High Relaxation Research Articles

An MMP-2 Responsive Nanotheranostic Probe Enabled Synergistic Therapy of Rheumatoid Arthritis and MR/CT Assessment of Therapeutic Response In Situ.

This study reports a facile and green synthesis of a new multifunctional nanotheranostic probe for the synergistic therapy of rheumatoid arthritis (RA) and in situ assessment of therapeutic response. The probe is synthesized through a one-step self-assembly of two exquisitely designed peptide-amphiphilic block copolymers (PEG-DTIPA-KGPLGVRK-MTX and Pal-GGGGHHHHD-TCZ) under mild conditions, requiring minimal energy input. The resultant probe demonstrates excellent biocompatibility, water solubility, and colloidal stability. It exhibits a strong IL-6R targeting ability toward inflamed joints, and releases drugs in an MMP-2-responsive manner. The co-loading of methotrexate(MTX) and tocilizumab (TCZ) into the probe enables synergistic RA therapy with improved efficacy by simultaneously decreasing the activity of adenosine synthetase and interfering with the binding of IL-6 to its receptor. In addition, the resultant probe exhibits a high r1 relaxation rate (7.00 mm-1 s-1 ) and X-ray absorption capability (69.04 Hu mm-1 ), enabling sensitive MR and CT dual-modal imaging for simultaneous evaluation of synovial thickness and bone erosion. Both in vitro experiments using lipopolysaccharide-treated RAW264.7 cells and in vivo experiments using collagen-induced arthritis mice demonstrate the probe's high effectiveness in synergistically inhibiting inflammation. This study provides new insights into RA theranostics, therapeutic monitoring, the design of multifunctional theranostic probes, and beyond.

Pore size distribution measurement with magnetic resonance [formula omitted] distributions outside the fast diffusion regime

Based on Brownstein-Tarr (BT) theory, a new method is proposed to determine the pore size distribution which is an important petrophysical property in studying fluid storage and fluid transport in reservoir rocks. For reservoir rocks with large pores, or high surface relaxivity, direct conversion from the magnetic resonance (MR) T2 distribution with the fast diffusion assumption may be unreliable. In this study, the ground mode lifetime T20 distribution was proposed to be utilized to estimate the pore size distribution. The T20 lifetime of large pores within a porous system can be determined directly through experiment. However, the T20 lifetimes of smaller pores may overlap with the first nonground mode T21 lifetimes of the larger pores, which collectively contribute to the MR signal with a shorter lifetime. To accurately determine the T20 lifetime of smaller pores, it is essential to remove the contribution to the distribution of the T21 lifetimes of the larger pores. The T21 distribution can be both experimentally observed and calculated through the proposed method. The proposed pore size distribution method is verified by calculation in the present work. Water-saturated glass bead packs were employed for initial experiments. The calculated pore size, and its distribution, match the geometric pore size. The proposed method was applied to determine the pore size distribution of a Berea sandstone. The results are in good agreement with SEM measurements.

Review of the Efficacy and Safety of Gadopiclenol: A Newly Emerging Gadolinium-Based Contrast Agent.

Gadolinium-based contrast agents (GBCAs) are one of the most commonly used agents in magnetic resonance imaging. Gadopiclenol is a new GBCA aimed at providing improved diagnostic efficacy with a favorable safety profile. The proposed advantages are due to its specific pharmacological properties, one of which is high relaxivity values. The aim of this review is to assess the efficacy, diagnostic accuracy, and safety of gadopiclenol in comparison to other currently used gadolinium-based contrast agents. PubMed and other database systems were used to identify relevant studies. The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed, resulting in 10 articles that were included in the review. The outcomes were reviewed according to several factors regarding efficacy and accuracy in terms of qualitative and quantitative descriptors relative to properties of enhancement provided by the contrast agent. In terms of safety profile, a number of outcomes were assessed such as the occurrence of serious adverse effects, severe kidney injury, and organ-based contrast retention. Gadopiclenol was found to provide outcomes comparable to other commonly used GBCAs at lower doses with further favorable results at higher doses while maintaining an acceptable safety profile. However, it was found to have high rates of retention within the liver and can cause nonsignificant QT prolongation in healthy individuals, which arguably creates the need for further research regarding more long-term implications of these possible adverse effects.

Preclinical Evaluation of a Protein-Based Nanoscale Contrast Agent for MR Angiography at an Ultralow Dose.

