Search

Featured Application: This magnetic marker material is used for large-scale field signal marking, offering the advantages of stable, rapid, and portable detection. With the widespread application of tagging materials, existing chemical tagging materials exhibit limitations in stability and detection under field conditions. This study introduces a novel magnetic detection scheme. Hydrophilic material-modified Fe3O4 nanoparticles (COOH-PEG@Fe3O4 NPs) were synthesized using the co-precipitation technique. The content of Fe3O4 nanoparticles in the magnetic tagging liquid can reach up to 10 wt% and remain stable in an aqueous phase system for seven days. This research details the preparation process, the characterization methods (IR, 1HNMR, EDX, XRD, SEM, TEM, VSM, DLS), and the performance effects of the materials in magnetic tagging. Experimental results indicate that COOH-PEG@Fe3O4 NPs exhibit high remanence intensity (Br = 1.75 emu/g) and considerable stability, making it possible to quickly detect tagged liquids in the field using portable flux meters and optical pump magnetometers. This study provides new insights into the design and application of magnetic tagging materials, making it particularly suitable for long-term tagging and convenient detection in field scenarios. [ABSTRACT FROM AUTHOR]

With the widespread application of tagging materials, existing chemical tagging materials exhibit limitations in stability and detection under field conditions. This study introduces a novel magnetic detection scheme. Hydrophilic material-modified Fe3O4 nanoparticles (COOH-PEG@Fe3O4 NPs) were synthesized using the co-precipitation technique. The content of Fe3O4 nanoparticles in the magnetic tagging liquid can reach up to 10 wt% and remain stable in an aqueous phase system for seven days. This research details the preparation process, the characterization methods (IR, 1HNMR, EDX, XRD, SEM, TEM, VSM, DLS), and the performance effects of the materials in magnetic tagging. Experimental results indicate that COOH-PEG@Fe3O4 NPs exhibit high remanence intensity (Br = 1.75 emu/g) and considerable stability, making it possible to quickly detect tagged liquids in the field using portable flux meters and optical pump magnetometers. This study provides new insights into the design and application of magnetic tagging materials, making it particularly suitable for long-term tagging and convenient detection in field scenarios.

Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great variety of commercially available separation instruments and reagents, which has permitted rapid dissemination of the technology. However, there is still an increasing demand for new tools and protocols which provide improved selectivity, yield and sensitivity of the separation process while reducing cost and providing a faster response. This review aims to introduce basic principles of magnetic cell separation for the neophyte, while giving an overview of recent research in the field, from the development of new cell labeling strategies to the design of integrated microfluidic cell sorters and of point-of-care platforms combining cell selection, capture, and downstream detection. Finally, we focus on clinical, industrial and environmental applications where magnetic cell separation strategies are amongst the most promising techniques to address the challenges of isolating rare cells.

The factors that affect the labeling of NIH 3T3 murine fibroblasts with Fe3O4-based magnetic nanoparticles (MNPs) were studied using MNPs produced by the gas condensation and solution precipitation methods and MNPs surface-modified with 3-aminopropylsilane or L-lysine. The production method, surface modifications, the particle concentration and size, the state of the cell population, and the method of MNP introduction were found to substantially affect the efficiency of MNP binding by cells. In particular, large MNP clusters may occur in MNP suspensions in DMSO, and their disruption by sonication increased the percent yield of magnetically labeled cells. Static incubation of a cell suspension led to a more efficient labeling as compared with continuous agitation. Cells attached to a plastic support could be labeled to a higher degree than cells in suspension, but required substantially longer incubations with MNPs. MNP centrifugation on cell layers (magnetic spinoculation) significantly increased the rate and efficiency of labeling. The stability of magnetic labeling was shown to depend on the MNP dose during labeling. Electron microscopy studies demonstrated that MNPs were associated with the cell surface after 20-min incubation with cells and were mostly in the cell interior after 4-h incubation. The results of the study may be useful for preparation and application of magnetized cell samples. [ABSTRACT FROM AUTHOR]

