The assembly state between magnetic nanosensors and their targets orchestrates their magnetic relaxation response

Anthrax revisited: how assessing the unpredictable can improve biosecurity

B. anthracis is one of the most often weaponized pathogens. States had it in their bioweapons programs and criminals and terrorists have used or attempted to use it. This study is motivated by the narrative that emerging and developing technologies today contribute to the amplification of danger through greater easiness, accessibility and affordability of steps in the making of an anthrax weapon. As states would have way better preconditions if they would decide for an offensive bioweapons program, we focus on bioterrorism. This paper analyzes and assesses the possible bioterrorism threat arising from advances in synthetic biology, genome editing, information availability, and other emerging, and converging sciences and enabling technologies. Methodologically we apply foresight methods to encourage the analysis of contemporary technological advances. We have developed a conceptual six-step foresight science framework approach. It represents a synthesis of various foresight methodologies including literature review, elements of horizon scanning, trend impact analysis, red team exercise, and free flow open-ended discussions. Our results show a significant shift in the threat landscape. Increasing affordability, widespread distribution, efficiency, as well as ease of use of DNA synthesis, and rapid advances in genome-editing and synthetic genomic technologies lead to an ever-growing number and types of actors who could potentially weaponize B. anthracis. Understanding the current and future capabilities of these technologies and their potential for misuse critically shapes the current and future threat landscape and underlines the necessary adaptation of biosecurity measures in the spheres of multi-level political decision making and in the science community.

Nuclear magnetic resonance immunoassay of tetanus antibodies based on the displacement of magnetic nanoparticles

A nuclear magnetic resonance (NMR) immunoassay based on the application of carbon-coated iron nanoparticles conjugated with recognition molecules was designed. The principle of the assay is that ELISA plates are coated with a capture element, and then an analyte is added and detected by conjugating the magnetic nanoparticles with recognition molecules. Afterwards, the elution solution (0.1-M sodium hydroxide) is added to displace the magnetic nanoparticles from the well surfaces into the solution. The detached magnetic nanoparticles reduce transverse relaxation time (T2) values of protons from the surrounding solution. A portable NMR relaxometer is used to measure the T2. Magnetic nanoparticles conjugated with streptavidin, monoclonal antibodies, and protein G were applied for the detection of biotinylated albumin, prostate-specific antigen, and IgG specific to tetanus toxoid (TT). The limit of detection of anti-TT IgG was 0.08-0.12 mIU/mL. The reproducibility of the assay was within the acceptable range (CV < 7.4%). The key novelty of the immunoassay is that the displacement of the nanoparticles from the solid support by the elution solution allows the advantages of the solid phase assay to be combined with the sensitive detection of the T2 changes in a volume of liquid.

Magnetic-Separation-Assisted Magnetic Relaxation Switching Assay for Mercury Ion Based on the Concentration Change of Oligonucleotide-Functionalized Magnetic Nanoparticle

Magnetic-separation-assisted magnetic relaxation switching (MRS) assay based on the concentration change of magnetic nanoparticles switches has been designed for bacteria, biological macromolecules, and small molecules detection because of its better analysis performance. As one of the most hazardous pollutants and highly dangerous elements, mercury ion (Hg²⁺) was employed as a model to further investigate the applicability of nanoparticle switches concentration change-based MRS assay mode for detecting metal ions in this study. The principle is based on the specific and strong interaction between mercury ion with the thymine-thymine(T-T) mismatch in double-stranded DNA duplexes by employing oligonucleotide functionalized magnetic nanoparticle as magnetic capture probe and MRS signal probe, respectively. The result shows that magnetic nanoparticles concentration-dependent MRS sensing mode could be facile applied to detect metal ion of Hg²⁺ in tap water, lake water and serum with wider detection range and higher accuracy. The as-presented magnetic-separation-assisted MRS assay of Hg²⁺ in complicated samples shows potential application values for Hg²⁺ assay in clinical and environmental monitoring, which broadens its application.

