Ultrasmall Iron Oxide Nanoparticles Research Articles

NIMG-48. TLR7/8-AGONIST-LOADED NANOPARTICLES REPROGRAM TUMOR-ASSOCIATED MYELOID CELLS FOR EFFECTIVE IMMUNOTHERAPY OF EXPERIMENTAL GLIOMA AND MRI-BASED TREATMENT MONITORING

Abstract Drivers of glioblastoma progression include the immunosuppressive tumor microenvironment (TME), dominated by tumor-associated myeloid cells. Therefore, we investigated a new approach targeting the myeloid compartment to reprogram myeloid cells in the TME using a β-cyclodextrin nanoparticle (CDNP) formulation encapsulating the toll-like receptor 7 and 8 (TLR7/8) agonist R848. Biodistribution confirmed specific targeting of CDNP-R848 to tumor-associated macrophages (TAMs) (labeling efficiency: 34.0% ± 22.2%), whereas tumor microglia (5.4% ± 4.4%) and splenic macrophages (13.2% ± 0.7%) revealed less uptake. Interestingly, intravenous application of CDNP-R848 induced strong tumor regression with an overall response rate of 80% (2.5% complete response, 52.5% partial response and 25% stable disease, n=40 mice) in Gl261 syngeneic experimental gliomas, while CDNP vehicle treated animals showed exponential tumor growth (100% progressive disease, n=12 mice). As advanced imaging is essential to monitor intracranial disease and possibly predict response and resistance, we performed high resolution magnetic resonance imaging using ultrasmall iron oxide nanoparticles (USPIO) for macrophage tracking. Increased levels of USPIO uptake in vehicle treated animals compared to CDNP-R848 treated animals were found as an early marker of responding mice (ΔT2*: -11.7 ± 4.2 vs -4.0 ± 2.8 ms, p=0.01). This correlated with an increased influx of myeloid cells into the TME of vehicle treated animals and showed a strong correlation of macrophage recruitment and USPIO uptake (R2: 0.78, p=0.004). Mechanistically, phenotyping of macrophages (CD45high/CD11b+) indicated a pro-inflammatory shift of TAMs with an increased infiltration of pro-inflammatory F4/80+/MHCII+ macrophages during CDNP-R848 treatment. Surprisingly, the anti-tumor effect of CDNP-R848 was independent of CD8+ T cells, CD4+ T cells or NK cells during selective depletion experiments. In summary, this work demonstrates the ability of myeloid-targeted therapies to re-shape the tumor microenvironment for an effective immunotherapy of glioma.

Cellular Toxicity Mechanisms and the Role of Autophagy in Pt(IV) Prodrug-Loaded Ultrasmall Iron Oxide Nanoparticles Used for Enhanced Drug Delivery.

Ultrasmall iron oxide nanoparticles (<10 nm) were loaded with cis-diamminetetrachloroplatinum (IV), a cisplatin (II) prodrug, and used as an efficient nanodelivery system in cell models. To gain further insight into their behavior in ovarian cancer cells, the level of cellular incorporation as well as the platination of mitochondrial and nuclear DNA were measured using inductively coupled plasma mass spectrometry (ICP-MS) strategies. Quantitative Pt results revealed that after 24 h exposure to 20 µM Pt in the form of the Pt(IV)-loaded nanoparticles, approximately 10% of the incorporated Pt was associated with nuclear DNA. This concentration increased up to 60% when cells were left to stand in drug-free media for 3 h. These results indicated that the intracellular reducing conditions permitted the slow release of cisplatin (II) from the cisplatin (IV)-loaded nanoparticles. Similar results were obtained for the platination of mitochondrial DNA, which reached levels up to 17,400 ± 75 ng Pt/ mg DNA when cells were left in drug-free media for 3 h, proving that this organelle was also a target for the action of the released cisplatin (II). The time-dependent formation of Pt-DNA adducts could be correlated with the time-dependent decrease in cell viability. Such a decrease in cell viability was correlated with the induction of apoptosis as the main route of cell death. The formation of autophagosomes, although observed upon exposure in treated cells, does not seem to have played an important role as a means for cells to overcome nanoparticles’ toxicity. Thus, the designed nanosystem demonstrated high cellular penetration and the “in situ” production of the intracellularly active cisplatin (II), which is able to induce cell death, in a sustained manner.

