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Influence of the pH Synthesis of Fe3O4 Magnetic Nanoparticles on Their Applicability for Magnetic Hyperthermia
Publication . Costa, Bárbara; Pereira, Eurico; Ferreira-Filho, Vital C.; Pires, Ana Salomé; Pereira, Laura C.J.; Soares, Paula I.P.; Botelho, Maria Filomena; Mendes, Fernando; Graça, Manuel P.F.; Teixeira, Sílvia Soreto; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Faculdade de Ciências e Tecnologia (FCT); MDPI - Multidisciplinary Digital Publishing Institute
Nanotechnology, specifically magnetic nanoparticles (MNPs), is revolutionizing cancer treatment. Magnetic hyperthermia is a treatment that, using MNPs, can selectively kill cancer cells without causing damage to the surrounding tissues. Background/Objectives: This work aimed to analyze how the synthesis conditions, namely, how the pH of the reaction can influence the magnetic properties of Fe3O4 nanoparticles for magnetic hyperthermia, using the hydrothermal synthesis. Methods: For the hydrothermal synthesis, FeCl3·6H2O and FeCl2·4H2O were mixed with different quantities of NaOH to adjust the pH. After obtaining a black precipitate, the samples were placed in an autoclave at 200 °C for 60 h, followed by a washing and drying phase. The obtained MNPs were analyzed using X-Ray Diffraction (XRD), Transmission Electron Microscopy, a Superconducting Quantum Interference Device, Specific Absorption Rate analysis, and cytotoxicity assays. Results: Different MNPs were analyzed (9.06 < pH < 12.75). The XRD results showed the presence of various iron oxide phases (magnetite, maghemite, and hematite), resulting from the oxidization of the iron phases present in the autoclave. In terms of the average particle size, it was verified that, by increasing the pH value, the size decreases (from 53.53 nm to 9.49 nm). Additionally, MNPs possess a superparamagnetic behaviour with high SAR values (above 69.3 W/g). Conclusions: It was found that the pH of the reaction can influence the size, morphology, magnetization, and thermal efficiency of the MNP. The MNP with the highest composition of Fe3O4 was synthesized with a pH of 12.75, with a cubic morphology and a SAR value of 92.7 ± 3.2 W/g.
Energy harvesting and movement tracking by polypyrrole functionalized textile for wearable IoT applications
Publication . Ferreira, Guilherme; Das, Shubham; Coelho, Guilherme; Silva, Rafael R. A.; Goswami, Sumita; Pereira, Rui N.; Pereira, Luís; Fortunato, Elvira; Martins, Rodrigo; Nandy, Suman; DCM - Departamento de Ciência dos Materiais; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); UNINOVA-Instituto de Desenvolvimento de Novas Tecnologias; Elsevier BV
Textiles for health and sporting activity monitoring are on the rise with the advent of smart portable wearables. The intention of this work is to design wireless monitoring wearables, based on widely available textiles and low environmental impact production technologies. Herein we have developed a polymeric ink which is able to functionalize different types of textile fibers (including silver conducting fibers, cotton, and commercial textile) with polypyrrole. These fibers were weaved together with a thinner silver conducting fiber and carbon fiber to form a touch-sensitive energy harvesting system that would generate an electric output when mechanical pressure is applied to it. Different prototypes were manufactured with loom weaving accessories to simulate real textile cloths. By simple touch, the prototypes produced a maximum voltage of 244 V and a maximum power density of 2.29 W m−2. The current generated is then transformed into a digital signal, which is further utilized for human motion or gesture monitorization. The system comprises a wireless block for the Internet of Things (IoT) applicability that will be eventually extended to future remote health and sports monitoring systems.
Ecofriendly Printed Wood-Based Honey-Gated Transistors for Artificial Synapse Emulation
Publication . Vieira, Douglas Henrique; Carlos, Emanuel; Ozório, Maíza Silva; Morais, Maria; Fortunato, Elvira; Alves, Neri; Martins, Rodrigo; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; John Wiley and Sons Inc.