BSA-biomineralized Gd nanoparticles (Gd@BSA NPs) have been recognized as promising nanoscale MR contrast agents. The aim of this study was to carry out a preclinical evaluation of these NPs in a middle-sized animal model (rabbits). New Zealand white rabbits were treated intravenously with Gd@BSA NPs (0.02 mmol Gd/kg) via a clinically-used high-pressure injector, with commercial Gd-diethylene triamine pentaacetate (Gd-DTPA)-injected group as control. Then MR angiography was performed according to the standard clinical protocol with a 3.0-T MR scanner. The SNR and CNR of the main arteries and branches were monitored. Pharmacokinetics and bioclearance were continuously evaluated in blood, urine, and feces. Gd deposition in vital organs was measured by ICP‒MS. Weight monitoring, HE staining, and blood biochemical analysis were also performed to comprehensively estimate systemic toxicity. The ultrasmall Gd@BSA NPs (<6 nm) exhibited high stability and T1 relaxivity. Compared to Gd-DTPA, Gd@BSA NPs demonstrated superior vascular system imaging performance at ultralow doses, especially of the cardiac artery and other main branches, and exhibited a significantly higher SNR and CNR. Notably, the Gd@BSA NPs showed a shorter half-life in blood, less retention in organs, and improved biocompatibility. The preclinical evaluations here demonstrated that Gd@BSA NPs are promising and advantageous MR CA candidates that can be used at a low dose with excellent MR imaging performance, thus suggesting its further clinical trials and applications.

Dynamic Behavior of Heavy Water Inside and Outside of Poly (N-Isopropylacrylamide) (PNIPAM) Microgel Using Broadband Dielectric Spectroscopy

One pot free radical precipitation polymerization was used to synthesize an aqueous suspension of non-ionic poly ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -isopropylacrylamide) [PNIPAM] microgel particles. For dielectric measurements in the frequency range of 100 MHz to 50 GHz and temperature range of 288 K to 323 K, 10 wt. % of freeze-dried PNIPAM microgels dispersed in heavy water were used. The relaxation process was seen at around 15 GHz, which corresponds to the entire rotational motion of the heavy water, both within and outside the microgel. Furthermore, in the high frequency relaxation spectrum, heavy water outside the microgel (h1-process with a relaxation time of h1, τ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h1</sub> , fixed as that of pure heavy water) and confined heavy water within the microgel (h2-process with a relaxation time of h2, τ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h2</sub> ) were evaluated in view of the two-water model’s assumption and contribution. Under volume phase transition temperature (VPTT), τ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h2</sub> is about 4 to 5 times larger than τ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h1</sub> , and it does not change much even though the temperature is raised. However, τ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">h2</sub> rapidly increases above VPTT from 7 to 14, which reveals that the dynamics of heavy water are severely constrained inside the shrunken state of the PNIPAM microgel. The obtained results are compared to the dynamics of pure water in PNIPAM microgels aqueous suspension to better understand the effect of deuterium substitution for hydrogen on the dynamics of heavy water inside and outside of PNIPAM microgels.

Biotin‐Conjugated Poly(Acrylic Acid)‐Grafted Ultrasmall Gadolinium Oxide Nanoparticles for Enhanced Tumor Imaging

AbstractHerein, biotin (Bio)‐conjugated poly(acrylic acid) (PAA)‐grafted ultrasmall gadolinium oxide nanoparticles (Bio‐PAA‐Gd2O3 NPs) were synthesized for enhanced tumor imaging using Bio as a tumor‐targeting ligand. The average particle diameter of Gd2O3 NPs was 2.1 nm. The Bio‐PAA‐Gd2O3 NPs exhibited excellent colloidal stability (i. e., no precipitation) and a high longitudinal water proton spin relaxivity (r1) of 23.8 s−1 mM−1 (r2/r1=1.6 and r2=transverse water proton spin relaxivity), which was ∼6 times higher than those of commercial Gd‐chelated magnetic resonance imaging (MRI) contrast agents. Cytotoxicity tests using two cell lines showed that the Bio‐PAA‐Gd2O3 NPs were almost non‐toxic up to the measured concentration of 500 μM Gd. The enhanced tumor imaging of the Bio‐PAA‐Gd2O3 NPs was demonstrated through their higher positive contrasts and longer contrast retention at the tumor after intravenous injection in T1 MR images, compared with those of the control PAA‐Gd2O3 NPs.

