Browsing by Author "Sharma, Surender K."

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Bi-phasic BiPO4 prepared through template-assisted hydrothermal method with enhanced electrochemical response for hybrid supercapacitor applications
(Springer Science and Business Media B.V., 2023-03-27T00:00:00) Monteles, Iara A.; Penha, Bruno V.; Fonseca, Weliton S.; Silva, Let�cia M. B.; Santos, Evelyn C. S.; de Souza, Luiz K. C.; Santos, C.C.; de Menezes, A.S.; Sharma, Surender K.; Javed, Yasir; Khawar, Muhammad R.; Tanaka, Auro A.; Almeida, Marcio A. P.
Abstract: We report the structural evolution of BiPO4 prepared in aqueous under different synthesis conditions viz., templates and temperatures to explore their electrochemical performance for supercapacitor applications. The templates [(hexadecyltrimethylammonium bromide (CTAB)), sodium dodecyl sulfate (SDS)] were added in bismuth precursor solution at 60��C, alternatively ethylene glycol (EG), a less toxic additive was incorporated at 90��C. BiPO4 exhibits a monoclinic phase, whereas a hexagonal structure was observed with the addition of the templates SDS and CTAB. Interestingly, both monoclinic and hexagonal phases were obtained by the addition of EG. The presence of mixed phase was thoroughly validated through Raman spectra, where vibrational modes for both monoclinic and hexagonal phases of BiPO4-EG were witnessed. The effect of template was clearly seen through electron microscopy with a rod-like morphology with (no template) and unfaceted (template). The electrochemical behavior of the synthesized materials was investigated, and it was found that the mixed structure of BiPO4-EG exhibited the highest specific capacity (167.15 C�g?1) at a scan rate of 5�mV�s?1, good capacitance retention at high current densities of up to 10 A�g?1 and the lowest electrochemical series resistance (ESR) of 57 ?. Graphical abstract: [Figure not available: see fulltext.]. � 2023, The Author(s), under exclusive licence to Springer Nature B.V.
BiOBr/ZnWO4 heterostructures: An important key player for enhanced photocatalytic degradation of rhodamine B dye and antibiotic ciprofloxacin
(Elsevier Ltd, 2022-11-07T00:00:00) Santana, Rafael W.R.; Lima, A.E.B.; Souza, Luiz K.C. de; Santos, Evelyn C.S.; Santos, C.C.; Menezes, A.S. de; Sharma, Surender K.; Cavalcante, L.S.; Maia da Costa, Marcelo E.H.; Sales, T.O.; Jacinto, Carlos; Luz, G.E.; Almeida, M.A.P.
We report a facile synthesis of p-BiOBr/n-ZnWO4 heterostructures by hydrothermal/precipitation method as an important key player to enhance the photocatalytic degradation of Rhodamine B (RhB) dye and ciprofloxacin antibiotic. The structural and microstructural features confirm that p-BiOBr/n-ZnWO4 heterostructures display a mixed tetragonal/monoclinic phase with the presence of several n-ZnWO4 nanocrystals on the surface of petals of flower-like p-BiOBr microcrystals. X-ray photoluminescence (XPS) analysis of BiOBr exhibits the existence of Bi, O, and Br, whereas BiOBr/ZnWO4-5%, in addition to Bi, O, and Br, consist of signature of Zn and W. UV�Visible spectra of p-BiOBr/n-ZnWO4-5% showed better absorption than p-BiOBr and n-ZnWO4, which displayed an enhanced collection of photons in the heterojunction. An intense photoluminescence emission at room temperature was observed for p-BiOBr microcrystals as compared to p-BiOBr/n-ZnWO4. We observed the best photocatalytic activity for p-BiOBr/n-ZnWO4-2.5% in the degradation of RhB dye at 99.4% in 25 min and CIP antibiotic at 58.2% in 170 min, which is assigned due to high surface area SBET (13 m2/g), pore size, providing active catalytic sites for bonding chemical and surface interaction and bonding chemical between the bromide/oxides. Finally, we have investigated the use of scavengers for isopropanol, benzoquinone, and sodium azide, which proves that the hydroxyl (�OH) and superoxide (O2?) radicals as the foremost reactive oxygen spicies (ROS) in photocatalytic degradation of RhB dye and antibiotic CIP. � 2022 Elsevier Ltd
