Corona protein impacts on alternating current biosusceptometry signal and circulation times of differently coated MnFe2O4 nanoparticles.

Background: We evaluated the impacts of corona protein (CP) formation on the alternating current biosusceptometry (ACB) signal intensity and in vivo circulation times of three differently coated magnetic nanoparticles (MNP): bare, citrate-coated and bovine serum albumin-coated MNPs. Methods: We employed the ACB system, gel electrophoresis and mass spectrometry analysis. Results: Higher CP formation led to a greater reduction in the in vitro ACB signal intensity and circulation time. We found fewer proteins forming the CP for the bovine serum albumin-coated MNPs, which presented the highest circulation time in vivo among the MNPs studied. Conclusion: These data showed better biocompatibility, stability and magnetic signal uniformity in biological media for bovine serum albumin-coated MNPs than for citrate-coated MNPs and bare MNPs.

AC biosusceptometry and magnetic nanoparticles to assess doxorubicin-induced kidney injury in rats.

Aim: This paper aims to investigate a doxorubicin (DOX) chronic kidney disease rat model using magnetic nanoparticles (MNPs) associated with the alternate current biosusceptometry (ACB) to analyze its different perfusion profiles in both healthy and DOX-injured kidneys. Materials & methods: We used the ACB to detect the MNP kidney perfusion in vivo. Furthermore, we performed biochemical and histological analyses, which sustained results obtained from the ACB system. We also studied the MNP biodistribution. Results: We found that DOX kidney injury alters the MNPs' kidney perfusion. These changes became more intense as the disease progressed. Moreover, DOX has an important effect on MNP biodistribution as the disease evolved. Conclusion: This study provides new applications of MNPs in nephrology, instrumentation, pharmacology, physiology and nanomedicine.

Predictive Model for Delivery Efficiency: Erythrocyte Membrane-Camouflaged Magnetofluorescent Nanocarriers Study.

Delivery efficiencies of theranostic nanoparticles (NPs) based on passive tumor targeting strongly depend either on their blood circulation time or on appropriate modulations of the tumor microenvironment. Therefore, predicting the NP delivery efficiency before and after a tumor microenvironment modulation is highly desirable. Here, we present a new erythrocyte membrane-camouflaged magnetofluorescent nanocarrier (MMFn) with long blood circulation time (92 h) and high delivery efficiency (10% ID for Ehrlich murine tumor model). MMFns owe their magnetic and fluorescent properties to the incorporation of manganese ferrite nanoparticles (MnFe2O4 NPs) and IR-780 (a lipophilic indocyanine fluorescent dye), respectively, to their erythrocyte membrane-derived camouflage. MMFn composition, morphology, and size, as well as optical absorption, zeta potential, and fluorescent, magnetic, and magnetothermal properties, are thoroughly examined in vitro. We then present an analytical pharmacokinetic (PK) model capable of predicting the delivery efficiency (DE) and the time of peak tumor uptake (tmax), as well as changes in DE and tmax due to modulations of the tumor microenvironment, for potentially any nanocarrier. Experimental PK data sets (blood and tumor amounts of MMFns) are simultaneously fit to the model equations using the PK modeling software Monolix. We then validate our model analytical solutions with the numerical solutions provided by Monolix. We also demonstrate how our a priori nonmechanistic model for passive targeting relates to a previously reported mechanistic model for active targeting. All in vivo PK studies, as well as in vivo and ex vivo biodistribution studies, were conducted using two noninvasive techniques, namely, fluorescence molecular tomography (FMT) and alternating current biosusceptometry (ACB). Finally, histopathology corroborates our PK and biodistribution results.

Noninvasive intratumoral thermal dose determination during in vivo magnetic nanoparticle hyperthermia: combining surface temperature measurements and computer simulations.

PURPOSE: Noninvasive thermometry during magnetic nanoparticle hyperthermia (MNH) remains a challenge. Our pilot study proposes a methodology to determine the noninvasive intratumoral thermal dose during MNH in the subcutaneous tumor model. METHODS: Two groups of Ehrlich bearing-mice with solid and subcutaneous carcinoma, a control group (n = 6), and a MNH treated group (n = 4) were investigated. Histopathology was used to evaluate the percentage of non-viable lesions in the tumor. MNH was performed at 301 kHz and 17.5 kA.m-1, using a multifunctional nanocarrier. Surface temperature measurements were obtained using an infrared camera, where an ROI with 750 pixels was used for comparison with computer simulations. Realistic simulations of the bioheat equation were obtained by combining histopathology intratumoral lesion information and surface temperature agreement of at least 50% of the pixel's temperature data calculated and measured at the surface. RESULTS: One animal of the MNH group showed tumor recurrence, while two others showed complete tumor remission (monitored for 585 days). Sensitivity analysis of the simulation parameters indicated low tumor blood perfusion. Numerical simulations indicated, for the animals with complete remission, an irreversible tissue injury of 91 ± 5% and 100%, while the one with recurrence had a lower value, 56 ± 7%. The computer simulations also revealed the in vivo heat efficiency of the nanocarrier. CONCLUSION: A new methodology for determining noninvasively the three-dimensional intratumoral thermal dose during MNH was developed. The method demonstrates the potential for predicting the long-term preclinical outcome of animals treated with MNH.

IR-780-Albumin-Based Nanocarriers Promote Tumor Regression Not Only from Phototherapy but Also by a Nonirradiation Mechanism.