Reinvestigation of conducting properties of Ca-doped barium titanate

Relaxation processes of Ba1−xCaxTiO3 ceramics with x = 0.05, 0.10 and 0.23 Ca contents were studied by combining the dielectric modulus and complex impedance experiments. Use of both methods permits an exploration of relaxation processes in both time and frequency domains, including relaxation distribution function at low and high frequency relaxation regions (grain and grain boundary). From an analysis using the complex impedance formalism, the predominant time distribution relaxation function turns out to be a Cole-Cole type, whereas from the dielectric modulus formalism it is described by non-Debye relaxation functions. While activation energies derived from the dielectric modulus formalism are characteristic of doubly-ionized oxygen vacancies (0.85–1.00 eV), they are from the complex impedance approach expressed as a typical electronic conduction (1.2–1.5 eV). It was identified that the impedance formalism describes well the relaxation in the low frequency regime with similar activation energy derived from the Jonscher power law (1.1–1.4 eV). The present study highlights the potential of using both impedance and dielectric modulus formalisms to identify and quantify non-Debye relaxation process and conducting properties in mixed electronic-ionic conductors.

Synthesis and Properties of (1R(S),5R(S),7R(S),8R(S))-1,8-Bis(hydroxymethyl)-6-azadispiro[4.1.4.2]tridecane-6-oxyl: Reduction-Resistant Spin Labels with High Spin Relaxation Times.

Site-directed spin labeling followed by investigation using Electron Paramagnetic Resonance spectroscopy is a rapidly expanding powerful biophysical technique to study structure, local dynamics and functions of biomolecules using pulsed EPR techniques and nitroxides are the most widely used spin labels. Modern trends of this method include measurements directly inside a living cell, as well as measurements without deep freezing (below 70 K), which provide information that is more consistent with the behavior of the molecules under study in natural conditions. Such studies require nitroxides, which are resistant to the action of biogenic reductants and have high spin relaxation (dephasing) times, Tm. (1R(S),5R(S),7R(S),8R(S))-1,8-bis(hydroxymethyl)-6-azadispiro[4.1.4.2]tridecane-6-oxyl is a unique nitroxide that combines these features. We have developed a convenient method for the synthesis of this radical and studied the ways of its functionalization. Promising spin labels have been obtained, the parameters of their spin relaxation T1 and Tm have been measured, and the kinetics of reduction with ascorbate have been studied.

Anomalously small magnetic relaxation rate of Ca10(Pt3As8)(Fe2−x Pt x As2)5 superconductor

Large critical current density and low magnetic relaxation are the main challenges for practical applications of high-temperature superconductors (HTSs). Magnetic relaxation refers to the decay of superconducting current density caused by thermal activation and/or quantum fluctuations. This process involves the motion of vortices, particularly vortex creep, which leads to energy dissipation. HTSs typically exhibit strong superconducting fluctuations and magnetic relaxation due to their short coherence length and large anisotropy. These characteristics are usually manifested by the large Ginzburg number Gi and high magnetic relaxation rate S. The correlation between the relaxation rate S and Gi is informative to understand the interplay between vortex dynamics and relevant parameters. Recently, Eley et al (2017 Nat. Mater. 16 409) proposed that almost all the HTSs follow a universal lower limit S∼ Gi 1/2(T/T c), providing new clues to design HTSs with small relaxation rate and evaluate their application potential. Here, we systematically studied the vortex dynamics in the Ca10(Pt3As8)(Fe2−x Pt x As2)5 superconductor with a large Gi∼ 0.16. Strikingly, this material exhibits a small relaxation rate (S ∼0.02 at T c/4 under 1 T), approaching the proposed lower limit of S∼ Gi 1/2(T/T c). We propose that such a small value of S in Ca10(Pt3As8)(Fe2−x Pt x As2)5 may originate from its unique structure with metallic skutterudite blocking layers. Our results suggest a promising new avenue for the search and design of HTSs with low magnetic relaxation.

N-Acetylcysteine-Loaded Magnetic Nanoparticles for Magnetic Resonance Imaging.

