Magnetic Nanoparticles Research Articles

MB based RT-qPCR increase the clinical application of cfEBV DNA for NPC in non-endemic area of China

To compare the performance of magnetic bead (MB) and the concentrated precipitation (CP) based RT-qPCR to qualify cell free EBV DNA (cfEBV DNA) for nasopharyngeal carcinoma (NPC) in non-endemic area of China. From January 2014 to June 2024, a retrospective analysis of 2 cohort studies on cfEBV DNA in NPC patients was conducted to assess the diagnostic value, positive detection rate and clinical application. cfEBV DNA detection with CP based RT-qPCR in cohort 1 and MB based RT-qPCR method in cohort 2. The MB based RT-qPCR for the quantitative measurement of cfEBV DNA load was higher than the CP based RT-qPCR in the same plasma samples from NPC patients (P < 0.001). CP based RT-qPCR measured cfEBV DNA in 1405 NPC and 244 healthy controls in cohort 1 with 40.8% sensitivity (AUC = 0.704, 95% CI: 0.676–0.731). In cohort 2(683 naive NPC and 303 controls), cfEBV DNA had a sensitivity of 75.84% (AUC = 0.879, 95% CI: 0.86–0.90). There were no significant differences in TNM stage among NPC between the two cohorts (P > 0.05). The MB method considerably increased the positive detection rate of cfEBV DNA in NPCs at stages III-IV, T2-T4, N1-N3, and M0 (P < 0.001). At the end of treatment, 97.51% of patients had no detectable EBV and just 2.49% had detectable cfEBV DNA. Those who received ≤ 2 or ≥ 3 cycles of NAC had a median t1/2 clearance rate of 9.8 days and 12.6 days, respectively. MB based RT-qPCR increased the quantity of cfEBV DNA. MB based RT-qPCR demonstrated superior sensitivity and positive detection rates for cfEBV DNA. cfEBV DNA can be more positively noticed, with a higher diagnostic value and a broader variety of clinical applications among NPC in non-endemic areas.

Pitfalls and Challenges in Specific Absorption Rate Evaluation for Functionalized and Coated Magnetic Nanoparticles Used in Magnetic Fluid Hyperthermia

In recent decades, magnetic hyperthermia (MH) has gained considerable scientific interest in cancer treatment due to its ability to heat tumor tissues deeply localized inside the body. Functionalizing magnetic nanoparticles (MNPs) with vector molecules via specific organic molecules that coat the particle surface has enabled targeting particular tissues, thereby increasing the specificity of MH. MH relies on applying radiofrequency (RF) magnetic fields to a magnetic nanoparticle distribution injected in a tumor tissue. The RF field energy is converted into thermal energy through specific relaxation mechanisms and magnetic hysteresis-driven processes. This increases the tumor tissue temperature over the physiological threshold, triggering a series of cellular apoptosis processes. Additionally, the mechanical effects of low-frequency AC fields on anisotropic MNPs have been shown to be highly effective in disrupting the functional cellular components. From the macroscopic perspective, a crucial parameter measuring the efficiency of magnetic nanoparticle systems in MH is the specific absorption rate (SAR). This parameter is experimentally evaluated by different calorimetric and magnetic techniques and methodologies, which have specific drawbacks and may induce significant errors. From a microscopic perspective, MH relies on localized thermal and kinetic effects in the nanoparticle proximity environment. Studying MH at the cellular level has become a focused research topic in the last decade. In the context of these two perspectives, inevitable questions arise: could the thermal and kinetic effects exhibited at the cellular scale be linked by the macroscopic SAR parameter, or should we find new formulas for quantifying them? The present work offers a general perspective of MH, highlighting the experimental pitfalls encountered in SAR evaluation and motivating the necessity of standardizing the devices and protocols involved. It also discusses the challenges that arise in MH performance evaluation at the cellular level.