Magnetic resonance imaging (MRI) provides a unique tool for in vivo visualization and tracking of stem cells in the brain. This is of particular importance when assessing safety of experimental cell treatments in the preclinical or clinical setup. Yet, specific imaging requires an efficient and non-perturbing cellular magnetic labeling which precludes adverse effects of the tag, e.g., the impact of iron-oxide-nanoparticles on the critical differentiation and integration processes of the respective stem cell population investigated. In this study we investigated the effects of very small superparamagnetic iron oxide particle (VSOP) labeling on viability, stemness, and neuronal differentiation potential of primary human adult neural stem cells (haNSCs). Cytoplasmic VSOP incorporation massively reduced the transverse relaxation time T2, an important parameter determining MR contrast. Cells retained cytoplasmic label for at least a month, indicating stable incorporation, a necessity for long-term imaging. Using a clinical 3T MRI, 1 × 103 haNSCs were visualized upon injection in a gel phantom, but detection limit was much lower (5 × 104 cells) in layer phantoms and using an imaging protocol feasible in a clinical scenario. Transcriptional analysis and fluorescence immunocytochemistry did not reveal a detrimental impact of VSOP labeling on important parameters of cellular physiology with cellular viability, stemness and neuronal differentiation potential remaining unaffected. This represents a pivotal prerequisite with respect to clinical application of this method.

Magnetic resonance imaging (MRI) provides a unique tool for in vivo visualization and tracking of stem cells in the brain. This is of particular importance when assessing safety of experimental cell treatments in the preclinical or clinical setup. Yet, specific imaging requires an efficient and non-perturbing cellular magnetic labeling which precludes adverse effects of the tag, e.g., the impact of iron-oxide-nanoparticles on the critical differentiation and integration processes of the respective stem cell population investigated. In this study we investigated the effects of very small superparamagnetic iron oxide particle (VSOP) labeling on viability, stemness, and neuronal differentiation potential of primary human adult neural stem cells (haNSCs). Cytoplasmic VSOP incorporation massively reduced the transverse relaxation time T2, an important parameter determining MR contrast. Cells retained cytoplasmic label for at least a month, indicating stable incorporation, a necessity for long-term imaging. Using a clinical 3T MRI, 1 × 103 haNSCs were visualized upon injection in a gel phantom, but detection limit was much lower (5 × 104 cells) in layer phantoms and using an imaging protocol feasible in a clinical scenario. Transcriptional analysis and fluorescence immunocytochemistry did not reveal a detrimental impact of VSOP labeling on important parameters of cellular physiology with cellular viability, stemness and neuronal differentiation potential remaining unaffected. This represents a pivotal prerequisite with respect to clinical application of this method. [ABSTRACT FROM AUTHOR]

With superior biocompatibility and unique magnetic properties, iron-based nanoparticles (IBNP) are commonly encapsulated in cells and extracellular vesicles (EV) to allow for magnetic force controlled drug delivery and non-invasive tracking. Based on their natural source and similar morphology, we classify both cells and EVs as being natural lipid encapsulations (NLEs), distinguishing them from synthetic liposomes. Both their imaging contrast and drug effects are dominated by the amount of iron encapsulated in each NLE, demonstrating the importance of magnetic labeling efficiency. It is known that the membranes function as barriers to ensure that substances pass in and out in an orderly manner. The most important issue in increasing the cellular uptake of IBNPs is the interaction between the NLE membrane and IBNPs, which has been found to be affected by properties of the IBNPs as well as NLE heterogeneity. Two aspects are important for effective magnetic labelling: First, how to effectively drive membrane wrapping of the nanoparticles into the NLEs, and second, how to balance biosafety and nanoparticle uptake. In this review, we will provide a systematic overview of the magnetic labeling of NLEs with IBNPs. This article provides a summary of the applications of magnetically labeled NLEs and the labeling methods used for IBNPs. The review also analyzes the role of IBNPs physicochemical properties, especially their magnetic properties, and the heterogeneity of NLEs in the internalization pathway. At the same time, the future development of magnetically labeled NLEs is also discussed. [ABSTRACT FROM AUTHOR]

Specific labelling of target cell surfaces using antibody-conjugated paramagnetic nanobeads is essential for efficient magnetic cell separation. However, studies examining parameters determining the kinetics of bead-cell binding are scarce. The present study determines the binding rates for specific and unspecific binding of 150 nm paramagnetic nanobeads to highly purified target and non-target cells. Beads bound to cells were enumerated spectrophotometrically. Results show that the initial bead-cell binding rate and saturation levels depend on initial bead concentration and fit curves of the form A(1 − exp(−kt)). Unspecific binding within conventional experimental time-spans (up to 60 min) was not detectable photometrically. For CD3-positive cells, the probability of specific binding was found to be around 80 times larger than that of unspecific binding.