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterized by the rapid onset of lung inflammation Therefore, monitoring the spatial distribution of the drug directly administered to heterogeneously damaged lungs is desirable. In this work, we focus on optimizing the drug N-acetylcysteine (NAC) adsorption on poly-l-lysine-modified magnetic nanoparticles (PLLMNPs) to monitor the drug spatial distribution in the lungs using magnetic resonance imaging (MRI) techniques. The physicochemical characterizations of the samples were conducted in terms of morphology, particle size distributions, surface charge, and magnetic properties followed by the thermogravimetric quantification of NAC coating and cytotoxicity experiments. The sample with the theoretical NAC loading concentration of 0.25 mg/mL was selected as an optimum due to the hydrodynamic nanoparticle size of 154 nm, the surface charge of +32 mV, good stability, and no cytotoxicity. Finally, MRI relaxometry confirmed the suitability of the sample to study the spatial distribution of the drug in vivo using MRI protocols. We showed the prevailing transverse relaxation with high transverse relaxivity values and a high r2(*)/r1 ratio, causing visible hypointensity in the final MRI signal. Furthermore, NAC adsorption significantly affects the relaxation properties of PLLMNPs, which can help monitor drug release in vitro/in vivo.

Coupling effects of heating pelleting and torrefaction on black pellets production from microalga Nannochloropsis Oceanica residues

Microalga Mannochloropsis Oceanica residues (MNOR) are a potential bioenergy source that can become fossil fuel substitute. Its low density, high moisture and content of carbon and oxygen content hinder its wide application. Heating pelleting coupled with torrefaction is an effective approach to update MNOR. In this study, the effects of compression time, compression load and mold temperature were investigated in self-made heating pelleting device. The cost-effective combination for pelleting were 30 s, 1.0 MPa and 75 °C, where the pellets had high shatter resistance and relaxation density. The results of torrefaction experiments in tubular furnace showed that CO2 was main gas product released from MNOR pellet. Two kinds of acid with high-value were detected from tar by GCMS. FTIR and XPS analyses confirmed that the torrefaction enhanced the carbonation of the MNOR pellets, where the relative content of C- (C, H) increased and the relative content of C = O(–OH) decreased. The two-step first-order kinetic model was used to reveal the mechanisms of MNOR torrefaction, with activation energies ranging from 4.98 to 74.95 kJ/mol for powder and from 5.83 to 77.71 kJ/mol for pellet.

Nature of the abnormally high photocurrent relaxation time in the a-Ga2O3-based Schottky diodes

Ga2O3 is an ultra-wideband material with excellent optical characteristics. It is a promising material for power applications and optoelectronics because of its high electrical breakdown voltage and radiation hardness. It is optically transparent for visible light and UVA but UVC-sensitive. One of the main disadvantages of this material is the anomalous slow photoeffect: photoconductivity rise and decay characteristic times can be more than hundreds of seconds long. This "slow" photoconductivity effect severely limits the utilisation of the Ga2O3-based devices. The aim of this work is the investigation of the nature of this effect. The results of the photoinduced current rise and decay under 530 nm and 259 nm LED are measured in the HVPE-grown α-Ga2O3-based Schottky diode. Upon UV-illumination the photocurrent rise consists of three parallel processes: fast signal growth, slow growth and very slow decay with characteristic times near 70 ms, 40 s and 300 s respectively. Subsequent 530 nm LED illumination resulted in photoinduced current rise consisting of two mechanisms with characterisatic times 130 ms and 40 s on which a very slow decrease of the photocurrent amplitude with characteristic time of 1500 s was superimposed. 530 nm illumination stimulates this process. Protoinduced current relaxation analysis shows the presence of the deep levels with energies (EC - 0.17 eV). It is suggested that extremely slow relaxations can be associated with potential fluctuations near the Schottky barrier.

Redox ferrocenylseleno compounds modulate longitudinal and transverse relaxation times of FNPs-Gd MRI contrast agents for multimodal imaging and photo-Fenton therapy.