Intelligent Design of Ultrasmall Iron Oxide Nanoparticle-Based Theranostics.

Rapid advances in nanotechnology have opened up innovative trails to break through the current limitation in clinical treatments of cancer and other critical diseases that plague human beings. Ultrasmall iron oxide nanoparticles (USIO NPs) with sizes smaller than 5 nm have been emerging as a novel category of nanomaterials with increasing interest in the biomedical domains. To overcome their intrinsic shortcomings, naked USIO NPs can be functionalized, clustered, assembled, or incorporated with other nanomaterials to generate various kinds of intelligent nanoplatforms for single-mode or dynamic magnetic resonance (MR) imaging, multimode imaging, as well as imaging-guided precision therapy. In this spotlight on applications, first, we propose the principal aspects in the design and application of USIO NPs for biomedical uses. Second, we cover the recent design strategies of USIO NP-based nanoplatforms mainly developed by our group, describe the rationale on the combination of other functional materials with USIO NPs, and review their resultant applications in theranostics. In addition, we provide herein a perspective on the possible future directions toward USIO NP-based nanoplatforms as smart nanomedicines.

Radiolabeling and PET\u2013MRI microdosing of the experimental cancer therapeutic, MN-anti-miR10b, demonstrates delivery to metastatic lesions in a murine model of metastatic breast cancer

BackgroundIn our earlier work, we identified microRNA-10b (miR10b) as a master regulator of the viability of metastatic tumor cells. This knowledge allowed us to design a miR10b-targeted therapeutic consisting of an anti-miR10b antagomir conjugated to ultrasmall iron oxide nanoparticles (MN), termed MN-anti-miR10b. In mouse models of breast cancer, we demonstrated that MN-anti-miR10b caused durable regressions of established metastases with no evidence of systemic toxicity. As a first step towards translating MN-anti-miR10b for the treatment of metastatic breast cancer, we needed to determine if MN-anti-miR10b, which is so effective in mice, will also accumulate in human metastases.ResultsIn this study, we devised a method to efficiently radiolabel MN-anti-miR10b with Cu-64 (64Cu) and evaluated the pharmacokinetics and biodistribution of the radiolabeled product at two different doses: a therapeutic dose, referred to as macrodose, corresponding to 64Cu-MN-anti-miR10b co-injected with non-labeled MN-anti-miR10b, and a tracer-level dose of 64Cu-MN-anti-miR10b, referred to as microdose. In addition, we evaluated the uptake of 64Cu-MN-anti-miR10b by metastatic lesions using both in vivo and ex vivo positron emission tomography–magnetic resonance imaging (PET–MRI). A comparable distribution of the therapeutic was observed after administration of a microdose or macrodose. Uptake of the therapeutic by metastatic lymph nodes, lungs, and bone was also demonstrated by PET–MRI with a significantly higher PET signal than in the same organs devoid of metastatic lesions.ConclusionOur results demonstrate that PET–MRI following a microdose injection of the agent will accurately reflect the innate biodistribution of the therapeutic. The tools developed in the present study lay the groundwork for the clinical testing of MN-anti-miR10b and other similar therapeutics in patients with cancer.

Macrophage-Laden Gold Nanoflowers Embedded with Ultrasmall Iron Oxide Nanoparticles for Enhanced Dual-Mode CT/MR Imaging of Tumors.

The design of multimodal imaging nanoplatforms with improved tumor accumulation represents a major trend in the current development of precision nanomedicine. To this end, we report herein the preparation of macrophage (MA)-laden gold nanoflowers (NFs) embedded with ultrasmall iron oxide nanoparticles (USIO NPs) for enhanced dual-mode computed tomography (CT) and magnetic resonance (MR) imaging of tumors. In this work, generation 5 poly(amidoamine) (G5 PAMAM) dendrimer-stabilized gold (Au) NPs were conjugated with sodium citrate-stabilized USIO NPs to form hybrid seed particles for the subsequent growth of Au nanoflowers (NFs). Afterwards, the remaining terminal amines of dendrimers were acetylated to form the dendrimer-stabilized Fe3O4/Au NFs (for short, Fe3O4/Au DSNFs). The acquired Fe3O4/Au DSNFs possess an average size around 90 nm, display a high r1 relaxivity (1.22 mM−1 s−1), and exhibit good colloidal stability and cytocompatibility. The created hybrid DSNFs can be loaded within MAs without producing any toxicity to the cells. Through the mediation of MAs with a tumor homing and immune evasion property, the Fe3O4/Au DSNFs can be delivered to tumors more efficiently than those without MAs after intravenous injection, thus significantly improving the MR/CT imaging performance of tumors. The developed MA-mediated delivery system may hold great promise for enhanced tumor delivery of other contrast agents or nanomedicines for precision cancer nanomedicine applications.