Bacterial contamination of water sources (e.g., lakes, rivers and springs) from waterborne bacteria is a crucial water safety issue and its prevention is of the utmost significance since it threatens the health and well-being of wildlife, livestock, and human populations and can lead to serious illness and even death. Rapid and multiplexed measurement of such waterborne pathogens is vital and the challenge is to instantly detect in these liquid samples different types of pathogens with high sensitivity and specificity. In this work, we propose a biosensing system in which the bacteria are labelled with streptavidin coated magnetic markers (MPs—magnetic particles) forming compounds (MLBs—magnetically labelled bacteria). Video microscopy in combination with a particle tracking software are used for their detection and quantification. When the liquid containing the MLBs is introduced into the developed, microfluidic platform, the MLBs are accelerated towards the outlet by means of a magnetic field gradient generated by integrated microconductors, which are sequentially switched ON and OFF by a microcontroller. The velocities of the MLBs and that of reference MPs, suspended in the same liquid in a parallel reference microfluidic channel, are calculated and compared in real time by a digital camera mounted on a conventional optical microscope in combination with a particle trajectory tracking software. The MLBs will be slower than the reference MPs due to the enhanced Stokes’ drag force exerted on them, resulting from their greater volume and altered hydrodynamic shape. The results of the investigation showed that the parameters obtained from this method emerged as reliable predictors for E. coli concentrations.

The majority of algal cells can interact with a wide range of nano- and microparticles. Upon interaction the modified cells usually maintain their viability and the presence of foreign material on their surfaces or in protoplasm can provide additional functionalities. Magnetic modification and labeling of microalgal biomass ensures a wide spectrum of biotechnological, bioanalytical and environmental applications. Different aspects of microalgal cell magnetic modification are covered in the review, followed by successful applications of magnetic algae. Modified cells can be employed during their harvesting and removal, applied in toxicity microscreening devices and also as efficient adsorbents of different types of xenobiotics. [ABSTRACT FROM AUTHOR]

Cell labeling with magnetic iron oxide nanoparticles (IONPs) is increasingly a routine approach in the cell-based cancer treatment. However, cell labeling with magnetic IONPs and their leading effects on the biological properties of human lung carcinoma cells remain scarcely reported. Therefore, in the present study the magnetic γ-FeO nanoparticles (MNPs) were firstly synthesized and surface-modified with cationic poly- l-lysine (PLL) to construct the PLL-MNPs, which were then used to magnetically label human A549 lung cancer cells. Cell viability and proliferation were evaluated with propidium iodide/fluorescein diacetate double staining and standard 3-(4,5-dimethylthiazol-2-diphenyl-tetrazolium) bromide assay, and the cytoskeleton was immunocytochemically stained. The cell cycle of the PLL-MNP-labeled A549 lung cancer cells was analyzed using flow cytometry. Apoptotic cells were fluorescently analyzed with nuclear-specific staining after the PLL-MNP labeling. The results showed that the constructed PLL-MNPs efficiently magnetically labeled A549 lung cancer cells and that, at low concentrations, labeling did not affect cellular viability, proliferation capability, cell cycle, and apoptosis. Furthermore, the cytoskeleton in the treated cells was detected intact in comparison with the untreated counterparts. However, the results also showed that at high concentration (400 µg mL), the PLL-MNPs would slightly impair cell viability, proliferation, cell cycle, and apoptosis and disrupt the cytoskeleton in the treated A549 lung cancer cells. Therefore, the present results indicated that the PLL-MNPs at adequate concentrations can be efficiently used for labeling A549 lung cancer cells and could be considered as a feasible approach for magnetic targeted anti-cancer drug/gene delivery, targeted diagnosis, and therapy in lung cancer treatment. [ABSTRACT FROM AUTHOR]

