Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.744
Filtrar
1.
Int J Mol Sci ; 22(16)2021 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-34445516

RESUMO

In this study, we prepared core-sheath nanofiber membranes (CSNFMs) with silver nanoparticles (Ag NPs) embedding in the polylactic acid (PLA) nanofiber sheath and hyaluronic acid (HA) in the nanofiber core. The PLA/Ag NPs sheath provides mechanical support as well as anti-bacterial and anti-inflammatory properties. The controlled release of HA from the core could exert anti-adhesion effects to promote tendon sliding while reducing fibroblast attachment. From the microfibrous structural nature of CSNFMs, they function as barrier membranes to reduce fibroblast penetration without hampering nutrient transports to prevent post-operative peritendinous adhesion. As the anti-adhesion efficacy will depend on release rate of HA from the core as well as Ag NP from the sheath, we fabricated CSNFMs of comparable fiber diameter, but with thick (Tk) or thin (Tn) sheath. Similar CSNFMs with thick (Tk+) and thin (Tn+) sheath but with embedded Ag NPs in the sheath were also prepared. The physico-chemical properties of the barrier membranes were characterized in details, together with their biological response including cell penetration, cell attachment and proliferation, and cytotoxicity. Peritendinous anti-adhesion models in rabbits were used to test the efficacy of CSNFMs as anti-adhesion barriers, from gross observation, histology, and biomechanical tests. Overall, the CSNFM with thin-sheath and Ag NPs (Tn+) shows antibacterial activity with low cytotoxicity, prevents fibroblast penetration, and exerts the highest efficacy in reducing fibroblast attachment in vitro. From in vivo studies, the Tn+ membrane also shows significant improvement in preventing peritendinous adhesions as well as anti-inflammatory efficacy, compared with Tk and Tn CSNFMs and a commercial adhesion barrier film (SurgiWrap®) made from PLA.


Assuntos
Antibacterianos/administração & dosagem , Ácido Hialurônico/administração & dosagem , Poliésteres/química , Prata/química , Traumatismos dos Tendões/tratamento farmacológico , Células 3T3 , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Modelos Animais de Doenças , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Ácido Hialurônico/química , Ácido Hialurônico/farmacologia , Nanopartículas Metálicas , Camundongos , Testes de Sensibilidade Microbiana , Nanofibras/química , Espectroscopia Fotoeletrônica , Coelhos , Traumatismos dos Tendões/cirurgia , Aderências Teciduais/prevenção & controle
2.
Chemosphere ; 281: 130904, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34289606

RESUMO

Reductive immobilization of 99Tc by a synthetic FeS2 mixture, i.e. marcasite-pyrite 60:40, was studied by a combined approach of batch experiments and powder X-ray diffraction, X-ray photoelectron spectroscopy as well as Raman microscopy. It was found that the FeS2 mixture removes 100% of Tc from the suspension after 7 days in contact at 6.0 < pH ≤ 9.0. The retention outside that pH range was slower and incomplete. Spectroscopic analysis showed that the redox active species at pH 6.0 is Fe2+ as expected from previous works with pyrite. However, at pH 10.0 the surprising oxidation of S2- to SO42- was found responsible for Tc immobilization. This was explained by the high reactivity of marcasite that is easily oxidized to produce H2SO4. Our work provides new molecular insights into the reductive mobilization of Tc(VII) by oxidative formation of sulfate. The assigned molecular reactions may also be relevant for the assessment of other redox reactive contaminants. Technetium re-oxidation experiments showed that the fast oxidation of marcasite is associated to the reduction of the remaining Tc(VII) in solution, which gives marcasite the potential of Tc natural remediation since it delays the re-oxidation of Tc(IV).


Assuntos
Sulfetos , Tecnécio , Oxirredução , Espectroscopia Fotoeletrônica , Sulfatos , Difração de Raios X
3.
Phys Chem Chem Phys ; 23(28): 15049-15058, 2021 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-34231588

RESUMO

The properties of mixed water-uracil nanoaggregates have been probed by core electron-photoemission measurements to investigate supramolecular assembly in the gas phase driven by weak interactions. The interpretation of the measurements has been assisted by multilevel atomistic simulations, based on semi-empirical tight-binding and DFT-based methods. Our protocol established a positive-feedback loop between experimental and computational techniques, which has enabled a sound and detailed atomistic description of such complex heterogeneous molecular aggregates. Among biomolecules, uracil offers interesting and generalized skeletal features; its structure encompasses an alternation of hydrophilic H-bond donor and acceptor sites and hydrophobic moieties, typical in biomolecular systems, that induces a supramolecular core-shell-like organization of the mixed clusters with a water core and an uracil shell. This structure is far from typical models of both solid-state hydration, with water molecules in defined positions, or liquid solvation, where disconnected uracil molecules are completely surrounded by water.