Effect of citric acid on the morpho-structural and magnetic properties of ultrasmall iron oxide nanoparticles

The structural and magnetic properties of iron oxide nanoparticles obtained by the precipitation of iron ions in the presence of different amounts of citric acid were studied. The citric acid acts as a capping agent and provides control of the particle size to be obtained. The size dependence of the magnetic properties was investigated by comparing the results for ~2, 4, 6, and 8 nm particles. With decreasing the particle size, a reduction of the saturation magnetization (from ~84 to 33 Am2/kg) and an increase of coercivity (from ~32 to ~100 mT) were observed, due to the increasing role of the disordered surface. The behaviour of the zero-field cooled/field cooled magnetization curves indicates a superspin-glass freezing for 2 nm and 4 nm particle samples. Memory experiments below the freezing temperature on the 2 nm particle sample provide further evidence of a glassy magnetic state. The observation of exchange bias, due to core/shell interface exchange coupling, for 2 nm and 4 nm particle samples provides evidence of a surface spin-glass type freezing, which contributes to the observed glassy properties.

Low-Molecular-Weight Poly(ethylenimine) Nanogels Loaded with Ultrasmall Iron Oxide Nanoparticles for T1-Weighted MR Imaging-Guided Gene Therapy of Sarcoma.

Cancer metastasis is still a major obstacle in clinical cancer therapy and a paramount cause of cancer deaths. Designing multifunctional nanoplatforms with an enhanced diagnostic sensitivity and anti-metastasis efficiency against tumors represents a major trend in current cancer management. Herein, we report the preparation of low-molecular-weight poly(ethylenimine) (PEI)-poly(ethylene glycol) (PEG) nanogels (NGs) loaded with transforming growth factor-β1 (TGF-β1) siRNA and ultrasmall iron oxide nanoparticles (Fe3O4 NPs) for gene therapy and T1-weighted magnetic resonance (MR) imaging of tumors and tumor metastasis in a mouse sarcoma model. In this work, ultrasmall Fe3O4 NPs stabilized by sodium citrate were first prepared and then mixed with PEI (800 Da) and PEG (400 Da)-diacrylate as a cross-linker to form Fe3O4/PEI-PEG NGs with an average size of 76.3 nm via an inverse microemulsion method. The developed hybrid NGs display good cytocompatibility and enhanced MR imaging performance (r1 relaxivity = 1.0346 mM-1 s-1). The Fe3O4/PEI-PEG NGs can be further used to compact TGF-β1 siRNA through electrostatic interaction and efficiently deliver siRNA to cancer cells and a tumor model to silence the TGF-β1 gene, which inhibits the growth and invasion of cancer cell in vitro significantly, as well as the growth of a subcutaneous sarcoma tumor model and lung metastasis in vivo. The designed hybrid NG-ultrasmall iron oxide NPs may be extended for the delivery of other drugs or genes for theranostics of different biological systems.

Ultrasmall iron oxide nanoparticles induced ferroptosis via Beclin1/ATG5-dependent autophagy pathway

Iron-based nanoparticles, which could elicit ferroptosis, is becoming a promising new way to inhibit tumor cell growth. Notably, ultrasmall iron oxide nanoparticles (USIONPs) have been found to upregulate the autophagy process in glioblastoma (GBM) cells. Whether USIONPs could also elicit ferroptosis and the relationship between the USIONPs-induced autophagy and ferroptosis need to be explored. In the current study, our synthesized USIONPs with good water solubility could significantly upregulate the ferroptosis markers in GBM cells, and downregulate the expression of anti-ferroptosis genes. Interestingly,ferrostatin-1 could reverse USIONPs- induced ferroptosis, but inhibitors of apoptosis, pyroptosis, or necrosis could not. Meanwhile, autophagy inhibitor 3-methyladenine could also reverse the USIONPs-induced ferroptosis. In addition, shRNA silencing of upstream genes Beclin1/ATG5 of autophagy process could significantly reverse USIONPs-induced ferroptosis, whereas overexpression of Beclin1/ATG5 of autophagy process could remarkably promote USIONPs-induced ferroptosis. Furthermore, lysosome inhibitors could significantly reverse the USIONPs-induced ferroptosis. Collectively, these facts suggest that USIONPs-induced ferroptosis is regulated via Beclin1/ATG5-dependent autophagy pathway.

