Magnetic 3D scaffold: A theranostic tool for tissue regeneration and non-invasive imaging in vivo. Sajesh Koythatta Meethaleveetil,Ashokan Anusha,Gowd Genekehal Siddaramana,Sivanarayanan Thangalazhi Balakrishanan,Unni A K K,Nair Shantikumar V,Koyakutty Manzoor Nanomedicine : nanotechnology, biology, and medicine We report an osteoconducting magnetic 3D scaffold using Fe doped nano-hydroxyapatite-Alginate-Gelatin (AGHFe1) for Magnetic Resonance Imaging based non-invasive monitoring of bone tissue regeneration. In rat cranial defect model, the scaffold facilitated non-invasive monitoring of cell migration, inflammatory response and matrix deposition by unique changes in transverse relaxation time (T2). Cell infiltration resulted in a considerable increase in T2 from ~37 to ~62 ms, which gradually returned to that of native bone (~23 ms) by 90 days. We used this method to compare in vivo performance of scaffold with bone-morphogenic protein-2 (AGHFe2) or faster degrading (AGHFe3). MRI and histological analysis over 90 days showed non-uniform bone formation in AGHFe1 with ∆T2 (T2 - T2 ) ~13 ms, whereas, AGHFe2 and AGHFe3 showed ∆T2 ~ 09 and 05 ms respectively, suggesting better bone formation in AGHFe3. Thus, we show that MR-contrast enabled scaffold can help better assessment of bone-regeneration non-invasively. 10.1016/j.nano.2019.02.022
    Nanoparticle-based Cell Trackers for Biomedical Applications. Ni Jen-Shyang,Li Yaxi,Yue Wentong,Liu Bin,Li Kai Theranostics The continuous or real-time tracking of biological processes using biocompatible contrast agents over a certain period of time is vital for precise diagnosis and treatment, such as monitoring tissue regeneration after stem cell transplantation, understanding the genesis, development, invasion and metastasis of cancer and so on. The rationally designed nanoparticles, including aggregation-induced emission (AIE) dots, inorganic quantum dots (QDs), nanodiamonds, superparamagnetic iron oxide nanoparticles (SPIONs), and semiconducting polymer nanoparticles (SPNs), have been explored to meet this urgent need. In this review, the development and application of these nanoparticle-based cell trackers for a variety of imaging technologies, including fluorescence imaging, photoacoustic imaging, magnetic resonance imaging, magnetic particle imaging, positron emission tomography and single photon emission computing tomography are discussed in detail. Moreover, the further therapeutic treatments using multi-functional trackers endowed with photodynamic and photothermal modalities are also introduced to provide a comprehensive perspective in this promising research field. 10.7150/thno.39915
    Colloidal polymer-coated Zn-doped iron oxide nanoparticles with high relaxivity and specific absorption rate for efficient magnetic resonance imaging and magnetic hyperthermia. Das Pradip,Salvioni Lucia,Malatesta Manuela,Vurro Federica,Mannucci Silvia,Gerosa Marco,Antonietta Rizzuto Maria,Tullio Chiara,Degrassi Anna,Colombo Miriam,Ferretti Anna M,Ponti Alessandro,Calderan Laura,Prosperi Davide Journal of colloid and interface science Colloidally stable nanoparticles-based magnetic agents endowed with very high relaxivity and specific absorption rate are extremely desirable for efficient magnetic resonance imaging and magnetic hyperthermia, respectively. Here, we report a water dispersible magnetic agent consisting of zinc-doped superparamagnetic iron oxide nanoparticles (i.e., Zn-SPIONs) of 15 nm size with high saturation magnetization coated with an amphiphilic polymer for effective magnetic resonance imaging and magnetic hyperthermia of glioblastoma cells. These biocompatible polymer-coated Zn-SPIONs had 24 nm hydrodynamic diameter and exhibited high colloidal stability in various aqueous media, very high transverse relaxivity of 471 mM s, and specific absorption rate up to 743.8 W g, which perform better than most iron oxide nanoparticles reported in the literature, including commercially available agents. Therefore, using these polymer-coated Zn-SPIONs even at low concentrations, T-weighted magnetic resonance imaging and moderate magnetic hyperthermia of glioblastoma cells under clinically relevant magnetic field were successfully implemented. In addition, the results of this in vitro study suggest the superior potential of Zn-SPIONs as a theranostic nanosystem for brain cancer treatment, simultaneously acting as a contrast agent for magnetic resonance imaging and a heat mediator for localized magnetic hyperthermia. 10.1016/j.jcis.2020.05.119