Specific labelling of target cell surfaces using antibody-conjugated paramagnetic nanobeads is essential for efficient magnetic cell separation. However, studies examining parameters determining the kinetics of bead-cell binding are scarce. The present study determines the binding rates for specific and unspecific binding of 150 nm paramagnetic nanobeads to highly purified target and non-target cells. Beads bound to cells were enumerated spectrophotometrically. Results show that the initial bead-cell binding rate and saturation levels depend on initial bead concentration and fit curves of the form A(1 - exp(-kt)). Unspecific binding within conventional experimental time-spans (up to 60 min) was not detectable photometrically. For CD3-positive cells, the probability of specific binding was found to be around 80 times larger than that of unspecific binding. [ABSTRACT FROM AUTHOR]

Effective therapies for malignant tumors are needed, and magnetic hyperthermia has shown positive results in biomedical studies. Here, we optimize the magnetic labeling process for intracellular hyperthermia and evaluate the cytotoxicity effects of cervical cancer cell (HeLa) mediated by intracellular hyperthermia. Experimentally, cells were incubated with different concentrations of 10 nm anionic iron oxide nanoparticles, and the incubation times varied from 6 to 24 h. Iron stain (Prussian blue) and magnetophoresis were performed to evaluate the efficiency of cells internalizing the nanoparticles. An optimized condition for intracellular magnetic label was obtained, and a trypan blue exclusion test analyzed the cytotoxicity effects after cells were exposed to ac magnetic field (f = 21~\kHz, H = 4~\kA/m). Cell viabilities decreased to 49\%\sim50\% immediately after 120 s of treatment. After culturing the cells for 48 h, it was found that only 5\%\sim8\% of cells remained viable. [ABSTRACT FROM PUBLISHER]

Abstract: Magnetic labeling of living cells creates opportunities for numerous biomedical applications. Here we describe an instantly cell magnetic labeling method based on ultrasound. We present a detailed study on the ultrasound performance of a simple and efficient labeling protocol for H-22 cells in vitro. High frequency focus ultrasound was investigated as an alternative method to achieve instant cell labeling with the magnetic particles without the need for adjunct agents or initiating cell cultures. Mean diameter of 168nm dextran-T40 coated superparamagnetic iron oxide (SPIO) nanoparticles were prepared by means of classical coprecipitation in solution in our laboratory. H-22 tumor cells suspended in phosphate-buffered saline (PBS, pH=7.2) were exposed to ultrasound at 1.37MHz for up to 120s in the presence of SPIOs. The cellular uptake of iron oxide nanoparticles was detected by prussion blue staining. The viability of cells was determined by a trypan blue exclusion test. At 2W power and 60s ultrasound exposure in presence of 410μg/ml SPIOs, H-22 cell labeling efficiency reached 69.4±6.3% and the labeled cells exhibited an iron content of 10.38±2.43pg per cell. Furthermore, 95.2±3.2% cells remained viable. The results indicated that the ultrasound protocol could be potentially applied to label cells with large-sized magnetic particles. We also calculated the shear stress at the 2W power and 1.37MHz used in experiments. The results showed that the shear stress threshold for ultrasonically induced H-22 cell reparable sonoporation was 697Pa. These findings provide a quantitative guidance in designing ultrasound protocols for cell labeling. [Copyright &y& Elsevier]

Abstract: Millions of people are stricken with the degenerative joint disease known as osteoarthritis. Osteoarthritis is associated with biochemical and mechanical processes, and is characterized by loss of articular cartilage and hypertrophy of bone. As cartilage and bone particles are released into the synovial fluid, a variety of biomarkers have been suggested for the analysis of this fluid. Here we have developed a method for isolating bone and cartilage wear particles suspended in the synovial fluid of the hip, knee and ankle joints of humans, based on specific magnetization of collagens I and II. Bio-ferrography is used to capture the particles on glass slides, allowing microscopic, chemical and statistical analyses. The relations between the level of the disease and the number, dimensions, shape and chemical composition of the particles were established. The method, which was found to be sensitive and reliable, can easily be extended to other applications, such as diagnosis of cancer and infectious diseases, determination of the efficacy of drugs or optimization of implants. [ABSTRACT FROM AUTHOR]