Nanomedicine-Assisted Combination Therapy of NSCLC: New Platinum-Based Anticancer Drug Synergizes the Therapeutic Efficacy of Ganetespib

Purpose: K-RAS is the most common mutated oncogene associated with Non-Small-Cell Lung Cancer (NSCLC). So far, there are no promising chemotherapies for the direct inhibition of K-RAS, and considered to be undruggable. In this work, we have introduced a new platinum-based cyanoximate complex, Pt(MCO)2, as an anti-cancer drug to enhance the therapeutic efficacy of Hsp90 inhibitor drug, ganetespib for the combination therapy of NSCLC. Methods: We have synthesized polyacrylic acid (PAA)-coated magnetic nanoparticles (MNPs) and used as drug delivery system. These MNPs were decorated with folic acid in order to target folate receptor-expressing NSCLC. The individual and combination of drugs as well as an optical dye DiI were co-encapsulated successfully inside the PAA-coating of MNPs to evaluate synergistic treatment option for NSCLC. The magnetic resonance (MR) and optical imaging modalities assisted for the monitoring drug loading and NSCLC treatment. Results: To evaluate the therapeutic efficacy of these customized MNPs, various cell-based assays including cell viability, apoptosis and necrosis, cell migration, comet and ROS experiments were performed. Results showed minimal toxicity for functional MNPs with no therapeutic drug and more than 60% cell death within 48 h of treatment, when single drug was encapsulated. Importantly, more than 90% cells were dead when both drugs were delivered. Overall, the results indicated that the Pt(MCO)2 drug enhances the therapeutic efficacy of ganetespib by more than 30% toxicity towards the targeted treatment of NSCLC, while showed minimal toxicity to the normal healthy tissues. Conclusion: We successfully developed new dual-modal magnetic nanomedicines for the rapid and controlled release of combination of drugs for the effective treatment of NSCLC. The MR and fluorescence modalities help monitoring the delivery of drugs, where the new platinum-based drug Pt(MCO)2 synergizes the therapeutic efficacy of ganetespib.

Structure-Relaxivity Relationships of Magnetic Nanoparticles for Magnetic Resonance Imaging

Magnetic nanoparticles (MNPs) have been extensively explored as magnetic resonance imaging (MRI) contrast agents. With the increasing complexity in the structure of modern MNPs, the classical Solomon-Bloembergen-Morgan and the outer-sphere quantum mechanical theories established on simplistic models have encountered limitations for defining the emergent phenomena of relaxation enhancement in MRI. Recent progress in probing MRI relaxivity of MNPs based on structural features at the molecular and atomic scales is reviewed, namely, the structure-relaxivity relationships, including size, shape, crystal structure, surface modification, and assembled structure. A special emphasis is placed on bridging the gaps between classical simplistic models and modern MNPs with elegant structural complexity. In the pursuit of novel MRI contrast agents, it is hoped that this review will spur the critical thinking for design and engineering of novel MNPs for MRI applications across a broad spectrum of research fields.

Novel magnetic relaxation nanosensors: an unparalleled "spin" on influenza diagnosis

Rapid detection and diagnosis of pathogenic strains of influenza is necessary for expedited treatment and quicker resolutions to the ever-rising flu pandemics. Considering this, we propose the development of novel magnetic relaxation nanosensors (MRnS) for the rapid detection of influenza through targeted binding with hemagglutinin. 2,6- and 2,3-sialic acid ligands and entry blocker peptides are conjugated to iron oxide nanoparticles to create functional MRnS. Positive detection of various hemagglutinin variants (H1 and H5) is possible with protein concentrations as little as 1.0 nM. Most importantly, detection using functional MRnS is achieved within minutes and differentiates between influenza subtypes. This specificity allows mixtures of MRnS to screen for multiple pathogens at once, discarding the need to conduct multiple individual tests. Current methods used to diagnose influenza, such as RT-PCR and viral culturing, while largely effective, are complex, time-consuming and costly. As well, they are not as sensitive or specific, and have been known to produce false-positive results. In contrast to these methods, targeted MRnS are robust, point-of-care diagnostic tools featuring simple, rapid and low-cost procedures. These qualities, as well as high sensitivity and specificity, and low turnaround times, make a strong case for the diagnostic application of MRnS in clinical settings.

Multiparametric Magneto-fluorescent Nanosensors for the Ultrasensitive Detection of Escherichia coli O157:H7

Enterohemorrhagic Escherichia coli O157:H7 presents a serious threat to human health and sanitation and is a leading cause in many food- and waterborne ailments. While conventional bacterial detection methods such as PCR, fluorescent immunoassays and ELISA exhibit high sensitivity and specificity, they are relatively laborious and require sophisticated instruments. In addition, these methods often demand extensive sample preparation and have lengthy readout times. We propose a simpler and more sensitive diagnostic technique featuring multiparametric magneto-fluorescent nanosensors (MFnS). Through a combination of magnetic relaxation and fluorescence measurements, our nanosensors are able to detect bacterial contamination with concentrations as little as 1 colony-forming unit (CFU). The magnetic relaxation property of our MFnS allow for sensitive screening at low target CFU, which is complemented by fluorescence measurements of higher CFU samples. Together, these qualities allow for the detection and quantification of broad-spectrum contaminations in samples ranging from aquatic reservoirs to commercially produced food.

