Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 53
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Neurosci Lett ; 715: 134626, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31726177

RESUMO

This study measured stimulus-evoked brain tissue oxygenation changes in a mouse model of Alzheimer disease (AD) and further explored the influence of exercise and angiotensin II-induced hypertension on these changes. in vivo two-photon phosphorescence lifetime microscopy was used to investigate local changes in brain tissue oxygenation following whisker stimulation. During rest periods, PO2 values close to the arteriolar wall were lower in the AD groups and the PO2 spatial decay as a function of distance to arteriole was increased by hypertension. During stimulation, tissue PO2 response had a similar spatial dependence across groups. Tissue PO2 response in post-stimulation period was larger in AD groups (e.g., AD6 and ADH6) than in the controls (WT6 and WTH6). After a 3-month voluntary exercise period, some of these changes were reversed in AD mice. This provides novel insight into tissue oxygen delivery and the impact of blood pressure control and exercise on brain tissue oxygenation in AD.

2.
J Cereb Blood Flow Metab ; 40(3): 501-512, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30829101

RESUMO

Despite the importance of understanding the regulation of microvascular blood flow in white matter, no data on subcortical capillary blood flow parameters are available, largely due to the lack of appropriate imaging methods. To address this knowledge gap, we employed two-photon microscopy using a far-red fluorophore Alexa680 and photon-counting detection to measure capillary red blood cell (RBC) flux in both cerebral gray and white matter, in isoflurane-anesthetized mice. We have found that in control animals, baseline capillary RBC flux in the white matter was significantly higher than in the adjacent cerebral gray matter. In response to mild hypercapnia, RBC flux in the white matter exhibited significantly smaller fractional increase than in the gray matter. Finally, during global cerebral hypoperfusion, RBC flux in the white matter was reduced significantly in comparison to the controls, while RBC flux in the gray matter was preserved. Our results suggest that blood flow in the white matter may be less efficiently regulated when challenged by physiological perturbations as compared to the gray matter. Importantly, the blood flow in the white matter may be more susceptible to hypoperfusion than in the gray matter, potentially exacerbating the white matter deterioration in brain conditions involving global cerebral hypoperfusion.

3.
Neurobiol Aging ; 88: 11-23, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31866158

RESUMO

Although vascular contributions to dementia and Alzheimer's disease (AD) are increasingly recognized, the potential brain oxygenation disruption associated with AD and whether preventive strategies to maintain tissue oxygenation are beneficial remain largely unknown. This study aimed to examine (1) whether brain oxygenation is compromised by the onset of AD and (2) how voluntary exercise modulates the influence of AD on brain oxygenation. In vivo 2-photon phosphorescence lifetime microscopy was used to investigate local changes of brain tissue oxygenation with the progression of AD and its modulation by exercise in the barrel cortex of awake transgenic AD mice. Our results show that cerebral tissue oxygen partial pressure (PO2) decreased with the onset of AD. Reduced PO2 was associated with the presence of small near-hypoxic areas, an increased oxygen extraction fraction, and reduced blood flow, observations that were all reverted by exercise. AD and age also increased the spatial heterogeneity of brain tissue oxygenation, which was normalized by exercise. Ex vivo staining also showed fewer amyloid-ß (Aß) deposits in the exercise group. Finally, we observed correlations between voluntary running distance and cerebral tissue oxygenation/blood flow, suggesting a dose-response relationship of exercise on the brain. Overall, this study suggests that compromised brain oxygenation is an indicator of the onset of AD, with the emergence of potential deleterious mechanisms associated with hypoxia. Furthermore, voluntary exercise enhanced the neurovascular oxygenation process, potentially offering a means to delay these changes.

