Near-infrared-light induced nanoparticles with enhanced tumor tissue penetration and intelligent drug release.

Tumor tissue presents much denser and stiffer extracellular matrix (ECM), which can hinder the penetration of most nanoparticles (NPs) and contribute to the tumor cell proliferation. Here, NIR-activated losartan was encapsulated in hollow mesoporous prussian blue nanoparticles (HMPBs) to degrade ECM. The results showed that losartan enhanced the penetration of DOX, 1.47% of the injected dose (ID) of DOX reached the tumor tissues, which was 3.00-fold higher than the control group (0.49%). In addition, as the existence of thermo-sensitive lauric acid, (Losartan + DOX)@HMPBs could achieve near "zero drug leakage" during blood circulation, so as to reduce the damage of DOX to normal tissues. Furthermore, the animal experiments proved tumor inhibition ability of (Losartan + DOX)@HMPBs in synergistic of photothermal/chemotherapy, with the tumor growth inhibition rate of 81.3%. Taken together, these findings can be a candidate for developing vectors with enhanced tumor penetration and therapeutic effect in future clinical application. STATEMENT OF SIGNIFICANCE: Due to the existence of denser extracellular matrices (ECM), only 0.7% of the administered nanoparticles dose is delivered to tumor, which will limit the tumors' therapeutic effect. Degradation of ECM can improve the penetration of nanoparticles in tumors. However, no researchers has encapsulated losartan in nanoparticles to degrade ECM. Herein, we developed a NIR induced losartan and DOX co-delivery system based on hollow mesoporous prussian blue nanoparticles (HMPBs) to degrade ECM and improve the penetration of nanoparticles in tumors. The prepared nanoparticles can also acheive near "zero drug leakage" during blood circulation and "fixed-point drug release" in tumor, so as to reduce the damage of DOX to normal tissues. We believe the prepared nanoparticles provide a new platform for cancer treatment.

Thallium Labeled Citrate-Coated Prussian Blue Nanoparticles as Potential Imaging Agent.

Background: The aim of this study was to develop and characterize a nanoparticle-based image-contrast platform which is biocompatible, chemically stable, and accessible for radiolabeling with 201Tl. We explored whether this nanoparticle enhanced the T1 signal which might make it an MRI contrast agent as well. Methods: The physical properties of citrate-coated Prussian blue nanoparticles (PBNPs) (iron(II);iron(III);octadecacyanide) doped with 201Tl isotope were characterized with atomic force microscopy, dynamic light scattering, and zeta potential measurement. PBNP biodistribution was determined by using SPECT and MRI following intravenous administration into C57BL6 mice. Activity concentrations (MBq/cm3) were calculated from the SPECT scans for each dedicated volume of interest (VOI) of liver, kidneys, salivary glands, heart, lungs, and brain. Results: PBNP accumulation peaked at 2 hours after injection predominantly in the kidneys and the liver followed by a gradual decrease in activity in later time points. Conclusion: We synthetized, characterized, and radiolabeled a Prussian blue-based nanoparticle platform for contrast material applications. Its in vivo radiochemical stability and biodistribution open up the way for further diagnostic applications.

Prussian Blue Nanoparticles as Multienzyme Mimetics and Reactive Oxygen Species Scavengers.

The generation of reactive oxygen species (ROS) is an important mechanism of nanomaterial toxicity. We found that Prussian blue nanoparticles (PBNPs) can effectively scavenge ROS via multienzyme-like activity including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) activity. Instead of producing hydroxyl radicals (•OH) through the Fenton reaction, PBNPs were shown to be POD mimetics that can inhibit •OH generation. We theorized for the first time that the multienzyme-like activities of PBNPs were likely caused by the abundant redox potentials of their different forms, making them efficient electron transporters. To study the ROS scavenging ability of PBNPs, a series of in vitro ROS-generating models was established using chemicals, UV irradiation, oxidized low-density lipoprotein, high glucose contents, and oxygen glucose deprivation and reperfusion. To demonstrate the ROS scavenging ability of PBNPs, an in vivo inflammation model was established using lipoproteins in Institute for Cancer Research (ICR) mice. The results indicated that PBNPs hold great potential for inhibiting or relieving injury induced by ROS in these pathological processes.