A brief overview of potential treatments for viral diseases using natural plant compounds: The case of sars-cov
(MDPI AG, 2021-06-24T00:00:00) Abiri, Rambod; Abdul-Hamid, Hazandy; Sytar, Oksana; Abiri, Ramin; de Almeida, Eduardo Bezerra; Sharma, Surender K.; Bulgakov, Victor P.; Arroo, Randolph R. J.; Malik, Sonia
The COVID-19 pandemic, as well as the more general global increase in viral diseases, has led researchers to look to the plant kingdom as a potential source for antiviral compounds. Since ancient times, herbal medicines have been extensively applied in the treatment and prevention of various infectious diseases in different traditional systems. The purpose of this review is to highlight the potential antiviral activity of plant compounds as effective and reliable agents against viral infections, especially by viruses from the coronavirus group. Various antiviral mechanisms shown by crude plant extracts and plant-derived bioactive compounds are discussed. The understanding of the action mechanisms of complex plant extract and isolated plant-derived compounds will help pave the way towards the combat of this life-threatening disease. Further, molecular docking studies, in silico analyses of extracted compounds, and future prospects are included. The in vitro production of antiviral chemical compounds from plants using molecular pharming is also considered. Notably, hairy root cultures represent a promising and sustainable way to obtain a range of biologically active compounds that may be applied in the development of novel antiviral agents. � 2021 by the authors. Licensee MDPI, Basel, Switzerland.
Energy Evolution, Stabilization, and Mechanotransducer Properties of Fe3 O4 Vortex Nanorings and Nanodisks
(American Physical Society, 2021-08-02T00:00:00) Niraula, Gopal; Toneto, Denilson; Joshy, Elma; Coaquira, Jose A. H.; Ayesh, Ahmad I.; Garcia, Flavio; Muraca, Diego; Denardin, Juliano C.; Goya, Gerardo F.; Sharma, Surender K.
Recent reports on spin structures produced in nanomaterials due to confinement of spins imposed by geometrical restrictions are at the center of rising scientific interest. Topological curling magnetic structures (vortices) exhibit unique properties, regarding the energy profile, good colloidal stability in suspensions, manipulation under a low-frequency magnetic field, and torque exertion. The last property provides the potential to mechanically eradicate cancer cells via magnetomechanical actuation using remote ac magnetic fields. Here, we study, theoretically and by micromagnetic simulations, the magnetic energy evolutions for vortex nanosystems, i.e., Fe3O4 nanodisks (NDs) and nanorings (NRs). The obtained results for magnetic energy, magnetic susceptibility, and magnetization reversal confirm that the vortex-domain structure in NRs exhibits better stability and avoids agglomeration in solution, owing to the presence of a central hole, whereas the presence of a vortex core in NDs induces magnetic remanence. Although NDs are found to exert slightly higher torques than NRs, this weakness can be compensated for by a small increase (i.e., approximately equals 20%) in the amplitude of the applied field. Our results provide evidence of the magnetic stability of the curling ground states in NRs and open the possibility of applying these systems to magnetomechanical actuation on single cells for therapeutics in biomedicine, such as cancer-cell destruction by low-frequency torque transduction. � 2021 American Physical Society.
Engineering Shape Anisotropy of Fe3O4-?-Fe2O3Hollow Nanoparticles for Magnetic Hyperthermia
(American Chemical Society, 2021-02-24T00:00:00) Niraula, Gopal; Coaquira, Jose A. H.; Zoppellaro, Giorgio; Villar, Bianca M. G.; Garcia, Flavio; Bakuzis, Andris F.; Longo, Jo�o P. F.; Rodrigues, Mosar C.; Muraca, Diego; Ayesh, Ahmad I.; Sinfr�nio, Francisco S�vio M.; De Menezes, Alan S.; Goya, Gerardo F.; Sharma, Surender K.