4.
ACS Appl Mater Interfaces ; 12(2): 2390-2399, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31846287

RESUMO

Sodium/Potassium-ion batteries (SIBs/PIBs) have recently received tremendous attention because of their particular features of cost-effectiveness and promising energy density, which hold great potential for large-scale applications. Nevertheless, it still has a common bottleneck issue that is the sluggish kinetics of Na+/K+ intercalation, which raises more rigorous requirement on the electrode candidates regarding the morphology, dimension, and architecture. Herein, we have constructed unique MoSe2-based hybrid nanotubes with wall structures composed of highly disordered MoSe2 layers embedded in phosphorus and nitrogen co-doped carbon matrix (denoted MoSe2⊂PNC-HNTs), by a facile two-step strategy using Se nanorods as the dual-functional template, i.e., shape-directed agent and in situ selenization resources. Benefitting from the combined features of the one-dimensional (1D) hollow interior, hybrid wall structure with high disorder, and the phosphorus and nitrogen co-doping-induced abundant defect sites in the carbon matrix, the MoSe2⊂PNC-HNT anode exhibits high specific capacities of 280 and 262 mA h g-1 over 200 cycles at the current density of 0.1 A g-1 for Na+ and K+ storage, respectively, and achieves remarkable capacity retention rates of 87.0% at 2 A g-1 over 3500 cycles for Na-ion storage and 80.1% at 1 A g-1 after 500 cycles for K-ion storage.

5.
Water Environ Res ; 2019 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-31529658

RESUMO

This study evaluated the application of recuperative thickening (RT) to enhance anaerobic digestion (AD) performance for AD systems with thermal hydrolysis pretreatment (THP). RT was applied for two different reasons: (a) for increasing the sludge retention time (SRT) to degrade slowly hydrolyzable materials more efficiently and (b) for maintaining SRT at decreased hydraulic retention time (HRT) thus showing potential for increased AD throughput rates. A SRT increase from 15 to 30 days by RT application did not improve AD performance or hydrolysis rates significantly as 15-day SRT was already a factor 2 higher than the estimated washout SRT. When applying RT to increase throughput rates (HRT of 7 days) while maintaining 15-day SRT, no negative impact on biogas production or hydrolysis kinetics was observed. It was estimated that RT application on THP digesters can increase digester throughput by 100% and thus show clear potential for further AD intensification. PRACTITIONER POINTS: Increased SRT from 15 to 30 days through recuperative thickening application did not improve biogas production. A lower required minimum SRT (6-7 days) was estimated in THP-AD systems compared to conventional AD. Operation at decreased HRT by RT application resulted in similar AD performance under constant organic loading rates. A 100% increase in throughput rates can be applied using RT without decreasing AD performance.

6.
ACS Nano ; 13(9): 10179-10190, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31424917

RESUMO

Silicon-carbon (Si-C) hybrids have been proven to be the most promising anodes for the next-generation lithium-ion batteries (LIBs) due to their superior theoretical capacity (∼4200 mAh g-1). However, it is still a critical challenge to apply this material for commercial LIB anodes because of the large volume expansion of Si, unstable solid-state interphase (SEI) layers, and huge internal stresses upon lithiation/delithiation. Here, we propose an engineering concept of multiscale buffering, taking advantage of a nanosized Si-C nanowire architecture through fabricating specific microsized wool-ball frameworks to solve all the above-mentioned problems. These wool-ball-like frameworks, prepared at high yields, nearly matching industrial scales (they can be routinely produced at a rate of ∼300 g/h), are composed of Si/C nanowire building blocks. As anodes, the Si-C wool-ball frameworks show ultrastable Li+ storage (2000 mAh g-1 for 1000 cycles), high initial Coulombic efficiency of ∼90%, and volumetric capacity of 1338 mAh cm-3. In situ TEM proves that the multiscale buffering design enables a small volume variation, only ∼19.5%, reduces the inner stresses, and creates a very thin SEI. The perfect multiscale elastic buffering makes this material more stable compared to common Si nanoparticle-assembled counterpart electrodes.

7.
PLoS One ; 14(8): e0221547, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31469849

RESUMO

Chronic atherosclerosis may cause cerebral hypoperfusion and inadequate brain oxygenation, contributing to the progression of cognitive decline. In this study, we exploited two-photon phosphorescence lifetime microscopy to measure the absolute partial pressure of oxygen (PO2) in cortical tissue in both young and old LDLR-/-, hApoB100+/+ mice, spontaneously developing atherosclerosis with age. Capillary red-blood-cell (RBC) speed, flux, hematocrit and capillary diameter were also measured by two-photon imaging of FITC-labelled blood plasma. Our results show positive correlations between RBC speed, flux, diameter and capillary-adjacent tissue PO2. When compared to the young mice, we observed lower tissue PO2, lower RBC speed and flux, and smaller capillary diameter in the old atherosclerotic mice. The old mice also exhibited a higher spatial heterogeneity of tissue PO2, and RBC speed and flux, suggesting a less efficient oxygen extraction.

