Chemical, magnetic and electronic properties of NaxCoO2 and related compounds

In the last years, NaxCoO2 has experienced a renewed interest in the field of solid state science. However, NaxCoO2 is not a novel material, it has been extensively studied for decades. In the 80´s, it was investigated due to its electrochemical properties (high ionic mobility, high electrical conduction) and tested as a cathod in reversible alkaline cells, as its analogous LixCoO2. In the 90’s, its thermoelectric properties raised the interest of this material for energy harvesting at high temperature and refrigeration. However, the discovery of novel properties (i.e. high thermoelectric power or, mainly, the occurrence of superconductivity below 5K) and their possible relationship with similar phenomena found in other materials boosted a renewed interest in this highly electronic correlated system. The structural, magnetic and electronic properties of NaxCoO2 have been studied in detail in order to understand deeply some of the most fundamental aspects which drive the chemical and physical behaviour of this system: presence of oxygen vacants, the role of water played in the occurrence of superconductivity, the proximity of the system to a quantum phase transition or the nature of the unconventional thermoelectric and magnetic properties with x, specifically at the half-doped x=0.5. All of them are kept under strong scientific discussions that, far from solving them, contribute to generate an even higher controversy. On other hand, the efficiency of topotactic reactions in order to exchange Na+ ions by other mono- or di-valent ions, such as Li+, Ca2+ or Sr2+, has been studied. The physical properties of the resulting compounds are shown and compared to those ones from the analogous NaxCoO2 precursor. Therefore, in the pages inside, the reader will can find our main results and conclusions achieved in each one of these subjects, in a modest attempt to explain the chemistry and physics involved in NaxCoO2 and related compounds

Magnetic solid nanoparticles and their counterparts: recent advances towards cancer theranostics

Cancer is currently a leading cause of death worldwide. The World Health Organization estimates an increase of 60% in the global cancer incidence in the next two decades. The inefficiency of the currently available therapies has prompted an urgent effort to develop new strategies that enable early diagnosis and improve response to treatment. Nanomedicine formulations can improve the pharmacokinetics and pharmacodynamics of conventional therapies and result in optimized cancer treatments. In particular, theranostic formulations aim at addressing the high heterogeneity of tumors and metastases by integrating imaging properties that enable a non-invasive and quantitative assessment of tumor targeting efficiency, drug delivery, and eventually the monitoring of the response to treatment. However, in order to exploit their full potential, the promising results observed in preclinical stages need to achieve clinical translation. Despite the significant number of available functionalization strategies, targeting efficiency is currently one of the major limitations of advanced nanomedicines in the oncology area, highlighting the need for more efficient nanoformulation designs that provide them with selectivity for precise cancer types and tumoral tissue. Under this current need, this review provides an overview of the strategies currently applied in the cancer theranostics field using magnetic nanoparticles (MNPs) and solid lipid nanoparticles (SLNs), where both nanocarriers have recently entered the clinical trials stage. The integration of these formulations into magnetic solid lipid nanoparticles—with different composition and phenotypic activity—constitutes a new generation of theranostic nanomedicines with great potential for the selective, controlled, and safe delivery of chemotherapy.This research was funded by the Portuguese Foundation for Science and Technology (Fundação para a Ciência e a Tecnologia—FCT) and the European Regional Development Fund (ERDF) through NORTE 2020 (2014–2020 North Portugal Regional Operational Program) under the project NORTE-01-0145-FEDER-031142 “Local specific treatment of triple-negative-breast-cancer through externally triggered target-less drug carriers (MagtargetON)”, and by 2014–2020 INTERREG Cooperation Programme Spain–Portugal (POCTEP) through the project 0624_2IQBIONEURO_6_E

Pseudomonas aeruginosa PAO 1 in vitro timekill kinetics using single phages and phage formulationsmodulating death, adaptation, and resistance