The use of microwave-assisted synthesis (in water) of ?-Fe2O3 nanomaterials followed by their transformation onto iron oxide Fe3O4-?-Fe2O3 hollow nanoparticles encoding well-defined sizes and shapes [nanorings (NRs) and nanotubes (NTs)] is henceforth described. The impact of experimental variables such as concentration of reactants, volume of solvent employed, and reaction times/temperatures during the shape-controlled synthesis revealed that the key factor that gated generation of morphologically diverse nanoparticles was associated to the initial concentration of phosphate anions employed in the reactant mixture. All the nanomaterials presented were fully characterized by powder X-ray diffraction, field emission scanning electron microscopy, Fourier transform infrared, M�ssbauer spectroscopy, and superconducting quantum interference device (SQUID). The hollow nanoparticles that expressed the most promising magnetic responses, NTs and NRs, were further tested in terms of efficiencies in controlling the magnetic hyperthermia, in view of their possible use for biomedical applications, supported by their excellent viability as screened by in vitro cytotoxicity tests. These systems NTs and NRs expressed very good magneto-hyperthermia properties, results that were further validated by micromagnetic simulations. The observed specific absorption rate (SAR) and intrinsic loss power of the NRs and NTs peaked the values of 340 W/g and 2.45 nH m2 kg-1 (NRs) and 465 W/g and 3.3 nH m2 kg-1 (NTs), respectively, at the maximum clinical field 450 Oe and under a frequency of 107 kHz and are the highest values among those reported so far in the hollow iron-oxide family. The higher SAR in NTs accounts the importance of magnetic shape anisotropy, which is well-predicted by the modified dynamic hysteresis (?-MDH) theoretical model. �
Enhanced Electrochemical Performance of Hydrothermally Synthesized NiS/ZnS Composites as an Electrode for Super-Capacitors
(Springer, 2021-08-22T00:00:00) Asghar, Ali; Yousaf, Muhammad Imran; Shad, Naveed Akhtar; Munir Sajid, M.; Afzal, Amir Muhammad; Javed, Yasir; Razzaq, Aamir; Shariq, Mohammad; Gulfam, Qurrat-ul-ain; Sarwar, Muhammad; Sharma, Surender K.
In this study, nickel sulfide (NiS), zinc sulfide (ZnS), and their composites have been synthesized by using surfactant driven hydrothermal method. Synthesized materials are investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy, UV�Vis and Photoluminescence spectroscopy. XRD results have shown the presence of corresponding structural planes. Crystallite size was much smaller (15�nm) in the case of ZnS nanomaterials, whereas, composite materials have shown size comparable to NiS nanomaterials. SEM images presented morphology of star-like, spherical, and mixture of two for NiS, ZnS, and NiS/ZnS nanocomposites respectively. EDX spectrum of composite materials showed Nickel, Zinc, and Sulfur, indicating the purity of the synthesized composite. Electrochemical measurements i.e. cyclic voltammetry and galvanostatic charge�discharge were determined for all three materials. Maximum specific capacitance is obtained as 1594.68 F�g?1 at a scan rate of 5�mV�S?1 for NiS/ZnS composite materials whereas a charging/discharging time of 461.97�s is observed. The composite materials have shown 95.4% retention for applied for 3000 charging�discharging cycles. The favorable behavior of NiS/ZnS composites indicated their potential as an electrode material for pseudo-capacitors. � 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Enhanced photocatalytic activity of BiOBr/ZnWO4 heterojunction: A combined experimental and DFT-based theoretical approach
(Elsevier B.V., 2023-03-28T00:00:00) Andrade, Alana O.C.; Lacerda, Lu�s Henrique da Silveira; Lage J�nior, M.M.; Sharma, Surender K.; Maia da Costa, M.E.H.; Alves, Odivaldo C.; Santos, Evelyn C.S.; dos Santos, C.C.; de Menezes, A.S.; San-Miguel, Miguel Angel; Filho, Francisco Moura; Longo, Elson; Almeida, Marcio A.P.
We report a successful fabrication of BiOBr/ZnWO4 heterojunction with enhanced photocatalytic performance for degrading Rhodamine B dye validated by joint experimental and theoretical approaches. The structural and microstructural analysis indicate that the heterostructures consist of a mixed tetragonal/monoclinic phase with enhanced surface area, which is crucial for photocatalysis. The results indicate increased photocatalytic activity for heterojunctions since BiOBr/ZnWO4 heterostructure showed a better degradation rate for Rhodamine B dye as compared to BiOBr due to higher surface area, pore size, and better photogenerated electron-hole pair separation efficiency. Additional analyses using isopropanol, benzoquinone, and sodium azide scavengers analysis were performed, showing that superoxide radicals (O2?) as the main responsible for the photocatalytic degradation of investigated materials. The theoretical analysis offers a complete overview of the composition and electronic structure of the interface. � 2023 Elsevier B.V.
