Fluorescent Magnetic Nanoparticles Research Articles

Albumin incorporation into recognising layer of HER2-specific magnetic nanoparticles as a tool for optimal targeting of the acidic tumor microenvironment

Cancer is unquestionably a global healthcare challenge, spurring the exporation of novel treatment approaches. In recent years, nanomaterials have garnered significant interest with the greatest hopes for targeted nanoformulations due to their cell-specific delivery, improved therapeutic efficacy, and reduced systemic toxicity for the organism. The problem of successful clinical translation of nanoparticles may be related to the fact that most in vitro tests are performed at pH values of normal cells and tissues, ranging from 7.2 to 7.4. The extracellular pH values of tumors are characterized by a shift to a more acidic region in the range of 5.6–7.0 and represent a crucial target for enhancing nanoparticle delivery to cancer cells. Here we show the method of non-active protein incorporation into the surface of HER2-targeted nanoparticles to achieve optimal cellular uptake within the pH range of the tumor microenvironment. The method efficacy was confirmed in vitro and in vivo showing the maximum binding of nanoparticles to cells at a pH value 6.4. Namely, fluorescent magnetic nanoparticles, modified with HER2-recognising affibody ZHER2:342, with proven specificity in terms of HER2 recognition (with 62-fold higher cellular uptake compared to control nanoparticles) were designed for targeting cancer cells at slightly acidic pH values. The stabilizing protein, namely, bovine serum albumin, one of the major blood components with widespread availability and biocompatibility, was used for the decoration of the nanoparticle surface to alter the pH response of the targeting magnetic conjugates. The optimally designed nanoparticles showed a bell-shaped dependency of interaction with cancer cells in the pH range of 5.6–8.0 with maximum cellular uptake at pH value 6.4 close to that of the tumor microenvironment. In vivo experiments revealed that after i.v. administration, BSA-decorated nanoparticles exhibited 2 times higher accumulation in tumors compared to magnetic nanoparticles modified with affibody only. Thus, we demonstrated a valid method for enhancing the specificity of targeted nanoparticle delivery to cancer cells without changing the functional components of nanoparticles.

Biocompatible polymer-coated magneto-fluorescent super nanoparticles for the homing of mesenchymal stem cells

Stem cell plays an important role in the clinical field. However, the effective delivery of stem cells to the targeted site relies on the efficient homing of the cells to the site of injury. In view of that, fluorescent magnetic nanoparticles stick out due to their wide range of enabling functions including cellular homing and tracking. The present study unravels the synthesis of polymer-coated biocompatible and fluorescent magnetic nanoparticles (FMNPs) by a single-step hydrothermal synthesis method. Importantly, the facile method developed the biological super nanoparticles consisting of the magnetic core, which is surrounded by the fluorescent nanodot-decorated polymeric shell. The synthesized particles showed an amorphous nature, and superparamagnetic properties, with efficient fluorescence properties of emission at the blue range (̴ 410 nm). The FMNP labeling showed the mesenchymal stem cell (MSC) homing to the desired site in the presence of an external magnetic field. The in-house synthesized nanoparticles showed significant cytocompatibility and hemocompatibility in vitro as well as in vivo conditions owing to their surface coating. This unprecedented work advances the efficient internalization of FMNPs in MSCs and their enhanced migration potential provides a breakthrough in stem cell delivery for therapeutic applications. Statement of significanceThe bi-modal fluorescent magnetic nanoparticles hold a promising role in the biomedical field for mesenchymal stem cell homing and tracking. Hence, in this study, for the first time, we have synthesized the fluorescent magnetic nanoparticle with polymer coating via an easy single-step method. The nanoparticle with a polymer coat enhanced the biocompatibility and effortless internalization of the nanoparticle into mesenchymal stem cells without hampering the native stem cell properties. Furthermore, the enhanced migration potential of such magnetized stem cells and their homing at the target site by applying an external magnetic field opened up avenues for the smart delivery of mesenchymal stem cells at complex sites such as retina for the tissue regeneration.