    Targeted T Magnetic Resonance Imaging Contrast Enhancement with Extraordinarily Small CoFeO Nanoparticles. Piché Dominique,Tavernaro Isabella,Fleddermann Jana,Lozano Juan G,Varambhia Aakash,Maguire Mahon L,Koch Marcus,Ukai Tomofumi,Hernández Rodríguez Armando J,Jones Lewys,Dillon Frank,Reyes Molina Israel,Mitzutani Mai,González Dalmau Evelio R,Maekawa Toru,Nellist Peter D,Kraegeloh Annette,Grobert Nicole ACS applied materials & interfaces Extraordinarily small (2.4 nm) cobalt ferrite nanoparticles (ESCIoNs) were synthesized by a one-pot thermal decomposition approach to study their potential as magnetic resonance imaging (MRI) contrast agents. Fine size control was achieved using oleylamine alone, and annular dark-field scanning transmission electron microscopy revealed highly crystalline cubic spinel particles with atomic resolution. Ligand exchange with dimercaptosuccinic acid rendered the particles stable in physiological conditions with a hydrodynamic diameter of 12 nm. The particles displayed superparamagnetic properties and a low r/ r ratio suitable for a T contrast agent. The particles were functionalized with bile acid, which improved biocompatibility by significant reduction of reactive oxygen species generation and is a first step toward liver-targeted T MRI. Our study demonstrates the potential of ESCIoNs as T MRI contrast agents. 10.1021/acsami.8b17162
    Optimization and Design of Magnetic Ferrite Nanoparticles with Uniform Tumor Distribution for Highly Sensitive MRI/MPI Performance and Improved Magnetic Hyperthermia Therapy. Du Yang,Liu Xiaoli,Liang Qian,Liang Xing-Jie,Tian Jie Nano letters Two major technical challenges of magnetic hyperthermia are quantitative assessment of agent distribution during and following administration and achieving uniform heating of the tumor at the desired temperature without damaging the surrounding tissues. In this study, we developed a multimodal MRI/MPI theranostic agent with active biological targeting for improved magnetic hyperthermia therapy (MHT). First, by systematically elucidating the magnetic nanoparticle magnetic characteristics and the magnetic resonance imaging (MRI) and magnetic particle imaging (MPI) signal enhancement effects, which are based on the magnetic anisotropy, size, and type of nanoparticles, we found that 18 nm iron oxide NPs (IOs) could be used as superior nanocrystallines for high performance of MRI/MPI contrast agents in vitro. To improve the delivery uniformity, we then targeted tumors with the 18 nm IOs using a tumor targeting peptide, CREKA. Both MRI and MPI signals showed that the targeting agent improves the intratumoral delivery uniformity of nanoparticles in a 4T1 orthotopic mouse breast cancer model. Lastly, the in vivo antitumor MHT effect was evaluated, and the data showed that the improved targeting and delivery uniformity enables more effective magnetic hyperthermia cancer ablation than otherwise identical, nontargeting IOs. This preclinical study of image-guided MHT using cancer-targeting IOs and a novel MPI system paves the way for new MHT strategies. 10.1021/acs.nanolett.9b00630