A Cost-Effective and Rapid Manufacturing Approach for Electrochemical Transducers with Magnetic Beads for Biosensing

Biosensors as advanced analytical tools have found various applications in food safety, healthcare, and environmental monitoring in rapid and specific detection of target analytes in small liquid samples. Up to now, planar electrochemical electrodes have shown the highest potential for biosensor applications due to their simple and compact construction and cost-effectiveness. Although a number of commercially available electrodes, manufactured from various materials on different substrates, can be found on the market, their high costs for single use and low reproducibility persist as major drawbacks. In this study, we present an innovative, cost-effective approach for the rapid fabrication of electrodes that combines lamination of 24-karat gold leaves with low-cost polyvinyl chloride adhesive sheets followed by laser ablation. Laser ablation enables the creation of electrodes with customizable geometries and patterns with microlevel resolutions. The developed electrodes are characterized by cyclic voltammetry and electrochemical impedance spectroscopy, scanning electronic microscopy, and 3D profiling. To demonstrate the manufacturing and biosensing potential, different geometries and shapes of electrodes were realized as the electrochemical transducing platform and applied for the realization of magnetic bead (MB)-labeled biosensors for quantitative detection of food-borne pathogens of Salmonella typhimurium (S. typhimurium) and Listeria monocytogenes (L. monocytogenes).

Magnetic beads masquerading as a bracelet causing ileal volvulus with multiple ileoileal fistulae in a child: A case report with systematic literature review.

Multiple magnetic foreign body ingestion can cause serious complications in children. Such events are now more frequently seen. We report such a case and present a systematic review to identify the variety of fistulae thereby caused. Timely diagnosis through radiographic imaging plays a pivotal role in guiding clinical decisions.

Hydrogel microwells with customizable bottom design: A one‐step approach to spheroid formation

AbstractConical microwells featuring a variety of bottom‐shape features have received increased recognition because of their enhanced surface characteristics that improve the in vitro‐in vivo correlation in a wide range of biological applications, such as in three‐dimensional cell culture models, specifically cell spheroidal formation, and drug screening. Conventional and microfluidics‐based emerging fabrication techniques for the formation of such conically shaped microwells with uniform spatiotemporal control require complex multistep procedures and costly equipment, or they face challenges in developing slanted V‐shaped well bottoms. Herein, we developed a microfluidics‐based method to produce three‐dimensional microwells with slanted V‐shaped well bottoms by exploring the 3D‐shape tuning ability using a non‐uniform photolithographic technique (NUPL), through a variation in the UV light intensity profile induced by the presence of magnetic nanoparticles, which makes an opaque precursor solution. We also characterize the change in the microwell's bottom profile through variation of UV dose. Finally, the effects of conical shape tuning parameters, that is, the non‐uniformity of UV light intensity and aspect ratio (diameter/height), on the microwell depth and bottom shape is investigated. Using NUPL, we demonstrate the facile and single‐step synthesis of conical microwells with highly slanted sidewalls that are used to create chondrocyte spheroids as a proof of concept.

Precision‐Engineered Cobalt‐Doped Iron Oxide Nanoparticles: From Octahedron Seeds to Cubical Bipyramids for Enhanced Magnetic Hyperthermia

AbstractDespite notable advancements, the significantly improved yet suboptimal heating efficiency of current magnetic nanoparticles hinders the effectiveness of systemically delivered magnetic hyperthermia in reducing tumor size or halting growth. Addressing this challenge, the seed‐and‐growth thermal decomposition method has been developed to synthesize cobalt‐doped iron oxide nanoparticles (Co‐IONPs) featuring a cubical bipyramid morphology, consisting of both magnetite and maghemite phases within their nanostructure. They possess an exceptional specific absorption rate (SAR) of 14 686 ± 396 W g⁻¹ Fe, inducing a temperature rise of 3.73 °C s−1 when subjected to an alternating magnetic field (AMF, 315 kHz; 26.8 kA m−1). The cubical bipyramid‐shaped Co‐IONPs, functionalized with LHRH peptide, efficiently accumulate in ovarian cancer xenografts following an intravenous injection at a relatively low dose of 4 mg kg−1, elevating intratumoral temperatures beyond 50 °C with a high heating rate. In contrast to previously reported magnetic nanoparticles with ultrahigh heating efficiency, the developed cubical bipyramid‐shaped nanoparticles effectively halt ovarian cancer tumor growth after a single 30‐min session of magnetic hyperthermia. These outcomes underscore the potential of shape‐dependent magnetic hyperthermia, where the cubical bipyramid morphology significantly enhances the heating efficiency and therapeutic efficacy of magnetic nanoparticles, improving the effectiveness of hyperthermia‐based cancer treatments.