Flower-shaped magnetic fluorescent nanoparticles based lateral flow biosensor for highly sensitive detection of cardiac troponin I

Magnetic fluorescent nanoparticles have demonstrated notable advantages as multifunctional immunoassays in lateral flow biosensor (LFB), contributing to the enhancement of both the flexibility and practicability of LFB. Herein, we synthesized flower-shaped magnetic fluorescent Nanoparticles (FMNP@QDs) with heightened fluorescence emission. The distinctive core/shell architecture of FMNP@QDs comprised the high saturation magnetization core encapsulated by oleic acid-modified Fe3O4, the flower-shaped shell made up of polymer colloids, and quantum dots (QDs) uniformly distributed on the outside. After surface modified with PEG-COOH and conjugate with cardiac troponin I (cTnI) antibodies, the FMNP@QDs were successfully applied in LFB for highly sensitive cTnI detection in samples. The limit of detection (LOD) of the proposed LFB for cTnI was 0.0097 ng/mL under fluorescent mode and 0.026 ng/mL under magnetic mode. A high level of concordance was observed between the FMNP@QDs based fluorescent LFB and the commercial CLIA method. The results indicated that the FMNP@QDs based LFB has a substantial potential for point-of-care test (POCT) technology, owing to its simple operating procedures, affordability, and enhanced sensitivity.

An ultra-sensitive SARS-CoV-2 antigen optical biosensor based on angiotensin converting enzyme 2 (ACE-2) functionalized magnetic-fluorescent silica nanoparticles.

This work reports on the design and synthesis of an angiotensin-converting enzyme 2 (ACE-2) functionalized magnetic fluorescent silica nanoparticles (Fe-FSNP) as a biosensing platform to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen. Iron oxide (Fe3O4) nanoparticles were synthesized via ultrasonic-assisted coprecipitation and then coated with fluorescent silica nanoparticles (FSNP) through thesol-gelmethod forming the Fe-FSNP samples. Silica obtained from local geothermal powerplant was used in this work and Rhodamine B was chosen as the incorporated fluorescent dye, hence this reports for the first time ACE-2 was immobilized on the natural silica surface. The Fe-FSNP nanoparticle consists of a 18-25 nm magnetic core and a silica shell with a thickness of 30 nm as confirmed from the transmission electron microscopy image. Successful surface functionalization of the Fe-FSNP with ACE-2 as bioreceptor was conducted through hydrosylilation reaction and confirmed through the Fourier transform infrared spectroscopy. The detection of SARS-Cov-2 antigen by Fe-FSNP/ACE2 was measured through the change in its maximum fluorescence intensity at 588 nm where fluorescence- quenching had occurred. The biosensing platform showed a rapid response at 30 min with a linear range of 10-6to 10-2μg ml-1. The magnetic-fluorescent properties of the nanoparticle enables an ultra-sensitive detection of SARS-Cov-2 antigen with the limit of detection as low as 2 fg ml-1.

Enzyme immobilized on magnetic fluorescent bifunctional nanoparticles for α-glucosidase inhibitors virtual screening from Agrimonia pilosa Ledeb extracts accompanied with molecular modeling

Agrimonia pilosa Ledeb (APL) is a significant source of inhibitors for α-glucosidase, which is an essential target enzyme for the treatment of type 2 diabetes, cancer and acquired immune deficiency syndrome. Ligand fishing is a suitable approach for the highly selective screening of bioactive substances in complex mixtures. Yet it is unable to conduct biomedical imaging screening, which is crucial for real-time identification. In this case, a bioanalytical platform combining magnetic fluorescent ligand fishing and in-situ imaging technique was established for the screening and identification of α-glucosidase inhibitors (AGIs) from APL crude extract, utilizing α-glucosidase coated CuInS2/ZnS-Fe3O4@SiO2 (AG-CIZSFS) nanocomposites as extracting material and fluorescent tracer. The AG-CIZSFS nanocomposites prepared through solvothermal and crosslinking methods displayed fast magnetic separation, excellent fluorescence performance and high enzyme activity. The tolerance of immobilized enzyme to temperature and pH was stronger than that of free enzyme. Prior to proof-of-concept with APL crude extract, a number essential parameters (glutaraldehyde concentration, immobilized time, enzyme amount, reaction solution pH, incubation temperature, incubation time, percentage of methanol in eluen, elution times and eluent volume) were optimized using an artificial test mixture. The fished ligands were identified by UPLC-MS/MS and their biological activities were preliminarily evaluated by real-time cellular morphological imaging of human colon carcinoma (HCT-116) cells based on confocal laser scanning microscope (CLSM). Their α-glucosidase inhibitory activities were further verified and studied by classical pNPG method and molecular docking. The isolated compounds exhibited significant α-glucosidase inhibitory activities with a IC50 value of 11.57 µg·mL−1. Six potential AGIs including tribuloside, ivorengenin A, tormentic acid, 1β, 2β, 3β, 19α-Tetra hydroxyurs-12-en-28-oic acid, corosolic acid and pomolic acid were ultimately screened out and identified from APL crude extracts. The proposed approach, which combined highly specific screening with in-situ visual imaging, provided a powerful platform for discovering bioactive components from multi-component and multi-target traditional Chinese medicine (TCM).