    Stem cell-mediated delivery of nanogels loaded with ultrasmall iron oxide nanoparticles for enhanced tumor MR imaging. Hao Xinxin,Xu Bei,Chen Huan,Wang Xiaomeng,Zhang Jiulong,Guo Rui,Shi Xiangyang,Cao Xueyan Nanoscale The development of new nanoplatforms with enhanced tumor accumulation for accurate diagnosis still remains a great challenge in current precision nanomedicine. Herein, we report the design of stem cell-mediated delivery of nanogels (NGs) loaded with ultrasmall iron oxide (Fe3O4) nanoparticles (NPs) for enhanced magnetic resonance (MR) imaging of tumors. In this study, sodium citrate-stabilized ultrasmall Fe3O4 NPs with a size of 3.16 ± 1.30 nm were first synthesized using a solvothermal route, coated with polyethyleneimine (PEI), and used as crosslinkers to crosslink alginate (AG) NGs formed via a double emulsion approach, where the AG carboxyl groups were pre-activated with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride. The thus prepared Fe3O4 NP-loaded NGs (AG/PEI-Fe3O4 NGs) with a size of 47.68 ± 3.41 nm are water-dispersible, colloidally stable, cytocompatible in a given concentration range, display a relatively high r1 relaxivity (r1 = 1.5 mM-1 s-1), and are able to be taken up by bone mesenchymal stem cells without compromising cell viability and stem cell characteristics. Due to the tumor-chemotaxis or tumor tropism, the BMSCs are able to mediate the enhanced delivery of AG/PEI-Fe3O4 NGs to the tumor site after intravenous injection, thus enabling significantly strengthened MR imaging of tumors when compared to free NGs. These findings suggest that the developed AG/PEI-Fe3O4NGs, once mediated by stem cells may serve as a novel, safe, effective and targeted platform for enhanced MR imaging of tumors. 10.1039/c8nr10490e
    Smart Bacterial Magnetic Nanoparticles for Tumor-Targeting Magnetic Resonance Imaging of HER2-Positive Breast Cancers. Zhang Yunlei,Ni Qianqian,Xu Chaoli,Wan Bing,Geng Yuanyuan,Zheng Gang,Yang Zhenlu,Tao Jun,Zhao Ying,Wen Jun,Zhang Junjie,Wang Shouju,Tang Yuxia,Li Yanjun,Zhang Qirui,Liu Li,Teng Zhaogang,Lu Guangming ACS applied materials & interfaces Supersensitive magnetic resonance (MR) imaging requires contrast with extremely high r values. However, synthesized magnetic nanoparticles generally have a relatively low r relaxivity. Magnetosomes with high saturation magnetization and good biocompatibility have shown potential values as MR imaging contrast agents. Magnetosomes that target human epidermal growth factor receptor-2 (HER2) were prepared using genetic technology and low-frequency sonication. Anti-HER2 affibody of the ability to target HER2 was displayed on the membrane surface of the magnetosomes through the anchor protein MamC, allowing the bacterial nanoparticles to target tumors overexpressing HER2. The prepared nanoparticles exhibited a very high relaxivity of 599.74 mM s and better dispersion, and their ability to target HER2 was demonstrated both in vitro and in vivo. Also, the HER2-targeting magnetosomes significantly enhanced the MR imaging of orthotopic breast cancer models with or without HER2 expression using a 7.0 T scanner. In particular, tumors overexpressing HER2 demonstrated better MR imaging than HER2-negative tumors after intravenous administration of HER2-targeting magnetosomes, and the MR signals of the augmented contrast could be detected from 3 to 24 h. The magnetosomes did not cause any notable pathogenic effect in the animals. Therefore, we expect that noninvasive imaging of tumors using HER2-targeting magnetosomes has potential for clinical applications in the near future. 10.1021/acsami.8b15838
    Exploring precision polymers to fine-tune magnetic resonance imaging properties of iron oxide nanoparticles. King Aaron M,Bray Caroline,Hall Stephen C L,Bear Joseph C,Bogart Lara K,Perrier Sebastien,Davies Gemma-Louise Journal of colloid and interface science The use of bio-polymers as stabilising agents for iron oxide-based negative magnetic resonance imaging (MRI) contrast agents has become popular in recent years, however the wide polydispersity of biologically-derived and commercially available polymers limits the ability to produce truly tuneable and reproducible behaviour, a major challenge in this area. In this work, stable colloids of iron oxide nanoparticles were prepared utilising precision-engineered bio-polymer mimics, poly(2-acrylamido-2-methylpropane sodium sulfonate) (P(AMPS)) polymers, with controlled narrow