Printed electronics have traditionally used substrates and materials derived from fuel-based or less abundant and toxic resources, raising environmental concerns. Wood as a substrate reduces processing steps and enables the integration of intelligent functionalities in wooden furniture, offering biodegradability, nontoxicity, and derivation from renewable sources. In this work, sustainably printed transistors using zinc oxide nanoparticles as the active layer and honey electrolyte on wood substrates are demonstrated as a promising approach to reduce the environmental footprint of electronics. Despite the substrate's high roughness, the transistor exhibits excellent performance for screen-printed devices, with low on-voltage of 0.32 ± 0.12 V and high Ion/Ioff of (2.4 ± 0.9) × 104. Further analysis of hysteresis in transfer curves under varying scan rates and sweep ranges reveals the device's ability to adjust memory windows and on-current. Notably, these devices successfully emulate synapses, exhibiting neural facilitation and plasticity, indicating a shift toward sustainable computing. The device's dynamic response to single and successive presynaptic pulses demonstrates its ability to adjust synaptic weight, transition from transient to persistent memory, and pulse width-, frequency-, voltage-, and number-dependent excitatory postsynaptic currents. The successful emulation of the learning–forgetting–relearning–forgetting process underscores the device's potential for use in sustainable high-performance neuromorphic systems.
New Insights into Polymeric Liquid Crystals and Their Applications
Publication . Trindade, A. C.; Canejo, J. P.; Almeida, P. L.; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); DCM - Departamento de Ciência dos Materiais; Faculdade de Ciências e Tecnologia (FCT); MDPI - Multidisciplinary Digital Publishing Institute
Green Sol–Gel Synthesis of Iron Oxide Nanoparticles for Magnetic Hyperthermia Applications
Publication . Jesus, Juliana; Regadas, Joana; Costa, Bárbara; Carvalho, João; Pádua, Ana; Henriques, Célia; Soares, Paula I.P.; Gavinho, Sílvia; Valente, Manuel A.; Graça, Manuel P.F.; Soreto, Sílvia; CENIMAT-i3N - Centro de Investigação de Materiais (Lab. Associado I3N); Faculdade de Ciências e Tecnologia (FCT); DF – Departamento de Física; DCM - Departamento de Ciência dos Materiais; MDPI - Multidisciplinary Digital Publishing Institute
Background/Objectives: The unique properties of iron oxide nanoparticles have attracted significant interest within the biomedical community, particularly for magnetic hyperthermia applications. Various synthesis methods have been developed to optimize these nanoparticles. Methods: In this study, we employed a powdered coconut water (PCW)-assisted sol–gel method to produce magnetite nanoparticles for the first time. A comprehensive analysis of the thermal (differential thermal analysis and thermogravimetry), structural (X-ray diffraction), morphological (scanning electron microscopy with energy dispersive spectroscopy), magnetic (vibrating sample magnetometer and hyperthermia), and biological (cytotoxicity essays) properties was conducted to assess their potential for magnetic hyperthermia. Results: Samples heat-treated at 700 °C and 400 °C (washed powder) for 4 h under argon presented only magnetite in their composition. The micrometer-sized particles exhibited ferrimagnetic behavior, with saturation magnetization values of 37, 76, and 10 emu/g and specific absorption rates (SAR) of 27.1, 19.9, and 14.1 W/g, respectively, for treatments at 350 °C (48 h), 700 °C (4 h), and 400 °C (washed powder, 4 h) under an argon atmosphere. Biological tests showed no cytotoxicity below 10 mg/mL. Conclusions: The findings highlight the potential of PCW-assisted synthesis as a sustainable and efficient strategy for producing pure magnetite, with powder washing preceding the heat treatment enabling the attainment of this phase at lower temperatures. Nevertheless, the micrometer-scale dimensions is observed in the morphological analysis limit their suitability for biomedical applications.
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Fundação para a Ciência e a Tecnologia
Programa de financiamento
Concurso de avaliação no âmbito do Programa Plurianual de Financiamento de Unidades de I&D (2017/2018) - Financiamento Base
Número da atribuição
UIDB/50025/2020