Ferrites as an Alternative Source of Renewable Energy for Hydroelectric Cell
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Mathpal, Mohan Chandra; Niraula, Gopal; Kumar, Promod; Chand, Mahesh; Singh, Manish Kumar; Sharma, Surender K.; Soler, Maria A. G.; Swart, H.C.
There are many conventional ways of producing energy at large scales such as fossil fuels, hydroelectric power station, wind energy, solar cell plants, marine energy, etc., but most of these require bulky plantation, huge manpower, wide land occupation and are non-portable and expensive to handle too. In the twenty-first century, there is still a huge gap between worldwide energy supply and its demand. The advances in the technology sector have also increased the consumption of energy, but the sources of generating the renewable energy remain limited. In order to account for these problems in recent years, several methods have been adopted and a significant research in this direction has been made by the invention of the hydroelectric cell by Dr. R. K. Kotnala�s group in 2016. Instead of using the magnetic character in the ferrite nanostructures, these nanomaterials were first time effectively exploited for direct energy harvesting application by using their capability to dissociate the absorbed water molecules on its porous surface. This allows the production of ions, which is then followed by the charge transfer of hydronium, hydroxyl and hydrogen ions between the electrodes of the ferrite nanostructures and results in the generation of an electric current across the circuit. The concept of the hydroelectric cell is new, and these cells are easily portable, inexpensive, biodegradable and eco-friendly in nature. This chapter provides an insight on the concept of spinel ferrite nanostructures for the application in the hydroelectric cell. � 2021, Springer Nature Switzerland AG.
Low Loss Soft Ferrites Nanoparticles for Applications Up to S-band
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Sharma, Sucheta; Verma, Ramesh; Singh, Mahavir; Sharma, Surender K.
This chapter aims at providing a better understanding of soft ferrites and their role in ultra-high-frequency applications. In wireless communication industry trends of miniaturized, highly efficient and wide-band antenna become the new research areas of the antenna technology. Antenna miniaturization cannot be achieved by simply changing the structural design, and it is important to improve the material characteristics of antenna substrates. Furthermore, to improve the antenna efficiency, almost matched permittivity and permeability values and low magnetic as well as dielectric loss tangents are required especially at ultra-high frequency (UHF), L-band, and S-band frequency range. For efficiency improvement and miniaturization of antennas, magneto-dielectric materials have significant advantages with matching permittivity and permeability values along with sufficiently low magnetic and dielectric loss tangents. Ferrites with very high resistance have been reported as the best host materials to produce low loss magneto-dielectric materials for high-frequency antenna applications as they present moderate permeability and permittivity values. In this chapter, the emphasis is given on the soft ferrites Mn�Zn, Ni�Zn spinel ferrite, and Co2Z type barium hexaferrite. The chapter also explains the effect of substitution of different dopant ions on the properties of soft ferrites. � 2021, Springer Nature Switzerland AG.
Magnetic Ferrites-Based Hybrids Structures for the Heavy Metal Removal
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Abbas, Muhammad Khawar; Yasin, Effat; Sajid, Muhammad Munir; Shad, Naveed Akhtar; Akhtar, Kanwal; Manhas, Anita; Sharma, Surender K.; Javed, Yasir
Adsorption is a major process for heavy metal removal and the research trend is focused toward the applications of new technologies in order to intensify the already existing processes. Intrinsic properties of magnetic materials (arrangement and surface-to-volume ratio) of adsorbate and adsorbent are critical for satisfactory results. Magnetic field strength plays an important role as it indicates the alignment of spins with the magnetic field to provide adsorbate mobility and generate heterogeneity at adsorbent surface. Applications of magnetic field for intensification of adsorption process provide environment friendly, safe and economic alternative. This chapter describes different types of magnetic ferrites-based hybrids for heavy metal removal. Surface modification of magnetic nanohybrids through different surface modification strategies and general adsorption mechanisms for different types of pollutants are discussed comprehensively. Major thrust of this chapter is to provide information about different features of magnetic ferrites for their potential application as adsorbent for heavy metal removal. � 2021, Springer Nature Switzerland AG.