Toxicological evaluation of Prussian blue nanoparticles after short exposure of mice.

Prussian blue nanoparticle (PBNP), a new type of theranostic nanomaterial, had been used for cancer magnetic resonance imaging and photothermal therapy. However, their long-term toxicity after short exposure in vivo was still unclear. In this study, we investigated the dynamic changes of the biochemical and immunity indicators of mice after PBNPs injection through tail vein. Histological results showed that the PBNPs were mainly accumulated in liver and spleen. In the spleen, we found the frequency of T cells was starting to decrease after 1 day of PBNPs injection, but then slowly recovered to normal level after 60 days of injection. Meanwhile, the frequency of T cells in the blood was firstly decreased after the PBNPs injection, and then the T cell frequency kept increasing and recovered back to normal levels after 7 days of injection. The serum indexes of liver functions (alanine transaminase, aspartate transaminase, total bilirubin, and alkaline phosphatase) increased rapidly to a relatively high level only after 1 h of injection, which meant certain acute liver damage, but these indexes were gradually decreased to normal levels after 60 days of injection. These results indicate that PBNPs have acute toxicity in vivo, however, their long-term toxicity after short-time exposure is low, which might provide guidance for further applications of PBNPs in future.

²°¹Tl⁺-labelled Prussian blue nanoparticles as contrast agents for SPECT scintigraphy.

Prussian blue (PB) and its analogues on the nanometric scale are exciting nano-objects that combine the advantages of molecular-based materials and nanochemistry. Herein, we demonstrate that ultra-small PB nanoparticles of 2-3 nm can be easily labelled with radioactive (201)Tl(+) to obtain new nanoprobes as radiotracers for 201-thallium-based imaging.

French contribution to develop Prussian blue.

PURPOSE: Prussian blue is an antidote indicated for the treatment of internal cesium radioisotope contamination. The French armed forces develop and manufacture some antidotal drugs meeting regulatory, analytical and pharmaceutical requirements in order to submit marketing authorization documentation. Prior to an initial meeting with the French National Agency for Medicines and Health Products Safety (ANSM) in 2011, the authors were following regulatory developments in free cyanide release, active pharmaceutical ingredient (API) synthesis, API specifications, ability of cesium/Prussian blue binding products and collection of pre-clinical data. MATERIALS AND METHODS: Free cyanide release was assessed by ultraviolet-visible (UV-Vis) spectrometry at 615 nm. The kinetics of cesium were evaluated in vitro by flame atomic absorption. Good laboratory practice (GLP) and mutagenic assays were examined in rat studies to assess 'no absorption'. RESULTS: A validated method makes it possible to assess the free cyanide in API according to the published tolerability in humans. The French synthesizer meets good manufacturing practice (GMP) to give a drug that is compliant with all specifications, ensuring its high quality. Two standard mutagenic assays showed mutagenic potential, leading to further tests to obtain more information on any induced chromosomal aberrations. Absorption could be an important factor in determining the risk posed by the drug. CONCLUSION: The French health service provides the country with several antidotal drugs reducing Chemical, Biological, Radiological and Nuclear (CBRN) risks. Using their GMP manufacturing facilities and pharmaceutical expertise, the French armed forces have contributed to developing drugs with marketing authorization, such as pentetate calcium trisodium (Ca-DTPA) for infusion, or under development with the French Alternative Energies and Atomic Energy Commission (CEA), such as Ca-DTPA by inhalation.

Manganese-containing Prussian blue nanoparticles for imaging of pediatric brain tumors.