Assuntos
Nanoestruturas/química , Uracila/química , Água/química , Teoria da Densidade Funcional , Ligação de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Espectroscopia Fotoeletrônica , Solventes/química , Espectrometria de Fluorescência , Termodinâmica
4.
Chem Commun (Camb) ; 57(59): 7284-7287, 2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34212953

RESUMO

Natural DNA was employed for the first time as a phosphorization agent and carbon source to controllably synthesize a RuP2/N,P-codoped carbon composite by a simple "mix-and-pyrolyze" strategy, which displays higher activity for alkaline and acidic HER and neutral activity compared to Pt/C together with outstanding durability.


Assuntos
DNA de Cadeia Simples/química , Grafite/química , Hidrogênio/química , Rutênio/química , Animais , Catálise , Concentração de Íons de Hidrogênio , Nitrogênio/química , Fósforo/química , Espectroscopia Fotoeletrônica , Salmão/genética
5.
Int J Biol Macromol ; 185: 1022-1035, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34197859

RESUMO

Biochemical modification can endow the surface of implants with superior biological activity. Herein, silk fibroin (SF) protein and its anionic derivative peptides (Cs) were covalently immobilized onto a titanium implant surface via a polydopamine layer. The successful conjugation of SF and Cs was revealed by X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), and contact angle measurements. The addition of Cs prevented the conformational transition of silk fibroin to silk II. The deposition of apatite on its surface was significantly accelerated, and the bioactive composite coating was observed to enhance protein adsorption and cell proliferation. More importantly, it also promoted the osteogenic differentiation of bone marrow stem cells (BMSCs) for the quantitative and qualitative detection of alkaline phosphatase (ALP) and alizarin red (ARS). Overall, the stable performance and enhanced osteogenic property of the composite coating promote an extensive application for clinical titanium-based implants.


Assuntos
Fibroínas/farmacologia , Indóis/química , Células-Tronco Mesenquimais/citologia , Osteogênese/efeitos dos fármacos , Polímeros/química , Titânio/química , Adsorção , Animais , Apatitas/química , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Fibroínas/química , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Microscopia de Força Atômica , Oxirredução , Peptídeos/química , Peptídeos/farmacologia , Espectroscopia Fotoeletrônica
6.
Int J Mol Sci ; 22(14)2021 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-34299241

RESUMO

In this paper, we suggest that the atmospheric pressure plasma treatment of pure titanium metal may be useful for improving the ability of rat bone marrow cells (RBMCs) to induce hard tissue differentiation. Previous studies have reported that the use of argon gas induces a higher degree of hard tissue formation. Therefore, this study compares the effects of plasma treatment with argon gas on the initial adhesion ability and hard tissue differentiation-inducing ability of RBMCs. A commercially available titanium metal plate was used as the experimental material. A plate polished using water-resistant abrasive paper #1500 was used as the control, and a plate irradiated with argon mixed with atmospheric pressure plasma was used as the experimental plate. No structural change was observed on the surface of the titanium metal plate in the scanning electron microscopy results, and no change in the surface roughness was observed via scanning probe microscopy. X-ray photoelectron spectroscopy showed a decrease in the carbon peak and the formation of hydroxide in the experimental group. In the distilled water drop test, a significant decrease in the contact angle was observed for the experimental group, and the results indicated superhydrophilicity. Furthermore, the bovine serum albumin adsorption, initial adhesion of RBMCs, alkaline phosphatase activity, calcium deposition, and genetic marker expression of rat bone marrow cells were higher in the experimental group than those in the control group at all time points. Rat distal femur model are used as in vivo model. Additionally, microcomputed tomography analysis showed significantly higher results for the experimental group, indicating a large amount of the formed hard tissue. Histopathological evaluation also confirmed the presence of a prominent newly formed bone seen in the images of the experimental group. These results indicate that the atmospheric pressure plasma treatment with argon gas imparts superhydrophilicity, without changing the properties of the pure titanium plate surface. It was also clarified that it affects the initial adhesion of bone marrow cells and the induction of hard tissue differentiation.


