Electrospinning has been exploited for almost one century to process polymers and related materials into nanofibers with controllable compositions, diameters, porosities, and porous structures for a variety of applications. Owing to its high porosity and large surface area, a non‐woven mat of electrospun nanofibers can serve as an ideal scaffold to mimic the extracellular matrix for cell attachment and nutrient transportation. The nanofiber itself can also be functionalized through encapsulation or attachment of bioactive species such as extracellular matrix proteins, enzymes, and growth factors. In addition, the nanofibers can be further assembled into a variety of arrays or architectures by manipulating their alignment, stacking, or folding. All these attributes make electrospinning a powerful tool for generating nanostructured materials for a range of biomedical applications that include controlled release, drug delivery, and tissue engineering.
Summary: A new phosphorylated derivative of carboxymethylcellulose and amidic carboxymethylcellulose containing one phosphate group for each disaccharide unit was synthesized using sodium trimetaphospahte (STMP) as the phosphating agent. The new polysaccharide was characterized by infrared spectroscopy (FT-IR) and the amount of phosphate groups was determined by elemental analysis. These modified polysaccharides were used both to prepare 3D scaffolds and functionalize titanium oxide surfaces with the aim to improve the osseointegration with the host tissue. The presence of phosphate groups modify the physical-chemical properties of the hydrogels with respect to the native ones. The evaluation of the bioactivity of the phosphorylated carboxymethylcellulose hydrogels towards osteoblast-like cells showed a significant increase in the osteocalcin production. The modified surfaces were chemically characterized by means of X-ray photoelectron spectroscopy (XPS) and FT-IR, whereas the surface topography was analysed by Atomic Force Measurements (AFM) measurements before and after the polysaccharide coating. In vitro biological tests using osteoblast-like cells demonstrated that phosphorylated carboxymethylcellulose functionalized TiO2 surfaces promoted better cell adhesion and significantly enhanced their proliferation. These findings suggest that the phosphate polysaccharide both as a 3D scaffold and as a surface coating promotes osteoblast growth potentially improving the biomaterial osseointegration rate. 相似文献
A new type of bioreducible poly(amido amine) copolymer is synthesized by the Michael addition polymerization of cystamine bisacrylamide (CBA) with 4‐aminobutylguanidine (agmatine, AGM) and 4‐aminobutanol (ABOL). Since the positively charged guanidinium groups of AGM and the hydroxybutyl groups of ABOL in the side chains have shown to improve the overall transfection efficiency of poly(amido amine)s, it is hypothesized that poly(CBA‐ABOL/AGM) synthesized at the optimal ratio of both components would result in high transfection efficiency and minimal toxicity. In this study, a series of the poly(CBA‐ABOL/AGM) copolymers is synthesized as gene carriers. The polymers are characterized and luciferase transfection efficiencies of the polymers in various cell lines are investigated to select the ideal ratio between AGM and ABOL. The poly(CBA‐ABOL/AGM) containing 80% AGM and 20% ABOL has shown the best transfection efficiency with the lowest cytotoxicity, indicating that this polymer is very promising as a potent and nontoxic gene carrier.
Most previous studies on coupled dynamical systems assume that all interactions between oscillators take place uniformly in time,but,in reality,this does not necessarily reflect the usual scenario. The heterogeneity in the timings of such interactions strongly influences the dynamical processes. Here,we introduce a time-evolving state-space-dependent coupling among an ensemble of identical coupled oscillators,where individual units are interacting only when the mean state of the system lies within a certain proximity of the phase space. They interact globally with mean-field diffusive coupling in a certain vicinity and behave like uncoupled oscillators with self-feedback in the remaining complementary subspace. Interestingly due to this occasional interaction,we find that the system shows an abrupt explosive transition from oscillatory to death state. Further,in the explosive death transitions,the oscillatory state and the death state coexist over a range of coupling strengths near the transition point. We explore our claim using Van der Pol,FitzHugh-Nagumo and Lorenz oscillators with dynamic mean field interaction. The dynamic interaction mechanism can explain sudden suppression of oscillations and concurrence of oscillatory and steady state in biological as well as technical systems.https://doi.org/10.1209/0295-5075/133/40003 相似文献
This review described the synthetic methods, chemical reactivity and biological applications of furan carboxamide compounds. Furan-carboxamides are reported to have important and variable biological properties. The aim of this review is to highlight the chemistry and biological importance of this class of bioactive compounds. The basic sections covers: structure studies, synthetic methods pathways, synthesis of different heterocycles, reactions and biological applications. The reactions mechanisms of the unexpected products are discussed. The present study covers all the published work on the furan-carboxamides until now. 相似文献
DNA aptamers are integrated into synthetic hydrogel networks with the aim of creating hydrogels that undergo volume changes when exposed to target molecules. Specifically, single‐stranded DNA aptamers in cDNA‐bound, extended state are incorporated into hydrogel networks as cross‐links, so that the nanoscale conformational change of DNA aptamers upon binding to target molecules will induce macroscopic volume decreases of hydrogels. Hydrogels incorporating adenosine triphosphate (ATP)–binding aptamers undergo controllable volume decreases of up to 40.3 ± 4.6% when exposed to ATP, depending on the concentration of DNA aptamers incorporated in the hydrogel network, temperature, and target molecule concentration. Importantly, this approach can be generalized to aptamer sequences with distinct binding targets, as demonstrated here that hydrogels incorporating an insulin‐binding aptamer undergo volume changes in response to soluble insulin. This work provides an example of bioinspired hydrogels that undergo macroscopic volume changes that stem from conformational shifts in resident DNA‐based cross‐links. 相似文献
In this paper, we study the subtle effect of constraints on the quantum dynamics of a point particle moving on a non-trivial torus knot. The particle is kept on the knot by the constraints, generated by curvature and torsion. In the Geometry-Induced Potential (GIP) approach, the Schrödinger equation for the system yields new results in particle energy eigenvalues and eigenfunctions, in contrast with existing results that ignored curvature and torsion effects. Our results depend on Γ, parameter that characterizes the global features of both the embedding torus and, more interestingly, the knottedness of the path.https://doi.org/10.1209/0295-5075/132/10004 相似文献
Plasma-assisted combustion is a growing field of applied physics. In this study, a DC gliding arc plasma reactor used as part of a swirler stabilized burner was characterized to evaluate the discharge repetition frequency as a function of process parameters. The discharge was generated in fuel-rich premixed mixtures of air and natural gas. The repetition frequency was determined by applying a fast Fourier transform to the voltage waveforms. The results show that the mean voltage and mean current of the gliding arc remain almost constant as a function of the total gas flow rate. The increase in fuel concentration promotes a drop in the breakdown voltage, which leads to a rise in the discharge repetition frequency. However, for a fixed natural gas flow rate, the repetition frequency grows with the increased total mass flow rate due to a higher arc velocity.https://doi.org/10.1209/0295-5075/123/65001 相似文献
The application of ESEM technology to the conservation of cultural heritage and other fields is reviewed. Several applications
are presented with a focus on reaction kinetics and micro to nano-scale material behaviours, including time-lapse studies
of reaction kinetics for NaCl and NaNO3; verification of the stone decay mechanism at the site of Copan, Honduras; and ESEM/EDS analysis of the first photograph
(1826). A review of other ESEM applications reveals some important trends, especially in the materials science, electronics
and biosciences fields, such as quantitative ESEM/EDS; 1.8 nm resolution imaging of extreme insulators in VP/ESEM; and ESEM
analysis of emulsions and cells. 相似文献