Pseudomonas aeruginosa is responsible for nosocomial and chronic infections in healthcare settings. The major challenge in treating P. aeruginosa-related diseases is its remarkable capacity for antibiotic resistance development. Bacteriophage (phage) therapy is regarded as a possible alternative that has, for years, attracted attention for fighting multidrug-resistant infections. In this work, we characterized five phages showing different lytic spectrums towards clinical isolates. Two of these phages were isolated from the Russian Microgen Sextaphage formulation and belong to the Phikmvviruses, while three Pbunaviruses were isolated from sewage. Different phage formulations for the treatment of P. aeruginosa PAO1 resulted in diversified timekill outcomes. The best result was obtained with a formulation with all phages, prompting a lower frequency of resistant variants and considerable alterations in cell motility, resulting in a loss of 73.7% in swimming motility and a 79% change in swarming motility. These alterations diminished the virulence of the phage-resisting phenotypes but promoted their growth since most became insensitive to a single or even all phages. However, not all combinations drove to enhanced cell killings due to the competition and loss of receptors. This study highlights that more caution is needed when developing cocktail formulations to maximize phage therapy efficacy. Selecting phages for formulations should consider the emergence of phage-resistant bacteria and whether the formulations are intended for short-term or extended antibacterial application.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2020 unit. S.S. acknowledges funding by FCT through the individual scientific employment program contract (2020.03171.CEECIND).info:eu-repo/semantics/publishedVersio

Enhanced performance of cobalt ferrite encapsulated in graphitic shell by means of AC magnetically activated catalytic wet peroxide oxidation of 4-nitrophenol

Here we report preliminary catalytic wet peroxide oxidation (CWPO) experiments performed in the presence of an alternating current (AC) magnetic field. One ferromagnetic graphitic nanocomposite – composed by a cobalt ferrite core and a graphitic shell (CoFe2O4/MGNC), was employed in the process, here named magnetically activated catalytic wet peroxide oxidation (MA-CWPO). An aqueous solution containing 5.0 g L−1 of 4-nitrophenol (4-NP) to simulate a high strength polluted stream was used as model system. The experiments were performed at room temperature and atmospheric pressure, with stoichiometric amount of hydrogen peroxide (H2O2), pH=3 and CoFe2O4/MGNC catalyst load=5.0 g L−1 (corresponding to a 4-NP/CoFe2O4 mass ratio of 6.9, as CoFe2O4 accounts for 14.4 wt% of CoFe2O4/MGNC). It was shown that the performance of CWPO is enhanced upon application of an AC magnetic field (frequency of 533.9 kHz and magnitude of 240 G). As a result, high 4-NP mineralization was obtained by MA-CWPO (as reflected by a total organic carbon abatement of 79% after 4 h of reaction, instead of 39% in the absence of a magnetic field). This positive effect was ascribed to the localised increase of CoFe2O4/MGNC surface temperature resulting from heat release upon exposure of the nanoparticulated catalyst to an AC magnetic field, which accelerates the catalytic decomposition of H2O2 via hydroxyl radicals (HO%) formation.info:eu-repo/semantics/publishedVersio

Control of planktonic bacterial cells and biofilms through magnetic hyperthermia

Disinfection of surfaces is a challenging task aggravated by bacteria's capacity to form biofilms, which enables them to survive and resist a wide variety of antimicrobial agents and hostile conditions. Potential application of magnetic hyperthermia (MH) as a new disinfection method against biofilms has been recently proposed however, studies comparing its performance and effectiveness on planktonic and biofilm cells from the same bacterial species remain unexplored. This work evaluated the effect of MH generated by iron oxide magnetic nanoparticles (MNP) against planktonic and biofilm cells Pseudomonas fluorescens, a major food spoilage microorganism. A P. fluorescens collection strain (ATCC 27663) was used and its biofilms allowed to form on silicone coupons during three days incubation in tryptic soy broth culture medium, at room temperature (20 ± 2ºC) and constant agitation of 120 rpm. Hyperthermia experiments were performed by applying an oscillating magnetic field of 873kHz and 100 Oe to several identical solutions of bacteria and MNP. To study cell viability as a function of temperature, magnetic heatings were performed at the same heating rate and up to different maximum temperatures. Bacterial survival was assessed through colony forming units count, while confocal laser scanning microscopy (CLS) was used to evaluate cellular membrane integrity of both bacterial life forms, as well as eventual effects of MH in biofilms' structure. Results showed a significant reduction (3 log) of viable planktonic cells when a maximum temperature of 40QC was reached, corresponding to only about 3 minutes of exposure to alternate magnetic field. A complete cellular eradication was achieved after only 8 minutes, when the maximum temperature was increased up to 55ºC. ln contrast, a significantly lower reduction of cellular viability was accomplished for biofilm s at the same temperatures, and no eradication was achieved even after 17 minutes of magnetic field exposure, reaching a maximum temperature of 60ºC. CLS images showed that MH inflicted cellular membrane damages both in planktonic and biofilm s cells, and also suggested that the outer cell layers of biofilms were more damaged than inner ones, as denoted by the higher amount of injured cells observed in the external layers. Summarizing, this work confirms the potential of MH as a disinfection method and shows for the first time its efficacy against a food spoilage microorganism. More importantly, it presents the first insights about how different bacterial life forms are affected by MH, showing a significantly different effectiveness against planktonic cells and biofilms