polydispersity molecular weights, as templating stabilisers. In addition to producing magnetic colloids with excellent MRI contrast capabilities (r values reaching 434.2 mM s at 25 °C and 23 MHz, several times higher than similar commercial analogues), variable field relaxometry provided unexpected important insights into the dynamic environment of the hydrated materials, and hence their exceptional MRI behaviour. Thanks to the polymer's templating backbone and flexible conformation in aqueous suspension, nanocomposites appear to behave as "multi-core" clustered species, enhancing interparticle interactions whilst retaining water diffusion, boosting relaxation properties at low frequency. This clustering behaviour, evidenced by small-angle X-ray scattering, and strong relaxometric response, was fine-tuned using the well-defined molecular weight polymer species with precise iron to polymer ratios. By also showing negligible haemolytic activity, these nanocomposites exhibit considerable potential for MRI diagnostics. 10.1016/j.jcis.2020.06.036
    Chitosan derived glycolipid nanoparticles for magnetic resonance imaging guided photodynamic therapy of cancer. Zhao Xin,Shen Ruoyu,Bao Lu,Wang Cheng,Yuan Hong Carbohydrate polymers Currently, the development of polysaccharide, especially chitosan (CS), based drug delivery system to afford magnetic resonance imaging (MRI) guided theranostic cancer therapy remains largely unexplored. Herein, we successfully developed a CS derived polymer (Gd-CS-OA) through chemical conjugation of CS, octadecanoic acid (OA) and gadopentetic acid (GA). After self-assemble into glycolipid nanoparticles to loaded chlorin e6 (Ce6), the resulted Gd-CS-OA/Ce6 was able to realize MRI guided photodynamic therapy (PDT) of cancer. Our results revealed that Gd-CS-OA was able to increase the MRI sensitivity as compared to Gd-DTPA with decent residence time and preferable excretion behavior in vivo. Moreover, the Gd-CS-OA/Ce6 showed negligible hemolysis, satisfactory ROS generation and stability in physiological environments with preferable cellular uptake and enhanced in vitro cytotoxicity (through elevated ROS generation) on 4T1 cells. Most importantly, Gd-CS-OA/Ce6 demonstrated promising in vivo tumor targetability (enhanced penetration and retention effect) and powerful MRI guided tumor ablation through PDT on in situ 4T1 tumor model. 10.1016/j.carbpol.2020.116509
    Dynamic magnetic characterization and magnetic particle imaging enhancement of magnetic-gold core-shell nanoparticles. Tomitaka Asahi,Ota Satoshi,Nishimoto Kizuku,Arami Hamed,Takemura Yasushi,Nair Madhavan Nanoscale Multifunctional nanoparticles with a magnetic core and gold shell structures are emerging multi-modal imaging probes for disease diagnosis, image-guided therapy, and theranostic applications. Owing to their multi-functional magnetic and plasmonic properties, these nanoparticles can be used as contrast agents in multiple complementary imaging modalities. Magnetic particle imaging (MPI) is a new pre-clinical imaging system that enables real-time imaging with high sensitivity and spatial resolution by detecting the dynamic responses of nanoparticle tracers. In this study, we evaluated the dynamic magnetic properties and MPI imaging performances of core-shell nanoparticles with a magnetic core coated with a gold shell. A change in AC hysteresis loops was detected before and after the formation of the gold shell on magnetic core nanoparticles, suggesting the influence of the core-shell interfacial effect on their dynamic magnetic properties. This alteration in the dynamic responses resulted in an enhancement of the MPI imaging capacity of magnetic nanoparticles. The gold shell coating also enabled a simple and effective functionalization of the nanoparticles with a brain glioma targeting ligand. The enhanced MPI imaging capacity and effective functionality suggest the potential application of the magnetic-gold core-shell nanoparticles for MPI disease diagnostics. 10.1039/c9nr00242a
    Age-Related Changes in Tissue Value Properties in Children: Simultaneous Quantification of Relaxation Times and Proton Density Using Synthetic Magnetic Resonance Imaging. Lee So Mi,Choi Young Hun,You Sun-Kyoung,Lee Won Kee,Kim Won Hwa,Kim Hye Jung,Lee Sang Yub,Cheon Hyejin Investigative radiology OBJECTIVES:The properties of brain tissue undergo dynamic changes during maturation. T1 relaxation time (T1), T2 relaxation time (T2), and proton density (PD) are now simultaneously quantifiable within a clinically acceptable time, using a synthetic magnetic resonance imaging (MRI) sequence. This study aimed to provide age-specific reference values for T1, T2, and PD in children, using synthetic MRI. MATERIALS AND METHODS:We included 89 children (median age, 18 months; range, 34 weeks of gestational age to 17 years) who underwent quantitative MRI, using a multidynamic, multiecho sequence on 3 T MRI, between December 2015 and November 2016, and had no abnormal MRI/neurologic assessment findings. T1, T2, and PD were simultaneously measured in each of the 22 defined white matter and gray matter regions of interest. The measured values were plotted against age, and a curve fitting model that best explained the age dependence of tissue values was identified. Age-specific regional tissue values were calculated using a fit equation. RESULTS:The tissue values of all brain regions, except cortical PD, decreased with increasing age, and the robust negative association was best explained by modified biexponential model of the form Tissue values = T1 × exp (-C1 × age) + T2 × exp (-C2 × age). The quality of fit to the modified biexponential model was high in white matter and deep gray matter (white matter, R = 97%-99% [T1], 88%-95% [T2], 88%-97% [PD]; deep gray matter, R = 96%-97% [T1], 96% [T2], 49%-88% [PD]; cortex, 70%-83% [T1], 87%-90% [T2], 5%-27% [PD]). The white matter and deep gray matter changed the most dynamically within the first year of life. CONCLUSIONS:Our study provides age-specific regional reference values, from the neonate to adolescent, of T1, T2, and PD, which could be objective tools for assessment of normal/abnormal brain development using synthetic MRI. 10.1097/RLI.0000000000000435
    Improved Visualization of Juxtaprosthetic Tissue Using Metal Artifact Reduction Magnetic Resonance Imaging: Experimental and Clinical Optimization of Compressed Sensing SEMAC. Jungmann Pia M,Bensler Susanne,Zingg Patrick,Fritz Benjamin,Pfirrmann Christian W,Sutter Reto Investigative radiology OBJECTIVES:The purpose of this study was to identify an optimal imaging protocol for metal artifact reduced magnetic resonance imaging by application of different imaging and postprocessing parameters in compressed sensing slice-encoding for metal artifact correction (CS-SEMAC) and to test it in patients with total hip arthroplasty (THA). MATERIALS AND METHODS:In an experimental setup, a phantom consisting of a standard THA embedded in gadolinium-containing agarose was scanned at 1.5 T. Pulse sequences included coronal short tau inversion recovery (STIR), T1-weighted (w), and T2-w CS-SEMAC sequences. All pulse sequences were acquired with 11, 19, and 27 slice-encoding steps (SESs), respectively. For each raw dataset, postprocessing was performed with variations of the parameters: (1) number of iterations (5, 10, 20, 30, 50) and (2) normalization factor (0.0005, 0.001, 0.002, 0.003, 0.005). Following, in clinical magnetic resonance scans of patients with THA, identical STIR, T1-w, and T2-w pulse sequences with 11 and 19 SESs were acquired and were postprocessed similarly with variations in parameters. Semiquantitative outcome measures were assessed on a 5-point scale (1 = best, 5 = worst). The overall best image quality was determined. Signal-to-noise ratio and contrast-to-noise ratio were calculated. Statistical analyses included descriptive statistics, t-tests, multivariate regression models, and partial Spearman correlations. RESULTS:Scan times varied between 2:24 (T2-w, 11 SESs) and 8:49 minutes (STIR, 27 SESs). Reconstruction times varied between 3:14 minutes (T1-w, 11 SESs, 5 iterations) and 85:00 minutes (T2-w, 27 SESs, 50 iterations). Signal-to-noise ratio and contrast-to-noise ratio increased with increasing SESs, iterations, and normalization factor. In phantom scans, artifact reduction was optimal with an intermediate normalization factor (0.001) and improved with higher SESs and iterations. However, iterations greater than 20 did not improve artifact reduction or image quality further. On the contrary, ripple artifacts increased with higher SESs and iterations. In clinical scans, up to 20 iterations reduced blurring of the image; no further reduction was observed with iterations greater than 20. A normalization factor of 0.001 or 0.002 was best for reduction of blurring, whereas the soft tissue contrast was better and the distortion of soft tissue was less severe with lower normalization factors. Overall best soft tissue image quality was found for STIR and T1-w images with 19 SESs, 10 iterations, and a normalization factor of 0.001, and for T2-w images with 11 SESs, 10 iterations, and a normalization factor of 0.0005. CONCLUSIONS:Optimized advanced acceleration and reconstruction algorithms of CS-SEMAC have been identified to reduce metal artifacts in patients with THA enabling imaging with clinically feasible acquisition and reconstruction times. 10.1097/RLI.0000000000000504
    Tracking Stem Cell Implants in Cartilage Defects of Minipigs by Using Ferumoxytol-enhanced MRI. Theruvath Ashok J,Nejadnik Hossein,Lenkov Olga,Yerneni Ketan,Li Kai,Kuntz Lara,Wolterman Cody,Tuebel Jutta,Burgkart Rainer,Liang Tie,Felt Stephen,Daldrup-Link Heike E Radiology Background Cartilage repair outcomes of matrix-associated stem cell implants (MASIs) in patients have been highly variable. Conventional MRI cannot help distinguish between grafts that will and grafts that will not repair the underlying cartilage defect until many months after the repair. Purpose To determine if ferumoxytol nanoparticle labeling could be used to depict successful or failed MASIs compared with conventional MRI in a large-animal model. Materials and Methods Between January 2016 and December 2017, 10 Göttingen minipigs ( = 5 male; = 5 female; mean age, 6 months ± 5.1; age range, 4-20 months) received implants of unlabeled ( = 12) or ferumoxytol-labeled ( = 20) viable and apoptotic MASIs in cartilage defects of the distal femur. All MASIs were serially imaged with MRI on a 3.0-T imaging unit at week 1 and weeks 2, 4, 8, 12, and 24, with calculation of T2 relaxation times. Cartilage regeneration outcomes were assessed by using the MR observation of cartilage repair tissue (MOCART) score (scale, 0-100), the Pineda score, and histopathologic quantification of collagen 2 production in the cartilage defect. Findings were compared by using the unpaired Wilcoxon rank sum test, a linear regression model, the Fisher exact test, and Pearson correlation. Results Ferumoxytol-labeled MASIs showed significant T2 shortening (22.2 msec ± 3.2 vs 27.9 msec ± 1.8; < .001) and no difference in cartilage repair outcomes compared with unlabeled control MASIs ( > .05). At week 2 after implantation, ferumoxytol-labeled apoptotic MASIs showed a loss of iron signal and higher T2 relaxation times compared with ferumoxytol-labeled viable MASIs (26.6 msec ± 4.9 vs 20.8 msec ± 5.3; = .001). Standard MRI showed incomplete cartilage defect repair of apoptotic MASIs at 24 weeks. Iron signal loss at 2 weeks correlated with incomplete cartilage repair, diagnosed at histopathologic examination at 12-24 weeks. Conclusion Ferumoxytol nanoparticle labeling can accelerate the diagnosis of successful and failed matrix-associated stem cell implants at MRI in a large-animal model. © RSNA, 2019 See also the editorial by Sneag and Potter in this issue. 10.1148/radiol.2019182176