Blu-ray based optomagnetic aptasensor for detection of small molecules

This paper describes an aptamer-based optomagnetic biosensor for detection of a small molecule based on target binding-induced inhibition of magnetic nanoparticle (MNP) clustering. For the detection of a target small molecule, two mutually exclusive binding reactions (aptamer-target binding and aptamer-DNA linker hybridization) are designed. An aptamer specific to the target and a DNA linker complementary to a part of the aptamer sequence are immobilized onto separate MNPs. Hybridization of the DNA linker and the aptamer induces formation of MNP clusters. The target-to-aptamer binding on MNPs prior to the addition of linker-functionalized MNPs significantly hinders the hybridization reaction, thus reducing the degree of MNP clustering. The clustering state, which is thus related to the target concentration, is then quantitatively determined by an optomagnetic readout technique that provides the hydrodynamic size distribution of MNPs and their clusters. A commercial Blu-ray optical pickup unit is used for optical signal acquisition, which enables the establishment of a low-cost and miniaturized biosensing platform. Experimental results show that the degree of MNP clustering correlates well with the concentration of a target small molecule, adenosine triphosphate (ATP) in this work, in the range between 10µM and 10mM. This successful proof-of-concept indicates that our optomagnetic aptasensor can be further developed as a low-cost biosensing platform for detection of small molecule biomarkers in an out-of-lab setting.

Advances in Anthrax Detection: Overview of Bioprobes and Biosensors

Anthrax is an infectious disease caused by Bacillus anthracis. Although anthrax commonly affects domestic and wild animals, it causes a rare but lethal infection in humans. A variety of techniques have been introduced and evaluated to detect anthrax using cultures, polymerase chain reaction, and immunoassays to address the potential threat of anthrax being used as a bioweapon. The high-potential harm of anthrax in bioterrorism requires sensitive and specific detection systems that are rapid, field-ready, and real-time monitoring. Here, we provide a systematic overview of anthrax detection probes with their potential applications in various ultra-sensitive diagnostic systems.

One-step detection of pathogens and viruses: combining magnetic relaxation switching and magnetic separation

We report a sensing methodology that combines magnetic separation (MS) and magnetic relaxation switching (MS-MRS) for one-step detection of bacteria and viruses with high sensitivity and reproducibility. We first employ a magnetic field of 0.01 T to separate the magnetic beads of large size (250 nm in diameter) from those of small size (30 nm in diameter) and use the transverse relaxation time (T2) of the water molecules around the 30 nm magnetic beads (MB30) as the signal readout of the immunoassay. An MS-MRS sensor integrates target enrichment, extraction, and detection into one step, and the entire immunoassay can be completed within 30 min. Compared with a traditional MRS sensor, an MS-MRS sensor shows enhanced sensitivity, better reproducibility, and convenient operation, thus providing a promising platform for point-of-care testing.

Paramagnetic relaxation based biosensor for selective dopamine detection

We report a new NMR relaxation time-based method for sensitive and selective dopamine detection using paramagnetic nanoparticles.

Identification of toxin inhibitors using a magnetic nanosensor-based assay

A magnetic nanosensor-based method is described to screen a library of drugs for potential binding to toxins. Screening is performed by measuring changes in the magnetic relaxation signal of the nanosensors (bMR nanosensors) in aqueous suspension upon addition of the toxin. The Anthrax lethal factor (ALF) is selected as a model toxin to test the ability of our bMR nanosensor-based screening method to identify potential inhibitors of the toxin. Out of 30 molecules screened, sulindac, naproxen and fusaric acid are found to bind LF, with dissociation constants in the low micromolar range. Further biological analysis of the free molecules in solution indicate that sulindac and its metabolic products inhibited LF cytotoxicity to macrophages with IC50 values in the micromolar range. Meanwhile, fusaric acid is found to be less effective at inhibiting LF cytotoxicity, while naproxen does not inhibit LF toxicity. Most importantly, when the sulindac and fusaric acid-bMR nanosensors themselves are tested as LF inhibitors, as opposed to the corresponding free molecules, they are stronger inhibitors of LF with IC50 values in the nanomolar range. Taken together, these studies show that a bMR nanosensors-based assay can be used to screen known drugs and other small molecules for inhibitor of toxins. The method can be easily modified to screen for inhibitors of other molecular interactions and not only the selected free molecule can be study as potential inhibitors but also the bMR nanosensors themselves achieving greater inhibitory potential.