8.
Small ; 15(42): e1902881, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31433124

RESUMO

Research on sodium-ion batteries (SIBs) has recently been revitalized due to the unique features of much lower costs and comparable energy/power density to lithium-ion batteries (LIBs), which holds great potential for grid-level energy storage systems. Transition metal dichalcogenides (TMDCs) are considered as promising anode candidates for SIBs with high theoretical capacity, while their intrinsic low electrical conductivity and large volume expansion upon Na+ intercalation raise the challenging issues of poor cycle stability and inferior rate performance. Herein, the designed formation of hybrid nanoboxes composed of carbon-protected CoSe2 nanoparticles anchored on nitrogen-doped carbon hollow skeletons (denoted as CoSe2 @C∩NC) via a template-assisted refluxing process followed by conventional selenization treatment is reported, which exhibits tremendously enhanced electrochemical performance when applied as the anode for SIBs. Specifically, it can deliver a high reversible specific capacity of 324 mAh g-1 at current density of 0.1 A g-1 after 200 cycles and exhibit outstanding high rate cycling stability at the rate of 5 A g-1 over 2000 cycles. This work provides a rational strategy for the design of advanced hybrid nanostructures as anode candidates for SIBs, which could push forward the development of high energy and low cost energy storage devices.

9.
Water Environ Res ; 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332909

RESUMO

This study evaluated the role of bulk and substrate physics on hydrolysis rates and biogas yields in anaerobic digestion (AD) pretreated by thermal hydrolysis (THP). Although THP decreases sludge viscosity, no evidence was found that bulk viscosity impacted the biogas yield or hydrolysis kinetics. In addition, no significant difference between the biogas yields for different total solids concentrations nor floc sizes was detected. However, increased mixing speeds did increase biogas yields. As a result of thermal treatment, the model protein, bovine serum albumin, was harder to degrade in terms of both overall biodegradability and hydrolysis rates when their macrostructures were changed from liquid to gel and to solid structures; the opposite was true for the model polysaccharide, amylopectin. These results demonstrated that hydrolysis in THP-AD systems was impacted mostly by the physical properties of the substrate (gelation) rather than the bulk physical properties within the digester. PRACTITIONER POINTS: Bulk viscosity does not significantly impact hydrolysis efficiency (biogas yield). However, mixing speed impacts hydrolysis beyond biogas holdup effect. Increasing the amount of substrate-microbe collisions through increasing biomass concentration does not have an impact on hydrolysis efficiency or biogas yield. Proteins are harder to degrade when macrostructure changes from liquid to gel/solid as a result of heat treatment. Polysaccharides are easier to degrade when macrostructure changes from liquid to gel/solid as a result of heat treatment. The time required for digesters to reach peak biogas production rates increased with decreasing specific surface available on gel and solid structures.

10.
Elife ; 82019 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-31305237

RESUMO

Our understanding of how capillary blood flow and oxygen distribute across cortical layers to meet the local metabolic demand is incomplete. We addressed this question by using two-photon imaging of resting-state microvascular oxygen partial pressure (PO2) and flow in the whisker barrel cortex in awake mice. Our measurements in layers I-V show that the capillary red-blood-cell flux and oxygenation heterogeneity, and the intracapillary resistance to oxygen delivery, all decrease with depth, reaching a minimum around layer IV, while the depth-dependent oxygen extraction fraction is increased in layer IV, where oxygen demand is presumably the highest. Our findings suggest that more homogeneous distribution of the physiological observables relevant to oxygen transport to tissue is an important part of the microvascular network adaptation to local brain metabolism. These results will inform the biophysical models of layer-specific cerebral oxygen delivery and consumption and improve our understanding of the diseases that affect cerebral microcirculation.


Assuntos
Capilares/fisiologia , Córtex Cerebral/fisiologia , Circulação Cerebrovascular , Oxigênio/metabolismo , Animais , Camundongos , Pressão Parcial
11.
Artigo em Inglês | MEDLINE | ID: mdl-30691968