Developing a feasible way to feature longitudinal (T1) and transverse (T2) relaxation performance of contrast agents for magnetic resonance imaging (MRI) is important in cancer diagnosis and therapy. Improved accessibility to water molecule is essential for accelerating the relaxation rate of water protons around the contrast agents. Ferrocenyl compounds have reversible redox property for modulating the hydrophobicity/hydrophilicity of assemblies. Thus, they could be the candidates that can change water accessibility to the contrast agent surface. Herein, we incorporated ferrocenylseleno compound (FcSe) with Gd3+-based paramagnetic UCNPs, to obtain FNPs-Gd nanocomposites using T1-T2 MR/UCL trimodal imaging and simultaneous photo-Fenton therapy. When the surface of NaGdF4:Yb,Tm UNCPs was ligated by FcSe, the hydrogen bonding between hydrophilic selenium and surrounding water molecules accelerated their proton exchange to initially endow FNPs-Gd with high r1 relaxivity. Then, hydrogen nuclei from FcSe disrupted the homogeneity of the magnetic field around the water molecules. This facilitated T2 relaxation and resulted in enhanced r2 relaxivity. Notably, upon the near-infrared light-promoted Fenton-like reaction in the tumor microenvironment, hydrophobic ferrocene(II) of FcSe was oxidized into hydrophilic ferrocenium(III), which further increased the relaxation rate of water protons to obtain r1=1.90±0.12 mM-1 s-1 and r2=12.80±0.60 mM-1 s-1. With an ideal relaxivity ratio (r2/r1) of 6.74, FNPs-Gd exhibited high contrast potential of T1-T2 dual-mode MRI in vitro and in vivo. This work confirms that ferrocene and selenium are effective boosters that enhance the T1-T2 relaxivities of MRI contrast agents, which could provide a new strategy for multimodal imaging-guided photo-Fenton therapy of tumors. STATEMENT OF SIGNIFICANCE: T1-T2 dual-mode MRI nanoplatform with tumor-microenvironment-responsive features has been an attractive prospect. Herein, we designed redox ferrocenylseleno compound (FcSe) modified paramagnetic Gd3+-based UCNPs, to modulate T1-T2 relaxation time for multimodal imaging and H2O2-responsive photo-Fenton therapy. Selenium-hydrogen bond of FcSe with surrounding water molecules facilitated water accessibility for fast T1 relaxation. Hydrogen nucleus in FcSe perturbed the phase coherence of water molecules in an inhomogeneous magnetic field and thus accelerated T2 relaxation. In tumor microenvironment, FcSe was oxidized into hydrophilic ferrocenium via NIR light-promoted Fenton-like reaction which further increased both T1 and T2 relaxation rates; Meanwhile, the released toxic •OH performed on-demand cancer therapy. This work confirms that FcSe is an effective redox mediate for multimodal imaging-guided cancer therapy.

High temperature flow synthesis of iron oxide nanoparticles: Size tuning via reactor engineering

Batch thermal decomposition syntheses of iron oxide nanoparticles (IONPs) provide precise control of particle properties, but their scalability and reproducibility is challenging. This is addressed in this work via a versatile high temperature flow reactor with adjustable temperature profiles through three individual stages operated between 180 °C and 280 °C. The tuneable temperature profiles in combination with self-seeded growth methods made it possible to synthesise IONPs between 2 and 17 nm (a size increase that corresponds to a >600 fold particle volume increase) at production rates of several gIONP per day. The precursor solutions contained only iron(III) acetylacetonate in a polyol solvent and no nucleation or growth inhibitors, oxidation or reducing agents, ligands or any other additives . This broad size range covers most biomedical applications and is of special interest for T1 MRI contrast agents (2–5 nm), as well as for magnetic hyperthermia cancer therapy (>10 nm). The potential of the IONPs produced was demonstrated by their high longitudinal relaxivity >16 mM−1s−1 at a transversal/longitudinal relaxivity ratio <2.5 (small IONPs) and specific absorption rates increasing with the IONP size up to180 W/gFe. In addition, the polyol method employed allowed for simple ligand exchange with biocompatible sodium tripolyphosphate to make the IONPs stable in water, thus rendering them suitable for biomedical applications. The continuous high temperature process presented shows how to control the particle size not via the chemistry (e.g., chemical additives affecting the particle size through the surface chemistry), but engineering parameters, i.e., reactor temperature profiles, reagent addition sequences and seeded growth strategies.