Solid Lipid Particles for Lung Metastasis Treatment

Solid lipid particles (SLPs) can sustainably encapsulate and release therapeutic agents over long periods, modifying their biodistribution, toxicity, and side effects. To date, no studies have been reported using SLPs loaded with doxorubicin chemotherapy for the treatment of metastatic cancer. This study characterizes the effect of doxorubicin-loaded carnauba wax particles in the treatment of lung metastatic malignant melanoma in vivo. Compared with the free drug, intravenously administrated doxorubicin-loaded SLPs significantly reduce the number of pulmonary metastatic foci in mice. In vitro kinetic studies show two distinctive drug release profiles. A first chemotherapy burst-release wave occurs during the first 5 h, which accounts for approximately 30% of the entrapped drug rapidly providing therapeutic concentrations. The second wave occurs after the arrival of the particles to the final destination in the lung. This release is sustained for long periods (>40 days), providing constant levels of chemotherapy in situ that trigger the inhibition of metastatic growth. Our findings suggest that the use of chemotherapy with loaded SLPs could substantially improve the effectiveness of the drug locally, reducing side effects while improving overall survival.This research was funded by the European Regional Development Fund (ERDF) and the Spanish MINECO Refs. PI16/00496 (AES 2016), PI19/00349 (AES 2019), and DTS19/00033; IDIVAL Refs. INNVAL17/11 and INNVAL19/12. J.G. and M.B.-L. also acknowledge financial support from the Fundação para a Ciência e a Tecnologia and the ERDF through NORTE2020 (2014–2020 North Portugal Regional Operational Program) through the projects UTAP-EXPL/NTec/0038/2017 (NANOTHER) and NORTE-01-0145-FEDER-031142 (MAGTARGETON). Nano2clinics COST Action CA17140

The influence of colloidal parameters on the specific power absorption of PAA-coated magnetite nanoparticles

The suitability of magnetic nanoparticles (MNPs) to act as heat nano-sources by application of an alternating magnetic field has recently been studied due to their promising applications in biomedicine. The understanding of the magnetic relaxation mechanism in biocompatible nanoparticle systems is crucial in order to optimize the magnetic properties and maximize the specific absorption rate (SAR). With this aim, the SAR of magnetic dispersions containing superparamagnetic magnetite nanoparticles bio-coated with polyacrylic acid of an average particle size of ≈10 nm has been evaluated separately by changing colloidal parameters such as the MNP concentration and the viscosity of the solvent. A remarkable decrease of the SAR values with increasing particle concentration and solvent viscosity was found. These behaviours have been discussed on the basis of the magnetic relaxation mechanisms involved

Magnetic lipid nanovehicles synergize the controlled thermal release of chemotherapeutics with magnetic ablation while enabling non-invasive monitoring by MRI for melanoma theranostics