Environment-responsive nanophores for therapy and treatment monitoring via molecular MRI quenching

The effective delivery of therapeutics to disease sites significantly contributes to drug efficacy, toxicity and clearance. Here we demonstrate that clinically approved iron oxide nanoparticles (Ferumoxytol) can be utilized to carry one or multiple drugs. These so called ‘nanophores’ retain their cargo within their polymeric coating through weak electrostatic interactions and release it in slightly acidic conditions (pH 6.8 and below). The loading of drugs increases the nanophores’ transverse T2 and longitudinal T1 NMR proton relaxation times, which is proportional to amount of carried cargo. Chemotherapy with translational nanophores is more effective than the free drug in vitro and in vivo, without subjecting the drugs or the carrier nanoparticle to any chemical modification. Evaluation of cargo incorporation and payload levels in vitro and in vivo can be assessed via benchtop magnetic relaxometers, common NMR instruments or MRI scanners.

Casein-coated iron oxide nanoparticles for high MRI contrast enhancement and efficient cell targeting

Surface properties, as well as inherent physicochemical properties, of the engineered nanomaterials play important roles in their interactions with the biological systems, which eventually affect their efficiency in diagnostic and therapeutic applications. Here we report a new class of MRI contrast agent based on milk casein protein-coated iron oxide nanoparticles (CNIOs) with a core size of 15 nm and hydrodynamic diameter ~30 nm. These CNIOs exhibited excellent water-solubility, colloidal stability, and biocompatibility. Importantly, CNIOs exhibited prominent T2 enhancing capability with a transverse relaxivity r2 of 273 mM(-1) s(-1) at 3 tesla. The transverse relaxivity is ~2.5-fold higher than that of iron oxide nanoparticles with the same core but an amphiphilic polymer coating. CNIOs showed pH-responsive properties, formed loose and soluble aggregates near the pI (pH ~4.0). The aggregates could be dissociated reversibly when the solution pH was adjusted away from the pI. The transverse relaxation property and MRI contrast enhancing effect of CNIOs remained unchanged in the pH range of 2.0-8.0. Further functionalization of CNIOs can be achieved via surface modification of the protein coating. Bioaffinitive ligands, such as a single chain fragment from the antibody of epidermal growth factor receptor (ScFvEGFR), could be readily conjugated onto the protein coating, enabling specific targeting to MDA-MB-231 breast cancer cells overexpressing EGFR. T2-weighted MRI of mice intravenously administered with CNIOs demonstrated strong contrast enhancement in the liver and spleen. These favorable properties suggest CNIOs as a class of biomarker targeted magnetic nanoparticles for MRI contrast enhancement and related biomedical applications.

Augmented anticancer activity of a targeted, intracellularly activatable, theranostic nanomedicine based on fluorescent and radiolabeled, methotrexate-folic Acid-multiwalled carbon nanotube conjugate

The present study reports the design, synthesis, and biological evaluation of a novel, intravenously injectable, theranostic prodrug based on multiwalled carbon nanotubes (MWCNTs) concomitantly decorated with a fluorochrome (Alexa-fluor, AF488/647), radionucleide (Technitium-99m), tumor-targeting module (folic acid, FA), and anticancer agent (methotrexate, MTX). Specifically, MTX was conjugated to MWCNTs via a serum-stable yet intracellularly hydrolyzable ester linkage to ensure minimum drug loss in circulation. Cell uptake studies corroborated the selective internalization of AF-FA-MTX-MWCNTs (1) by folate receptor (FR) positive human lung (A549) and breast (MCF 7) cancer cells through FR mediated endocytosis. Lysosomal trafficking of 1 enabled the conjugate to exert higher anticancer activity as compared to its nontargeted counterpart that was mainly restricted to cytoplasm. Tumor-specific accumulation of 1 in Ehlrich Ascites Tumor (EAT) xenografted mice was almost 19 and 8.6 times higher than free MTX and FA-deprived MWCNTs. Subsequently, the conjugate 1 was shown to arrest tumor growth more effectively in chemically breast tumor induced rats, when compared to either free MTX or nontargeted controls. Interestingly, the anticancer activities of the ester-linked CNT-MTX conjugates (including the one deprived of FA) were significantly higher than their amide-linked counterpart, suggesting that cleavability of linkers between drug and multifunctional nanotubes critically influence their therapeutic performance. The results were also supported by in silico docking and ligand similarity analysis. Toxicity studies in mice confirmed that all CNT-MTX conjugates were devoid of any perceivable hepatotoxicity, cardiotoxicity, and nephrotoxicity. Overall, the delivery property of MWCNTs, high tumor binding avidity of FA, optical detectability of AF fluorochromes, and radio-traceability of (99m)Tc could be successfully integrated and partitioned on a single CNT-platform to augment the therapeutic efficacy of MTX against FR overexpressing cancer cells while allowing a real-time monitoring of treatment response through multimodal imaging.