Surface modification of Nd3+ activated gadolinium core-shell nanospheres for near-infrared and magnetic resonance dual functional bioimaging system

Visualization techniques are effective tools in diagnosis and therapy for biomedical applications. Due to the unavoidable shortcomings of single optical or magnetic resonance imaging, the introduction of dual functional imaging system is of great significance. Herein a new Gd1-xNdx(CO3)OH@SiO2 core–shell nanostructure were developed to fulfill the corresponding demands. Uniform nanospheres were acquired with surface modification and coated with thickness tunable silica shells. The samples presented strong luminescence penetrating biological tissue, due to the wide spectral region covering NIR I & II window of Nd3+ under 808 nm laser excitation. On the other hand, distinct contrast enhancement could be viewed for in vitro and in vivo MRI trials, which generates from high paramagnetic relaxation of Gd3+ and well dispersibility caused by silica shells. Along with the non-toxicity proved by the low concentration of leaching Gd3+ and nice biocompatibility of silica coated nanospheres, it is a superior candidate for NIR and MRI dual functional imaging platform in biological applications.

Manganese-Doped Carbon Dots as a Promising Nanoprobe for Luminescent and Magnetic Resonance Imaging

Luminescent carbon nanodots (CDs) are a low-toxic nanomaterial with a tunable emission in a wide spectral range and with various functional groups on the surface. Therefore, CDs can prospectively serve as luminescent nanoprobes for biomedical applications, such as drug-delivery, visualization, sensing, etc. The doping of CDs with paramagnetic or transition metals allows the expansion of the range of applications of CDs and the fabrication of a multimodal nanoprobe for bioimaging. Here, we developed CDs doped with manganese (Mn) based on commonly used precursors—o-phenylenediamine or citric acid and formamide. The chemical structure, morphology, optical properties, and magnetic resonance responses have been carefully studied. The obtained CDs are up to 10 nm, with emissions observed in the 400–650 nm spectral region. CDs exhibit an ability to reduce both T1 and T2 relaxation times by up to 6.4% and 42.3%, respectively. The high relaxivity values suggest the use of CDs as promising dual-mode contrast agents for T1 and T2 MRI. Therefore, our developed CDs can be utilized as a new multifunctional nanoscale probe for photoluminescent and magnetic resonance bioimaging.

Application of magnetic iron oxide nanoparticles: Thrombotic activity, imaging and cytocompatibility of silica-coated and carboxymethyl dextrane-coated particles

Coated iron oxide nanoparticles (IONs) are promising candidates for various applications in nanomedicine, including imaging, magnetic hyperthermia, and drug delivery. The application of IONs in nanomedicine is influenced by factors such as biocompatibility, surface properties, agglomeration, degradation behavior, and thrombogenicity. Therefore, it is essential to investigate the effects of coating material and thickness on the behavior and performance of IONs in the human body. In this study, IONs with a carboxymethyl dextran (CMD) coating and two thicknesses of silica coating (TEOS0.98, and TEOS3.91) were screened and compared to bare iron oxide nanoparticles (BIONs). All three coated particles showed good cytocompatibility (>70%) when tested with smooth muscle cells over three days. To investigate their potential long term behavior inside the human body, the Fe2+ release and hydrodynamic diameters of silica-coated and CMD (carboxymethyl dextrane)-coated IONs were analyzed in simulated body fluids for 72 h at 37 °C. The ION@CMD showed moderate agglomeration of around 100 nm in all four simulated fluids and dissolved faster than the silica-coated particles in artificial exosomal fluid and artificial lysosomal fluid. The particles with silica coating agglomerated in all tested simulated media above 1000 nm. Increased thickness of the silica coating led to decreased degradation of particles. Additionally, CMD coating resulted in nanoparticles with the least prothrombotic activity, and the thick silica coating apparently decreased the prothrombotic properties of nanoparticles compared to BIONs and ION@TEOS0.98. For magnetic resonance applications, ION@CMD and ION@TEOS3.91 showed comparatively high relaxation rates R2 values. In magnetic particle imaging experiments ION@TEOS3.91 yielded the highest normalized signal to noise ratio values and in magnetic hyperthermia studies, ION@CMD and ION@TEOS0.98 showed similar specific loss power. These findings demonstrate the potential of coated IONs in nanomedicine and emphasize the importance of understanding the effect of coating material and thickness on their behavior and performance in the human body.