Pediatric brain tumors (PBTs) are a leading cause of death in children. For an improved prognosis in patients with PBTs, there is a critical need to develop molecularly-specific imaging agents to monitor disease progression and response to treatment. In this paper, we describe manganese-containing Prussian blue nanoparticles as agents for molecular magnetic resonance imaging (MRI) and fluorescence-based imaging of PBTs. Our core-shell nanoparticles consist of a core lattice structure that incorporates and retains paramagnetic Mn(2+) ions, and generates MRI contrast (both negative and positive). The biofunctionalized shell is comprised of fluorescent avidin, which serves the dual purpose of enabling fluorescence imaging and functioning as a platform for the attachment of biotinylated ligands that target PBTs. The surfaces of our nanoparticles are modified with biotinylated antibodies targeting neuron-glial antigen 2 or biotinylated transferrin. Both neuron-glial antigen 2 and the transferrin receptor are protein markers overexpressed in PBTs. We describe the synthesis, biofunctionalization, and characterization of these multimodal nanoparticles. Further, we demonstrate the MRI and fluorescence imaging capabilities of manganese-containing Prussian blue nanoparticles in vitro. Finally, we demonstrate the potential of these nanoparticles as PBT imaging agents by measuring their organ and brain biodistribution in an orthotopic mouse model of PBTs using ex vivo fluorescence imaging.

Synthesis of gold coated magnetic microparticles and their application for electrochemical glucose sensing by the enzymatically precipitated prussian blue.

An enzyme stimulated deposition of prussian blue onto the gold-coated magnetic microparticles is described. We propose to synthesize the continuous outer gold layer on the magnetic particle for a gold working electrode and its superparamagnetic property. In-depth characterization of the gold shell formation was studied with scanning electron microscopy, energy-dispersive X-ray spectroscopy, cyclic voltammetry. The gold-coated magnetic microparticles offered adhesive layer for the immobilization of glucose oxidase catalyzing the generation of prussian blue in the presence of glucose. The assembled prussian blue on the gold shell surfaces was detected with electrochemical measurements depending on the glucose concentration. With accomplishing the linear response range from 0.2 mM to 10 mM of glucose, this approach successfully proposed the applicability of the magnetic core-gold shell structures to the electrochemical bioassay area.

Cellular transfer of magnetic nanoparticles via cell microvesicles: impact on cell tracking by magnetic resonance imaging.

PURPOSE: Cell labeling with magnetic nanoparticles can be used to monitor the fate of transplanted cells in vivo by magnetic resonance imaging. However, nanoparticles initially internalized in administered cells might end up in other cells of the host organism. We investigated a mechanism of intercellular cross-transfer of magnetic nanoparticles to different types of recipient cells via cell microvesicles released under cellular stress. METHODS: Three cell types (mesenchymal stem cells, endothelial cells and macrophages) were labeled with 8-nm iron oxide nanoparticles. Then cells underwent starvation stress, during which they produced microvesicles that were subsequently transferred to unlabeled recipient cells. RESULTS: The analysis of the magnetophoretic mobility of donor cells indicated that magnetic load was partially lost under cell stress. Microvesicles shed by stressed cells participated in the release of magnetic label. Moreover, such microvesicles were uptaken by naïve cells, resulting in cellular redistribution of nanoparticles. Iron load of recipient cells allowed their detection by MRI. CONCLUSIONS: Cell microvesicles released under stress may be disseminated throughout the organism, where they can be uptaken by host cells. The transferred cargo may be sufficient to allow MRI detection of these secondarily labeled cells, leading to misinterpretations of the effectiveness of transplanted cells.

The potential for phytoremediation of iron cyanide complex by willows.

Hybrid willows (Salix matsudana Koidz x Salix alba L.), weeping willows (Salix babylonica L.) and hankow willows (Salix matsudana Koidz) were exposed to potassium ferrocyanide to determine the potential of these plants to extract, transport and metabolize this iron cyanide complex. Young rooted cuttings were grown in hydroponic solution at 24.0 +/- 0.5 degrees C for 144 h. Ferrocyanide in solution, air, and aerial tissues of plants was analyzed spectrophotometrically. Uptake of ferrocyanide from the aqueous solution by plants was evident for all treatments and varied with plant species, ranging from 8.64 to 15.67% of initial mass. The uptake processes observed from hydroponic solution showed exponential disappearance kinetics. Very little amounts of the applied ferrocyanide were detected in all parts of plant materials, confirming passage of ferrocyanide through the plants. No ferrocyanide in air was found due to plant transpiration. Mass balance analysis showed that a large fraction of the reduction of initial mass in hydroponic solution was metabolized during transport within the plant materials. The difference in the metabolic rate of ferrocyanide between the three plant species was comparably small, indicating transport of ferrocyanide from hydroponic solution to plant materials and further transport within plant materials was a limiting step for assimilating this iron cyanide complex. In conclusion, phytoremediation of ferrocyanide by the plants tested in this study has potential field application.