Assuntos
Argônio/farmacologia , Osseointegração/efeitos dos fármacos , Gases em Plasma/química , Animais , Argônio/química , Pressão Atmosférica , Células da Medula Óssea/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Masculino , Microscopia Eletrônica de Varredura/métodos , Osseointegração/fisiologia , Osteogênese/efeitos dos fármacos , Espectroscopia Fotoeletrônica/métodos , Gases em Plasma/farmacologia , Ratos , Ratos Sprague-Dawley , Propriedades de Superfície , Titânio/química , Microtomografia por Raio-X/métodos
7.
J Nanosci Nanotechnol ; 21(12): 6151-6159, 2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34229816

RESUMO

In this work, we demonstrate controlled introduction of O-functional groups on commercial carbon nanotube fibers (CNTFs) with different nanotube morphologies obtained by dry- and wet-spinning by treatment with gaseous ozone (O3(g)). Our test samples were (1) wet-spun fibers of smalldiameter (1-2 nm) singlewall (SW)-CNTs and (2) dry-spun fibers containing large-diameter (20 nm) multiwall (MW)-CNTs. Our results indicate that SW-CNTFs undergo oxygenation to a higher extent than MW-CNTFs due to the higher reactivity of SW-CNTs with a larger curvature strain. Oxygenation resulting from O3 exposure was evidenced as increase in surface O atomic% (at% by X-ray photoelectron spectroscopy, XPS) and as reductions in G/D (by Raman spectroscopy) as well as electrical conductivities due to changes in nanotube graphitic structure. By XPS, we identified the emergence of various types of O-functionalities on the fiber surfaces. After long duration O3 exposure (>300 s for SW-CNTFs and >600 s for MW-CNTFs), both sp² C═O (carbonyl) and sp³ C-O moieties (ether/hydroxy) were observed on fiber surfaces. Whereas, only sp³ C-O (ether/hydroxy) components were observed after shorter exposure times. O3 treatment led to only changes in surface chemistry, while the fiber morphology, microstructure and dimensions remained unaltered. We believe the surface chemistry controllability demonstrated here on commercial fibers spun by different methods containing nanotubes of different structures is of significance in aiding the practical application development of CNTFs.


Assuntos
Nanotubos de Carbono , Ozônio , Fibra de Carbono , Condutividade Elétrica , Espectroscopia Fotoeletrônica
8.
Molecules ; 26(11)2021 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-34205177

RESUMO

Fibrous Ti/Ce oxide photocatalysts were prepared for the first time by a biomimetic solution process using short flax fibers (flax straw processing waste) as a biotemplate. Titanium polyhydroxy complex solutions with 3% and 5% cerium were used as precursors. Flax fibers were impregnated in an autoclave under hydrothermal conditions. Ti/Ce oxides were obtained from the biotemplate by annealing at 600 °C. The photocatalytic activity of the Ti/Ce oxides was studied by the adsorption and decomposition of the dye rhodamine B under UV irradiation. The photocatalytic decomposition of the dye was 50% and 75% faster for Ti/Ce oxides with 3% and 5% Ce, respectively, than for the analogous undoped fibrous TiO2. The morphologies, textures, and structures of the photocatalysts were studied by scanning electron microscopy, low temperature N2 adsorption/desorption, UV-Vis spectroscopy, and X-ray and XPS analytical methods. It was shown that the introduction of Ce into the precursor solution increased the surface irregularity of the Ti/Ce oxide crystallites compared to pure TiO2. This effect scaled with the Ce concentration. Ce improved the UV light absorption of the material. The Ti/Ce oxides contained Ce4+/Ce3+ pairs that played an important role in redox processes and intensified the photocatalytic activity.