Physico-chemical and MR relaxometry study of bovine serum albumin-coated magneto-plasmonic nanoparticles designed for potential use in cancer nanotheranostics

PurposeIn recent years, the use of nanoparticles has been developed to improve MRI contrast. To improve the contrast agents in image-guided therapy by Multifunctional nanoparticles, in this study, we synthesized a theranostic magneto-plasmonic nanocomplex based on magnetic iron oxide nanoparticles and bovine serum albumin-modified gold nanorod (Au@BSA-Fe3O4@CMD). The purpose of synthesizing these nanoparticles was to use them as MRI contrast agent and photothermal agents in in vitro and in vivo experiments. Materials and methodsInitially, the properties of the synthesized nanoparticles were investigated by methods such as DLS, TEM, FTIR. MTT assay was used to evaluate the toxicity of nanoparticles. Finally, to evaluate the contrast ability of nanoparticles, MRI images were taken in in vitro and in vivo conditions and then the images were analyzed. ResultsMTT test results on CT26 cell line showed no significant cytotoxicity for Au@BSA-Fe3O4@CMD nanoparticles at concentrations up to 20 ppm. The in vitro results demonstrated that the Au@BSA-Fe3O4@CMD nanocomplex has high T2 relaxation rate and great relaxivities (r2 = 140.14 mM−1 s−1, r1 = 2.066 mM−1 s−1, r2/r1 = 67.83). For in vivo conditions, a decrease in T2 signal of 9.64 and 11.01, respectively, was observed for intratumoral and intraperitoneal injection of nanoparticles. ConclusionThese in vitro and in vivo studies show that Au @ BSA-Fe3O4@CMD nanoparticles can significantly reduce the signal intensity of T2-weight MRI images, and therefore can offer significant potential as a theranostic platform for effective tumor MR imaging.

Uncooled 100-GBaud Directly Modulated Membrane Lasers on SiC Substrate

We investigate the temperature dependence of the dynamic characteristics of a 1.3-μm InGaAlAs-based directly modulated membrane laser on a SiC substrate. The laser is fabricated by combining direct wafer bonding of SiC and InP substrates using a very thin (∼10 nm) oxide layer and epitaxial regrowth of a membrane InP layer on the InP/SiC template. The membrane laser structure on SiC with a high thermal conductivity (490 Wm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> ) and a moderate refractive index (∼2.6) ensures both high thermal dissipation and a large optical confinement factor in the active region, which are ideal for increasing the relaxation oscillation frequency even at high operating temperatures. We further leverage the optical feedback effect from the output facet of a waveguide to enhance the bandwidth and enable signal modulation at 100 GBaud and beyond. Owing to the high relaxation oscillation frequency and the photon-photon resonance effect, it is possible to obtain a flat frequency response at temperatures ranging from 25 to 85°C. The fabricated membrane laser on SiC with an active-region length of 50 μm exhibits 3dB bandwidths of >110, 97, and 74 GHz at 25, 55, and 85°C, respectively. We successfully demonstrate 2-km transmissions of 100-Gbit/s NRZ signals under uncooled conditions (25 to 85°C). Furthermore, the laser is capable of 112-Gbit/s NRZ modulation at 85°C.

Exploring the impact of pH on the properties of citric acid-coated iron oxide nanoparticles as high-performance T2 contrast agent for MRI applications

Iron oxide nanoparticles (IONPs) were synthesized using an aqueous co-precipitation method at various pH levels ranging from 8 to 12. The impact of solution pH on IONPs' properties was analyzed by studying their size, shape, and surface charge. Both the crystalline structure and size of IONPs were significantly affected by pH levels, as revealed by X-ray diffraction analysis. Across all pH values, magnetite was found to be the predominant phase. Interestingly, the smallest nanoparticle size was observed at pH 10. The IONPs synthesized at the optimal pH were then coated with citric acid to be used as contrast agents in Magnetic Resonance Imaging (MRI). The citric acid coating was applied to the IONPs to increase their biocompatibility and optimize their dispersity. The coated samples were further characterized using Zetasizer, Fourier-Transform Infrared Spectroscopy (FTIR), and Vibrating Sample Magnetometry (VSM). The results indicated high stability and appropriate magnetization, with a relaxivity ratio (r2/r1) of 73.75, making citric acid-coated IONPs a promising candidate for use as T2 MRI contrast agents. FTIR, Zetasizer, and VSM measurements indicated that the citric acid coating had a positive effect on the biocompatibility, stability, and magnetization of the IONPs. IONPs are excellent T2 MRI contrast agents because of their enhanced physiochemical properties, and their high relaxivity ratio confirms their effectiveness. The findings of this study emphasize the crucial role that pH plays in determining the properties of IONPs and highlight the potential use of citric acid-coated IONPs in medical imaging applications such as MRI.