Transcranial application of magnetic pulses for improving brain drug delivery efficiency via intranasal injection of magnetic nanoparticles.

As the blood-brain barrier (BBB) hinders efficient drug delivery to the brain, drug delivery via the intranasal pathway, bypassing the BBB, has received considerable attention. However, intranasal administration still has anatomical and physiological limitations, necessitating further solutions to enhance effectiveness. In this study, we used transcranial magnetic stimulation (TMS) on fluorescent magnetic nanoparticles (MNPs) of different sizes (50, 100, and 300 nm) to facilitate MNP's transportation and delivery to the brain parenchyma. To validate this concept, anesthetized rats were intranasally injected with the MNPs, and TMS was applied to the center of the head. As the result, a two-fold increase in brain MNP delivery was achieved using TMS compared with passive intranasal administration. In addition, histological analysis that was performed to investigate the safety revealed no gross or microscopic damages to major organs caused by the nanoparticles. While future studies should establish the delivery conditions in humans, we expect an easy clinical translation in terms of device safety, similar to the use of conventional TMS. The strategy reported herein is the first critical step towards effective drug transportation to the brain.

Bioimaging Probes Based on Magneto-Fluorescent Nanoparticles.

Novel nanomaterials are of interest in biology, medicine, and imaging applications. Multimodal fluorescent-magnetic nanoparticles demand special attention because they have the potential to be employed as diagnostic and medication-delivery tools, which, in turn, might make it easier to diagnose and treat cancer, as well as a wide variety of other disorders. The most recent advancements in the development of magneto-fluorescent nanocomposites and their applications in the biomedical field are the primary focus of this review. We describe the most current developments in synthetic methodologies and methods for the fabrication of magneto-fluorescent nanocomposites. The primary applications of multimodal magneto-fluorescent nanoparticles in biomedicine, including biological imaging, cancer treatment, and drug administration, are covered in this article, and an overview of the future possibilities for these technologies is provided.

Tubulins show susceptibility to magnetic nanoparticle interaction.

Low piconewton forces can induce axonal specification and outgrowth in neurons. However, the secondary mechanism underlying force-mediated axon specification is poorly understood. Within the axon shaft, microtubules, composed of α and β tubulin dimers, are stabilized by the protein Tau. These microtubules polymerize toward the axonal tip, where actin provides a tensile force against the membrane to maintain or extend the structure of the tip. We hypothesize that exogenous forces manipulate one or more of these structural proteins, which could induce axonal lineage. Our previous work has shown that hTau40, the brain's most ubiquitous isoform of Tau, can be directly dragged by internalized magnetic nanoparticles (MNPs) within primary neurons. Here, we sought to establish whether this direct relationship between the nanoparticles and Tau applied to other axonal structural proteins. We transduced (BacMam) dissociated primary cortical neurons (rat, E18) at the day in vitro two (DIV 2) with one of three vectors containing a gene for a fluorescently labeled structural protein: α-tubulin-mCherry, β-tubulin-GFP, or β-actin-GFP. At DIV 4, the neurons were incubated for 24 h with starch-NH2-coated, far-red fluorescent magnetic nanoparticles (d: 100 nm) at 10 µg/mL. Cells were then washed and imaged using a Leica DMi8 inverted fluorescent microscope to determine whether there was high colocalization, indicating direct interaction, between the MNPs and the fluorescent proteins. Compared to the high-intensity protein spots, α-tubulin-mCherry showed the greatest percentage of correlated MNP clusters (45.7 ± 6.8 %, n = 11 cells), followed by β-tubulin-GFP, with 36.9 ± 11.7 % (n = 6) of high protein spots correlated to MNP clusters. Only 8.27 ± 5.32% (n = 7) of β-actin-GFP spots correlating to MNP clusters. These preliminary data suggest tubulins may be more susceptible to direct nanomagnetic force manipulation (mean ± SEM).

Manipulation of New Fluorescent Magnetic Nanoparticles with an Electromagnetic Needle, Allowed Determining the Viscosity of the Cytoplasm of M-HeLa Cells.

Magnetic nanoparticles (MNPs) have recently begun to be actively used in biomedicine applications, for example, for targeted drug delivery, in tissue engineering, and in magnetic resonance imaging. The study of the magnetic field effect on MNPs internalized into living cells is of particular importance since it allows a non-invasive influence on cellular activity. There is data stating the possibility to manipulate and control individual MNPs utilizing the local magnetic field gradient created by electromagnetic needles (EN). The present work aimed to demonstrate the methodological and technical approach for manipulating the local magnetic field gradient, generated by EN, novel luminescent MNPs internalized in HeLa cancer cells. The controlling of the magnetic field intensity and estimation of the attractive force of EN was demonstrated. Both designs of EN and their main characteristics are also described. Depending on the distance and applied voltage, the attractive force ENs ranged from 0.056 ± 0.002 to 37.85 ± 3.40 pN. As a practical application of the presented, the evaluation of viscous properties of the HeLa cell's cytoplasm, based on the measurement of the movement rate of MNPs inside cells under impact of a known magnetic force, was carried out; the viscosity was 1.45 ± 0.04 Pa·s.

Fluorescent core-shell magnetic nanoparticles by type II photoinitiated polymerisation.

We report a fluorescent monomer-free method for the synthesis of fluorescent and stable magnetic nanocomposites using a benzophenone/rhodamine B bimolecular photoinitiator system. The method allows the synthesis of a fluorescent polymer shell layer around magnetic nanoparticles in one step by UV irradiation at ambient temperature.

Fluorescent Magnetic Nanoparticles for Bioimaging through Biomimetic Surface Modification

Nanostructured materials and systems find various applications in biomedical fields. Hybrid organo-inorganic nanomaterials are intensively studied in a wide range of areas, from visualization to drug delivery or tissue engineering. One of the recent trends in material science is biomimetic approaches toward the synthesis or modification of functional nanosystems. Here, we describe an approach toward multifunctional nanomaterials through the biomimetic polymerization of dopamine derivatives. Magnetite nanoparticles were modified with a combination of dopamine conjugates to give multifunctional magneto-fluorescent nanocomposites in one synthetic step. The obtained material showed excellent biocompatibility at concentrations up to 200 μg/mL and an in vivo biodistribution profile typical for nanosized formulations. The synthesized systems were conjugated with antibodies against HER2 to improve their selectivity toward HER2-positive cancer cells. The produced material can be used for dual magneto-optical in vivo studies or targeted drug delivery. The applied synthetic strategy can be used for the creation of various multifunctional hybrid nanomaterials in mild conditions.

Sensitive and quantitative in vivo analysis of PD-L1 using magnetic particle imaging and imaging-guided immunotherapy.

The programmed cell death protein-1 (PD-1) and programmed cell death ligand-1 (PD-L1) expression correlate with the immunotherapeutic response rate. The sensitive and non-invasive imaging of immune checkpoint biomarkers is favorable for the accurate detection and characterization, image-guided immunotherapy in cancer precision medicine. Magnetic particle imaging (MPI), as a novel and emerging imaging modality, possesses the advantages of high sensitivity, no image depth limitation, positive contrast, and absence of radiation. Hence, in this study, we performed the pioneer investigation of monitoring PD-L1 expression using MPI and the MPI-guided immunotherapy. We developed anti-PD-L1 antibody (aPDL1)-conjugated magnetic fluorescent hybrid nanoparticles (MFNPs-aPDL1) and utilized MPI in combination with fluorescence imaging (FMI) to dynamically monitor and quantify PD-L1 expression in various tumors with different PD-L1 expression levels. The ex vivo real-time polymerase chain reaction (qPCR), western blotting, and immunofluorescence staining analysis were further performed to validate the in vivo imaging observation. Moreover, the MPI was further performed for the guidance of immunotherapy. Our data showed that PD-L1 expression can be specifically and sensitively monitored and quantified using MPI and FMI imaging methods, which were validated by ex vivo qPCR and western blotting analysis. In addition, MPI-guided PD-L1 immunotherapy can enhance the effectiveness of cancer immunotherapy. To our best knowledge, this is the pioneer study to utilize MPI in combination with a newly developed MFNPs-aPDL1 imaging probe to dynamically visualize and quantify PD-L1 expression in tumor microenvironment. This imaging strategy may facilitate the clinical optimization of immunotherapy management.

Preparation of magnetic fluorescent nanoparticles with quaternary ammonium chitosan derivatives and its properties

To explore a novel solution to the challenges in constructing polymer coated magnetic fluorescent nanoparticles, HTCC/Fe3O4/CdTe magnetic fluorescent nanoparticles (MFCNPs) that can be well dispersed in water were prepared via the electrostatic interaction of the cationic N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) and the anion precoated water-soluble cadmium telluride (CdTe) quantum dots (QDs) and the sodium citrate-coated Fe3O4 (SC-Fe3O4) magnetic nanoparticles (MNPs), which overcame the performance defects of hydrophobic polymer for surface coating and the possible toxicity of cross-linking agent induced by the hydrophilic polymer coating materials. The structural characterizations by FTIR, XRD and XPS reveal that the surfaces of SC-Fe3O4 MNPs and CdTe QDs are coated with HTCC. TEM imaging suggests that the MFCNPs are spherical particles with the diameters of ∼15–20 nm. The MFCNPs exhibit good biocompatibility. Further investigation suggests that the UV-Vis and fluorescence spectral properties and surface electrical properties of HTCC/Fe3O4/CdTe MFCNPs are mainly affected by the relative ratios of SC-Fe3O4 MNPs, CdTe QDs and HTCC. The adsorption and release properties of the MFCNPs were studied using bovine serum albumin (BSA) as the model. The results indicate that the chitosan-based magnetic fluorescent composite is a promising delivery carrier candidate with excellent comprehensive properties for both magnetic response and fluorescence imaging.

Magnetic relaxation switch and fluorescence dual-mode biosensor for rapid and sensitive detection of ricin B toxin in edible oil and tap water

The ultrasensitive and rapid detection of ricin B toxin (RTB) is essential for food safety and environmental monitoring. Herein, a dual-mode magnetic relaxation switch (MRS) and fluorescence (FL) biosensing strategy was developed to efficiently detect RTB using fluorescent magnetic nanoparticles (MNP300@SiO2(FITC)). Meanwhile, the as-prepared composite MNP300@SiO2(FITC) exhibited superior biocompatibility and increased FL readout and was coupled with aptamer (Apt) to form a captured probe. Magnetic nanoparticles, 30 nm in diameter (MNP30), were coupled to a Blocker to form a paired probe to compete with RTB for Apt binding. The presence of the RTB triggered the dual-mode detection switch, thus, weakening the magnetic and fluorescent signals. Compared with the single-mode detection method, the Δ T2 and Δ FL intensity here exhibited an excellent linear relationship with logarithm of RTB concentrations at 0.001–500 ng/mL and 0.005–500 ng/mL, and obtained ultrahigh sensitivities of 0.8 pg/mL and 3 pg/mL, respectively. In addition, the dual-mode biosensor gained satisfactory spiked recoveries and relative standard deviations for quantitative detection of spiked RTB in edible oil and tap water samples. To our knowledge, this is the first study to describe the accurate quantification of RTB using a sensitive MRS-FL biosensor. We anticipate that this strategy will provide novel avenues for the development of dual-mode sensing assays.

Superior CdSe/ZnS@Fe2O3 Yolk‐Shell Nanoparticles as Optically Active MRI Contrast Agents**

AbstractWe have developed a robust synthesis methodology for quantum dots (QDs) nanoparticles with magnetic properties designed for biomodal imaging. These nanocrsytlas consists of a semiconductor quantum dot core with engineered fluorescence, which is located in a paramagnetic iron oxide shell that acts as a magnetic resonance imaging (MRI) contrast agent. Yolk‐shell CdSe/ZnS@Fe2O3 nanoparticles (NPs) are synthesized via sonochemical decomposition of iron pentacarbonyl (Fe(CO)5) using the oleylamine (OAm) as the ligand. The sonochemical synthesis method of magnetic fluorescent NPs that can be used as MRI contrast agents provided advantages such as improved quantum efficiency and homogeneous size distributions. It has been determined that the luminescence efficiency of quantum dots decreases in coatings that can be made at high temperatures by thermal decomposition. In order to eliminate the disadvantage of elevated temperatures, the sonochemical decomposition method, which allows coating at low temperatures, has been used. With this method, yolk‐shell (CdSe/ZnS@Fe2O3) nanoparticles were produced with high photoluminescence quantum efficiency and homogeneous size distributions. The synthesis magnetic fluorescent NPs optimized was determined to have the injection temperature of Fe(CO)5 at 60 ° C, Fe(CO)5/CdSe@ZnS ratio 0.7, OAm/Fe(CO)5 volume ratio 1.43 with an oxidation time 5 min. Under these conditions, the quantum efficiency was found to be 78 %, nanoparticle sizes between 11–14 nm and r1 value was 0.199, r2 value was 0.518 in MRI analysis. These optically active magnetic fluorescent nanoparticles as positive contrast agents (T1 weighted) are predicted to pave the way for the future of advanced bio‐imaging systems.

Folic Acid-Modified Fluorescent-Magnetic Nanoparticles for Efficient Isolation and Identification of Circulating Tumor Cells in Ovarian Cancer.

Ovarian cancer (OC) is a lethal disease occurring in women worldwide. Due to the lack of obvious clinical symptoms and sensitivity biomarkers, OC patients are often diagnosed in advanced stages and suffer a poor prognosis. Circulating tumor cells (CTCs), released from tumor sites into the peripheral blood, have been recognized as promising biomarkers in cancer prognosis, treatment monitoring, and metastasis diagnosis. However, the number of CTCs in peripheral blood is low, and it is a technical challenge to isolate, enrich, and identify CTCs from the blood samples of patients. This work develops a simple, effective, and inexpensive strategy to capture and identify CTCs from OC blood samples using the folic acid (FA) and antifouling-hydrogel-modified fluorescent-magnetic nanoparticles. The hydrogel showed a good antifouling property against peripheral blood mononuclear cells (PBMCs). The FA was coupled to the hydrogel surface as the targeting molecule for the CTC isolation, held a good capture efficiency for SK-OV-3 cells (95.58%), and successfully isolated 2–12 CTCs from 10 OC patients’ blood samples. The FA-modified fluorescent-magnetic nanoparticles were successfully used for the capture and direct identification of CTCs from the blood samples of OC patients.

Preparation and Characterization of Enzyme-immobilized Fluorescent Magnetic Iron Oxide Nanoparticles for the Detection of Glucose and Urea

Preparation and Characterization of Enzyme-immobilized Fluorescent Magnetic Iron Oxide Nanoparticles for the Detection of Glucose and Urea

Fabrication of monoBODIPY-functionalized Fe3O4@SiO2@TiO2 nanoparticles for the photocatalytic degradation of rhodamine B under UV irradiation and the detection and removal of Cu(II) ions in aqueous solutions

In this study, the potential of magnetic fluorescence hybrid nanoparticle (Fe3O4@SiO2@TiO2-APTMS-monoBODIPY) for simultaneous detection and removal of inorganic contaminant Cu(II) ions and photocatalytic degradation of organic contaminant Rhodamine B (RhB) dye in aqueous solutions under UV light was investigated. Samples were synthesized at each stage, and the magnetic fluorescence hybrid nanoparticle was characterized by SEM, TEM, EDX, FTIR, and XRD. When Cu(II) ions were added to the Fe3O4@SiO2@TiO2-APTMS-monoBODIPY suspension mixture, the fluorescence intensity at ~ 543 nm decreased. In addition, the addition of Cu(II) ions in the presence of different cation species caused dramatic fluorescent quenching that was very selective for Cu(II) ions. The detection limit values of Cu(II) ions using the Fe3O4@SiO2@TiO2-APTMS-monoBODIPY is 0.47 µM. The prepared magnetic fluorescent hybrid nanoparticle was used for Cu(II) adsorption from aqueous solutions. Four different adsorption isotherms were calculated, and it was found that the Langmuir isotherm fit better, and the maximum adsorption capacity was 50.505 mg/g. Kinetic research followed the pseudo-second-order kinetics model. Thermodynamic parameters were calculated, and the adsorption of Cu(II) ions turned out to be endothermic, favorable, and spontaneous. RhB dyes in the suspension mixture were adsorbed on magnetic fluorescent hybrid nanomaterial in the dark with stirring for 30 min. Then after 60 min of mixing under UV light, they showed an RhB degradation percentage of 29.49%.