For efficient labeling and tracking via magnetic resonance (MR) imaging of human mesenchymal stem cells (h-MSCs), magnetic labeling agents must be responsive to an external magnetic field. Thus, we developed ultrasensitive magnetoplex as a magnetic labeling agent composed of PEGylated MnFe2O4 nanocrystals (PMNCs) and polycationics (poly- l-lysine, PLL) for efficient labeling of the h-MSCs and monitoring of the transplanted h-MSCs for a long term. PMNCs were prepared by nanoemulsion methods composed of MnFe2O4 nanocrystals (MNCs) and amphiphilic polymers (mPEG–dodecanoic acid). The prepared PMNCs exhibited excellent biocompatibility and their polycationic complexes (PMNCs/PLL) demonstrated remarkable sensitivity compared with magnetic iron oxide nanoparticles (MION)/PLL or Ferumoxides/PLL. Furthermore, PMNCs demonstrated the potentials for novel diagnostic and therapeutic strategies with potential applications in various biomedical fields. [ABSTRACT FROM AUTHOR]

Abstract: Ultrasmall particles of iron oxide (USPIOs) coated with 3,3′-bis(phosphonate)propionic acid were covalently coupled to a home-made Arg-Gly-Asp (RGD) peptidomimetic molecule via a short oligoethyleneglycol (OEG) spacer. The conjugation rate was measured by X-ray photoelectron spectroscopy (XPS). The particle size and magnetic characteristics were kept. Our novel conjugate targeted efficiently Jurkat cells (increase of 229% vs the control). [Copyright &y& Elsevier]

Detection of magnetically labeled biomolecules is a promising method for fast and inexpensive medical diagnosis. Recently, there has been an increasing interest in using magnetic labels with diameters of 20-150 nm—dimensions that are similar to actual biomolecules. However, detection of small numbers of nanometer-scale magnetic beads (labels) distributed over large surface areas by magnetoresistive devices is extremely challenging due to the intrinsic noise and design limitations of giant magnetoresistance (GMR) and Hall-type of biosensors. Here, we describe proof of principle experiments on exploiting magnetically induced self-assembly of superparamagnetic beads for detecting superparamagnetic nanobeads with diameters of less than 150 nm. We successfully detected low areal densities of ~130 nm diameter superparamagnetic "target beads" immobilized over millimeter-sized substrates, by optically monitoring the "capture" of easily visible, micrometer-sized superparamagnetic beads by the targets. Our procedure could readily be extended for the detection of magnetically labeled biomolecules. [ABSTRACT FROM AUTHOR]

• Iron oxide nanoworms could contribute to CAR-T manufacturing and labeling in vitro. • CAR-T cytotoxicity to tumor cells is not affected by iron oxide nanoworms in vitro.. • CAR-T cells labeled with iron oxide nanoworms could be tracked in vivo. Cell based therapies including chimeric antigen receptor (CAR) T cells are promising for treating leukemias and solid cancers. At the same time, there is interest in enhancing the functionality of these cells via surface decoration with nanoparticles (backpacking). Magnetic nanoparticle cell labeling is of particular interest due to opportunities for magnetic separation, in vivo manipulation, drug delivery and magnetic resonance imaging (MRI). While modification of T cells with magnetic nanoparticles (MNPs) was explored before, we questioned whether MNPs are compatible with CAR-T cells when introduced during the manufacturing process. We chose highly aminated 120 nm crosslinked iron oxide nanoworms (CLIO NWs, ~36,000 amines per NW) that could efficiently label different adherent cell lines and we used CD123 CAR-T cells as the labeling model. The CD123 CAR-T cells were produced in the presence of CLIO NWs, CLIO NWs plus protamine sulfate (PS), or PS only. The transduction efficiency of lentiviral CD123 CAR with only NWs was ~ 23% lower than NW + PS and PS groups (~33% and 35%, respectively). The cell viability from these three transduction conditions was not reduced within CAR-T cell groups, though lower compared to non-transduced T cells (mock T). Use of CLIO NWs instead of, or together with cationic protamine sulfate for enhancement of lentiviral transduction resulted in comparable levels of CAR expression and viability but decreased the proportion of CD8 + cells and increased the proportion of CD4 + cells. CD123 CAR-T transduced in the presence of CLIO NWs, CLIO NWs plus PS, or PS only, showed similar level of cytotoxicity against leukemic cell lines. Furthermore, fluorescence microscopy imaging demonstrated that CD123 CAR-T cells labeled with CLIO NW formed rosettes with CD123 + leukemic cells as the non-labeled CAR-T cells, indicating that the CAR-T targeting to tumor cells has maintained after CLIO NW labeling. The in vivo trafficking of the NW labeled CAR-T cells showed the accumulation of CAR-T labeled with NWs primarily in the bone marrow and spleen. CAR-T cells can be magnetically labeled during their production while maintaining functionality using the positively charged iron oxide NWs, which enable the in vivo biodistribution and tracking of CAR-T cells. [ABSTRACT FROM AUTHOR]