IR-780 iodide is a fluorescent dye with optical properties in the near-infrared region that has applications in tumor detection and photothermal/photodynamic therapy. This multifunctional effect led to the development of theranostic nanoparticles with both IR-780 and chemotherapeutic drugs such as docetaxel, doxorubicin, and lonidamine. In this work, we developed two albumin-based nanoparticles containing near-infrared IR-780 iodide multifunctional dyes, one of them possessing a magnetic core. Molecular docking with AutoDock Vina studies showed that IR-780 binds to bovine serum albumin (BSA) with greater stability at a higher temperature, allowing the protein binding pocket to better fit this dye. The theoretical analysis corroborates the experimental protocols, where an enhancement of IR-780 was found coupled to BSA at 60 °C, even 30 days after preparation, in comparison to 30 °C. In vitro assays monitoring the viability of Ehrlich ascites carcinoma cells revealed the importance of the inorganic magnetic core on the nanocarrier photothermal-cytotoxic effect. Fluorescence molecular tomography measurements of Ehrlich tumor-bearing Swiss mice revealed the biodistribution of the nanocarriers, with marked accumulation in the tumor tissue (≈3% ID). The histopathological analysis demonstrated strong increase in tumoral necrosis areas after 24 and 72 h after treatment, indicating tumor regression. Tumor regression analysis of nonirradiated animals indicate a IR-780 dose-dependent antitumoral effect with survival rates higher than 70% (animals monitored up to 600 days). Furthermore, an in vivo photothermal therapy procedure was performed and tumor regression was also verified. These results show a novel insight for the biomedical application of IR-780-albumin-based nanocarriers, namely cancer therapy, not only by photoinduced therapy but also by a nonirradiation mechanism. Safety studies (acute oral toxicity, cardiovascular evaluation, and histopathological analysis) suggest potential for clinical translation.

Specific T cell induction using iron oxide based nanoparticles as subunit vaccine adjuvant.

Metal-based nanoparticles (NPs) stimulate innate immunity; however, they have never been demonstrated to be capable of aiding the generation of specific cellular immune responses. Therefore, our objective was to evaluate whether iron oxide-based NPs have adjuvant properties in generating cellular Th1, Th17 and TCD8 (Tc1) immune responses. For this purpose, a fusion protein (CMX) composed of Mycobacterium tuberculosis antigens was used as a subunit vaccine. Citrate-coated MnFe2O4 NPs were synthesized by co-precipitation and evaluated by transmission electron microscopy. The vaccine was formulated by homogenizing NPs with the recombinant protein, and protein corona formation was determined by dynamic light scattering and field-emission scanning electron microscopy. The vaccine was evaluated for the best immunization route and strategy using subcutaneous and intranasal routes with 21-day intervals between immunizations. When administered subcutaneously, the vaccine generated specific CD4+IFN-γ+ (Th1) and CD8+IFN-γ+ responses. Intranasal vaccination induced specific Th1, Th17 (CD4+IL-17+) and Tc1 responses, mainly in the lungs. Finally, a mixed vaccination strategy (2 subcutaneous injections followed by one intranasal vaccination) induced a Th1 (in the spleen and lungs) and splenic Tc1 response but was not capable of inducing a Th17 response in the lungs. This study shows for the first time a subunit vaccine with iron oxide based NPs as an adjuvant that generated cellular immune responses (Th1, Th17 and TCD8), thereby exhibiting good adjuvant qualities. Additionally, the immune response generated by the subcutaneous administration of the vaccine diminished the bacterial load of Mtb challenged animals, showing the potential for further improvement as a vaccine against tuberculosis.

Real-time in vivo monitoring of magnetic nanoparticles in the bloodstream by AC biosusceptometry.

BACKGROUND: We introduce and demonstrate that the AC biosusceptometry (ACB) technique enables real-time monitoring of magnetic nanoparticles (MNPs) in the bloodstream. We present an ACB system as a simple, portable, versatile, non-invasive, and accessible tool to study pharmacokinetic parameters of MNPs, such as circulation time, in real time. We synthesized and monitored manganese doped iron oxide nanoparticles in the bloodstream of Wistar rats using two different injection protocols. Aiming towards a translational approach, we also simultaneously evaluated cardiovascular parameters, including mean arterial pressure, heart rate, and episodes of arrhythmia in order to secure the well-being of all animals. RESULTS: We found that serial injections increased the circulation time compared with single injections. Immediately after each injection, we observed a transitory drop in arterial pressure, a small drop in heart rate, and no episodes of arrhythmia. Although some cardiovascular effects were observed, they were transitory and easily recovered in both protocols. CONCLUSIONS: These results indicate that the ACB system may be a valuable tool for in vivo, real-time MNP monitoring that allows associations with other techniques, such as pulsatile arterial pressure and electrocardiogram recordings, helping ensuring the protocol safety, which is a fundamental step towards clinical applications.

Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects.

Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (-dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications.

Effect of magnetic dipolar interactions on nanoparticle heating efficiency: implications for cancer hyperthermia.

Nanostructured magnetic systems have many applications, including potential use in cancer therapy deriving from their ability to heat in alternating magnetic fields. In this work we explore the influence of particle chain formation on the normalized heating properties, or specific loss power (SLP) of both low- (spherical) and high- (parallelepiped) anisotropy ferrite-based magnetic fluids. Analysis of ferromagnetic resonance (FMR) data shows that high particle concentrations correlate with increasing chain length producing decreasing SLP. Monte Carlo simulations corroborate the FMR results. We propose a theoretical model describing dipole interactions valid for the linear response regime to explain the observed trends. This model predicts optimum particle sizes for hyperthermia to about 30% smaller than those previously predicted, depending on the nanoparticle parameters and chain size. Also, optimum chain lengths depended on nanoparticle surface-to-surface distance. Our results might have important implications to cancer treatment and could motivate new strategies to optimize magnetic hyperthermia.