and MNDa-HSA-DOX (without MF). The results indicate that MNDa-HSA could be a potential carrier for vectoring drugs using an external magnetic field, also enabling to be used as a biolabeling agent which can be tracked using fluorescence imaging.

Room Temperature Magnetic Memory Effect in Nanodiamond/γ-Fe2O3 Composites.

We report a room temperature magnetic memory effect (RT-MME) from magnetic nanodiamond (MND) (ND)/γ-Fe2O3 nanocomposites. The detailed crystal structural analysis of the diluted MND was performed by synchrotron radiation X-ray diffraction, revealing the composite nature of MND having 99 and 1% weight fraction ND and γ-Fe2O3 phases, respectively. The magnetic measurements carried out using a DC SQUID magnetometer show the non-interacting superparamagnetic nature of γ-Fe2O3 nanoparticles in MND have a wide distribution in the blocking temperature. Using different temperature, field, and time relaxation protocols, the memory phenomenon in the DC magnetization has been observed at room temperature (RT). These findings suggest that the dynamics of MND are governed by a wide distribution of particle relaxation times, which arise from the distribution of γ-Fe2O3 nanoparticle size. The observed RT ferromagnetism coupled with MME in MND will find potential applications in ND-based spintronics.

Fabrication and characterization of SiO2@Fe3O4@nanodiamonds for vortex-assisted magnetic solid-phase extraction of lead in cigarette samples prior to FAAS detection

A novel, speed and accurate vortex-assisted magnetic solid-phase extraction procedure for separation–preconcentration and flame atomic absorption spectrometric determination of lead at trace levels has been proposed. Silica-coated magnetic nanodiamonds (SiO2@MNDs) as magnetic solid-phase extractor were fabricated and characterized by Fourier transform infrared spectroscopy, X-ray diffraction spectrometry and scanning electron microscopy. Pb(II) could be easily separated from the aqueous solution on the SiO2@MNDs by using a neodymium magnet. Analytical factors affecting the recoveries of Pb(II) such as pH, adsorbent amount, type and volume of eluent and sample volume were optimized. The preconcentration factor, the precision (RSD %, n = 5), the limit of detection and the limit of quantification were 5, 5.3%, 40.8 and 135 µg L−1, respectively. The effects of matrix ions have been investigated. The presented extraction method has been applied for the determination of lead in cigarette samples and Bush Branches and Leaves certified reference material. Quantitative recoveries changing from 94 to 106% were obtained for accuracy studies.

Secondary ion mass spectrometry to verify the implantation of magnetic ions in nanodiamonds

Ion implantation is used to create nanodiamonds (NDs) with embedded magnetic ions for use in a wide range of biological and medical applications; however, the effectiveness of this process depends heavily on separating magnetic NDs from nonmagnetic ones. In this study, we use secondary ion mass spectrometry to verify the implantation of magnetic ions in NDs and the success of separation. When applied to a series of NDs with embedded iron or manganese ions, the sorting tool used in this study proved highly effective in selecting magnetic NDs. Besides, multienergy ion implantation and precise thickness control of NDs coating on the silicon wafer were suggested to improve this technology.

Iron embedded magnetic nanodiamonds for in vivo MRI contrast enhancement

Although nanodiamonds have long being considered as a potential tool for biomedical research, the practical in vivo magnetic resonance imaging (MRI) application of nanodiamonds remains relatively unexplored. In this paper, we present the first application of in vivo MRI contrast enhancement using only iron embedded magnetic nanodiamonds. An MR image enhancement was clearly demonstrated in the rendering of T2-weighted images of mice obtained using an unmodified commercial MRI scanner. The excellent contrast obtained using these nanodiamonds opens the door to the non-invasive in vivo tracking of nanodiamonds and image enhancement. In the future, one can apply these magnetic nanodiamonds together with surface modifications to facilitate drug delivery, targeted therapy, localized thermal treatment, and diagnostic imaging.

Fluorescent Fe Embedded Magnetic Nanodiamonds Made by Ion Implantation

We demonstrate fluorescent Fe embedded magnetic nanodiamonds by ion implantation and two-step annealing. The diamond characteristics with a highly ordered core and a graphite surface layer are maintained after the implantation process. After the two-step annealing process, a bright red fluorescence associated with nitrogen-vacancy centers is observed. These new fluorescent magnetic nanodiamonds can be used as a dual-function in vivo tracer with both optical visibility and magnetic resonance imaging capabilities. They are potentially useful for the more advanced in vivo biological and medical applications.