Mechanism of magnetic relaxation switching sensing

Magnetic relaxation switching (MRSw) assays that employ target-induced aggregation (or disaggregation) of magnetic nanoparticles (MNPs) can be used to detect a wide range of biomolecules. The precise working mechanisms, however, remain poorly understood, often leading to confounding interpretation. We herein present a systematic and comprehensive characterization of MRSw sensing. By using different types of MNPs with varying physical properties, we analyzed the nature and transverse relaxation modes for MRSw detection. The study found that clustered MNPs are universally in a diffusion-limited fractal state (dimension of ~2.4). Importantly, a new model for transverse relaxation was constructed that accurately recapitulates observed MRSw phenomena and predicts the MRSw detection sensitivities and dynamic ranges.

Gadolinium-encapsulating iron oxide nanoprobe as activatable NMR/MRI contrast agent

Herein we report a novel gadolinium-encapsulating iron oxide nanoparticle-based activatable NMR/MRI nanoprobe. In our design, Gd-DTPA is encapsulated within the poly(acrylic acid) (PAA) polymer coating of a superparamagnetic iron oxide nanoparticle (IO-PAA), yielding a composite magnetic nanoprobe (IO-PAA-Gd-DTPA) with quenched longitudinal spin-lattice magnetic relaxation (T(1)). Upon release of the Gd-DTPA complex from the nanoprobe's polymeric coating in acidic media, an increase in the T(1) relaxation rate (1/T(1)) of the composite magnetic nanoprobe was observed, indicating a dequenching of the nanoprobe with a corresponding increase in the T(1)-weighted MRI signal. When a folate-conjugated nanoprobe was incubated in HeLa cells, a cancer cell line overexpressing folate receptors, an increase in the 1/T(1) signal was observed. This result suggests that, upon receptor-mediated internalization, the composite magnetic nanoprobe degraded within the cell's lysosome acidic (pH 5.0) environment, resulting in an intracellular release of Gd-DTPA complex with subsequent T(1) activation. In addition, when an anticancer drug (Taxol) was coencapsulated with the Gd-DTPA within the folate receptor targeting composite magnetic nanoprobe, the T(1) activation of the probe coincided with the rate of drug release and corresponding cytotoxic effect in cell culture studies. Taken together, these results suggest that our activatable T(1) nanoagent could be of great importance for the detection of acidic tumors and assessment of drug targeting and release by MRI.

Immunosensor based on magnetic relaxation switch and biotin-streptavidin system for the detection of Kanamycin in milk

A rapid, sensitive, and simple immunosensor was developed for the detection of Kanamycin (KM) in milk. This immunosensor is based on magnetic relaxation switch (MRS) assay and biotin-streptavidin system (B-SA system). The target analyte (KM) competed with those on the surface of the superparamagnetic iron oxide (SPIO) nanoparticles and hence affected the formation of SPIO aggregates. The dispersed and aggregated states of SPIO can modulate the spin-spin relaxation time (T(2)) of the neighboring water molecule. T(2) was then changed as an effect of the target analyte. The B-SA system was used to amplify the SPIO binding, thus enhance the sensitivity. The detection working was 1.5 to 25.2ng mL(-1) and limit of detection (LOD) was determined to be 0.1ng mL(-1). The LOD of the immunosensor decreased tenfold, and its analysis time (45min) was much shorter than that of enzyme-linked immunosorbent assay (6h to 8h). The average recoveries of the KM at various spiking levels ranged from 80.2% to 85.6% with a relative standard deviation (RSD) below 4.0%. The results showed that the MRS immunosensor was a promising platform for the determination of small molecular residues because of its high sensitivity, specificity, homogeneity, and speed.