Magnetic Nanoflowers: Synthesis, Formation Mechanism and Hyperthermia Application
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Niraula, Gopal; Mathpal, Mohan Chandra; Herrera, Edher Z.; Soler, Maria A. G.; Coaquira, Jose A. H.; Sharma, Surender K.
Magnetic hyperthermia is becoming a very propitious supplementary technique for cancer treatments such as chemotherapy radiotherapy and radiotherapy. In this regard, magnetic nanoflowers (MNFs) are novel system in terms of morphology showing a structure similar to flower and exhibiting higher stability and enhanced heating efficiency when compared with similar nanoparticles displaying standard formats; enabling them for magneto-hyperthermia applications. In this chapter, different types of nanoflowers such as magnetic-oxide, magneto-plasmonic, and magnetic-organic/inorganic and their applicability are discussed. Moreover, a discussion on the most common chemical routes to design nanoflowers emphasizing hydro/solvothermal techniques, microwave-assisted hydrothermal, co-precipitations, and polyol are highlighted. Furthermore, the nucleation of MNFs and their growing process with a physical parameter are presented. At last, the magnetic hyperthermia properties of MNFs and their recent findings are critically scrutinized along with their future perspectives in biomedicine. � 2021, Springer Nature Switzerland AG.
Modern Applications of Ferrites: An Important Class of Ferrimagnetic System
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Gomes, Gabriel Alves; Akhtar, Kanwal; da Costa, Gisela Lara; Javed, Yasir; Sharma, Surender K.
Magnetic nanoparticles (MNPs) have been used in engineering applications for different purposes in the last few decades, increasing their relevance recently on biomedical studies, with alternative treatments to most complex diseases, and microelectronic fields, as an excellent way to improve aspects such as thermal and electric conductivity. The use of nanomagnetic ferrite particles in cancer therapy and to control antibacterial agents is also noteworthy, because of their advantages in terms of resistance to temperature variations, chemical stability, and long-term durability. One of the promising applications of these nanoparticles includes water-purifying systems. In this chapter, those outstanding aspects of nanoparticle ferrites were treated since their very applicable point-of-view. In this sense, the structure properties of this class of materials are a very important matter to discuss, investigating how their unique ferrimagnetic face centered behavior could directly influence their potential in technological fields and innovative medical treatments. � 2021, Springer Nature Switzerland AG.
Observation of magnetic vortex configuration in non-stoichiometric Fe3O4 nanospheres
(Royal Society of Chemistry, 2023-08-31T00:00:00) Niraula, Gopal; Toneto, Denilson; Goya, Gerardo F.; Zoppellaro, Giorgio; Coaquira, Jose A. H.; Muraca, Diego; Denardin, Juliano C.; Almeida, Trevor P.; Knobel, Marcelo; Ayesh, Ahmad I.; Sharma, Surender K.
Theoretical and micromagnetic simulation studies of magnetic nanospheres with vortex configurations suggest that such nanostructured materials have technological advantages over conventional nanosystems for applications based on high-power-rate absorption and subsequent emission. However, full experimental evidence of magnetic vortex configurations in spheres of submicrometer size is still lacking. Here, we report the microwave irradiation fabrication of Fe3O4 nanospheres and establish their magnetic vortex configuration based on experimental results, theoretical analysis, and micromagnetic simulations. Detailed magnetic and electrical measurements, together with M�ssbauer spectroscopy data, provide evidence of a loss of stoichiometry in vortex nanospheres owing to the presence of a surface oxide layer, defects, and a higher concentration of cation vacancies. The results indicate that the magnetic vortex spin configuration can be established in bulk spherical magnetite materials. This study provides crucial information that can aid the synthesis of magnetic nanospheres with magnetically tailored properties; consequently, they may be promising candidates for future technological applications based on three-dimensional magnetic vortex structures. � 2023 RSC.