Parameter estimation of a plant uptake model for cyanide: application to hydroponic data.

A plant uptake model is applied to describe free cyanide and ferrocyanide transport and fate in willow (Salix eriocephala var. Michaux) grown in hydroponics. The model is applied to experimental data to determine best-fit parameter values, their associated uncertainty, and their relative importance to field-scale phytoremediation applications. The fitted model results, using least-squares optimization of the observed log concentrations, indicate that free cyanide volatilization from leaf tissue and free cyanide cell wall adsorption were negligible. The free cyanide maximum uptake rate and assimilate (noncyanide 15N) first-order leaf loss rate were the only coefficients that significantly affected the model goodness of fit and were concurrently sensitive to data uncertainty in the parameter optimization. Saturation kinetics may be applicable for free cyanide uptake into plants, but not for ferrocyanide uptake, which may occur via preferential protein-mediated or inefficient transpiration stream uptake. Within the free cyanide system, the relative magnitudes of the saturation uptake parameters and the demonstration of an active role for plants in uptake relative to transpiration suggest the potential importance of preferential diffusion through the cell membranes as reported in the literature, rather than protein-mediated uptake. The fitted 13-parameter model matched the observed data well except for the predicted stem and leaf tissue assimilate concentrations, which were significantly underestimated, particularly in the free cyanide system. These low predicted values, combined with the slightly underestimated solution free cyanide removal, suggest that noncyanide 15N redistribution in phloem should be considered.

Development of a plant uptake model for cyanide.

A model for cyanide species uptake by willow (Salix eriocephala L. var. Michaux) was developed to interpret data from hydroponic experiments quantitatively. While the potential for cyanide phytoremediation has been demonstrated modeling will aid in determining plant processes that contribute to cyanide transport and metabolism in willow and will target specific physiological parameters for field-scale phytoremediation design and optimization. The objective of the model development was to gain insight into the relative role of different processes with respect to dissolved free and iron-complexed cyanide transport and assimilation in plants and to determine rates at which these processes occur within the willow plant under the experimental conditions. A physiologically-based model describing plant uptake, transport, and metabolism of cyanide species was developed to reflect the processes that influence the movement of cyanide into and throughout the plant. Plant compartmentalization (root, stem, and leaf) corresponded to the level of detail in the data collected via hydroponic experiments. Inclusion of more detailed intra- and intercellular processes would create a model inconsistent with the macroscale nature of the data. Mass balances around each compartment were developed via kinetic representations for the mass transfer processes and were combined to form a model describing the fate of cyanide species within plant-water systems.

Dynamic, equilibrium and human studies of adsorption of 201Tl by Prussian blue.

Prussian blue is the recommended but infrequently required antidote for radiocesium and thallium chemical poisoning. Conceivably, its most frequent application will be the decontamination of radiothallium (thallous chloride) from human body following myocardial scintigraphy. Dosage schedule and physicochemical parameters of interaction with radiothallium, however, need to be defined, as the known data is inadequate on this account. The objective of the present study is to create physiologically relevant and mathematically rigorous data on interaction of Prussian blue with Tl, to estimate dosage schedule of Prussian blue suitable for myocardial scintigraphy, and to perform preliminary human studies to evaluate the efficacy of the antidote in reducing the considerable radiation burden imparted by this radiotracer. Adsorption efficacy of Prussian blue for radiothallium was found to be more than 95% at basic (intestinal) pH even at low concentrations and in presence of the physiological cations, potassium and sodium. Isotherm analysis and derivations using Langmuir, Bajpai, Lagergreen, and Freundlich equations suggest a favorable adsorption of Tl on Prussian blue with qmax being 5,000 MBq g. Based on these findings and clinical considerations, particularly preferential gall bladder excretion and enterohepatic recycling of radioactive thallous chloride, a dose of 100 mg Prussian blue with every major meal for 3 days was considered adequate for the purpose. Our experience with the first two patients (serving as their own self-controls) suggests that Prussian blue therapy is a safe and effective method to significantly reduce radiation burden imparted by thallium myocardial scintigraphy.

Possible evidence for transport of an iron cyanide complex by plants.

Barley (Hordeum vulgare L.), oat (Avena sativa L.), and wild cane (Sorghum bicolor L.), were exposed to 15N-labeled ferrocyanide to determine whether these plant species can transport this iron cyanide complex. Plants were treated with ferrocyanide in a nutrient solution that simulated iron cyanide contaminated groundwater and soil solutions. This nutrient solution has been shown to maintain ferrocyanide speciation with minimal dissociation to free cyanide. Following treatment, all three plants showed dramatic enrichments in roots (delta 15N per thousand =1000-1500) and shoots (delta 15N per thousand =500). Barley and oat showed enrichment primarily in roots while wild cane showed a near equal enrichment in root and shoot tissues. Nitrogen-deficient barley plants treated with ferrocyanide showed a significantly greater 15N enrichment as compared to nitrogen-sufficient plants. While the results are suggestive of ferrocyanide transport by these plant species, additional study will be required to verify these results.

Interaction of tryptophan and phenylalanine with metal ferrocyanides and its relevance in chemical evolution.

The interaction of two naturally occurring aromatic alpha-amino acids, namely, tryptophan and phenylalanine, with zinc, nickel, cobalt, and copper ferrocyanides has been studied. Both amino acids showed a high adsorption affinity toward metal ferrocyanides at neutral pH (7.0). Adsorption trends followed the Langmuir adsorption isotherm. Values of the Langmuir constants K(L) and X(m) suggest tryptophan is a better adsorbate than phenylalanine. Zinc ferrocyanide showed the highest adsorption, while the minimum adsorption was found in the case of copper ferrocyanide. Infrared spectral studies of adsorbate, adsorbent, and adsorption adducts indicate that adsorption occurs because of the interaction of adsorbate molecules with outer divalent metal ions present in the lattice of metal ferrocyanides. The present investigation supports the hypothesis that metal ferrocyanides might have concentrated the biomonomers on their surface in primeval seas during the course of chemical evolution.

Prussian blue for treatment of radiocesium poisoning.

Prussian blue is a crystal lattice that exchanges potassium for cesium at the surface of the crystal. When given orally, it binds cesium that is secreted in the gut before it can be reabsorbed. Data suggest that in humans, Prussian blue can reduce cesium's half-life by approximately 43% and reduce total body burdens. Prussian blue is well tolerated at a dosage of 3 g/day with appropriate monitoring of serum potassium levels and observing for signs of constipation. Clinical data on the efficacy of Prussian blue in the management of radiocesium poisoning were evaluated. Articles published in English describing distribution and elimination of cesium in both humans and animals were reviewed, along with articles describing administration of Prussian blue in clinical toxicology.

Passive absorption of hydrophilic carbohydrate probes by the house sparrow Passer domesticus.

To evaluate the permeability of the intestine of the house sparrow Passer domesticus to hydrophilic compounds, we applied a pharmacokinetic technique to measure in vivo absorption of two carbohydrate probes, l-arabinose and d-mannitol. Probes were fed or injected, and blood and excreta were subsequently collected and analyzed by gas chromatography/mass spectrometry. Following injection, plasma probe concentration decreased in a log-linear fashion, implying single-compartment, first-order kinetics. Following oral administration, plasma probe concentrations increased, reached a maximum at 10 min and then decreased in log-linear fashion. Mannitol and arabinose absorption were calculated from the areas under the post-absorption plasma curve and the respective distribution spaces and elimination constants. The amounts absorbed increased linearly with the concentration administered (range 1-1000 mmol x l(-1)), implying a passive process. The mouth-to-cloaca retention time of digesta, measured using the non-absorbable compound potassium ferrocyanide, was independent of probe concentration. On average, 69% of the oral dose of probe was absorbed and this was independent of the concentration of probe administered. This paper supports an earlier report of substantial passive glucose absorption in house sparrows and offers a method to study the extent of hydrophilic solute absorption, which has importance for future research in areas as diverse as biomedical, ecological and evolutionary physiology.

