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Stancu V, Galatanu A, Enculescu M, Onea M, Popescu B, Palade P, Aradoaie M, Ciobanu R, Pintilie L. Influences of Dispersions' Shapes and Processing in Magnetic Field on Thermal Conductibility of PDMS-Fe 3O 4 Composites. Materials (Basel) 2021; 14:3696. [PMID: 34279266 PMCID: PMC8269840 DOI: 10.3390/ma14133696] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/22/2021] [Accepted: 06/28/2021] [Indexed: 12/19/2022]
Abstract
Composites of magnetite (Fe3O4) nanoparticles dispersed in a polydimethylsiloxane (PDMS) matrix were prepared by a molding process. Two types of samples were obtained by free polymerization with randomly dispersed particles and by polymerization in an applied magnetic field. The magnetite nanoparticles were obtained from magnetic micrograins of acicular goethite (α-FeOOH) and spherical hematite (α-Fe2O3), as demonstrated by XRD measurements. The evaluation of morphological and compositional properties of the PDMS:Fe3O4 composites, performed by SEM and EDX, showed that the magnetic particles were uniformly distributed in the polymer matrix. Addition of magnetic dispersions promotes an increase of thermal conductivity compared with pristine PDMS, while further orienting the powders in a magnetic field during the polymerization process induces a decrease of the thermal conductivity compared with the un-oriented samples. The shape of the magnetic dispersions is an important factor, acicular dispersions providing a higher value for thermal conductivity compared with classic commercial powders with almost spherical shapes.
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Affiliation(s)
- V Stancu
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - A Galatanu
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - M Enculescu
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - M Onea
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
- Faculty of Physics, University of Bucharest, Atomistilor 405, 077125 Magurele, Romania
| | - B Popescu
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - P Palade
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
| | - M Aradoaie
- Department of Electrical Measurements and Materials, Faculty of Electrical Engineering, Technical University Gh. Asachi Iasi, Boulevard Profesor Dimitrie Mangeron 67, 70050 Iasi, Romania
| | - R Ciobanu
- Department of Electrical Measurements and Materials, Faculty of Electrical Engineering, Technical University Gh. Asachi Iasi, Boulevard Profesor Dimitrie Mangeron 67, 70050 Iasi, Romania
- All Green SRL, 8 G. Cosbuc Street, 700470 Iasi, Romania
| | - L Pintilie
- National Institute of Materials Physics, Atomistilor 405A, 077125 Magurele, Romania
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Daescu M, Baibarac M, Enculescu M, Serbschi C. Screen-Printed Carbon Electrodes Modified with Double-Walled Carbon Nanotubes Functionalized with Polypyrrole and Their Electrochemical Processes in the Presence of Folic Acid. J Nanosci Nanotechnol 2021; 21:2376-2387. [PMID: 33500054 DOI: 10.1166/jnn.2021.18973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In this work, the electrochemical polymerization of pyrrole in the presence of H₃PMo12O40 onto the screen-printed carbon electrodes (SPCE) modified with double-walled carbon nanotubes (DWNTs) is reported. The influence of the pyrrole and H₃PMo12O40 concentration as well as a scan rate used to recording of cyclic voltammograms that describe the electrochemical synthesis of polypyrrole (PPY) onto the DWNTs surface is assessed. Using scanning electron microscopy (SEM) we demonstrate that the electrosynthesis of PPY doped with H₃PMo12O40 heteropolyanions (PPY-PMo12) results in the generation of a globular morphology. Considering the variations induced of DWNTs in the IR and Raman spectra of PPY doped with H₃PMo12O40 heteropolyanions, a functionalization process of carbon nanotubes with macromolecular compound is invoked. According to SEM investigations, DWNTs allow the realization of connections between the globular structures of the macromolecular compound. The changes induced of folic acid (FA) during the oxidation-reduction processes at the interface of the DWNTs functionalized with PPY doped with H₃PMo12O40 heteropolyanions (SPCE-DWNT/PPY-PMo12) with electrolyte solution are reported.