Adsorptive Removal of Congo Red Dye From Aqueous Media Using Composite of Graphitic Carbon Nitride Nanosheet and the Biopolymer Alginate

ABSTRACTThe removal of dyes from wastewater using stable adsorbents is well documented in numerous scientific reports. Therefore, this study aimed to evaluate a composite of graphitic carbon nitride nanosheet (g‐C3N4NS) and the biopolymer alginate for the removal of Congo red (CR) dye from aqueous media. To address the challenges associated with the independent use of calcium alginate and g‐C3N4NS in water, particularly regarding recovery issues, silica‐coated magnetic nanoparticles (SMNPs) were incorporated into the composite. To achieve this objective, an alginate‐based bioadsorbent was synthesized by crosslinking sodium alginate with calcium chloride in the presence of g‐C3N4NS and SMNPs using an in situ method. Structural characterization was conducted using BET, TGA, TEM, FE‐SEM, and EDX‐Mapping analyses. Subsequently, the bioadsorbent was utilized to remove CR dye. The influence of various parameters, including initial concentration, contact time, adsorbent dosage, and pH, was subsequently investigated. According to the isotherm models, the linear Langmuir model exhibited a good fit to the experimental data for CR, indicating a maximum adsorption capacity of 68.03 mg g−1 at pH 5 within 120 min. The synthesized composite has the potential to pave the way for novel applications in both organic and inorganic transformations, as well as in the physical or chemical remediation of diverse pollutants.

Detecting monogenic disorders in utero non-invasively based on fetal nucleated red blood cells highly-purified by multi-functional magnetic nanoparticles.

Detecting monogenic disorders in utero non-invasively based on fetal nucleated red blood cells highly-purified by multi-functional magnetic nanoparticles.

Antibiotic-Modified Nanoparticles Combined with Lysozyme for Rapid Extraction of Pathogenic Bacteria DNA in Blood.

Rapid and precise identification of the pathogens causing sepsis remains a significant diagnostic challenge. Blood culture is time-consuming and insensitive, while molecular diagnostic techniques, such as the polymerase chain reaction (PCR), are fast but greatly influenced by template quality. Here, we present a new approach to separate trace amounts of pathogen DNA from blood, which utilizes lysozyme to destroy bacteria and release DNA, followed by enrichment and purification using magnetic nanoparticles (MNPs) modified with kanamycin (Kan) or tobramycin (TM). We demonstrate that the prepared Kan@MNPs and TM@MNPs can efficiently adsorb DNA, with the mechanism involving interaction with the minor groove of DNA. Notably, the adoption of lysozyme ensures bacterial lysis while avoiding damage to blood cells, minimizing the interference from human genomic DNA background and inhibitory components, thereby obtaining relatively pure bacterial DNA. For artificially infected whole blood samples, our method shortens the sample processing time to 35 min and achieves a 10-fold improvement in PCR sensitivity compared to a commercial kit. Through clinical evaluation of blood samples collected from suspected infected patients, we identified positive samples that were 100% consistent with the clinical practice. Therefore, this method holds promising potential for clinical application in advancing rapid sepsis diagnosis and earlier interventions.