    Tendon Regeneration After Partial-Thickness Peroneus Longus Tendon Harvesting: Magnetic Resonance Imaging Evaluation and In Vivo Animal Study. Lee Ho Won,Wang Chenyu,Bae Tae Soo,Yang Ik,Liu Yuxuan,Park Chang Won,Kim Hyong Nyun The American journal of sports medicine BACKGROUND:In recent years, the use of the anterior half of the peroneus longus tendon (AHPLT) as an autograft source for ligament reconstruction has gained popularity. However, no reports are available regarding tendon regeneration after harvesting of the AHPLT. HYPOTHESIS:When half of the tendon is preserved during tendon harvesting, the quality of the regenerated tendon is better than that of the regenerated tendon after full-thickness harvesting. STUDY DESIGN:Case series; Level of evidence, 4; controlled laboratory study. METHODS:A total of 21 patients who underwent AHPLT harvesting for lower extremity ligament reconstruction participated in the magnetic resonance imaging (MRI) study to evaluate tendon regeneration 1 year after the harvesting. An in vivo animal study was performed to compare the quality of the regenerated tendon after partial-thickness and full-thickness tendon harvesting. A total of 30 adult female Sprague-Dawley rats were allocated to 2 groups-15 rats underwent partial-thickness Achilles tendon harvesting (partial-thickness harvesting [PTH] group), and 15 rats underwent full-thickness Achilles tendon harvesting (full-thickness harvesting [FTH] group). The quality of the regenerated tendons was compared 180 days after tendon harvesting. RESULTS:All 21 patients showed regeneration of the peroneus longus tendon (PLT) (homogeneously dark on both T1- and T2-weighted sequences). The cross-sectional area of the regenerated tendon divided by that of the preoperative tendon was 92.6% and 84.5% at 4 cm and 9 cm proximal to the tip of the distal fibula, respectively. In the animal study, the mean histologic score was better for the PTH group compared with the FTH group (9.17 ± 1.35 vs 14.72 ± 0.74; < .001). The ultimate strength and the stiffness of the regenerated Achilles tendon were significantly higher for the PTH group compared with the FTH group (35.5 ± 8.3 vs 22.4 ± 8.3 N, = .004; and 31.6 ± 7.7 vs 23.5 ± 4.8 N/mm, = .016). CONCLUSION:The PLT was found to regenerate after partial-thickness harvesting on MRI. In the animal study, the quality of the regenerated tendon when half of the tendon was preserved during tendon harvesting was better than that after full-thickness tendon harvesting. 10.1177/0363546520933628
    Iron Oxide Nanoparticles with Grafted Polymeric Analogue of Dimethyl Sulfoxide as Potential Magnetic Resonance Imaging Contrast Agents. Yan Jiajun,Li Sipei,Cartieri Francis,Wang Zongyu,Hitchens T Kevin,Leonardo Jody,Averick Saadyah E,Matyjaszewski Krzysztof ACS applied materials & interfaces Novel water-dispersible hybrid iron oxide nanoparticles grafted with a polymeric analogue of dimethyl sulfoxide (DMSO) were prepared. Superparamagnetic iron oxide nanoparticles with immobilized atom-transfer radical polymerization (ATRP) initiators were prepared via an in situ method using 12-(2-bromoisobutyramido)dodecanoic acid as a surface ligand/initiator. The initiator-functionalized particles were employed in a surface-initiated initiator for continuous activator regeneration ATRP to graft poly(2-(methylsulfinyl)ethyl acrylate) (a polyacrylate analogue of DMSO) from the surface. The resulting hybrid nanoparticles showed a high magnetic relaxivity ratio ( r/ r) of 600 at 7 T in fetal bovine serum, and a good biocompatibility up to 1000 mg L. 10.1021/acsami.8b06416
    Cubic Anisotropic Co- and Zn-Substituted Ferrite Nanoparticles as Multimodal Magnetic Agents. Pardo Alberto,Yáñez Susana,Piñeiro Yolanda,Iglesias-Rey Ramón,Al-Modlej Abeer,Barbosa Silvia,Rivas José,Taboada Pablo ACS applied materials & interfaces The use of magnetic nanoparticles as theranostic agents for the detection and treatment of cancer diseases has been extensively analyzed in the last few years. In this work, cubic-shaped cobalt and zinc-doped iron oxide nanoparticles with edge lengths in the range from 28 to 94 nm are proposed as negative contrast agents for magnetic resonance imaging and to generate localized heat by magnetic