Assuntos
Cério/química , Linho/química , Rodaminas/análise , Titânio/química , Adsorção , Catálise , Relação Dose-Resposta a Droga , Microscopia Eletrônica de Varredura , Fotoquímica , Espectroscopia Fotoeletrônica
9.
Molecules ; 26(12)2021 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-34208392

RESUMO

Lyocell fabrics are widely applied in textiles, however, its high flammability increases the risk of fire. Therefore, to resolve the issue, a novel biomass-based flame retardant with phosphorus and nitrogen elements was designed and synthesized by the reaction of arginine with phosphoric acid and urea. It was then grafted onto the lyocell fabric by a dip-dry-cure technique to prepare durable flame-retardant lyocell fabric (FR-lyocell). X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated that the flame retardant was successfully introduced into the lyocell sample. Thermogravimetric (TG) and Raman analyses confirmed that the modified lyocell fabric featured excellent thermal stability and significantly increased char residue. Vertical combustion results indicated that FR-lyocell before and after washing formed a complete and dense char layer. Thermogravimetric Fourier-transform infrared (TG-FTIR) analysis suggested that incombustible substances (such as H2O and CO2) were produced and played a significant fire retarding role in the gas phase. The cone calorimeter test corroborated that the peak of heat release rate (PHRR) and total heat release (THR) declined by 89.4% and 56.4%, respectively. These results indicated that the flame retardancy of the lyocell fabric was observably ameliorated.


Assuntos
Arginina/química , Retardadores de Chama/síntese química , Ácidos Fosfóricos/química , Têxteis/análise , Ureia/química , Animais , Calorimetria/métodos , Temperatura Alta , Espectroscopia Fotoeletrônica/métodos , Fenômenos Físicos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
10.
Int J Mol Sci ; 22(13)2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34206400

RESUMO

Seeds of common bean (Phaseolus vulgaris L.), of the Etna variety, were treated with low-pressure oxygen plasma sustained by an inductively coupled radiofrequency discharge in the H-mode for a few seconds. The high-intensity treatment improved seed health in regard to fungal contamination. Additionally, it increased the wettability of the bean seeds by altering surface chemistry, as established by X-ray photoelectron spectroscopy, and increasing surface roughness, as seen with a scanning electron microscope. The water contact angle at the seed surface dropped to immeasurably low values after a second of plasma treatment. Hydrophobic recovery within a month returned those values to no more than half of the original water contact angle, even for beans treated for the shortest time (0.5 s). Increased wettability resulted in accelerated water uptake. The treatment increased the bean radicle length, which is useful for seedling establishment in the field. These findings confirm that even a brief plasma treatment is a useful technique for the disinfection and stimulation of radicle growth. The technique is scalable to large systems due to the short treatment times.


Assuntos
Germinação/efeitos dos fármacos , Phaseolus/efeitos dos fármacos , Phaseolus/crescimento & desenvolvimento , Gases em Plasma/farmacologia , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Espectroscopia Fotoeletrônica , Desenvolvimento Vegetal/efeitos dos fármacos , Sementes/ultraestrutura , Propriedades de Superfície , Água , Molhabilidade
11.
Int J Biol Macromol ; 182: 2066-2075, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34087297

RESUMO

Herein, a novel strategy for surface functionalization and drug loading of cellulose nanocrystals (CNCs) through formation of hydrazone bonds between functionalized CNCs and aldehyde group containing polyethylene glycol (CHO-PEG)/anticancer drug doxorubicin (DOX) was reported for the first time. DOX could be loaded on PEGylated CNCs with high capacity and released from drug complexes (P-CNCs-D) with pH dependent behavior. The biological evaluation results demonstrated that drug carriers (CNCs-EBO-NH) showed negative cytotoxicity while DOX could be transported into cells and exhibits desirable anticancer effects. As compared with other method, the method developed in this work is rather simple and effective and can be achieved for simultaneous for surface functionalization and drug loading in a one-pot route. This work will open a new avenue for fabrication of various multifunctional composites based on other carbohydrate polymers or materials and to explore their applications in biomedical fields.


Assuntos
Celulose/química , Sistemas de Liberação de Medicamentos , Nanopartículas/química , Animais , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/farmacologia , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Endocitose/efeitos dos fármacos , Células Hep G2 , Humanos , Concentração de Íons de Hidrogênio , Camundongos Endogâmicos BALB C , Nanopartículas/ultraestrutura , Espectroscopia Fotoeletrônica , Espectroscopia de Prótons por Ressonância Magnética , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura , Termogravimetria , Carga Tumoral/efeitos dos fármacos
12.
J Environ Manage ; 294: 113046, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34130139

RESUMO

The development of highly efficient photocatalysts is crucial for the remediation of organic pollutants. Herein, we reported a facile synthesis of oxygen vacancy rich Bi(OH)SO4·H2O photocatalyst by the control of precursor. The samples were characterized by XRD, scanning electron microscope, electron paramagnetic resonance, X-ray photoelectron spectroscopy etc. With more oxygen vacancies introduced, the photocatalytic activity on the degradation of RhB and tetracycline was significantly boosted. Density functional theory calculation was used to further reveal the influence of oxygen vacancy on the band structure of Bi(OH)SO4·H2O. The results and finding of this work are helpful for the development of sustainable environmental protection.