Magnetic cell separation has become a key methodology for the isolation of target cell populations from biological suspensions, covering a wide spectrum of applications from diagnosis and therapy in biomedicine to environmental applications or fundamental research in biology. There now exists a great variety of commercially available separation instruments and reagents, which has permitted rapid dissemination of the technology. However, there is still an increasing demand for new tools and protocols which provide improved selectivity, yield and sensitivity of the separation process while reducing cost and providing a faster response. This review aims to introduce basic principles of magnetic cell separation for the neophyte, while giving an overview of recent research in the field, from the development of new cell labeling strategies to the design of integrated microfluidic cell sorters and of point-of-care platforms combining cell selection, capture, and downstream detection. Finally, we focus on clinical, industrial and environmental applications where magnetic cell separation strategies are amongst the most promising techniques to address the challenges of isolating rare cells. [ABSTRACT FROM AUTHOR]

There is an identified need for point-of-care diagnostic systems for detecting and counting specific rare types of circulating cells in blood. By adequately labeling such cells with immunomagnetic beads and quantum dots, they can be efficiently collected magnetically for quantification using fluorescence methods. Automation of this process requires adequate mixing of the labeling materials with blood samples. A static mixing device can be employed to improve cell labeling efficiency and eliminate error-prone laboratory operations. Computational fluid dynamics (CFD) were utilized to simulate the flow of a labeling-materials/blood mixture through a 20-stage in-line static mixer of the interfacial-surface-generator type. Optimal fluid mixing conditions were identified and tested in a magnetic bead/tumor cell model, and it was found that labeled cells could be produced at 1.0 mL/min flow rate and fed directly into an in-line magnetic trap. The trap design consists of a dual flow channel with three bends and a permanent magnet positioned at the outer curve of each bend. The capture of labeled cells in the device was simulated using CFD, finite-element analysis and magnetophoretic mobility distributions of labeled cells. Testing with cultured CRL14777 human melanoma cells labeled with anti-CD146 1.5 μm diameter beads indicated that 90 ± 10% are captured at the first stage, and these cells can be captured when present in whole blood. Both in-line devices were demonstrated to function separately and together as predicted. [ABSTRACT FROM AUTHOR]