Potential of Iron Oxide Nanoparticles as Drug Delivery Vehicle
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Hassan, Muhammad Aamir; Khan, Aqib Zafar; Sajid, Muhammad Munir; Javed, Yasir; Ullah, Asmat; Shad, Naveed Akhtar; Sharma, Surender K.; Shafique, Muhammad; Sarwar, Muhammad
Nanotechnology has introduced new techniques and therapeutic approaches for the treatment of different cancer types. Current cancer-curing drugs have many limitations such as use of high concentrations, effects on other cells, and non-confinement at cancer sites, which reduce the efficacy of drugs and also induce toxic effects in other normal cells. Nanomaterials have provided new ways to increase the efficacy of already used cancer drugs by providing drug delivery systems. Anticancer drugs can be encapsulated/attached with the nanomaterials and delivered at specific sites and cells under certain microenvironment conditions. Among metallic oxide nanoparticles, iron-based particles have shown great potential in drug delivery and at the same time for cancer treatment by producing localized heat. Therefore, researchers have focused on iron oxide nanoparticles as drug delivery vehicles. This chapter highlights the synthesizing methods of iron oxide nanoparticles such as co-precipitation, thermal decomposition, microemulsion, sol�gel, and additional chemical methods including hydrothermal, sonochemical decomposition, and electrochemical for their wide range of biomedical applications. It also provides a brief overview of recent developments in iron oxide nanoparticles, some limitations in the explored research areas. and suggests future directions to overcome these limitations. � 2021, Springer Nature Switzerland AG.
Progress in Ferrites Materials: The Past, Present, Future and Their Applications
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Manhas, Anita; Singh, Mahavir; Hussain, Muhammad Irfan; Javed, Yasir; Sharma, Surender K.
Ferrite is a magnetic substance consist essentially of an oxide of iron combined with one or more other metals such as manganese, copper, nickel, or zinc. They are being routinely utilized especially in electronic devices owing to its good magnetic properties along with high resistivity. � 2021, Springer Nature Switzerland AG.
State of Art of Spinel Ferrites Enabled Humidity Sensors
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Mathpal, Mohan Chandra; Niraula, Gopal; Chand, Mahesh; Kumar, Promod; Singh, Manish Kumar; Sharma, Surender K.; Soler, Maria A. G.; Swart, H.C.
Controlling the moisture level in air and gases is an important aspect in defense, weather station, industry, laboratory and healthcare systems. The accurate measurement and sensing of the humidity/moisture level in the surrounding environment can help to maintain the temperature level for ideal living conditions; from a safety point of view, it can help to prevent the virus/disease transmission; importantly, it can protect expensive equipment, electronic devices and optical devices against damage which are sensitive to high humidity in the atmosphere. The controlled monitoring, regulation and management of humidity necessarily require humidity sensors with high sensitivity, high stability and low response time. Currently, there are various types of humidity sensors available in the market, but there are always limitations on the practical applications as the main problems are associated with their eco-friendly nature, cost, sensitivity, response time (rapid action) and lifetime. Aiming to address these issues, the spinel ferrite nanostructures arise as promising nanomaterials due to their moderate semiconducting features with high resistance, porous nature and high surface activities enabling easy fabrication of the humidity sensors. This chapter provides an overview of the role of spinel ferrite nanostructures for their applications in humidity sensors. � 2021, Springer Nature Switzerland AG.
Stoichiometry and Orientation- And Shape-Mediated Switching Field Enhancement of the Heating Properties of Fe3 O4 Circular Nanodiscs
(American Physical Society, 2021-01-28T00:00:00) Niraula, Gopal; Coaquira, Jose A. H.; Aragon, Fermin H.; Bakuzis, Andris F.; Villar, Bianca M. G.; Garcia, Flavio; Muraca, Diego; Zoppellaro, Giorgio; Ayesh, Ahmad I.; Sharma, Surender K.
The generation of topological magnetic vortex-domain structures in iron-oxide nanomaterials has promising applications in biomedical scenarios, such as heat generators for hyperthermia treatments. In this report we describe alternative kinds of magnetic-vortex nanoparticles, circular Fe3O4 nanodiscs (NDs), and dissect their heating properties by in-depth investigation of their shape and size, stoichiometry, orientations, and switching field "HS"behaviors, through experiments and theoretical simulation. We find that the stoichiometric NDs show better heating performance than nonstoichiometric materials because of the significant electron hopping between Fe3+ and Fe2+ ion. The higher heating efficiency (in terms of specific absorption rate, SAR) is observed only for the higher switching field regime, an effect that is associated with the parallel and perpendicular alignment of nanodiscs with respect to low and high ac magnetic field, respectively. A higher SAR of approximately 270 W/g is observed at a higher switching field (approximately 700 Oe) for NDs of diameter 770 nm, which increases by a factor of 4 at a switching field of approximately 360 Oe for NDs of diameter 200 nm. The reported results suggest that the heating efficiency in these systems can be enhanced by controlling the switching field, which is, in turn, tuned by size, shape, and orientation of circular magnetic vortex nanodiscs. � 2021 American Physical Society.