Biorecognition-Based Nanodiagnostics: Maltotriose-Functionalized Magnetic Nanoparticles for Targeted Magnetic Resonance Imaging of Bacterial Infections

Bacterial infections remain a global healthcare challenge, requiring precise diagnostic modalities to guide therapeutic interventions. Current molecular imaging agents predominantly detect nonspecific hemodynamic alterations and lack pathogen-specific targeting capabilities for magnetic resonance imaging (MRI). Leveraging the selective bacterial uptake of maltotriose via the maltodextrin transport pathway, we engineered maltotriose-functionalized magnetic nanoparticles (Malt-MNPs) as a novel MRI contrast agent. Basic physicochemical characterization confirmed the nanosystem’s colloidal stability, biocompatibility, and superparamagnetism (saturation magnetization &gt; 50 emu/g). In a rat bacterial infection model, intravenously administered Malt-MNPs selectively accumulated at infection sites, inducing a &gt;50% MRI signal change within 24 h while exhibiting minimal off-target retention in sterile inflammatory lesions (&lt;10% signal change). This specificity enabled clear MRI-based differentiation between bacterial infections and noninfectious inflammation. These findings provide a promising strategy for clinical translation in infection imaging and treatment.

Adsorption of Fe(III) using Fe3O4@MNPs modified with Silica through a simple and time-saving method: Optimization by RSM

This study aims to develop a simple method for preparing modified magnetic nanoparticles. This is created by preparing Fe3O4 nanoparticles modified with Silica (Fe3O4@MNPs@Silica) using a quick, simple, and easy solid-phase extraction approach for Fe(III) removal from aqueous solutions. This nanocomposite was characterized using FTIR, XRD, and SEM analysis. In this context the optimization of Fe(III) adsorption by silica-coated Fe3O4 nanoparticles was studied. The effects of various parameters such as pH, adsorbent dosage, initial concentration, and time on the adsorption process were investigated. It was found that the adsorption capacity of Fe(III) increased with increasing adsorbent dosage and initial concentration and decreased with increasing pH and time. The experimental adsorption conditions were optimized using Response Surface Methodology (RSM). Fe3O4@MNPs@Silica adsorbent has an adsorption capacity of 3.870 mmol-Fe(III) g–1, at pH = 2.5. This confirms a high affinity of Fe3O4@MNPs@Silica towards Fe(III).

The Lumped-Parameter Calorimetric Model of an AC Magnetometer Designed to Measure the Heating of Magnetic Nanoparticles

The Lumped-Parameter Calorimetric Model of an AC Magnetometer Designed to Measure the Heating of Magnetic Nanoparticles

Control of cardiac waves in human iPSC-CM syncytia by a Halbach array and magnetic nanoparticles.

Control of cardiac waves in human iPSC-CM syncytia by a Halbach array and magnetic nanoparticles.

Deposition of Air Pollution-Derived Magnetic Nanoparticles in Human Kidney Revealed by High-Resolution Microstructural Characterization.

Exposure to air pollutants, especially fine particulate matter (PM2.5), has been recognized as a major contributor to the increasing prevalence of kidney diseases. However, until now, evidence for the translocation of airborne nanoparticles (NPs) in the human kidney has been lacking, hindering the understanding of the relationships between PM2.5 exposure and kidney diseases. Here, we report the discovery and analysis of airborne magnetite nanoparticles in human kidney stones (with mass concentrations ranging from 363 to 740 ng/g dry tissue weight) by high-resolution microstructural characterization. Notably, we established a methodology for highly selective extraction and accurate characterization of distinctive magnetite NPs and identified the abundant presence of these NPs with a distinctive core-shell structure of Fe3O4/SiO2 in both kidney stones and human blood. We demonstrate that such distinctive core-shell magnetite NPs are indicative of a coal-burning source. Hence, magnetite NPs deposited in the human kidneys in this study area most likely derived from air pollution emissions from coal-fired power plants and were transported via blood circulation to the kidney. Our results provide compelling evidence for understanding the systemic health risks of exposure to nanoparticulate, Fe-bearing air pollution and the associations observed between kidney diseases and PM2.5 exposure.

Docetaxel-loaded, dipeptide-functionalized γ-Fe2O3 magnetic nanoparticles: Synthesis, characterization and targeting to prostate cancer.