RESUMO

BACKGROUND: Functional magnetic resonance imaging (fMRI) in awake behaving mice is well positioned to bridge the detailed cellular-level view of brain activity, which has become available owing to recent advances in microscopic optical imaging and genetics, to the macroscopic scale of human noninvasive observables. However, though microscopic (e.g., two-photon imaging) studies in behaving mice have become a reality in many laboratories, awake mouse fMRI remains a challenge. Owing to variability in behavior among animals, performing all types of measurements within the same subject is highly desirable and can lead to higher scientific rigor. METHODS: We demonstrated blood oxygenation level-dependent fMRI in awake mice implanted with long-term cranial windows that allowed optical access for microscopic imaging modalities and optogenetic stimulation. We started with two-photon imaging of single-vessel diameter changes (n = 1). Next, we implemented intrinsic optical imaging of blood oxygenation and flow combined with laser speckle imaging of blood flow obtaining a mesoscopic picture of the hemodynamic response (n = 16). Then we obtained corresponding blood oxygenation level-dependent fMRI data (n = 5). All measurements could be performed in the same mice in response to identical sensory and optogenetic stimuli. RESULTS: The cranial window did not deteriorate the quality of fMRI and allowed alternation between imaging modalities in each subject. CONCLUSIONS: This report provides a proof of feasibility for multiscale imaging approaches in awake mice. In the future, this protocol could be extended to include complex cognitive behaviors translatable to humans, such as sensory discrimination or attention.


Assuntos
Imagem por Ressonância Magnética/métodos , Modelos Animais , Neuroimagem/métodos , Córtex Somatossensorial/fisiologia , Animais , Camundongos , Imagem Óptica/métodos , Optogenética/métodos , Córtex Somatossensorial/irrigação sanguínea , Vigília
12.
Materials (Basel) ; 11(12)2018 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-30469548

RESUMO

Multi-laser beam selective laser melting (SLM) technology based on a powder bed has been used to manufacture AlSi10Mg samples. The AlSi10Mg alloy was used as research material to systematically study the performance consistency of both the laser overlap areas and the isolated areas of the multi-laser beam SLM manufactured parts. The microstructures and mechanical properties of all isolated and overlap processing areas were compared under optimized process parameters. It was discovered that there is a raised platform at the junction of the overlap areas and the isolated areas of the multi-laser SLM samples. The roughness is significantly reduced after two scans. However, the surface roughness of the samples is highest after four scans. As the number of laser scans increases, the relative density of the overlap areas of the samples improves, and there is no significant change in hardness. The tensile properties of the tensile samples are poor when the overlap area width is 0, 0.1, or 0.2 mm. When the widths of the overlap areas are equal to or greater than 0.3 mm, there is no significant difference in the tensile strength between the overlap and the isolated areas.

13.
Biomacromolecules ; 19(8): 3351-3360, 2018 08 13.
Artigo em Inglês | MEDLINE | ID: mdl-29995388

RESUMO

As one of important biomaterials for localized drug delivery system, chitosan hydrogel still suffer several challenges, including poor mechanical properties, passive drug release behavior and lack of remote stimuli response. To address these challenges, a facile in situ hybridization method was reported for fabricate tough magnetic chitosan hydrogel (MCH), which remotely switched drug release from passive release to pulsatile release under a low frequency alternating magnetic field (LAMF). The in situ hybridization method avoided the aggregation of magnetic nanoparticles (MNPs) in hydrogel, which simultaneously brings 416% and 265% increase in strength and elastic modulus, respectively. The mechanical property enhancement was contributed by the physical crosslinking of in situ synthesized MNPs. When a LAMF with 15 min ON-15 min OFF cycles was applied to MCH, the fraction release showed zigzag shape and pulsatile release behavior with quick response. The cumulative release and fraction release of drug from MCH were improved by 67.2% and 31.9%, respectively. MTT results and cell morphology indicated that the MCH have excellent biocompatibility and no acute adverse effect on MG-63 cells. The developed tough MCH system holds great potential for applications in smart drug release system with noninvasive characteristics and magnetic field stimulated drug release behavior.


Assuntos
Quitosana/análogos & derivados , Liberação Controlada de Fármacos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Nanopartículas de Magnetita/química , Nanocompostos/química , Linhagem Celular Tumoral , Humanos , Campos Magnéticos
14.
Materials (Basel) ; 11(7)2018 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-29987242

RESUMO

A 3D Finite Element (FE) model was developed to investigate the thermal behaviour within the melt pool during point exposure to Selective Laser Melting (SLM) processed AlSi10Mg powder. The powder⁻solid transition, temperature-dependent thermal properties, melt pool convection, and recoating phase were taken into account. The effects of Exposure Time (ET) and Point Distance (PD) on SLM thermal behaviour were also investigated and showed that the short liquid phase time and high cooling rate of the melt pool reduced the viscosity of the melt pool at a lower ET or a higher PD. This resulted in poor wettability and the occurrence of balling and micropores. At a higher ET or lower PD the melt pool became unstable and allowed for easy formation of the self-balling phenomenon, as well as further partial remelting in the depth direction resulting in the creation of larger pores. The proper melt pool width (119.8 μm) and depth (48.65 μm) were obtained for a successful SLM process using an ET of 140 μs and a PD of 80 μm. The surface morphologies and microstructures were experimentally obtained using the corresponding processing conditions, and the results aligned with those predicted in the simulation.