Rapid and sensitive detection of an intracellular pathogen in human peripheral leukocytes with hybridizing magnetic relaxation nanosensors

Bacterial infections are still a major global healthcare problem. The quick and sensitive detection of pathogens responsible for these infections would facilitate correct diagnosis of the disease and expedite treatment. Of major importance are intracellular slow-growing pathogens that reside within peripheral leukocytes, evading recognition by the immune system and detection by traditional culture methods. Herein, we report the use of hybridizing magnetic nanosensors (hMRS) for the detection of an intracellular pathogen, Mycobacterium avium spp. paratuberculosis (MAP). The hMRS are designed to bind to a unique genomic sequence found in the MAP genome, causing significant changes in the sample’s magnetic resonance signal. Clinically relevant samples, including tissue and blood, were screened with hMRS and results were compared with traditional PCR analysis. Within less than an hour, the hMRS identified MAP-positive samples in a library of laboratory cultures, clinical isolates, blood and homogenized tissues. Comparison of the hMRS with culture methods in terms of prediction of disease state revealed that the hMRS outperformed established culture methods, while being significantly faster (1 hour vs 12 weeks). Additionally, using a single instrument and one nanoparticle preparation we were able to detect the intracellular bacterial target in clinical samples at the genomic and epitope levels. Overall, since the nanoparticles are robust in diverse environmental settings and substantially more affordable than PCR enzymes, the potential clinical and field-based use of hMRS in the multiplexed identification of microbial pathogens and other disease-related biomarkers via a single, deployable instrument in clinical and complex environmental samples is foreseen.

Development of multifunctional hyaluronan-coated nanoparticles for imaging and drug delivery to cancer cells

Currently, there is high interest in developing multifunctional theranostic platforms for cancer monitoring and chemotherapy. Herein, we report hyaluronan (HA)-coated superparamagnetic iron oxide nanoparticles (HA-SPION) as a promising system for targeted imaging and drug delivery. When incubated with cancer cells, HA-SPIONs were rapidly taken up and the internalization of HA-SPION by cancer cells was much higher than the NPs without HA coating. The high magnetic relaxivity of HA-SPION coupled with enhanced uptake enabled magnetic resonance imaging of cancer cells. Furthermore, doxorubicin (DOX) was attached onto the nanoparticles through an acid responsive linker. While HA-SPION was not toxic to cells, DOX-HA-SPION was much more potent than free DOX to kill not only drug-sensitive but also multi-drug-resistant cancer cells. This was attributed to differential uptake mechanisms and cellular distributions of free DOX and DOX-HA-SPION in cancer cells.

A cerium oxide nanoparticle-based device for the detection of chronic inflammation via optical and magnetic resonance imaging

Monitoring of microenvironmental parameters is critical in healthcare and disease management. Harnessing the antioxidant activity of nanoceria and the imaging capabilities of iron oxide nanoparticles in a device setup, we were able to image changes in the device's aqueous milieu. The device was able to convey and process changes in the microenvironment's pH and reactive oxygen species' concentration, distinguishing physiological from abnormal levels. As a result under physiological and transient inflammatory conditions, the device's fluorescence and magnetic resonance signals, emanating from multimodal iron oxide nanoparticles, were similar. However, under chronic inflammatory conditions that are usually associated with high local concentrations of reactive oxygen species and pH decrease, the device's output was considerably different. Specifically, the device's fluorescence emission significantly decreased, while the magnetic resonance signal T2 increased. Further studies identified that the changes in the device's output are attributed to inactivation of the sensing component's nanoceria that prevents it from successfully scavenging the generated free radicals. Interestingly, the buildup of free radical excess led to polymerization of the iron oxide nanoparticle's coating, with concomitant formation of micron size aggregates. Our studies indicate that a nanoceria-based device can be utilized for the monitoring of pro-inflammatory biomarkers, having important applications in the management of numerous ailments while eliminating nanoparticle toxicity issues.

Designed synthesis of uniformly sized iron oxide nanoparticles for efficient magnetic resonance imaging contrast agents

Various magnetic nanoparticles have been extensively investigated as novel magnetic resonance imaging (MRI) contrast agents owing to their unique characteristics, including efficient contrast effects, biocompatibility, and versatile surface functionalization capability. Nanoparticles with high relaxivity are very desirable because they would increase the accuracy of MRI. Recent progress in nanotechnology enables fine control of the size, crystal structure, and surface properties of iron oxide nanoparticles. In this tutorial review, we discuss how MRI contrast effects can be improved by controlling the size, composition, doping, assembly, and surface properties of iron-oxide-based nanoparticles.