Ultrasmall iron oxide nanoparticles cisplatin (IV) prodrug nanoconjugate: ICP-MS based strategies to evaluate the formation and drug delivery capabilities in single cells

Ultrasmall iron oxide nanoparticles (<10 nm) were explored here as nanotransporters of cis-diamminetetrachloroplatinum (IV) (a cisplatin prodrug) in cellular models. The coating of the particles containing reactive carboxylic acid groups enabled the formation of a stable conjugate between the prodrug and the nanoparticles using one pot reaction. The nanoconjugate was characterized by different techniques exhibiting diameters of about 6.6 ± 1.0 nm. The use of a hyphenated strategy based on high performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS) permitted the quantitative evaluation of Fe and Pt in the nanoconjugate. Furthermore, the cellular uptake of the synthetic nanoconjugate was explored by single cell-ICP-MS (SC-ICP) which was used for the first time in this type of studies. The experiments in A2780 and A2780cis, sensitive and resistant ovarian cancer cell models respectively, revealed intracellular platinum concentrations of 12 fg/cell and 4 fg/cell, respectively which were 4-fold higher with respect to the uptake of cisplatin in both models. Intracellular drug release from the nanoconjugate was proved by measuring DNA platination in the same cells. In this case, levels of about 250 ng Pt/mg DNA were observed, about 5-fold higher when the nanoconjugate was used in comparison to cisplatin. Furthermore, the differences between the two lines turned to be significantly smaller than in the case of using cisplatin. The quantitative analytical tools developed here provided essential information required to fully characterize the developed nanoplatforms particularly important to overcome drug resistance.

Hypoxia-Triggered Self-Assembly of Ultrasmall Iron Oxide Nanoparticles to Amplify the Imaging Signal of a Tumor.

Hypoxia is a common phenomenon among most solid tumors that significantly influences tumor response toward chemo- and radiotherapy. Understanding the distribution and extent of tumor hypoxia in patients will be very important to provide personalized therapies in the clinic. Without sufficient vessels, however, traditional contrast agents for clinical imaging techniques will have difficulty in accumulating in the hypoxic region of solid tumors, thus challenging the detection of hypoxia in vivo. To overcome this problem, herein we develop a novel hypoxia imaging probe, consisting of a hypoxia-triggered self-assembling ultrasmall iron oxide (UIO) nanoparticle and assembly-responding fluorescence dyes (NBD), to provide dual-mode imaging in vivo. In this strategy, we have employed nitroimidazole derivatives as the hypoxia-sensitive moiety to construct intermolecular cross-linking of UIO nanoparticles under hypoxia, which irreversibly form larger nanoparticle assemblies. The hypoxia-triggered performance of UIO self-assembly not only amplifies its T2-weighted MRI signal but also promotes the fluorescence intensity of NBD through its emerging hydrophobic environment incorporated into self-assemblies. In vivo results further confirm that our hypoxic imaging probe can display a prompt MRI signal for the tumor interior region, and its signal enhancement performs a long-term effective feature and gradually reaches 3.69 times amplification. Simultaneously, this probe also exhibits obvious green fluorescence in the hypoxic region of tumor sections. Accordingly, we also have developed a MRI difference value method to visualize the 3D distribution and describe the extent of the hypoxic tumor region within the whole bodies of mice. Due to its notable efficiency of penetration and accumulation inside a hypoxic tumor, our hypoxia imaging probe could also be considered as a potential candidate as a versatile platform for hypoxia-targeted drug delivery, and meanwhile its hypoxia-related therapeutic efficacy can be monitored.

Ultrasmall iron oxide nanoparticles functionalized with BODIPY derivatives as potential bimodal probes for MRI and optical imaging

AbstractThe synthesis and characterization of small monodisperse multimodal iron oxide nanoparticles (IONPs), functionalized with boron‐dipyrromethene (BODIPY) derivatives is described. Optical and relaxometric properties of the nanoparticles have been evaluated, suggesting a potential applicability of the particles as bimodal contrast agent for magnetic resonance and optical imaging. The BODIPY funcionalized IONPs showed bright fluorescence and high transverse relaxivity r2 which was in the range 47‐49 mM−1 s−1. Two‐photon fluorescence microscopy experiments performed at 1100 nm revealed that BODIPY‐functionalized IONPs showed significant increase in two‐photon fluorescence compared to the bare nanoparticles, suggesting their potential for applications in multimodal imaging. Cell viability studies on rat tumor (AR42J) and human ovarian cancer (SKOV3) cells showed no significant cytotoxicity at any of the tested concentrations, while greater sensitivity was observed for human hepatic stellate (GRX), human umbilical vein (HUVEC) and rat insulinoma (INS1) cells at higher nanoparticle concentrations.

Ultrasound-enhanced precision tumor theranostics using cell membrane-coated and pH-responsive nanoclusters assembled from ultrasmall iron oxide nanoparticles

Design of novel theranostic nanoplatforms integrating precision dynamic imaging modalities, tumor targeting ligands and therapeutic components with enhanced tumor accumulation still remains to be challenging. Here we report a facile strategy to prepare cell membrane (CM)-coated nanoclusters assembled from ultrasmall iron oxide nanoparticles (USIO NPs) with pH-responsiveness as a nanocarrier to load anti-cancer drug doxorubicin (DOX). Citric-stabilized USIO NPs with a size of 3.2 nm were synthesized, modified to have surface amine groups, and crosslinked to obtain pH-responsive nanoclusters (NCs). Then, the formed USIO NCs were loaded with DOX, and coated with cancer CMs to render them with resistance to macrophage cellular uptake and homologous cancer cell targeting specificity. Within the acidic tumor microenvironment, the pH-responsive USIO NCs/DOX@CM with dominant T2 magnetic resonance (MR) imaging performance can be dissociated to form single USIO NPs with T1 MR imaging ability, and simultaneously rapidly release DOX, thereby enabling dynamic T2/T1-weighted MR imaging and chemotherapy of tumors. Further, through the ultrasound-induced sonoporation effect, the dynamic MR imaging and tumor chemotherapy can be further enhanced. The designed USIO NCs/DOX@CM may be developed as a versatile theranostic platform for ultrasound-enhanced targeted precision theranostics of different cancer types.

One pot synthesis of zwitteronic 99mTc doped ultrasmall iron oxide nanoparticles for SPECT/T1-weighted MR dual-modality tumor imaging

In this study, we have synthesized 99mTc intrinsically labeled ultrasmall magnetic iron oxide nanoparticles with zwitterionic surface coating (99mTc-ZW-USIONPs) via one pot synthesis using sulfobetains functionalized poly (acrylic acid) as stabilizer and Na99mTcO4 and SnCl2 as additives. The commercialization of single photon emission computed tomography (SPECT)/magnetic resonance imaging (MRI) scanner made the combination use of 99mTc and iron oxide nanoparticles attracting much attention. Direct doping radioisotope into nanoparticles has the advantages of excellent radiochemical stability and no restriction on the surface functionalization. The complex Technetium chemistry made it challenging to direct dope 99mTc into IONPs, especially those ultrasmall ones without precipitation. We proved that it is possible to prepare 99mTc doped USIONPs with excellent water solubility and favorable T1 signal by controlling the radioactivity and reducing agent amount. With no need of chelator, the zwitterionic surface resists the protein corona formation, resulting in a reduced RES uptake and higher tumor contrast. The 99mTc-ZW-USIONPs demonstrated excellent performance of tumor SPECT and T1-weighted MR imaging capability in 4T1 tumor bearing mice. Together with their ease of preparation and superior biocompatibility, we believe these 99mTc-ZW-USIONPs represent a type of promising dual contrast agent for SPECT/T1 MRI.