A new delivery system was designed and synthesized to increase the efficiency of Docetaxel. For this aim, γ-Fe2O3 was synthesized in order to give the nanoparticle the ability to be magnetic targeted. It was functionalized with citric acid to prevent clumping and maintain stability. To increase the interaction efficiency between the delivery system and the drug, leucine-glycine dipeptideand an amphiphilic polymer, Pluronic-F127, were attached to the nanoparticle. Characterization studies were carried out with XRD, ICP-MS, VSM, TEM, and zeta potential to elucidate the structure of this carrier system. After docetaxel was bound to the synthesized carrier, its therapeutic effect was measured by spectrophotometric and flowcytometric methods (MTT, ROS and apoptosis). Docetaxel-bound nanoparticles significantly reduced the viability of the tumor cell compared to the healthy cell in a dose-dependent manner, especially at 24 (50.14±13.25 to 22.32±5.51 at 100 μg/mL) and 48 (41.46±2.22 o 18.80±2.81 at 100 μg/mL) hours. The rate of apoptosis and reactive oxygen species in the negative sample increased from 2.7% to 15.4% and from 9.6% to 74.7%, respectively, as a result of treatment with 15 μg/mL γ-Fe2O3/C/LG/F127/Dotx. Thus, it can be said that the synthesized carrier system is a suitable candidate for the improvement of docetaxel transport.

SplintR ligation-triggered in-situ rolling circle amplification on magnetic bead for accurate detection of circulating microRNAs.

The circulating microRNAs (miRNAs), endogenous noncoding RNAs, post-transcriptionally participate in multiple processes during cell growth and development. Moreover, dysregulation of miRNAs expression is intricately associated with cancer. Currently, challenges of high homology, sequence similarity, and low abundance encountered in the detection of target miRNAs in complex samples need to be addressed. Biosensors established for miRNAs detection suffer from limitations in terms of sensitivity, specificity and high cost. Herein, a miRNA detection method based on in-situ RCA on magnetic bead catalyzed by SplintR ligase was proposed to achieve high sensitivity and high specificity. The following steps are included: (1) formation of P1-P2-miRNA double-stranded complex under catalyzation of SplintR ligase, and the release of P1-P2 single strand under denaturation; (2) enrichment of P1-P2 single chain by streptavidin-modified magnetic beads (SM-MB); (3) in situ RCA on surface of magnetic beads; (4) fluorescence detection. After optimization of experimental conditions, miRNA-155 detection with improved sensitivity and specificity was achieved. The detection limit was low to 36.39 fM, and one-base mismatch discrimination was demonstrated. Also, the clinical practicability for circulating miRNA-155 detection was preliminarily validated in human serum samples.

Hysteresis loops of exchange-coupled magnetic nanoparticle clusters

Abstract Experimental evidence indicates that significant exchange coupling may exist between magnetic nanoparticles (MNPs) in dense MNP aggregates such as nanoflower clusters. Here, we examine the role of inter-particle exchange interactions in determining the magnetic properties of MNP clusters, in particular their athermal hysteresis in a low-frequency alternating field. We consider mechanically fixed close-packed clusters where each particle is modeled as a single macrospin coupled to the others by both dipolar interactions and nearest-neighbor exchange. Upon simulating the quasi-static hysteresis curves, we compute the loop area, remanent moment and coercive field, and we classify each curve by its shape. Computing curve types across parameter space reveals how their shape is determined by the interplay between exchange coupling, dipolar interactions, and uniaxial anisotropy. Strong exchange coupling produces fully saturated loops with coherent moment rotation. Moderate exchange and anisotropy result in magnetically soft clusters with high susceptibility. Finally, for complex clusters, weak to moderate exchange and strong anisotropy may produce highly irregular curves with several abrupt changes in magnetization. Our analysis demonstrates that exchange coupling between MNPs significantly increases the cluster energy product, thereby contributing to explain the exceptional heating power of nanoflowers.

Cascaded Gravity-Driven Microfluidic Chip with Tilt-Actuated Siphon Valves for Rapid Detection of Salmonella Typhimurium.