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Affiliation(s)
- M Daescu
- National Institute of Materials Physics, Laboratory of Optical Processes in Nanostructured Materials Physics, Atomistilor Street 405A, Magurele, 077125, Romania
| | - M Baibarac
- National Institute of Materials Physics, Laboratory of Optical Processes in Nanostructured Materials Physics, Atomistilor Street 405A, Magurele, 077125, Romania
| | - M Enculescu
- National Institute of Materials Physics, Laboratory of Optical Processes in Nanostructured Materials Physics, Atomistilor Street 405A, Magurele, 077125, Romania
| | - C Serbschi
- Bioelectronic SRL, Cercelus Street, No. 54, Ploiesti, 100028, Romania
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Lepadatu AM, Slav A, Palade C, Dascalescu I, Enculescu M, Iftimie S, Lazanu S, Teodorescu VS, Ciurea ML, Stoica T. Dense Ge nanocrystals embedded in TiO 2 with exponentially increased photoconduction by field effect. Sci Rep 2018; 8:4898. [PMID: 29559710 PMCID: PMC5861074 DOI: 10.1038/s41598-018-23316-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 03/06/2018] [Indexed: 01/21/2023] Open
Abstract
Si and Ge nanocrystals in oxides are of a large interest for photo-effect applications due to the fine-tuning of the optical bandgap by quantum confinement in nanocrystals. In this work, dense Ge nanocrystals suitable for enhanced photoconduction were fabricated from 60% Ge in TiO2 amorphous layers by low temperature rapid thermal annealing at 550 °C. An exponential increase of the photocurrent with the applied voltage was observed in coplanar structure of Ge nanocrystals composite films deposited on oxidized Si wafers. The behaviour was explained by field effect control of the Fermi level at the Ge nanocrystals-TiO2 layer/substrate interfaces. The blue-shift of the absorption gap from bulk Ge value to 1.14 eV was evidenced in both photocurrent spectra and optical reflection-transmission experiments, in good agreement with quantum confinement induced bandgap broadening in Ge nanocrystal with sizes of about 5 nm as found from HRTEM and XRD investigations. A nonmonotonic spectral dependence of the refractive index is associated to the Ge nanocrystals formation. The nanocrystal morphology is also in good agreement with the Coulomb gap hopping mechanism of T-1/2 -type explaining the temperature dependence of the dark conduction.
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Affiliation(s)
- A-M Lepadatu
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - A Slav
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - C Palade
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - I Dascalescu
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - M Enculescu
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - S Iftimie
- University of Bucharest, Faculty of Physics, 077125, Magurele, Romania
| | - S Lazanu
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - V S Teodorescu
- National Institute of Materials Physics, 077125, Magurele, Romania
| | - M L Ciurea
- National Institute of Materials Physics, 077125, Magurele, Romania. .,Academy of Romanian Scientists, 050094, Bucharest, Romania.
| | - T Stoica
- National Institute of Materials Physics, 077125, Magurele, Romania.
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Popa AC, Stan GE, Enculescu M, Tanase C, Tulyaganov DU, Ferreira JMF. Superior biofunctionality of dental implant fixtures uniformly coated with durable bioglass films by magnetron sputtering. J Mech Behav Biomed Mater 2015; 51:313-27. [PMID: 26282074 DOI: 10.1016/j.jmbbm.2015.07.028] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 07/26/2015] [Accepted: 07/27/2015] [Indexed: 12/11/2022]
Abstract
Bioactive glasses are currently considered the suitable candidates to stir the quest for a new generation of osseous implants with superior biological/functional performance. In congruence with this vision, this contribution aims to introduce a reliable technological recipe for coating fairly complex 3D-shaped implants (e.g. dental screws) with uniform and mechanical resistant bioactive glass films by the radio-frequency magnetron sputtering method. The mechanical reliability of the bioactive glass films applied to real Ti dental implant fixtures has been evaluated by a procedure comprised of "cold" implantation in pig mandibular bone from a dead animal, followed by immediate tension-free extraction tests. The effects of the complex mechanical strains occurring during implantation were analysed by scanning electron microscopy coupled with electron dispersive spectroscopy. Extensive biocompatibility assays (MTS, immunofluorescence, Western blot) revealed that the bioactive glass films stimulated strong cellular adhesion and proliferation of human dental pulp stem cells, without promoting their differentiation. The ability of the implant coatings to conserve a healthy stem cell pool is promising to further endorse the fabrication of new osseointegration implant designs with extended lifetime.