Comparison of ultrasmall IONPs and Fe salts biocompatibility and activity in multi-cellular in vitro models

In the paper, the results of the first regular studies of ultra-small iron oxide nanoparticles (IONPs) toxicity in vitro were presented. The influence of PEG-coated NPs with 5 nm magnetite core on six different cell lines was examined. These were: human bronchial fibroblasts, human embryonic kidney cells (HEK293T), two glioblastoma multiforme (GBM) cell lines as well as GBM cells isolated from a brain tumor of patient. Additionally, mouse macrophages were included in the study. The influence of IONPs in three different doses (1, 5 and 25 µg Fe/ml) on the viability, proliferation and migration activity of cells was assessed. Moreover, quantifying the intracellular ROS production, we determined the level of oxidative stress in cells exposed to IONPs. In the paper, for the first time, the effect of Fe in the form of IONPs was compared with the analogical data obtained for iron salts solutions containing the same amount of Fe, on the similar oxidation state. Our results clearly showed that the influence of iron on the living cells strongly depends not only on the used cell line, dose and exposure time but also on the form in which this element was administered to the culture. Notably, nanoparticles can stimulate the proliferation of some cell lines, including glioblastoma multiforme. Compared to Fe salts, they have a stronger negative impact on the viability of the cells tested. Ultra-small NPs, also, more often positively affect cell motility which seem to differ them from the NPs with larger core diameters.

The Evolution of Iron Oxide Nanoparticles as MRI Contrast Agents

While the use of iron oxide nanoparticles as magnetic resonance contrast agents for clinical imaging is established, they are more recently experiencing renewed interest as alternatives to gadolinium-based contrast agents. Ultra-small iron oxide nanoparticles have unique pharmacokinetics, metabolic and imaging properties. These properties have led to improved techniques for imaging a variety of vascular, oncologic and inflammatory conditions with iron oxide nanoparticles. Current research efforts are aimed at harnessing the characteristics of these nanoparticles to advance magnetic resonance imaging techniques and explore new therapeutic potentials. While there are some limitations to the use of iron oxide nanoparticles, including allergies to parenteral iron and iron storage disorders, the practicable applications for these agents will continue to expand. The purpose of this review is to provide a brief overview of the history and synthesis of iron oxide nanoparticles, their current applications in clinical imaging and their prospective clinical applications.

NMR rapid detection of Salmonella in milk based on ultra-small iron oxide nanobiosensor

The monitoring and control of foodborne pathogenic microorganisms to protect food safety is of great significance. A biosensor based on superparamagnetic ultra-small iron oxide nanoparticles (USIO NPs) combined with membrane filtration and low field nuclear magnetic resonance (LF-NMR) for rapid detection of Salmonella is introduced. First, free biotin-capture-antibodies and biotin-detection-antibodies were specifically bound to different targets of Salmonella in milk samples. Then streptavidin-coated USIO NP probes were coupled with the biotinylated monoclonal antibody to capture Salmonella. Finally, polyethersulfone membrane filtration was performed on the final reaction system to remove unbound-probes, and the transverse magnetisation time (T2) of the filtrate was measured by NMR to indirectly reflect the content of the target substance retained on the filter membrane. This method shows high specificity and anti-interference to Salmonella, and the limit of detection (LOD) in pure culture and real samples was 2.3 × 103 cfu mL−1 within 150 min.

Targeted NIRF/MR dual-mode imaging of breast cancer brain metastasis using BRBP1-functionalized ultra-small iron oxide nanoparticles.

Tumor metastasis to brain is the main clinical manifestation of patients with advanced breast cancer, leading to poor survival prognosis. In order to detect the early incidence of brain metastasis, it is urgent to develop hypersensitive contrast agents for multimode imaging. In this study, PEG-phospholipids coated, a phage play derived peptide, BRBP1 peptide modified ultra-small iron oxide nanoparticles were prepared for targeted NIRF and MR imaging of breast cancer brain metastasis. The nanoparticles showed 10nm core-shell, high relaxivity values and photon emission efficiency in vitro. The nanoparticles offered a T2 contrast imaging effect and near-infrared fluorescent signal enhancement. Compared with control peptide modified nanoparticles, the MR/NIRF imaging signal of BRBP1-modified nanoparticles in tumor tissue was significantly enhanced, which should be induced by the targeting ability of BRBP1 peptide. These results indicated that BRBP1-SPIO@mPEG (DiR) nanoparticles could be applied as an effective targeted delivery system for diagnosis of breast cancer brain metastasis.

Evaluation of scaffold microstructure and comparison of cell seeding methods using micro-computed tomography-based tools.