Nowadays, a number of promising strategies are being developed that aim at combining diagnostic and therapeutic capabilities into clinically effective formulations. Thus, the combination of a modified release provided by an organic encapsulation and the intrinsic physico-chemical properties from an inorganic counterpart opens new perspectives in biomedical applications. Herein, a biocompatible magnetic lipid nanocomposite vehicle was developed through an efficient, green and simple method to simultaneously incorporate magnetic nanoparticles and an anticancer drug (doxorubicin) into a natural nano-matrix. The theranostic performance of the final magnetic formulation was validated in vitro and in vivo, in melanoma tumors. The systemic administration of the proposed magnetic hybrid nanocomposite carrier enhanced anti-tumoral activity through a synergistic combination of magnetic hyperthermia effects and antimitotic therapy, together with MRI reporting capability. The application of an alternating magnetic field was found to play a dual role, (i) acting as an extra layer of control (remote, on-demand) over the chemotherapy release and (ii) inducing a local thermal ablation of tumor cells. This combination of chemotherapy with thermotherapy establishes a synergistic platform for the treatment of solid malignant tumors under lower drug dosing schemes, which may realize the dual goal of reduced systemic toxicity and enhanced anti-tumoral efficacy.Funding: This work was partially supported by NORTE 2020 (2014–2020 North Portugal Regional Operational Program), and the ERDF (European Regional Development Fund) under Grant NORTE-01-0145-FEDER-000019, by European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 686009, by “TAMs-targeted and externally controlled nanotheranostics of triple-negative-breast-cancer (Nanother)" project UTAPEXPL/NTec/0038/2017, by “Local specific treatment of triple-negativebreast-cancer through externally triggered target-less drug carriers (MagtargetON)" project NORTE-01-0145-FEDER-031142, co-funded by FCT and the ERDF through NORTE2020, and by 2014–2020 INTERREG Cooperation Programme Spain–Portugal (POCTEP) through the Project 0624_2IQBIONEURO_6_E. Co-authors also acknowledge support from Raman4clinics COST Action BM1401 and Radiomag COST action TD1402. ML-F also acknowledges the ERDF and the Spanish MINECO under project ref. PI19/00349 (AES 2019). LGH thanks the Instituto de Salud Carlos III for the Sara Borrell Grant (CD19/00035)

Enhanced performance of cobalt ferrite encapsulated in graphitic shell by means of AC magnetically activated catalytic wet peroxide oxidation of 4-nitrophenol

Here we report preliminary catalytic wet peroxide oxidation (CWPO) experiments performed in the presence of an alternating current (AC) magnetic field. One ferromagnetic graphitic nanocomposite - composed by a cobalt ferrite core and a graphitic shell (CoFe2O4/MGNC), was employed in the process, here named magnetically activated catalytic wet peroxide oxidation (MA-CWPO). An aqueous solution containing 5.0 g L-1 of 4-nitrophenol (4-NP) to simulate a high strength polluted stream was used as model system. The experiments were performed at room temperature and atmospheric pressure, with stoichiometric amount of hydrogen peroxide (H2O2), pH = 3 and CoFe2O4/MGNC catalyst load = 5.0 g L-1 (corresponding to a 4-NP/CoFe2O4 mass ratio of 6.9, as CoFe2O4 accounts for 14.4 wt% of CoFe2O4/MGNC). It was shown that the performance of CWPO is enhanced upon application of an AC magnetic field (frequency of 533.9 kHz and magnitude of 240 G). As a result, high 4-NP mineralization was obtained by MA-CWPO (as reflected by a total organic carbon abatement of 79% after 4 h of reaction, instead of 39% in the absence of a magnetic field). This positive effect was ascribed to the localised increase of CoFe2O4/MGNC surface temperature resulting from heat release upon exposure of the nanoparticulated catalyst to an AC magnetic field, which accelerates the catalytic decomposition of H2O2 via hydroxyl radicals (HO center dot) formation

Graphene-based magnetic nanoparticles for theranostics: an overview for their potential in clinical application

The combination of diagnostics and therapy (theranostic) is one of the most complex, yet promising strategies envisioned for nanoengineered multifunctional systems in nanomedicine. From the various multimodal nanosystems proposed, a number of works have established the potential of Graphene-based Magnetic Nanoparticles (GbMNPs) as theranostic platforms. This magnetic nanosystem combines the excellent magnetic performance of magnetic nanoparticles with the unique properties of graphene-based materials, such as large surface area for functionalization, high charge carrier mobility and high chemical and thermal stability. This hybrid nanosystems aims toward a synergistic theranostic effect. Here, we focus on the most recent developments in GbMNPs for theranostic applications. Particular attention is given to the synergistic effect of these composites, as well as to the limitations and possible future directions towards a potential clinical application.This work is the result of the project NORTE-01-0145-FEDER-029394, RTChip4Theranostics, and was supported by Programa Operacional Regional do Norte-Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement through the European Regional Development Fund (FEDER) and by Fundação para a Ciência e Tecnologia (FCT), IP, project reference PTDC/EMD-EMD/29394/2017. The authors also acknowledge the partial financial support by the projects UID/EEA/04436/2020 and by the project NORTE-01-0145-FEDER- 030171