Magnetophoretic Control of Diamagnetic Particles Inside an Evaporating Droplet.

The present study reports the magnetophoresis of diamagnetic particles in an evaporating ferrofluid droplet. Both solid and ring magnet arrangements are used to investigate the effect of magnetic field distribution. The distance of the magnet from the droplet is varied to study the effect of magnetic field strength. The magnetic field distribution is computed using COMSOL multiphysics software. Magnetometer measurements have been carried out to validate the simulation results. The motion of particles and the drying pattern of evaporating ferrofluid droplets are visualized using the confocal microscopy technique. Both bright-field and fluorescence imagings have been carried out to observe the differential deposition of the fluorescent particle (microparticle) and magnetic nanoparticles in the absence and presence of a magnetic field. The velocity of diamagnetic particles as a function of magnetic field distribution and strength has been studied using the micro-PIV technique. In the absence of the magnetic field, a ring-shaped deposition pattern is observed. The mixture of microparticles (diamagnetic) and nanoparticles (magnetic) is deposited between the outer and inner edges of the ring. The diamagnetic particles occupy the inner and outer edges of the ring. Magnetic particles travel toward the higher magnetic field zone and diamagnetic particles move toward the smaller magnetic field zone when a magnetic field is applied by a solid magnet placed over the droplet. This can be attributed to the negative magnetic force originating from the difference between the susceptibility of magnetic and nonmagnetic particles. The negative magnetic force on the microparticle increases as the magnetic field intensity increases, causing the microparticle to convect faster toward the contact line. The deposition behavior can be reversed or suppressed using a ring magnet in place of a solid magnet. In this case, the negative magnetic force is stronger at the contact line region of the droplet and decreases as it approaches the center region of the droplet. The deposition behavior of diamagnetic particle depends on the balance between the Marangoni force and the magnetophoretic force. Overall, the present study demonstrates the capability of the controlled deposition of diamagnetic polystyrene particles by suitable arrangement of the solid and ring magnet.

Multimodal Tracking of Hematopoietic Stem Cells from Young and Old Mice Labeled with Magnetic–Fluorescent Nanoparticles and Their Grafting by Bioluminescence in a Bone Marrow Transplant Model

This study proposes an innovative way to evaluate the homing and tracking of hematopoietic stem cells from young and old mice labeled with SPIONNIRF-Rh conjugated with two types of fluorophores (NIRF and Rhodamine), and their grafting by bioluminescence (BLI) in a bone marrow transplant (BMT) model. In an in vitro study, we isolated bone marrow mononuclear cells (BM-MNC) from young and old mice, and analyzed the physical–chemical characteristics of SPIONNIRF-Rh, their internalization, cell viability, and the iron quantification by NIRF, ICP-MS, and MRI. The in vivo study was performed in a BMT model to evaluate the homing, tracking, and grafting of young and old BM-MNC labeled with SPIONNIRF-Rh by NIRF and BLI, as well as the hematological reconstitution for 120 days. 5FU influenced the number of cells isolated mainly in young cells. SPIONNIRF-Rh had adequate characteristics for efficient internalization into BM-MNC. The iron load quantification by NIRF, ICP-MS, and MRI was in the order of 104 SPIONNIRF-Rh/BM-MNC. In the in vivo study, the acute NIRF evaluation showed higher signal intensity in the spinal cord and abdominal region, and the BLI evaluation allowed follow-up (11–120 days), achieving a peak of intensity at 30 days, which remained stable around 108 photons/s until the end. The hematologic evaluation showed similar behavior until 30 days and the histological results confirm that iron is present in almost all tissue evaluated. Our results on BM-MNC homing and tracking in the BMT model did not show a difference in migration or grafting of cells from young or old mice, with the hemogram analysis trending to differentiation towards the myeloid lineage in mice that received cells from old animals. The cell homing by NIRF and long term cell follow-up by BLI highlighted the relevance of the multimodal nanoparticles and combined techniques for evaluation.