Superparamagnetic Iron Oxide-Based Nanomaterials for Magnetic Resonance Imaging
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Niraula, Gopal; Mathpal, Mohan Chandra; Medrano, Jason J. A.; Singh, Manish Kumar; Coaquira, Jose A. H.; Verma, Ramesh; Sharma, Surender K.
Magnetic resonance imaging (MRI) is the technique for the visualization of targeted macromolecules or cells in biological system. Nowadays, superparamagnetic iron oxide nanoparticles (SPIONs) have been attracted and remarkably emerging as a negative contrast agent (T2-weighted) offering sufficient detection sensitivity as compared to positive contrast agent (T1-weighted). In the present chapter, we first introduce the necessary background of superparamagnetic iron oxide-based nanoparticles and MRI taking into an account to discuss both T1�T2-weighted imaging. The liquid-based synthesis methods of SPIONs and their applicability in MRI have been thoroughly revised. Finally, several nanohybrids such as magnetic-silica, magneto-luminescent, magneto-plasmonic along with ferrite-based SPIONs are thoroughly presented in light of MRI application. � 2021, Springer Nature Switzerland AG.
Tuning the shape, size, phase composition and stoichiometry of iron oxide nanoparticles: The role of phosphate anions
(Elsevier Ltd, 2020-09-17T00:00:00) Niraula, Gopal; Coaquira, Jose A.H.; Aragon, Fermin H.; Galeano Villar, Bianca M.; Mello, Alexandre; Garcia, Flavio; Muraca, Diego; Zoppellaro, Giorgio; Vargas, Jose M.; Sharma, Surender K.
This work describes a microwave synthetic approach for the controlled assembly of ?-Fe2O3 nanosystems with defined morphologies, such as hollow nanotubes (NTs), solid nanorods (NRs) and nanodisks (NDs). The morphological control is aided during the crystallization processes by using phosphate anions as key surfactants in solution. Furthermore, the thermal reduction under H2 atmosphere of these NTs, NRs and NDs ?-Fe2O3 systems to the correspondent Fe3O4 nanomaterials preserved their initial morphologies. It was observed that the concentration of phosphate anions and volume of solvent had significant impact not only on controlling the shapes and sizes, but also phase composition and stoichiometry of the NTs, NRs and NDs nanoparticles. X-ray Rietveld refinement analysis of the NTs, NRs and NDs systems, after reduction in H2, revealed the presence of zero-valent iron (Fe0) in the final materials, with Fe0 fractions that decreased gradually in % from NTs (?16%), NRs (?11%) to NDs (?0%) upon increasing amount of phosphate anions. Bulk magnetic susceptibility measurements showed clear alterations of the Verwey transition temperatures (TV) and the development of unusual magnetic phenomena, such as magnetic vortex states in NDs, which was subsequently verified by micro-magnetic simulations. From the combination of XRD analysis, bulk magnetic susceptibility and M�ssbauer results, we provide herein a detailed mechanistic description of the chemical processes that gated the development of shape-controlled synthesis of NTs, NRs and NDs and give a detailed correlation between specific morphology and magneto-electronic behaviors. � 2020 Elsevier B.V.
Wet Chemical Synthesis and Processing of Nanoferrites in Terms of Their Shape, Size and Physiochemical Properties
(Springer Science and Business Media Deutschland GmbH, 2021-10-29T00:00:00) Sarveena; Kumar, Gagan; Kondal, Neha; Singh, Mahavir; Sharma, Surender K.
Nanoferrites are found to showcase superior and substantially distinct�properties due to the ease with which they can be synthesized and modified chemically. The nanoparticles are synthesized by various methods classified primarily into two categories: top-down and bottom-up methods. Wet chemical synthesis methods offer unlimited control over size distribution and shape of nanoparticles and provide the opportunity of scale-up for production of nanomaterials in bulks for practical application. This chapter covers sol-gel, solvothermal, co-precipitation, thermal decomposition and microwave-assisted methods for the production of nanoferrites. A variety of nanoferrites and its composites with remarkable properties can be synthesized by these methods mentioned in this chapter. � 2021, Springer Nature Switzerland AG.