Micro-computed tomography (micro-CT) provides a means to analyse and model three-dimensional (3D) tissue engineering scaffolds. This study proposes a set of micro-CT-based tools firstly for evaluating the microstructure of scaffolds and secondly for comparing different cell seeding methods. The pore size, porosity and pore interconnectivity of supercritical CO2 processed poly(l-lactide-co-ɛ-caprolactone) (PLCL) and PLCL/β-tricalcium phosphate scaffolds were analysed using computational micro-CT models. The models were supplemented with an experimental method, where iron-labelled microspheres were seeded into the scaffolds and micro-CT imaged to assess their infiltration into the scaffolds. After examining the scaffold architecture, human adipose-derived stem cells (hASCs) were seeded into the scaffolds using five different cell seeding methods. Cell viability, number and 3D distribution were evaluated. The distribution of the cells was analysed using micro-CT by labelling the hASCs with ultrasmall paramagnetic iron oxide nanoparticles. Among the tested seeding methods, a forced fluid flow-based technique resulted in an enhanced cell infiltration throughout the scaffolds compared with static seeding. The current study provides an excellent set of tools for the development of scaffolds and for the design of 3D cell culture experiments.

Yolk-shell nanovesicles endow glutathione-responsive concurrent drug release and T1 MRI activation for cancer theranostics

The effort of incorporating therapeutic drugs with imaging agents has been one of the mainstreams of nanomedicine, which holds great promise in cancer treatment in terms of monitoring therapeutic drug activity and evaluating prognostic index. However, it is still technically challenging to develop nanomedicine endowing a spatiotemporally controllable mechanism of drug release and activatable imaging capability. Here, we developed a yolk-shell type of GSH-responsive nanovesicles (NVs) in which therapeutic drug (Doxorubicin, DOX) and magnetic resonance imaging (MRI) contrast agent (ultrasmall paramagnetic iron oxide nanoparticles, USPIO NPs) formed complexes (denoted as USD) and were encapsulated inside the NVs. The formation of USD complexes is mediated by both the electrostatic adsorption between DOX and poly(acrylic acid) (PAA) polymers and the DOX-iron coordination effect on USPIO NPs. The obtained USD NVs showed a unique yolk-shell structure with restrained drug activity and quenched T1 MRI contrast ability which, on the other hand, can respond to glutathione (GSH) and lead to drug release and T1 contrast activation in a spatiotemporally concurrent manner. Furthermore, the USD NVs exhibited great potential to kill HCT116 cancer cells in vitro and effectively inhibit the tumor growth in vivo. This study may shed light on the design of sophisticated nanotheranostics in precision nanomedicine.

Polyethylenimine Nanogels Incorporated with Ultrasmall Iron Oxide Nanoparticles and Doxorubicin for MR Imaging-Guided Chemotherapy of Tumors.

Development of versatile nanoplatforms for cancer theranostics remains a hot topic in the area of nanomedicine. We report here a general approach to create polyethylenimine (PEI)-based hybrid nanogels (NGs) incorporated with ultrasmall iron oxide (Fe3O4) nanoparticles (NPs) and doxorubicin for T1-weighted MR imaging-guided chemotherapy of tumors. In this study, PEI NGs were first prepared using an inverse emulsion approach along with Michael addition reaction to cross-link the NGs, modified with citric acid-stabilized ultrasmall Fe3O4 NPs through 1-ethyl-3-(3-(dimethylamino)propyl) carbodiimide hydrochloride (EDC) coupling, and physically loaded with anticancer drug doxorubicin (DOX). The formed hybrid NGs possess good water dispersibility and colloidal stability, excellent DOX loading efficiency (51.4%), pH-dependent release profile of DOX with an accelerated release rate under acidic pH, and much higher r1 relaxivity (2.29 mM-1 s-1) than free ultrasmall Fe3O4 NPs (1.15 mM-1 s-1). In addition, in contrast to the drug-free NGs that possess good cytocompatibility, the DOX-loaded hybrid NGs display appreciable therapeutic activity and can be taken up by cancer cells in vitro. With these properties, the developed hybrid NGs enabled effective inhibition of tumor growth under the guidance of T1-weighted MR imaging. The developed hybrid NGs may be applied as a versatile nanoplatform for MR imaging-guided chemotherapy of tumors.