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1.
Phys Chem Chem Phys ; 16(46): 25557-63, 2014 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-25351254

RESUMO

The performance of organic electronic devices often shows a strong dependence on the presence of impurities, for example oxygen and water molecules. Here we use first-principles calculations to examine oxygen- and water-related effects in poly(3-hexylthiophene) (P3HT), one of the most widely used donors in organic photovoltaics. We find that oxygen species may be stabilized in P3HT crystals in several different impurity configurations, including physisorbed and chemisorbed geometries. We also find that a number of these structures gives rise to levels inside the P3HT band gap and can thus act as carrier traps. In contrast, water molecules remain physisorbed between the polymer chains and induce only minimal changes in the electronic properties of the host system. The results are in agreement with pertinent experiments and elucidate the atomic-scale details of oxygen-related degradation of P3HT-based devices.

2.
Int Ophthalmol ; 34(3): 519-23, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24037592

RESUMO

The purpose of the study was to appraise the effect of loading force magnitude on the determination of the elastic modulus of the anterior lens capsule through atomic force microscopy. Four human anterior lens capsules taken during phacoemulsification cataract surgery were studied, free of epithelial cells, with atomic force microscopy. For the experiment, five different indentation loading forces were applied to near areas of the specimen. Experimental data was exported and analyzed according to the Hertz model to obtain the Young's modulus with regards to the elastic behavior of the material. Force-distance curves were acquired by applying a load of 2, 5, 10, 20 and 30 nN. When examining the results it was evident that determination of Young's modulus of the anterior lens capsule is dependent on the loading force concerning the examined range. Loading forces of 10 and 20 nN led to results without significant difference (p > 0.05) and more reproducible (coefficients of variation 12.4 and 11.7 %, respectively).


Assuntos
Catarata/fisiopatologia , Módulo de Elasticidade , Elasticidade/fisiologia , Cápsula do Cristalino/fisiologia , Microscopia de Força Atômica , Idoso , Idoso de 80 Anos ou mais , Tecido Elástico , Humanos , Reprodutibilidade dos Testes , Estresse Mecânico
3.
Micromachines (Basel) ; 15(9)2024 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-39337749

RESUMO

Organometallic complexes containing reactive alkali metals, such as lithium (Li), represent a promising material approach for electron injection layers and electron transport layers (EILs and ETLs) to enhance the performance of Organic Light-Emitting Diodes (OLEDs). 8-Quinolinolato Lithium (Liq) has shown remarkable potential as an EIL and ETL when conveyed in very thin films. Nevertheless, the deposition of nano-layers requires precise control over both thickness and morphology. In this work, we investigate the optical properties and morphological characteristics of Liq thin films deposited via Organic Vapor Phase Deposition (OVPD). Specifically, we present our methodology for analyzing the measured pseudodielectric function <ε(ω)> using Spectroscopic Ellipsometry (SE), alongside the nano-topography of evaporated Liq nano-layers using Atomic Force Microscopy (AFM). This information can contribute to the understanding of the functionality of this material, since ultra-thin Liq interlayers can significantly increase the operational stability of OLED architectures.

4.
Nanomaterials (Basel) ; 14(15)2024 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-39120351

RESUMO

In this study, fully aromatic polyether sulfones were developed, bearing blue, yellow, and orange-red π-conjugated semiconducting units. Carbazole-, anthracene-, and benzothiadiazole-based fluorophores are copolymerized with a diphenylsulfone moiety. A diphenylpyridine comonomer was additionally utilized, acting as both a solubilizing unit and a weak blue fluorescent group. Using this rationale, fluorescent polyarylethers with high molecular weights, up to 70 kDa, were developed, showing film formation ability and high thermal stability, while preserving excellent solubility in common organic, nonvolatile, and nonchlorinated solvents. Fine-tuning of the emission color was achieved through subtle changes of the comonomers' type and ratio. Single-chromophore-bearing copolymers emitted in the blue or the yellow region of the visible spectrum, while the dual-chromophore-bearing terpolymers emitted throughout the visible spectrum, resulting in white light emission. Solutions of 20 wt% in polar aprotic solvents at ambient conditions allowed the deposition of fluorescent copolyethers and printing from non-chlorinated solvents. All polyethers were evaluated for their structural and optoelectronic properties, and selected copolymers were successfully used in the emitting layer (EML) of organic light-emitting diode (OLED) devices, using either rigid or flexible substrates. Remarkable color stability was displayed in all cases for up to 15 V of bias voltage. The Commission Internationale de L'Eclairage (CIE) of the fabricated devices is located in the blue (0.16, 0.16), yellow (0.44, 0.50), or white region of the visible spectrum (0.33, 0.38) with minimal changes according to the ratio of the comonomers. The versatile methodology toward semiconducting polyethersulfones for polymer light-emitting diodes (PLEDs) developed herein led to the scaled-up production of luminescent polymers of up to 25 g of high-molecular-weight single batches, demonstrating the effectiveness of this approach as a straightforward tool to facilitate the synthesis of flexible and printable EMLs for large-area PLED coverage.

5.
Virchows Arch ; 483(6): 775-786, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37402995

RESUMO

Over the last years, there has been an increasing number of proposals for the use of nanomaterials in medicine. The safety of novel technologies must be verified, prior to their clinical application. Pathology has much to contribute towards this end. In this study, we compared the in vivo toxicity effects of poly- (lactic-co-glycolic acid) nanoparticles with and without chitosan shell. Both nanoparticle types were loaded with curcumin. The nanoparticles were assessed in vitro for potential cytotoxicity with cell viability studies. For the in vivo test, 36 adult Wistar rats were used, four of which were the control group. The remaining 32 were divided into 2 groups, each of which was administered differentially coated drug carriers: (A) nanoparticles without chitosan coating and (B) nanoparticles with chitosan coating. For both groups, the subcutaneous route was used for administration. Each group was further divided into 2 sub-groups of 8 animals each. The animals of the first sub-groups were sacrificed 24 h after the injection and those of the second on the 7th day. The control group was also divided into 2 subgroups of 2 animals each. At the appointed post-administrative date, the rats were sacrificed, and specimens from the brain, liver, kidneys, heart, stomach, lungs, and from the skin at the injection site were collected and studied histopathologically. The evaluation of both in vitro and in vivo testing shows that nanoparticles with chitosan have significantly less, if any, toxic effects compared to those without chitosan.


Assuntos
Quitosana , Nanopartículas , Ratos , Humanos , Animais , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Quitosana/toxicidade , Ácido Poliglicólico/toxicidade , Ácido Láctico , Nanomedicina , Ratos Wistar , Nanopartículas/toxicidade
6.
Materials (Basel) ; 17(1)2023 Dec 23.
Artigo em Inglês | MEDLINE | ID: mdl-38203932

RESUMO

Extensive research has been dedicated to the solution-processable white organic light-emitting diodes (WOLEDs), which can potentially influence future solid-state lighting and full-color flat-panel displays. The proposed strategy based on WOLEDs involves blending two or more emitting polymers or copolymerizing two or more emitting chromophores with different doping concentrations to produce white light emission from a single layer. Toward this direction, the development of blends was conducted using commercial blue poly(9,9-di-n-octylfluorenyl2,7-diyl) (PFO), green poly(9,9-dioctylfluorenealt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, whereas the synthesized copolymers were based on different chromophores, namely distyryllanthracene, distyrylcarbazole, and distyrylbenzothiadiazole, as yellow, blue, and orange-red emitters, respectively. A comparative study between the two approaches was carried out to examine the main challenge for these doping systems, which is ensuring the proper balance of emissions from all the units to span the entire visible range. The emission characteristics of fabricated WOLEDs will be explored in terms of controlling the emission from each emitter, which depends on two possible mechanisms: energy transfer and carrier trapping. The aim of this work is to achieve pure white emission through the color mixing from different emitters based on different doping concentrations, as well as color stability during the device operation. According to these aspects, the WOLED devices based on the copolymers of two chromophores exhibit the most encouraging results regarding white color emission coordinates (0.28, 0.31) with a CRI value of 82.

7.
Materials (Basel) ; 15(22)2022 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-36431703

RESUMO

Ultrafast laser patterning is an essential technology for the low-cost and large area production of flexible Organic Electronic (OE) devices, such as Organic Photovoltaics (OPVs). In order to unleash the potential of ultrafast laser processing to perform the selective and high precision removal of complex multilayers from printed OPV stacks without affecting the underlying nanolayers, it is necessary to optimize its parameters for each nanolayer combination. In this work, we developed an efficient on-the-fly picosecond (ps) laser scribing process (P1, P2 and P3) using single wavelength and single step/pass for the precise and reliable in-line patterning of Roll-to-Roll (R2R) slot-die-coated nanolayers. We have investigated the effect of the key process parameters (pulse energy and overlap) on the patterning quality to obtain high selectivity on the ablation of each individual nanolayer. Finally, we present the implementation of the ultrafast laser patterning process in the manufacturing of fully R2R printed flexible semitransparent OPV modules with a 3.4% power conversion efficiency and 91% Geometric Fill Factor (GFF).

8.
Nanomaterials (Basel) ; 12(22)2022 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-36432386

RESUMO

Obtaining white light from organic LEDs is a considerable challenge and, to realize white light emission, many studies have been conducted, primarily addressing two- or three-color blend systems as a promising strategy. In this work, pristine films, grown by spin coating, consisting of commercial blue Poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO), green Poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), and red spiro-copolymer (SPR) light-emitting materials, were studied as reference materials. Afterward, binary (SPR doped in host PFO) and ternary (SPR and F8BT doped in host PFO) thin films were successfully prepared with various ratios. The characterization of the as-grown and thermally-treated blend films was focused on their optical and photophysical properties. After, the fabrication of OLED devices on glass substrates was carried out for the evaluation of a blend's composition and annealing in terms of the devices' electrical characteristics and electro-emission properties in order to achieve white light emission. Their analysis provided insights into the energy transfer mechanisms between the constituent materials, which were correlated to host-guest interactions as well as to the structural changes originated by thermal treatment, leading to the crystallization of PFO. Finally, the OLEDs based on ternary blends approach the white light emission with (x, y) of (0.272, 0.346). These fabricated devices also exhibit turn-on voltages as low as 3 V, accompanied by remarkable luminance values above 3000 cd/m2.

9.
Cureus ; 13(11): e19674, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34976462

RESUMO

Background Cataract surgery is a very popular operation that requires a postoperative period of frequent instillation of antibiotic and anti-inflammatory eye drops. Modified drug-eluting intraocular lenses (IOLs) may eliminate the need for eye drops after surgery. Aim The purpose of this study is to compare the morphological characteristics of dexamethasone eluting biodegradable polymeric thin films developed on the surface of commercially available IOLs by three different methods. Method This experimental study was conducted between May and August of 2021 in the Lab for Thin Films - Nanobiomaterials - Nanosystems & Nanometrology (LTFN) of the Aristotle University of Thessaloniki. A mixture of two organic polymers [Poly (D, L-lactide-co-glycolide)(PLGA), lactide: glycolide (75:25) and Polycaprolactone (PCL)] and dexamethasone was prepared and then deposited on the surface of three-piece IOLs by spin coating, by spray coating, and by gravure printing. The modified IOLs were sterilized with the use of ultraviolet (UV) radiation and plasma treatment. Their structural properties were studied with the use of atomic force microscopy (AFM). Results Spin coating and gravure printing produced uniform thin films on the surface of the IOLs which were not damaged during the sterilization process. Spray coating led to the partial coating of the surface of the IOLs; the thin films underwent alterations following plasma treatment. Conclusions Thin films developed by spin coating and gravure printing on IOLs demonstrate the desired morphological characteristics that make them suitable candidates for further research.

10.
Nanomaterials (Basel) ; 11(10)2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34685063

RESUMO

In this study, novel copolymers consisting of blue and red chromophores are presented to induce emission tuning, enabling the definition of white light emission in a single polymeric layer. These aromatic polyether sulfones exhibit high molecular weights, excellent solubility and processability via solution deposition techniques. In addition, by carefully controlling the molar ratios of chromophores composition, the energy transfer mechanism, from blue to red chromophores, takes place enabling us to define properly the emission covering the entire range of the visible spectrum. The optical and photophysical properties of the monomers and copolymers were thoroughly investigated via NIR-Vis-far UV Spectroscopic Ellipsometry (SE), Absorbance and Photoluminescence (PL). These copolymers are used as an emissive layer and applied in solution-processed WOLED devices. The fabricated WOLED devices have been subsequently studied and characterized in terms of their electroluminescence properties. Finally, the WOLED devices possess high color stability and demonstrate CIE Coordinates (0.33, 0.38), which approach closely the pure white light CIE coordinates.

11.
IET Nanobiotechnol ; 14(6): 501-507, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32755960

RESUMO

To design, develop and study a novel drug delivery system for intraocular applications. The spin coating technique was applied to develop a polymeric, drug-eluting thin film consisting of a blend of organic polymers [poly (D, L lactide coglycolide) lactide: glycolide 75: 25, PLGA and polycaprolactone, PCL] and dexamethasone on the surface of intraocular lenses (IOLs). The initial durability of the IOLs during spinning was assessed. Information about the structural and optical properties of the modified IOLs was extracted using atomic force microscopy, scanning electron microscopy and spectroscopic ellipsometry. A drug release study was conducted for 8 weeks. The IOLs were durable in spinning speeds higher than the ones used to develop thin films. Single-layer thin films were successfully developed on the optics and the haptics of the lenses. The films formed nanopores with encapsulated aggregates of dexamethasone. The spectroscopic ellipsometry showed an acceptable optical transparency of the lenses regardless of the deposition of the drug-eluting films on their surface. The drug release study demonstrated gradual dexamethasone release over the selected period. In conclusion, the novel drug-eluting IOL system exhibited desired properties regarding its transparency and drug release rate. Further research is necessary to assess their suitability as an intraocular drug delivery system.


Assuntos
Materiais Revestidos Biocompatíveis/química , Lentes Intraoculares , Poliésteres/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Anti-Inflamatórios/química , Anti-Inflamatórios/farmacocinética , Materiais Revestidos Biocompatíveis/farmacocinética , Dexametasona/química , Dexametasona/farmacocinética , Sistemas de Liberação de Medicamentos , Liberação Controlada de Fármacos , Microscopia de Força Atômica
12.
Nanomedicine ; 5(1): 64-72, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18848813

RESUMO

There is increasing interest in developing novel coatings to enhance the biocompatibility of medical implants. A key issue in biocompatibility research is platelet activation and aggregation on the biomaterials' surface. Stoichiometric and nonstoichiometric titanium nitride (TiN(x)) films were developed by sputtering as case study materials, for probing platelet activation behavior onto them. Atomic force microscopy (AFM) facilitates the real-time studies of cells and guarantees cellular viability. In this work a methodology for platelets study by AFM was developed. The morphological, structural, optical, and wettability properties of the TiN(x) films were obtained by AFM, x-ray diffraction, spectroscopic ellipsometry, and contact angle measurements.The properties of TiN(x) films were correlated with their thrombogenicity involving platelets' adhesion, activation and protein clustering mechanisms. It was found that the TiN(x) films stoichiometry and surface roughness affect the platelet response. The stoichiometric and smoother TiN films promote platelets adhesion and activation.


Assuntos
Microscopia de Força Atômica/métodos , Nanomedicina/métodos , Ativação Plaquetária/efeitos dos fármacos , Titânio/farmacologia , Materiais Biocompatíveis/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Adesividade Plaquetária/efeitos dos fármacos
13.
Beilstein J Nanotechnol ; 9: 1986-1994, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30116690

RESUMO

There is, as a matter of fact, an ever increasing number of patients requiring total hip replacement (Pabinger, C.; Geissler, A. Osteoarthritis Cartilage2014,22, 734-741). Implant-associated acute inflammations after an invasive orthopedic surgery are one of the major causes of implant failure. In addition, there are instability, aseptic loosening, infection, metallosis and fracture (Melvin, J. S.; Karthikeyan, T.; Cope, R.; Fehring, T. K. J. Arthroplasty2014,29, 1285-1288). In this work, a drug-delivery nanoplatform system consisting of polymeric celluloce acetate (CA) scaffolds loaded with dexamethasone was fabricated through electrospinning. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) indicated the successful fabrication of these structures. Cytotoxicity studies were performed by using MTT assay, methylene-blue staining and SEM fixation and showed very good cell adhesion and proliferation, indicating the cytocompatibility of these fibrous scaffolds. Drug-release kinetics was measured for the evaluation of a controllable and sustained release of anti-inflammatory drug onto the engineered implants and degradation study was conducted in order to assess the mass loss of polymers. This drug-delivery nanoplatform as coating on titanium implants may be a promising approach not only to alleviate but also to prevent implant-associated acute inflammations along with a simultaneous controlled release of the drug.

14.
IET Nanobiotechnol ; 12(8): 1074-1079, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30964016

RESUMO

To study the development, characterisation, and drug release of one- and two-layered thin films based on organic polymers [poly(D,L-lactide-co-glycolide) lactide:glycolide (65:35), poly(D,L-lactide-co-glycolide) lactide:glycolide (75:25), and polycaprolactone] and dexamethasone. To examine their applicability for intraocular lenses (IOLs) and function in intraocular drug delivery systems. Four series of thin films, single and double-layer, were prepared by the spin-coating method on a silicon substrate. The films were studied using atomic force microscopy and spectroscopic ellipsometry. The release rate of dexamethasone was studied for a period of ten weeks. Series A and C demonstrated the formation of large dexamethasone aggregates. The monolayer films of series C and D formed pores, in agreement with previous findings. The spectroscopic ellipsometry study demonstrated that the samples were transparent. The drug release study demonstrated that dexamethasone was released during the first 6 weeks at a desirable rate. The films exhibited properties suitable for use in intraocular drug delivery systems. The single-layer thin films demonstrated a sufficient encapsulation of dexamethasone and appropriate release of the therapeutic substance. Further studies are necessary to investigate the possibility of developing the films directly on the surface of the IOL.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Poliésteres/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/química , Dexametasona/química , Dexametasona/farmacocinética , Liberação Controlada de Fármacos , Lentes Intraoculares , Modelos Químicos , Soluções Oftálmicas/química , Soluções Oftálmicas/farmacocinética , Desenho de Prótese
15.
Int J Nanomedicine ; 12: 6343-6355, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28919738

RESUMO

This study describes the development of drug-loaded nanofibrous scaffolds as a nanocoating for endovascular stents for the local and sustained delivery of rosuvastatin (Ros) and heparin (Hep) to injured artery walls after endovascular procedures via the electrospinning process. PURPOSE: The proposed hybrid covered stents can promote re-endothelialization; improve endothelial function; reduce inflammatory reaction; inhibit neointimal hyperplasia of the injured artery wall, due to well-known pleiotropic actions of Ros; and prevent adverse events such as in-stent restenosis (ISR) and stent thrombosis (ST), through the antithrombotic action of Hep. METHODS: Biodegradable nanofibers were prepared by dissolving cellulose acetate (AC) and Ros in N,N-dimethylacetamide (DMAc) and acetone-based solvents. The polymeric solution was electrospun (e-spun) into drug-loaded AC nanofibers onto three different commercially available stents (Co-Cr stent, Ni-Ti stent, and stainless steel stent), resulting in nonwoven matrices of submicron-sized fibers. Accordingly, Hep solution was further used for fibrous coating onto the engineered Ros-loaded stent. The functional encapsulation of Ros and Hep drugs into polymeric scaffolds further underwent physicochemical analysis. Morphological characterization took place via scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses, while scaffolds' wettability properties were obtained by contact angle (CA) measurements. RESULTS: The morphology of the drug-loaded AC nanofibers was smooth, with an average diameter of 200-800 nm, and after CA measurement, we concluded to the superhydrophobic nature of the engineered scaffolds. In vitro release rates of the pharmaceutical drugs were determined using a high-performance liquid chromatography assay, which showed that after the initial burst, drug release was controlled slowly by the degradation of the polymeric materials. CONCLUSION: These results imply that AC nanofibers encapsulated with Ros and Hep drugs have great potential in the development of endovascular grafts with anti-thrombogenic properties that can accelerate the re-endothelialization, reduce the neointimal hyperplasia and inflammatory reaction, and improve the endothelial function.


Assuntos
Stents Farmacológicos , Heparina/administração & dosagem , Nanofibras/química , Nanotecnologia/métodos , Rosuvastatina Cálcica/administração & dosagem , Acetamidas/química , Materiais Biocompatíveis , Desenho de Equipamento , Heparina/química , Heparina/farmacocinética , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Polímeros/química , Rosuvastatina Cálcica/química , Rosuvastatina Cálcica/farmacocinética
16.
Materials (Basel) ; 10(8)2017 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-28817090

RESUMO

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is among the most widely used polymers that are used as printed transparent electrodes for flexible Organic Electronic (OE) devices, such as Organic Photovoltaics (OPVs). The understanding of their optical properties and the correlation of the optical properties with their electronic properties and metallic-like behavior can lead to the optimization of their functionality as transparent electrodes in multilayer OE device architectures. In this work, we study the optical properties of different PEDOT:PSS formulations by non-destructive Spectroscopic Ellipsometry (SE), from the infrared to the far ultraviolet spectral regions. The optical response of PEDOT:PSS includes an intense optical absorption originated from the conductive part (PEDOT) at lower photon energies, whereas the electronic transition energies of the non-conductive PSS part have been measured at higher photon energies. Based on the different PEDOT:PSS formulations, the optical investigation revealed significant information on the relative contribution of conductive PEDOT and insulating PSS parts of the PEDOT:PSS formulation in the overall optical response, which can strongly impact the final device functionality and its optical transparency.

17.
Future Sci OA ; 2(2): FSO113, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28031960

RESUMO

Thromboembolic diseases constitute a plague in our century, wherein an imbalance of hemostasis leads to thrombus formation and vessels constriction reducing blood flow. Hence, the recent rise of nanomedicine gives birth to advanced diagnostic modalities and therapeutic agents for the early diagnosis and treatment of such diseases. Multimodal nanoagents for the detection of intravascular thrombi and nanovehicles for thrombus-targeted fibrinolytic therapy are few paradigms of nanomedicine approaches to overcome current diagnostic treatment roadblocks and persistent clinical needs. This review highlights the nanomedicine strategies to improve the imaging and therapy of acute thrombi by nanoparticles and nanotheranostics, the detailed imaging of thrombogenic proteins and platelets via atomic force microscopy with the knowledge basis of thrombosis pathophysiology and nanotoxicity.

18.
Front Physiol ; 7: 364, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27621708

RESUMO

Removable complete and partial dentures are supported by the residual alveolar ridges consisting of mucosa, submucosa, periosteum, and bone. An understanding of the biomechanical behavior of the oral mucosa is essential in order to improve the denture-bearing foundations for complete and partially edentulous patients. The purpose of this paper was to examine the biomechanical behavior of the soft tissues supporting a removable denture and develop a model for that reason. Keratinized oral mucosa blocks with their underlying bone were harvested from the maxillary palatal area adjacent to the edentulous ridges of a cadaver. The compressive response of the oral mucosa was tested by using atomic force microscopy. The specimens were first scanned in order their topography to be obtained. The mechanical properties of the specimens were tested using a single crystal silicon pyramidal tip, which traversed toward the keratinized oral mucosa specimens. Loading-unloading cycles were registered and four mathematical models were tested using MATLAB to note which one approximates the force-displacement curve as close as possible: a. spherical, b. conical, c. third order polynomial, d. Murphy (fourth order polynomial, non-linear Hertzian based). The third order polynomial model showed the best accuracy in representing the force-displacement data of the tested specimens. A model was developed in order to analyze the biomechanical behavior of the human oral keratinized mucosa and obtain information about its mechanical properties.

19.
J Biomed Nanotechnol ; 11(2): 191-210, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26349296

RESUMO

Cardiovascular diseases (CVDs) and the underlying process of atherosclerosis are considered to be the most frequent causes of mortality and morbidity in developed societies. Atherosclerosis constitutes a systemic, chronic and progressive inflammatory disease that is initiated by early endothelial dysfunction and is subsequently amplified by oxidative stress, lipid deposition and monocyte recruitment. An interplay occurs among diverse cells, chemoattractants, adhesion molecules and low-density lipoproteins in the subendothelium. Due to the complexity of its pathogenesis, effective therapeutic strategies have not yet been applied in routine clinical practice. With the advent of nanotechnology, nanoparticulate systems with diagnostic and therapeutic moieties for the site-specific targeting of atherosclerotic lesions as well as nanomaterials that are suitable for cardiovascular implants may offer possible solutions to certain shortfalls of current treatment regimens. This article describes the recent advances that involve different types of nanoparticles for the early detection and concurrent therapy of atherosclerotic lesions. Moreover, it provides a state-of-the-art overview of stent technology in the restoration of normal blood flow to ischemic myocardial sites and underscores its drawbacks in light of substantial nanotechnology-based improvements. Emphasis is placed on the contribution of nanomedicine to the development of novel and effective therapies for atherosclerosis, ranging from 'nanotheranostic' strategies for vulnerable plaques to the nanoporous and nanoparticulate drug-delivery platforms that have been applied to stent technology. By striking a balance between the efficacy and the potential toxicity of nanotechnology-enabled systems, new frontiers in atherosclerosis treatment will emerge.


Assuntos
Aterosclerose/diagnóstico , Aterosclerose/terapia , Imagem Molecular/métodos , Nanomedicina/métodos , Animais , Aterosclerose/etiologia , Sistemas de Liberação de Medicamentos , Humanos , Inflamação/terapia , Nanopartículas/uso terapêutico , Nanoestruturas/química , Nanoestruturas/uso terapêutico , Stents
20.
ACS Appl Mater Interfaces ; 7(12): 6496-504, 2015 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-25767897

RESUMO

Functionalized acenes have proven to be promising compounds in the field of molecular electronics because of their unique features in terms of the stability, performance, and ease of processing. The emerging concept of large-area-compatible techniques for flexible electronics has brought about a wide variety of well-established techniques for the deposition of soluble acenes, with spray-coating representing an especially fruitful approach. In the present study, electrostatic spray deposition is proposed as an alternative to the conventional spray-coating processes, toward the realization of high-performance organic field-effect transistors (OFETs), on both rigid and flexible substrates. Particularly, a thorough study on the effect of the solvent and spraying regime on the resulting crystalline film's morphology is performed. By optimization of the process conditions in terms of control over the size as well as the crystallization scheme of the droplets, desirable morphological features along with high-quality crystal domains are obtained. The fabricated OFETs exhibit excellent electrical characteristics, with high field-effect mobility up to 0.78 cm(2)/(V s), I(on)/I(off) >10(4), and near-zero threshold voltages. Additionally, the good performance of the OFETs realized on plastic substrates gives great potentiality to the proposed method for applications in the challenging field of large-area electronics.

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