Tracer studies in the rat demonstrate misdirected filtration and peritubular filtrate spreading in nephrons with segmental glomerulosclerosis.

In two genetic models of "classic" focal segmental glomerulosclerosis (FSGS), the Milan normotensive and the Fawn-hooded hypertensive rats, tracer studies were performed to test the hypothesis that misdirected glomerular filtration and peritubular filtrate spreading are relevant mechanisms that contribute to nephron degeneration in this disease. Two exogenous tracers, lissamine green and horse spleen ferritin, were administered by intravenous injection and subsequently traced histologically in serial kidney sections. In contrast to control rats, both tracers in kidneys of Milan normotensive and Fawn-hooded hypertensive rats with established FSGS were found to accumulate extracellularly at the following sites: (1) within tuft adhesions to Bowman's capsule and associated paraglomerular spaces, (2) at the glomerulotubular junction contained within extensions of the paraglomerular spaces onto the tubule, and (3) within subepithelial peritubular spaces eventually encircling the entire proximal convolution of an affected nephron. This distribution strongly suggests the existence of misdirected filtration into tuft adhesions to Bowman's capsule and subsequent spreading of the filtrate around the entire circumference of a glomerulus and, alongside the glomerulotubular junction, onto the outer aspect of the corresponding tubule. This leads to an interstitial response that consists of the formation of a barrier of sheet-like fibroblast processes around the affected nephron, which confines the filtrate spreading and, subsequently, the destructive process to the affected nephron. No evidence was found that either misdirected filtration and peritubular filtrate spreading themselves or the associated tubulo-interstitial process led to the transfer of the injury from an affected nephron to an unaffected nephron. It is concluded that in the context of FSGS development, misdirected filtration and peritubular filtrate spreading are important damaging mechanisms that underlie the extension of glomerular injury to the corresponding tubulointerstitium, thus leading finally to degeneration of both the glomerulus and the tubule of a severely injured nephron.

Copper- and zinc-containing superoxide dismutase can act as a superoxide reductase and a superoxide oxidase.

The copper- and zinc-containing superoxide dismutase can catalyze the oxidation of ferrocyanide by O(2) as well as the reduction of ferricyanide by O(2). Thus, it can act as a superoxide dismutase (SOD), a superoxide reductase (SOR), and a superoxide oxidase (SOO). The human manganese-containing SOD does not exert SOR or SOO activities with ferrocyanide or ferricyanide as the redox partners. It is possible that some biological reductants can take the place of ferrocyanide and can also interact with human manganese-containing superoxide dismutase, thus making the SOR activity a reality for both SODs. The consequences of this possibility vis à vis H(2)O(2) production, the overproduction of SODs, and the role of copper- and zinc-containing superoxide dismutase mutations in causing familial amyotrophic lateral sclerosis are discussed, as well as the likelihood that the biologically effective SOD mimics, as described to date, actually function as SORs.

Ferrocyanide ingestion may cause false positives in cyanide determination.

CASE REPORT: The authors present a patient who ingested a cyanide containing solution and arrived at the hospital without any clinical evidence of intoxication but an elevated blood cyanide level. The authors explain this discrepancy with the following hypotheses: 1) the patient ingested cyanide as an iron-chelated complex; and 2) the sulfuric acid used in the standard microdiffusion technique released cyanide from its iron-bound state to result in the observed elevated blood cyanide. Through a series of in vitro analyses, the authors demonstrate the following: 1) the ingested solution tested positive for cyanide with the sulfuric acid technique and negative for cyanide with acetic acid; 2) the presence of a ferrous salt in the ingested product by a colorimetric redox titration technique; and 3) release of a small fraction of the total cyanide from ferrocyanide by the sulfuric acid technique. The authors conclude: 1) the patient ingested potassium ferrocyanide; and 2) the strong acid used in the cyanide microdiffusion assay will liberate cyanide that is chelated to iron to yield false positive results.