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Affiliation(s)
- A C Popa
- Army Centre for Medical Research, Bucharest 020012, Romania
| | - G E Stan
- National Institute of Materials Physics, Magurele-Ilfov 077125, Romania.
| | - M Enculescu
- National Institute of Materials Physics, Magurele-Ilfov 077125, Romania
| | - C Tanase
- "Victor Babes" National Institute of Pathology, Bucharest 050096, Romania
| | - D U Tulyaganov
- Turin Polytechnic University in Tashkent, Tashkent 100174, Uzbekistan
| | - J M F Ferreira
- Department of Materials and Ceramics Engineering, CICECO, University of Aveiro, Aveiro 3810-193, Portugal.
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Grumezescu AM, Cristescu R, Chifiriuc MC, Dorcioman G, Socol G, Mihailescu IN, Mihaiescu DE, Ficai A, Vasile OR, Enculescu M, Chrisey DB. Fabrication of magnetite-based core-shell coated nanoparticles with antibacterial properties. Biofabrication 2015; 7:015014. [PMID: 25797361 DOI: 10.1088/1758-5090/7/1/015014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We report the fabrication of biofunctionalized magnetite core/sodium lauryl sulfate shell/antibiotic adsorption-shell nanoparticles assembled thin coatings by matrix assisted pulsed laser evaporation for antibacterial drug-targeted delivery. Magnetite nanoparticles have been synthesized and subsequently characterized by transmission electron microscopy and x-ray diffraction. The obtained thin coatings have been investigated by FTIR and scanning electron microscope, and tested by in vitro biological assays, for their influence on in vitro bacterial biofilm development and cytotoxicity on human epidermoid carcinoma (HEp2) cells.
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Affiliation(s)
- A M Grumezescu
- Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, Politehnica University of Bucharest, 1-7 Polizu Street, 011061, Bucharest, Romania
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Ulmeanu M, Sima LE, Ursescu D, Enculescu M, Bazan X, Quintana I. Cell adhesion response on femtosecond laser initiated liquid assisted silicon surface. Curr Top Med Chem 2014; 14:624-9. [PMID: 24444164 DOI: 10.2174/1568026614666140118204946] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 09/30/2013] [Accepted: 11/18/2013] [Indexed: 11/22/2022]
Abstract
Silicon substrates were irradiated at normal incidence with a femtosecond Ti:sapphire laser (Quatronix, 90 fs pulse duration, 1 kHz repetition rate, M(2) ~ 1.2, maximum energy peak 350 mJ ) operating at a wavelength of 400 nm and focused via a microscope objective (Newport; UV Objective Model, 37x 0.11 N.A.). The laser scanning was assisted by liquids precursors media such as methanol and 1,1,2-trichlorotrifluoroethane. By altering the processing parameters, such as incident laser energy, scanning speed, and different irradiation media, various surface structures were produced on areas with 1 mm(2) dimensions. We analyzed the dependence of the surface morphology on laser pulse energy, scanning speed and irradiation media. Well ordered areas are developed without imposing any boundary conditions for the capillary waves that coarsens the ripple pattern. To assess biomaterial-driven cell adhesion response we investigated actin filaments organization and cell morphological changes following growth onto processed silicon substrates. Our study of bone cell progenitor interaction with laser nanoprocessed silicon lines has shown that cells anchor mainly to contact points along the nanostructured surface. Consequently, actin filaments are stretched towards the 15 µm wide parallel lines increasing lateral cell spreading and changing the bipolar shape of mesenchymal stem cells.