In recent years, urgent food safety issues have heightened the demand for rapid detection technologies for foodborne pathogens, especially biosensors featuring simplicity, rapidity, and high sensitivity. Yet despite a booming surge in related published studies, commercializing these biosensors remains a constant challenge and persistent objective for researchers. In this study, a gravity-driven microfluidic chip with tilt-actuated siphon valves was developed, integrating silica magnetic beads based nucleic acid separation and recombinase-aided amplification (RAA) detection of Salmonella Typhimurium by simple operations along with a portable biosensing device. By chip inclination, the balance between gravity of reagents and capillary force around siphon valves is altered; thus, simple tilting operations could provide a driving force for fluid flow without the need for external pumps. Siphon valves were designed geometrically with surface modifications to generate comfortable tilting angles, and a chip holder with a built-in angle guide was designed to ensure consistent operational performance. A smartphone app was developed to monitor fluorescence signals for quantitative detection of S. Typhimurium. Experimental results showed that this portable biosensing device could detect S. Typhimurium in spiked chicken samples at concentrations as low as 1.1 × 101 CFU/mL within 60 min, with recovery rates ranging from 91.54% to 117.27%. The siphon valves also demonstrated compatibility with diverse liquid properties, offering scalability and adaptability for various detection scenarios and potential for the detection of various pathogens in food safety and clinical diagnostics by using related nucleic acid probes and reagents.

DNA Framework‐Ensembled Aptamers Enhance Fluid Stability in Circulating Tumor Cells Capture for Tumor Treatment Evaluation

AbstractThe recognition and binding via receptor‐ligand interactions on cell membranes often weaken in complex environments, such as whole blood samples from cancer patients, making disease diagnosis and treatment evaluation unfavorable. Constructing multivalent ligands with sufficient fluid stability in complex environments remains a challenge. Herein, we develop a tetrahedral DNA framework (TDF) ensembled multivalent aptamers (TEAn, n = 1–3) with programmable ligands size, enabling efficient capture of circulating tumor cells (CTCs) and accurate monitoring of clinical treatment progress. The precisely structured TEAn ensures the size‐matching and cooperative hybridization with epithelial cell adhesion molecule (EpCAM) on cell membrane. Compared to traditional aptamer approach, the dissociation constants (Kd) of TEA3 exhibits ∼20‐fold growth in serum due to its precise size and rigid DNA framework. This high‐affinity interaction significantly enhances capture efficiency by improving fluid stability of TEAn and magnetic beads complex in complex environment. In addition, this CTC detection strategy is applied for clinical tumor treatment evaluation and progress monitoring in liver cancer patient samples, achieving an accuracy of ∼83.3% in classifying patients as complete or partial responses (CR/PR). Overall, this strategy will strongly promote potential clinical application of DNA framework for cancer diagnosis and disease progression monitoring.

Quercetin-loaded magnetic nanoparticles: a promising tool for antitumor treatment in human breast cancer cells

Quercetin (QUE) is a phytoestrogen with known antitumor properties; however, its hydrophobic nature and low bioavailability limit its efficacy as an anticancer drug. To address this, we explored loading QUE onto a non-toxic nanocarrier. This study focused on the biological activity of magnetic iron oxide nanoparticles coated with polyethylene glycol (MAG@PEG) loaded with QUE (MAG@PEG@QUE) in MCF-7 cells. The MAG@PEG nanosystem was synthesised using a hydrothermal method, and QUE was incorporated by adding an alcoholic solution of QUE to an aqueous dispersion of MAG@PEG. QUE incorporation was confirmed qualitatively by FTIR spectroscopy and quantitatively through UV–visible spectroscopy. Cytotoxicity studies showed that MAG@PEG@QUE, at a concentration equivalent to the half-maximal inhibitory concentration (IC50) of free QUE, significantly reduced cell proliferation and viability while increasing apoptosis. MCF-7 cells treated with MAG@PEG@QUE also displayed actin cytoskeleton alterations typical of apoptotic cells. Transmission electron microscopy revealed clusters of magnetic nanoparticles within cellular vesicles. Targeted delivery of these nanoparticles was achieved using a static magnetic field, leading to high intracellular accumulation and selective cell death in targeted areas, without affecting adjacent cells. In conclusion, MAG@PEG@QUE shows comparable antitumor effects to free QUE and has the potential to enhance QUE’s bioavailability and targeted delivery for breast cancer treatment.