Fe Doped Magnetic Nanodiamonds Made by Ion Implantation as Contrast Agent for MRI

We report in this paper a new MRI contrast agent based on magnetic nanodiamonds fabricated by Fe ion implantation. The Fe atoms that are implanted into the nanodiamonds are not in direct contact with the outside world, enabling this new contrast agent to be free from cell toxicity. The image enhancement was shown clearly through T2 weighted images. The concentration dependence of the T2 relaxation time gives a relaxivity value that is about seven times that of the regular non-magnetic nanodiamonds. Cell viability study has also been performed. It was shown that they were nearly free from cytotoxicity independent of the particle concentration used. The imaging capability demonstrated here adds a new dimension to the medical application of nanodiamonds. In the future one will be able to combine this capability of magnetic nanodiamonds with other functions through surface modifications to perform drug delivery, targeted therapy, localized thermal treatment and diagnostic imaging at the same time.

Multifunctional biomedical applications of magnetic nanodiamond (Erratum)

This errata corrects an error in “Multifunctional biomedical applications of magnetic nanodiamond.”

Multifunctional biomedical applications of magnetic nanodiamond

The research and development for biomedical applications are recently focused on multifunctional nanoparticles. To integrate various functionalities, different methods of modifying the particle’s physical properties are developed. Among the considered, nanodiamond (ND) is a promising candidate for the development of multifunctional complex due to its variable features in size, structure, surface chemistry, physical properties, and biocompatibility. In addition to its well-studied structural, surface, electrochemical and photonic properties, strong magnetism of ND can be observed. In the present work, magnetically modified ND is introduced in terms of its bioapplications. Along with the soft ferromagnetism of ND, the increased fluorescence at one- and two-photon excitation is realized. Utilizing the combined magnetic and fluorescence properties of the magnetically modified ND, fluorescence imaging, fluorescence lifetime imaging and manipulation of cells by magnetic field are demonstrated. The perspectives to use the magnetic ND for drug delivery, cells magnetic separation and filtration, in bioengineering to control the cell distribution combined with imaging and treatment are discussed.

Fe doped Magnetic Nanodiamonds made by Ion Implantation

Here we present a simple physical method to prepare magnetic nanodiamonds (NDs) using high dose Fe ion-implantation. The Fe atoms are embedded into NDs through Fe ion-implantation and the crystal structure of NDs are recovered by thermal annealing. The results of TEM and Raman examinations indicated the crystal structure of the Fe implanted NDs is recovered completely. The SQUID-VSM measurement shows the Fe-NDs possess room temperature ferromagnetism. That means the Fe atoms are distributed inside the NDs without affecting NDs crystal structure, so the NDs can preserve the original physical and chemical properties of the NDs. In addition, the ion-implantation-introduced magnetic property might make the NDs to become suitable for variety of medical applications.

Cancer cell labeling and tracking using fluorescent and magnetic nanodiamond

Nanodiamond, a promising carbon nanomaterial, develops for biomedical applications such as cancer cell labeling and detection. Here, we establish the nanodiamond-bearing cancer cell lines using the fluorescent and magnetic nanodiamond (FMND). Treatment with FMND particles did not significantly induce cytotoxicity and growth inhibition in HFL-1 normal lung fibroblasts and A549 lung cancer cells. The fluorescence intensities and particle complexities were increased in a time- and concentration-dependent manner by treatment with FMND particles in lung cancer cells; however, the existence of FMND particles inside the cells did not alter cellular size distribution. The FMND-bearing lung cancer cells could be separated by the fluorescent and magnetic properties of FMNDs using the flow cytometer and magnetic device, respectively. The FMND-bearing cancer cells were identified by the existence of FMNDs using flow cytometer and confocal microscope analysis. More importantly, the cell morphology, viability, growth ability and total protein expression profiles in the FMND-bearing cells were similar to those of the parental cells. The separated FMND-bearing cells with various generations were cryopreservation for further applications. After re-thawing the FMND-bearing cancer cell lines, the cells still retained the cell survival and growth ability. Additionally, a variety of human cancer types including colon (RKO), breast (MCF-7), cervical (HeLa), and bladder (BFTC905) cancer cells could be used the same strategy to prepare the FMND-bearing cancer cells. These results show that the FMND-bearing cancer cell lines, which reserve the parental cell functions, can be applied for specific cancer cell labeling and tracking.

Preparation of Fluorescent Magnetic Nanodiamonds and Cellular Imaging

Magnetic nanodiamonds were prepared via solid-state microwave arcing of a nanodiamond-ferrocene mixed powder in a focused microwave oven. High-resolution transmission electron microscope (HRTEM) images show that a magnetic nanodiamond is composed of iron nanoparticles encapsulated by graphene layers on the surface of nanodiamonds. Fluorescence property was introduced onto magnetic nanodiamonds by chemical modification of magnetic nanodiamonds via surface grafting of poly(acrylic acids) and fluorescein o-methacrylate. Fluorescent magnetic nanodiamonds are water soluble with a solubility of approximately 2.1 g/L. Cellular-imaging experiments show that fluorescent magnetic nanodiamonds could be ingested by HeLa cells readily in the absence of agonist (i.e., folate) moieties on the surface of nanodiamonds.