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Affiliation(s)
| | | | | | | | | | - I Quintana
- National Institute for Laser, Plasma and Radiation Physics, Laser Department, Atomistilor 409, P. O. Box MG-36, 077125 Magurele, Romania.
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Ulmeanu M, Anghel I, Filipescu M, Luculescu C, Enculescu M, Zamfirescu M. Periodic arrays of nanostructures in silicon and gallium arsenide by near-field enhanced laser irradiation in liquid precursors. Colloids Surf A Physicochem Eng Asp 2013. [DOI: 10.1016/j.colsurfa.2012.11.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Mihaiescu DE, Cristescu R, Dorcioman G, Popescu CE, Nita C, Socol G, Mihailescu IN, Grumezescu AM, Tamas D, Enculescu M, Negrea RF, Ghica C, Chifiriuc C, Bleotu C, Chrisey DB. Functionalized magnetite silica thin films fabricated by MAPLE with antibiofilm properties. Biofabrication 2012; 5:015007. [PMID: 23254399 DOI: 10.1088/1758-5082/5/1/015007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
We report on the fabrication of magnetite/salicylic acid/silica shell/antibiotics (Fe(3)O(4)/SA/SiO(2)/ATB) thin films by matrix-assisted pulsed laser evaporation (MAPLE) to inert substrates. Fe(3)O(4)-based powder have been synthesized and investigated by XRD and TEM. All thin films were studied by FTIR, SEM and in vitro biological assays using Staphylococcus aureus and Pseudomonas aeruginosa reference strains, as well as eukaryotic HEp-2 cells. The influence of the obtained nanosystems on the microbial biofilm development as well as their biocompatibility has been assessed. For optimum deposition conditions, we obtained uniform adherent films with the composition identical with the raw materials. Fe(3)O(4)/SA/SiO(2)/ATB thin films had an inhibitory activity on the ability of microbial strains to initiate and develop mature biofilms, in a strain- and antibiotic-dependent manner. These magnetite silica thin films are promising candidates for the development of novel materials designed for the inhibition of medical biofilms formed by different pathogenic agents on common substrates, frequently implicated in the etiology of chronic and hard to treat infections.
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Affiliation(s)
- D E Mihaiescu
- Faculty of Applied Chemistry and Materials Science, Politehnica University of Bucharest, 1-7 Polizu Street, Bucharest, Romania
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Abstract
Luminescent nanorods of potassium acid phthalate (KAP) doped with rhodamine 6G (Rh 6G) dye molecules were grown by template assisted crystallization. Pores with diameters ranging from tens of nanometers to few micrometers were obtained in polycarbonate foils after heavy-ion irradiation and subsequent chemical etching of the damage trails along the ion trajectories. Crystallization from solution was employed for filling of the pores with the dye-doped KAP rods. These nanostructures were characterized using scanning electron microscopy, optical absorption spectroscopy and photoluminescence detection. X-ray diffraction was used for structural analysis. The luminescence of the dye-doped rods undergoes a redshift when the diameter of the structures decreases. This shift is probably caused by increasing dye concentration in the rods with decreasing pore diameter. The luminescence originating from the Rh 6G presence is up-converted due to the second-harmonic generation in KAP.
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Affiliation(s)
- M Enculescu
- National Institute of Materials Physics, PO Box MG-7, 77125 Magurele-Bucharest, Romania
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Enculescu I, Iliescu B, Enculescu M, Covalcica I. A Model for Structures Growth by Sodium Electrodiffusion in Quartz Crystals. Zeitschrift für experimentelle und technische Kristallographie 2002. [DOI: 10.1002/1521-4079(200208)37:8<868::aid-crat868>3.0.co;2-j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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