Assuntos
Oxigênio , Tetraciclina , Antibacterianos , Catálise , Espectroscopia Fotoeletrônica
13.
J Phys Chem Lett ; 12(23): 5503-5511, 2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34087076

RESUMO

The properties of aerosols are of paramount importance in atmospheric chemistry and human health. The hydrogen bond network of glycerol-water aerosols generated from an aqueous solution with different mixing ratios is probed directly with X-ray photoelectron spectroscopy. The carbon and oxygen X-ray spectra reveal contributions from gas and condensed phase components of the aerosol. It is shown that water suppresses glycerol evaporation up to a critical mixing ratio. A dielectric analysis using terahertz spectroscopy coupled with infrared spectroscopy of the bulk solutions provides a picture of the microscopic heterogeneity prevalent in the hydrogen bond network when combined with the photoelectron spectroscopy analysis. The hydrogen bond network is composed of three intertwined regions. At low concentrations, glycerol molecules are surrounded by water forming a solvated water network. Adding more glycerol leads to a confined water network, maximizing at 22 mol %, beyond which the aerosol resembles bulk glycerol. This microscopic view of hydrogen bonding networks holds promise in probing evaporation, diffusion dynamics, and reactivity in aqueous aerosols.


Assuntos
Aerossóis/química , Glicerol/química , Espectroscopia Fotoeletrônica/métodos , Água/química , Aerossóis/análise , Glicerol/análise , Ligação de Hidrogênio , Soluções/análise , Soluções/química , Água/análise
14.
Molecules ; 26(9)2021 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-34067007

RESUMO

As film-forming agents, fillers and adsorbents, microplastics are often added to daily personal care products. Because of their chemical stability, they remain in the environment for thousands of years, endangering the safety of the environment and human health. Therefore, it is urgent to find an environmentally friendly substitute for microplastics. Using n-octyltrimethoxysilane (OTMS) and tetraethoxysilane (TEOS) as silicon sources, a novel, environmentally friendly, organic hollow mesoporous silica system is designed with a high loading capacity and excellent adsorption characteristics in this work. In our methodology, sandalwood essential oil (SEO) was successfully loaded into the nanoparticle cavities, and was involved in the formation of Pickering emulsion as well, with a content of up to 40% (w/w). The developed system was a stable carrier for the dispersion of SEO in water. This system can not only overcome the shortcomings of poor water solubility and volatility of sandalwood essential oil, but also act as a microplastic substitute with broad prospects in the cosmetics and personal care industry, laying a foundation for the preparation and applications of high loading capacity microcapsules in aqueous media.


Assuntos
Portadores de Fármacos/química , Óleos Voláteis/química , Compostos Orgânicos/química , Óleos Vegetais/química , Sesquiterpenos/química , Dióxido de Silício/química , Cápsulas , Emulsões , Espectroscopia Fotoeletrônica , Porosidade , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Vibração , Água/química
15.
Int J Biol Macromol ; 182: 1445-1454, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34015404

RESUMO

Cancer is becoming a major threat to national public health security. The integration of disease diagnosis and monitoring with treatment has become a hot spot for researchers. The amorphous calcium phosphate (ACP) nanoparticles prepared by the group in the previous stage could not precisely treat the lesion without tumor targeting and imaging characteristics. In this paper, water-soluble hyaluronic acid fluorescent carbon nanoparticles (HA-FCNs) were prepared and co-interacting with ACP nanoparticles to form hyaluronic acid fluorescent carbon/amorphous calcium phosphate (HA-FCNs/ACP) nanoparticles. The basic characteristics were characterized and the biological characteristics before and after drug loading were evaluated. HA-FCNs/ACP nanoparticles have good hemocompatibility, pH responsiveness, and enzymatic release. HA-FCNs and HA-FCNs/ACP nanoparticles are dispersed in the cytoplasm through the overexpressed CD44 receptors, which are actively targeted into A549 cells. Besides, the migration of A549 cells would be inhibited after cells were treated with drug-loaded nanomaterials. Therefore, the as-prepared nanoparticles can be used to monitor and treat focal sites through tumor-targeting bioimaging, pH-responsive, and enzymatic drug release properties, thus enabling integrated diagnosis and treatment.


Assuntos
Antineoplásicos/farmacologia , Fosfatos de Cálcio/síntese química , Portadores de Fármacos/síntese química , Ácido Hialurônico/síntese química , Carbono/química , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Liberação Controlada de Fármacos , Fluorescência , Hemólise/efeitos dos fármacos , Humanos , Nanopartículas/química , Nanopartículas/ultraestrutura , Espectroscopia Fotoeletrônica , Espectroscopia de Prótons por Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
16.
J Photochem Photobiol B ; 220: 112214, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34049181

RESUMO

We investigate the photon/matter interactions between soft X-rays and three selected polypeptides, poly-glycine (poly-Gly), poly-L-arginine (poly-Arg), and poly-l-lysine (poly-Lys), where the effects of molecular packing under the influence of solvent, e.g., water, substrates (Au foil or Si wafer) and X-ray irradiation under different durations were systematically investigated. Compared with negligible photo-damage on bare polypeptide powders, significantly enhanced degradation in pre-solvated polypeptides was observed likely because of the formation photo-generated radicals. X-ray photoemission spectroscopy (XPS) were employed as the analysis means to identify and quantify the chemical changes, especially the high-resolution photoemission spectra of C 1s, O 1s, N 1s and their evolution under continuous X-ray irradiation. The photo-degradation was found to preferentially occur on the CO entity in poly-Gly and the guanidinium group in poly-Arg. In poly-Arg, deprotonation occurs via the switch from zwittterionic to a neutral configuration, whereas poly-Lys deprotonates by directly losing the corresponding amine. The critical role of the interactions between amino acids, the building blocks of protein and almost all forms of biological activities, and the free-radical-generating living environment under irradiation was critically analyzed. The present study found that the preparation history of a sample, especially its inadvertent exposure to the sources of H2O, O2 and OH, could significantly alter the outcome of a radiation-related chemical process. Implications on the non-destructive probe of biologically important systems using physical methods involving X-rays were discussed as well.


Assuntos
Luz , Peptídeos/efeitos da radiação , Peptídeos/química , Espectroscopia Fotoeletrônica , Solubilidade , Raios X
17.
Int J Biol Macromol ; 183: 1222-1235, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-33984386

RESUMO

Bacterial contamination in implanted biomedical devices is a critical daily concern. The most used material for permanent implant in biomedical field is Ti6Al4V alloy due to its beneficial mechanical properties and high biocompatibility. Accordingly, in this work different polymeric antibacterial coatings poly(N-vinyl pyrrolidone) (PVP), hyaluronic acid (HA) and chitosan (CHI) were developed and comparatively analysed for Ti6Al4V surface covering. The adhesion of these coatings to Ti6Al4V substrates were carried out after the conjugation of these polymers with the so well-known bioadhesive properties of catechol (CA) anchor group. These surface modifications were characterized by X-ray photoelectronic spectroscopy, contact angle measurements and atomic force microscopy. In addition, the stability of CA-conjugated polymeric coatings was compared with the coatings formed with unconjugated polymers. Finally, the cytocompatibility and antibacterial properties against gram-positive and gram-negative strains on coated Ti6Al4V substrates were assessed confirming the effectiveness of these polymeric coatings against bacterial infections for future applications in protecting biomedical implants.


Assuntos
Ligas/síntese química , Antibacterianos/síntese química , Catecóis/química , Ácido Hialurônico/química , Pirrolidinonas/química , Ligas/química , Ligas/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Linhagem Celular , Quitosana , Materiais Revestidos Biocompatíveis/síntese química , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Teste de Materiais , Testes de Sensibilidade Microbiana , Microscopia de Força Atômica , Espectroscopia Fotoeletrônica , Próteses e Implantes , Propriedades de Superfície , Titânio/química , Titânio/farmacologia
18.
Int J Biol Macromol ; 183: 1560-1573, 2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34022317

RESUMO

This work describes the preparation of palladium-based catalyst supported on magnetic chitosan (Pd@IO-Chitosan) for Suzuki Miyaura C-C coupling reaction. The Pd@IO-Chitosan catalyst was characterized using different spectroscopic and microscopic techniques such as Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), vibrating sample magnetometer (VSM), X-ray powder diffraction (XRD), X-ray Absorption Near Edge Structure (XANES) Spectroscopy and X-ray photoelectron spectroscopy (XPS). Pd@IO-Chitosan was further analysed by thermogravimetric analysis (TGA) in order to determine its thermal behavior. The catalyst comprised Pd, PdO species stabilised by chitosan that facilitated Suzuki coupling reactions. Palladium loading as low as 0.0055 mol% was found to be effective for aqueous Suzuki cross-couplings with excellent yields of over 99%. The catalyst could be recycled and reused at least 12 times with no significant decrease in its catalytic activity.