hyperthermia, obtaining high values of transverse relaxation coefficients and specific adsorption rates. The applied magnetic fields presented suitable characteristics for the potential validation of the results into the clinical practice in all cases. Pure iron oxide and cobalt- and zinc-substituted ferrites have been structurally and magnetically characterized, observing magnetite as the predominant phase and weak ferrimagnetic behavior at room temperature, with saturation values even larger than those of bulk magnetite. The coercive force increased due to the incorporation of cobalt ions, while zinc substitution promotes a significant increase in saturation magnetization. After their transfer to aqueous solution, those particles showing the best properties were chosen for evaluation in in vitro cell models, exhibiting high critical cytotoxic concentrations and high internalization degrees in several cell lines. The magnetic behavior of the nanocubes after their successful cell internalization was analyzed, detecting negligible variations on their magnetic hysteresis loops and a significant decrease in the specific adsorption rate values. 10.1021/acsami.9b20496
    Nanoscale magnetic imaging enabled by nitrogen vacancy centres in nanodiamonds labelled by iron-oxide nanoparticles. Barbiero Martina,Castelletto Stefania,Zhang Qiming,Chen Ye,Charnley Mirren,Russell Sarah,Gu Min Nanoscale Nanodiamonds containing the nitrogen vacancy centre (NV) have a significant role in biosensing, bioimaging, drug delivery, and as biomarkers in fluorescence imaging, due to their photo-stability and biocompatibility. The optical read out of the NV unpaired electron spin has been used in diamond magnetometry to image living cells and magnetically labelled cells. Diamond magnetometry is mostly based on the use of bulk diamond with a large concentration of NV centres in a wide field fluorescence microscope equipped with microwave excitation. It is possible to correlate the fluorescence maps with the magnetic field maps of magnetically labelled cells with diffraction limit resolution. Nanodiamonds have not as yet been implemented to image magnetic fields within complex biological systems at the nanometre scale. Here we demonstrate the suitability of nanodiamonds to correlate the fluorescence map with the magnetic imaging map of magnetically labelled cells. Nanoscale optical images with 17 nm resolution of nanodiamonds labelling fixed cells bound to iron oxide magnetic nanoparticles are demonstrated by using a single molecule localisation microscope. Nanoscale magnetic field images of the magnetised magnetic nanoparticles spatially assigned to individual cells are superresolved by the NV centres within nanodiamonds conjugated with the magnetic nanoparticles with 20 nm resolutions. Our method offers a new platform for the super-resolution of optical magnetic imaging in biological samples conjugated with nanodiamonds and iron-oxide magnetic nanoparticles. 10.1039/c9nr10701k
    Zero valent iron core-iron oxide shell nanoparticles as small magnetic particle imaging tracers. Gloag Lucy,Mehdipour Milad,Ulanova Marina,Mariandry Kevin,Nichol Muhammad Azrhy,Hernández-Castillo Daniela J,Gaudet Jeff,Qiao Ruirui,Zhang Ji,Nelson Melanie,Thierry Benjamin,Alvarez-Lemus Mayra A,Tan Thiam T,Gooding J Justin,Braidy Nady,Sachdev Perminder S,Tilley Richard D Chemical communications (Cambridge, England) Nanoparticle tracers with small sizes and large magnetization are critical for biomedical imaging and especially for magnetic particle imaging (MPI). Small size is important for accessing future intracellular and neurological in vivo applications Here, we show <15 nm nanoparticles made of zero valent iron cores, iron oxide shells and coated with a strongly binding brush co-polymer are effective MPI tracers. The small nanoparticle cores create a hydrodynamic diameter that is half of the state-of-the-art iron oxide tracers while the strongly magnetic zero valent iron maintains similar MPI signal magnitude and resolution. 10.1039/c9cc08972a