15.
Carbohydr Polym ; 184: 214-220, 2018 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-29352914

RESUMO

Non-degradable plastic food packages threaten the security of environment. The cost-effective and biodegradable polymer films with good mechanical properties and low permeability are very important for food packages. Among of biodegradable polymers, PVA/chitosan (CS) biodegradable films have attracted considerable attention because of feasible film forming ability. However, PVA/CS biodegradable films suffered from poor mechanical properties. To improve mechanical properties of PVA/CS biodegradable films, we developed SiO2in situ to enhance PVA/CS biodegradable films via hydrolysis of sodium metasilicate in presence of PVA and chitosan solution. The tensile strength of PVA/CS biodegradable films was improved 45% when 0.6 wt.% SiO2 was incorporated into the films. Weight loss of PVA/CS biodegradable films was 60% after 30 days in the soil. The permeability of oxygen and moisture of PVA/CS biodegradable films was reduced by 25.6% and 10.2%, respectively. SiO2in situ enhanced PVA/CS biodegradable films possessed not only excellent mechanical properties, but also barrier of oxygen and water for food packages to extend the perseveration time.


Assuntos
Quitosana/química , Álcool de Polivinil/química , Dióxido de Silício/química , Embalagem de Alimentos , Concentração de Íons de Hidrogênio , Oxigênio/química , Resistência à Tração
16.
J Biophotonics ; 11(2)2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28700129

RESUMO

Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress and the diffusion coefficient of red blood cells (RBCs), are fundamental in understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic light scattering-optical coherence tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained three-dimensional volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of ~0.1 to 0.5 × 10-6 mm2 . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion.


Assuntos
Difusão Dinâmica da Luz , Eritrócitos/metabolismo , Fenômenos Mecânicos , Tomografia de Coerência Óptica , Algoritmos , Animais , Fenômenos Biomecânicos , Difusão , Feminino , Camundongos
17.
Pak J Med Sci ; 33(4): 997-1001, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29067081

RESUMO

OBJECTIVE: To investigate the clinical effect of budesonide nebulization in the treatment of ventilator associated pneumonia of newborns and its safety. METHODS: Forty-five newborns who had ventilator associated pneumonia and were admitted into the Binzhou People's Hospital between May 2014 and May 2015 were selected and included as an observation group. Moreover, another forty-five newborns who had ventilator associated pneumonia but did not undergo budesonide treatment in 2014 were randomly selected and included as a control group. Patients in the observation group were given budesonide suspension nebulization in addition to the conventional treatment. The evaluation indicators for therapeutic effect were compared between the two groups. The changes of head circumference, height and weight and death rate were observed by follow up after treatment. RESULTS: The mechanical ventilation time, time for recovering from chest X-ray scan and hospitalization time of patients in the observation group were shorter than that of the control group, and the difference had statistical significance (P<0.05). The oxygen index of the patients in the observation group was significantly improved compared to that of the control group, and the difference had statistical significance (P<0.05). Patients in the two groups were followed up for six months after discharge. The head circumference, height and weight of the patients in the observation group in the 3rd and 6th month were compared to those of the control group, suggesting no significant differences (P>0.05). The cumulative death rate of the observation group in the 6th month after treatment was significantly lower than that of the control group, and the difference had statistical significance (P<0.05). CONCLUSION: Treating ventilator associated pneumonia of newborns with budesonide nebulization can effectively shorten mechanical ventilation time, time for recovering from chest X-ray scan and hospitalization time, improve pulmonary diffusion function and reduce the death rate, without affecting the growth and development of patients in the future.