Assuntos
Quitosana/química , Nanopartículas Magnéticas de Óxido de Ferro/química , Paládio/química , Catálise , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria , Difração de Raios X
19.
Int J Biol Macromol ; 182: 1843-1851, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34029583

RESUMO

The promising adsorbent like graphene oxide (GO), chitosan (CS) and amine functionalized graphene oxide (AGO) decorated chitosan (CS) namely AGO@CS composite beads was efficiently prepared for defluoridation studies. The prepared AGO@CS composite beads possess enriched defluoridation capacity (DC) of 4650 mgF- kg-1. Batch method was used to optimize the maximum DC of AGO@CS composite beads. The physicochemical properties of AGO@CS composite beads were explored by numerous instrumental techniques viz., FTIR, Raman, XPS, SEM and TGA investigation. The experimental values of AGO@CS composite beads for fluoride removal at various temperature conditions were assessed with adsorption isotherms, kinetic and thermodynamic studies. The possible defluoridation mechanism of AGO@CS beads was mostly proposed that electrostatic attraction. The reusability and field investigation results of AGO@CS beads shows they are regenerable and applicable at field circumstances.


Assuntos
Aminas/química , Quitosana/síntese química , Fluoretos/isolamento & purificação , Grafite/síntese química , Microesferas , Poluentes Químicos da Água/isolamento & purificação , Água/química , Adsorção , Quitosana/química , Grafite/química , Concentração de Íons de Hidrogênio , Íons , Cinética , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Análise Espectral Raman , Temperatura , Termogravimetria , Fatores de Tempo
20.
Int J Nanomedicine ; 16: 3201-3216, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34007174

RESUMO

Purpose: Polyetheretherketone (PEEK) exhibits high mechanical strengths and outstanding biocompatibility but biological inertness that does not excite the cell responses and stimulate bone formation. The objective of this study was to construct submicro-nano structures on PEEK by femtosecond laser (FSL) for exciting the responses of MC3T3-E1 cells and gingival epithelial (GE) cells, which induce regeneration of bone/gingival tissues for long-term stability of dental implants. Materials and Methods: In this study, submicro-nano structures were created on PEEK surface by FSL with power of 80 mW (80FPK) and 160 mW (160FPK). Results: Compared with PEEK, both 80FPK and 160FPK with submicro-nano structures exhibited elevated surface performances (hydrophilicity, surface energy, roughness and protein absorption). Furthermore, in comparison with 80FPK, 160FPK further enhanced the surface performances. In addition, compared with PEEK, both 80FPK and 160FPK significantly excited not only the responses (adhesion, proliferation, alkaline phosphatase [ALP] activity and osteogenic gene expression) of MC3T3-E1 cells but also responses (adhesion as well as proliferation) of GE cells of human in vitro. Moreover, in comparison with 80FPK, 160FPK further enhanced the responses of MC3T3-E1 cells/GE cells. Conclusion: FSL created submicro-nano structures on PEEK with elevated surface performances, which played crucial roles in exciting the responses of MC3T3-E1 cells/GE cells. Consequently, 160FPK with elevated surface performances and outstanding cytocompatibility would have enormous potential as an implant for dental replacement.


Assuntos
Células Epiteliais/citologia , Células Epiteliais/efeitos da radiação , Gengiva/citologia , Cetonas/química , Lasers , Nanoestruturas/química , Tamanho da Partícula , Polietilenoglicóis/química , Adsorção , Fosfatase Alcalina/metabolismo , Animais , Adesão Celular , Linhagem Celular , Proliferação de Células , Forma Celular , Células Epiteliais/ultraestrutura , Regulação da Expressão Gênica , Humanos , Microscopia de Força Atômica , Osteogênese/genética , Espectroscopia Fotoeletrônica , Propriedades de Superfície , Água/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...