Small particles of iron oxide (SPIO) and ultrasmall particles of iron oxide (USPIO), inducing a strong negative contrast on T2 and T2*-weighted MR images, are the most commonly used systems for the magnetic labeling of cultured cells and their subsequent detection by magnetic resonance imaging (MRI). The purpose of this work is to study the influence of iron incubation concentration, nanoparticle size and nanoparticle coating on the magnetic labeling and the viability of non-phagocytic adherent cells in culture. The magnetic labeling of 3T6 fibroblasts was studied by T2-weighted MRI at 4.7 T and by dosing-or cytochemical revealing-of iron through methods based on Perl's Prussian blue staining. Cells were incubated for 48 h with increasing iron concentrations of SPIO (25-1000 µg Fe/ml Endorem®). Sinerem®, a USPIO (20-40 nm) coated with neutral dextran, and Resovist® (65 nm), a SPIO bearing an anionic carboxydextran coating, were compared with Endorem® (dextran-coated, 80-150 nm) as magnetic tags. The iron loading of marrow stromal cell primary cultures (MSCs) isolated from rat femurs was compared with that of 3T6 fibroblasts. The SPIO-labeling of cells with Endorem® was found to be dependent on the iron incubation concentration. MSCs, more sparsely distributed in the culture, exhibited higher iron contents than more densely populated 3T6 fibroblast cultures. A larger iron loading was achieved with Resovist® than with Endorem®, which in turn was more efficient than Sinerem® as a magnetic tag. The magnetic labeling of cultured non-phagocytic adherent cells with iron oxide nanoparticles was thus found to be dependent on the relative concentration of the magnetic tag and of the cells in culture, on the nanoparticle size, and on the coating type. The viability of cells, estimated by methods assessing cell membrane permeability, was not affected by magnetic labeling in the conditions used in this work. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A characteristic feature of atherosclerotic cardiovascular disease is the diffuse involvement of arteries across the entire human body and the presence of multiple, simultaneous lesions. The diffuse nature of this disease creates a unique challenge for early diagnosis and effective treatment. We believe that recent progress in the field of molecular MRI has opened new avenues towards solving the problem. A new technology has been developed that uses molecular MRI to monitor the migration and homing of hematopoietic stem-progenitor cells to injured arteries and atherosclerosis. In this Review, we introduce several novel technical developments in the field of molecular MRI of atherosclerosis, including advanced techniques for magnetic labeling of stem-progenitor cells and molecular MRI of hematopoietic bone marrow cells migrating to injured arteries and homing to atherosclerotic plaques. In addition, we examine molecular MRI of vascular gene therapy mediated by stem-progenitor cells. These new techniques provide the basis for the further development of in vivo MRI techniques to monitor stem-cell-mediated vascular gene therapy for multiple and diffuse atherosclerotic cardiovascular lesions. [ABSTRACT FROM AUTHOR]

Abstract: Cellular magnetic resonance imaging (MRI) relies on the use of intracellular contrast agents, primarily iron oxide compounds. Several techniques have been used to efficiently shuttle iron oxides into nonphagocytic cells, but all methods used until now require a prolonged incubation of cells. We hypothesized that instant magnetic labeling of cells could be achieved using electroporation. Neural stem cells (NSCs) and leukocytes from spleen and lymph nodes were suspended in a ferumoxide labeling solution, loaded into cuvettes, and subjected to electromechanical permeabilization using electroporation. Magnetically labeled cells were assayed for labeling efficiency, as well as for potential toxicity or altered function. To confirm the method''s applicability to detect cells, MRI experiments were performed at 11.7 T. Magnetoelectroporation of NSCs, as demonstrated by Prussian blue staining, anti-dextran immunostaining, and a quantitative iron uptake assay, proved to be an efficient intracellular magnetic labeling method. Leukocytes including lymphocytes, which are notoriously difficult to label because of their membrane properties and small cytoplasmic volume, also demonstrated a pronounced uptake of ferumoxide. MRI experiments showed that labeled NSCs could be visualized as single cells and cell clusters in gelatin phantoms, and as proliferating cell masses in mouse brain. We have developed a convenient technique for instant magnetic labeling of cells. Because magnetoelectroporation allows the use of ferumoxides approved by the US Food and Drug Administration without additional agents, it has excellent potential for clinical translation. [Copyright &y& Elsevier]

Research on medical diagnostics for point of care treatment (POCT) is driven by demand for rapid, high sensitivity, and inexpensive point of care diagnosis of heart disease, infection, allergies and cancer. Demands to improve quantification and affinity necessitate magnetic labels with sizes comparable to target molecules. However, it is extremely challenging to detect small concentrations of sub-200 nm functionalized magnetic labels using magnetoresistive-based sensors. In order to overcome these limitations we have developed a simple procedure for detecting \sim130 nm sized magnetic labels via magnetically induced capture of micrometer sized superparamagnetic beads by several 130 nm-diameter target beads immobilized on substrates. Here we demonstrate a new method to improve the quantification of our protocol that exploits magnetically induced frictional forces between micro-sized beads and target magnetic labels. By reducing the external magnetic field, the magnetically captured micro-sized beads restart to flow due to electrostatic forces and the strength of the critical external magnetic field for release depends on the number of nano-sized beads immobilized on substrate. Our protocol has the possibility for quantitative biomaterial detection. [ABSTRACT FROM PUBLISHER]

• Novel material based on MNPs modified with L-Lys for cell labeling was developed. • FTIR spectroscopy and TGA was used for evaluation of Fe 3 O 4 MNP surface hydration. • A surface hydration of chemically and physically obtained MNPs was compared. • Lys-modified MNPs efficiently label rAD-MSCs, Lin(–) and human leukemia K562 cells. The efficiency of magnetic labeling with L-Lys-modified Fe 3 O 4 magnetic nanoparticles (MNPs) and the stability of magnetization of rat adipose-derived mesenchymal stem cells, lineage-negative (Lin(–)) hematopoietic progenitor cells from mouse bone marrow and human leukemia K562 cells were studied. For this purpose, covalent modification of MNPs with 3-aminopropylsilane and N-di-Fmoc-L-lysine followed by removal of N-protecting groups was carried out. Since the degree of hydroxylation of the surface of the starting nanoparticles plays a crucial role in the silanization reaction and the possibility of obtaining stable colloidal solutions. In present work we for the first time performed a comparative qualitative and quantitative evaluation of the number of adsorbed water molecules and hydroxyl groups on the surface of chemically and physically obtained Fe 3 O 4 MNPs using comprehensive FTIR spectroscopy and thermogravimetric analysis. The results obtained can be further used for magnetic labeling of cells in experiments in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Bacterial contamination of water sources (e.g., lakes, rivers and springs) from waterborne bacteria is a crucial water safety issue and its prevention is of the utmost significance since it threatens the health and well-being of wildlife, livestock, and human populations and can lead to serious illness and even death. Rapid and multiplexed measurement of such waterborne pathogens is vital and the challenge is to instantly detect in these liquid samples different types of pathogens with high sensitivity and specificity. In this work, we propose a biosensing system in which the bacteria are labelled with streptavidin coated magnetic markers (MPs—magnetic particles) forming compounds (MLBs—magnetically labelled bacteria). Video microscopy in combination with a particle tracking software are used for their detection and quantification. When the liquid containing the MLBs is introduced into the developed, microfluidic platform, the MLBs are accelerated towards the outlet by means of a magnetic field gradient generated by integrated microconductors, which are sequentially switched ON and OFF by a microcontroller. The velocities of the MLBs and that of reference MPs, suspended in the same liquid in a parallel reference microfluidic channel, are calculated and compared in real time by a digital camera mounted on a conventional optical microscope in combination with a particle trajectory tracking software. The MLBs will be slower than the reference MPs due to the enhanced Stokes’ drag force exerted on them, resulting from their greater volume and altered hydrodynamic shape. The results of the investigation showed that the parameters obtained from this method emerged as reliable predictors for E. coli concentrations. [ABSTRACT FROM AUTHOR]

Platelets are the smallest blood cells and important for hemostasis. Platelet concentrates (PC) are medicinal products transfused to prevent or treat bleeding. Typically, platelets in PCs are assessed by in vitro tests for their function. However, in vivo testing of these platelets is highly desirable. To distinguish transfused platelets from patients or probands own cells after PC transfusions within the scope of clinical studies, platelets need to be efficiently labeled with minimal preactivation prior to transfusion. Here we report on a method for improved cell uptake of ferucarbotran magnetic nanoparticles contained in Resovist, an FDA-approved MRI contrast agent, by modifying the nanoparticle shell with human serum albumin (HSA). Both HSA-ferucarbotran nanoparticles and magnetically labeled platelets were produced according to EU-GMP guidelines. Platelet function after labeling was evaluated by light transmission aggregometry and by determination of expression of CD62P as platelet activation marker. Magnetic labeling does not impair platelet function and platelets showed reasonable activation response to agonists. Platelet survival studies in NOD/SCID-mice resulted in comparable survival behavior of magnetically labeled and nonlabeled platelets. Additionally, labeled platelets can be recovered from whole blood by magnetic separation.

A magnetic ligation method is utilized for the detection of microRNAs among a complex biological background without polymerase chain reaction or nucleotide modification. The sandwich probes assay can be adapted to analyze a panel of microRNAs associated with cardiovascular diseases in heart tissue samples., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)