18.
Biomaterials ; 145: 192-206, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28869865

RESUMO

Visual in vivo degradation of hydrogel by fluorescence-related tracking and monitoring is crucial for quantitatively depicting the degradation profile of hydrogel in a real-time and non-invasive manner. However, the commonly used fluorescent imaging usually encounters limitations, such as intrinsic photobleaching of organic fluorophores and uncertain perturbation of degradation induced by the change in molecular structure of hydrogel. To address these problems, we employed photoluminescent carbon nanodots (CNDs) with low photobleaching, red emission and good biocompatibility as fluorescent indicator for real-time and non-invasive visual in vitro/in vivo degradation of injectable hydrogels that are mixed with CNDs. The in vitro/in vivo toxicity results suggested that CNDs were nontoxic. The embedded CNDs in hydrogels did not diffuse outside in the absence of hydrogel degradation. We had acquired similar degradation kinetics (PBS-Enzyme) between gravimetric and visual determination, and established mathematical equation to quantitatively depict in vitro degradation profile of hydrogels for the predication of in vivo hydrogel degradation. Based on the in vitro data, we developed a visual platform that could quantitatively depict in vivo degradation behavior of new injectable biomaterials by real-time and non-invasive fluorescence tracking. This fluorescence-related visual imaging methodology could be applied to subcutaneous degradation of injectable hydrogel with down to 7 mm depth in small animal trials so far. This fluorescence-related visual imaging methodology holds great potentials for rational design and convenient in vivo screening of biocompatible and biodegradable injectable hydrogels in tissue engineering.


Assuntos
Carbono/química , Corantes Fluorescentes/química , Hidrogel de Polietilenoglicol-Dimetacrilato/farmacologia , Injeções , Nanopartículas/química , Animais , Carbono/toxicidade , Fluorescência , Camundongos , Células NIH 3T3 , Nanopartículas/toxicidade , Nanopartículas/ultraestrutura , Tela Subcutânea/efeitos dos fármacos
19.
Carbohydr Polym ; 174: 904-914, 2017 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-28821147

RESUMO

Innovative drug delivery technologies based on smart hydrogels for localized on-demand drug delivery had aroused great interest. To acquire smart UV-crosslinkable chitosan hydrogel for NIR-triggered localized on-demanded drug release, a novel UV-crosslinkable and thermo-responsive chitosan was first designed and synthesized by grafting with poly N-isopropylacrylamide, acetylation of methacryloyl groups and embedding with photothermal carbon. The UV-crosslinkable unit (methacryloyl groups) endowed chitosan with gelation via UV irradiation. The thermo-responsive unit (poly N-isopropylacrylamide) endowed chitosan hydrogel with temperature-triggered volume shrinkage and reversible swelling/de-swelling behavior. The chitosan hybrid hydrogel embedded with photothermal carbon exhibited distinct NIR-triggered volume shrinkage (∼42% shrinkage) in response to temperature elevation as induced by NIR laser irradiation. As a demonstration, doxorubicin release rate was accelerated and approximately 40 times higher than that from non-irradiated hydrogels. The UV-crosslinkable and thermal-responsive hybrid hydrogel served as in situ forming hydrogel-based drug depot is developed for NIR-triggered localized on-demand release.


Assuntos
Quitosana/química , Sistemas de Liberação de Medicamentos , Hidrogéis/química , Raios Infravermelhos , Liberação Controlada de Fármacos , Temperatura Ambiente , Raios Ultravioleta
20.
Mater Sci Eng C Mater Biol Appl ; 76: 908-917, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28482606

RESUMO

The sub-microporous microarc oxidation (MAO) coating covered Ti implant with micro-scale gouges has been fabricated via a multi-step MAO process to overcome the compromised bone-implant integration. The as-prepared implant has been further mediated by post-heat treatment to compare the effects of -OH functional group and the nano-scale orange peel-like morphology on osseointegration. The bone regeneration, bone-implant contact interface, and biomechanical push-out force of the modified Ti implant have been discussed thoroughly in this work. The greatly improved push-out force for the MAO coated Ti implants with micro-scale gouges could be attributed to the excellent mechanical interlocking effect between implants and biologically meshed bone tissues. Attributed to the -OH functional group which promotes synostosis between the biologically meshed bone and the gouge surface of implant, the multi-step MAO process could be an effective strategy to improve the osseointegration of Ti implant.


Assuntos
Osseointegração , Materiais Revestidos Biocompatíveis , Oxirredução , Próteses e Implantes , Propriedades de Superfície , Titânio
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA