There is a great deal of interest in the development of nanoplatforms gathering versatility and multifunctionality. The strategy reported herein meets these requirements and further integrates a ...cell-friendly shell in a bio-inspired approach. By taking advantage of a cell mechanism of biomolecule transport using vesicles, we engineered a hybrid biogenic nanoplatform able to encapsulate a set of nanoparticles regardless of their chemistry or shape. As a proof of versatility, different types of hybrid nanovesicles were produced: magnetic, magnetic-metallic and magnetic-fluorescent vesicles, either a single component or multiple components, combining the advantageous properties of each integrant nanoparticle. These nanoparticle-loaded vesicles can be manipulated, monitored by MRI and/or fluorescence imaging methods, while acting as efficient nano-heaters. The resulting assets for targeting, imaging and therapy converge for the outline of a new generation of nanosystems merging versatility and multifunctionality into a bio-camouflaged and bio-inspired approach.
The controlled delivery of growth factors is a very challenging task because many different issues have to be addressed to develop the best suited system. A wide range of approaches have been ...employed for the controlled delivery of growth factors by hydrogels. Direct loading, electrostatic interaction, covalent binding, and the use of carriers are the main strategies presented in the literature. They are all detailed in the first part of this review. Recent work emphasizing biologically inspired strategies is also included. Also, both natural and synthetic materials are discussed. The second part comprises the methods to evaluate such delivery approaches. Both in vivo and in vitro techniques are presented. Improvements based on the discussed approaches may illustrate future paths toward the development of an ideal growth factor delivery system.
Cell microcarriers and microcapsules have presented a wide range of potential applications. This article overviews their role in biotechnology with focus on the progress accomplished using ...stimuli-responsive polymers. Key properties of cell microcarriers and microcapsules are identified, followed by a description of the chemistry and gel formation mechanism of some of the stimuli-responsive polymers used to design them. Production methods are introduced and characterization techniques for evaluating such microsystems are equally presented.
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ABSTRACT
Purpose
Cell labeling with magnetic nanoparticles can be used to monitor the fate of transplanted cells
in vivo
by magnetic resonance imaging. However, nanoparticles initially internalized ...in administered cells might end up in other cells of the host organism. We investigated a mechanism of intercellular cross-transfer of magnetic nanoparticles to different types of recipient cells via cell microvesicles released under cellular stress.
Methods
Three cell types (mesenchymal stem cells, endothelial cells and macrophages) were labeled with 8-nm iron oxide nanoparticles. Then cells underwent starvation stress, during which they produced microvesicles that were subsequently transferred to unlabeled recipient cells.
Results
The analysis of the magnetophoretic mobility of donor cells indicated that magnetic load was partially lost under cell stress. Microvesicles shed by stressed cells participated in the release of magnetic label. Moreover, such microvesicles were uptaken by naïve cells, resulting in cellular redistribution of nanoparticles. Iron load of recipient cells allowed their detection by MRI.
Conclusions
Cell microvesicles released under stress may be disseminated throughout the organism, where they can be uptaken by host cells. The transferred cargo may be sufficient to allow MRI detection of these secondarily labeled cells, leading to misinterpretations of the effectiveness of transplanted cells.
Most of the research efforts in magnetic targeting have been focused on the development of magnetic nanovectors, while the investigation of methods for tracking their magnetic targeting efficiency ...remains inappropriately addressed. We propose herein a miniaturized approach for appraising magnetophoretic mobility at the nanoscale.
A simple and easy-to-use chamber including a microtip as a magnetic attractor was developed to perform magnetophoretic measurement at the size scale of nano-objects, and under bright field or fluorescence microscopy. Different sets of magnetic nanocontainers were produced and their magnetophoretic mobility was investigated. Real-time observations of the Brownian motion of the nanocontainers were also carried out for simultaneous size determination.
Attraction of the nanocontainers at the microtip is demonstrated as a qualitative method that immediately distinguishes magnetically responsive nano-objects. The combination of the analysis of Brownian motion, together with the magnetophoretic mobility, inferred both the size, the magnetophoretic velocity and the magnetic content of the nanocontainers. Additionally, nanomagnetophoresis experiments under fluorescence microscopy provided information on the constitutive core/shell integrity of the nanocontainers and the co-internalization of a fluorescent cargo.
This nanomagnetophoresis method represents a promising tool to estimate the feasibility of magnetic targeting in laboratory routine.
Partially degalactosylated xyloglucan is a temperature-responsive polymer very promising for biotechnological purposes. We have studied the sol–gel transition of xyloglucan hydrogels with different ...galactose removal ratios. Rheological analysis was carried out, and the sol–gel transition temperature was determined at the cross-over point of
G′ and
G″. As a general trend, the sol–gel transition temperature was reduced as the galactose removal ratio increased, and at higher polymer concentrations. The reversible gelation was studied, and a thermal hysteresis was for the first time observed and discussed. The intrinsic viscosity
η values of the samples and the molar mass decreased with increasing galactose removal. Light scattering analysis demonstrated that the increase in the hydrophobic content by galactose removal induced an increase in polymer–polymer interactions and a change in the molecule conformation to a more compact structure.
In this study, the influence of different sterilization methods on the thermo-gelation and structural properties of xyloglucan hydrogels was investigated. Xyloglucan samples were treated by either ...70% ethanol, 70% isopropanol, γ-irradiation (10 kGy) at room temperature, γ-irradiation (10 kGy) in dry ice or autoclaving. These samples were tested for sterility by incubation with sterile Lysogeny Broth (LB) at room temperature, 30 °C and 37 °C for 30 days. According to the results obtained, xyloglucan hydrogels were only effectively sterilized by autoclaving or by γ-irradiation either at room temperature or in dry ice. These samples were analyzed by rheology measurements and dynamic and static light scattering analysis. Gamma-irradiation at room temperature markedly changed the polymer structure, preventing thermo-gelation. Only autoclaving and γ-irradiation in dry ice preserved the rheological properties of the polymer. The sol–gel transition as a function of the temperature was similar for these samples and the control sample.
This work evaluates an experimental set-up to coat superparamagnetic particles in order to protect them from gastric dissolution. First, magnetic particles were produced by coprecipitation of iron ...salts in alkaline medium. Afterwards, an emulsification/cross-linking reaction was carried out in order to produce magnetic polymeric particles. The sample characterization was performed by X-ray powder diffraction, laser scattering particle size analysis, optical microscopy, thermogravimetric analysis and vibrating sample magnetometry. In vitro dissolution tests at gastric pH were evaluated for both magnetic particles and magnetic polymeric particles. The characterization data have demonstrated the feasibility of the presented method to coat, and protect magnetite particles from gastric dissolution. Such systems may be very promising for oral administration.
Safety concerns related to magnetic field exposure Silva, Amanda K Andriola; Silva, Erica L; Egito, E Sócrates T ...
Radiation and environmental biophysics,
11/2006, Letnik:
45, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The recent development of superconducting magnets has resulted in a huge increase in human exposure to very large static magnetic fields of up to several teslas (T). Considering the rapid advances in ...applications and the great increases in the strength of magnetic fields used, especially in magnetic resonance imaging, safety concerns about magnetic field exposure have become a key issue. This paper points out some of these safety concerns and gives an overview of the findings about this theme, focusing mainly on mechanisms of magnetic field interaction with living organisms and the consequent effects.
Recently, there has been considerable interest in the development of materials whose surface properties can be dynamically modulated by external stimuli. Stimuli-responsive polymers and their ...hydrogels, also known as smart or intelligent systems, are promising candidates for surface modification because of their interesting characteristics. This article reviews the state-of-the art in thermoresponsive surfaces for cell culture and enzyme-free cell detachment. The paper initially describes different types of stimuli-sensitive polymers and then highlights temperature-sensitive ones, such as poly(
N-isopropylacrylamide), xyloglucan, and poloxamers. The review also discusses chemical routes to functionalize such thermoresponsive polymers before presenting a survey of the recent literature on the approaches concerning temperature-sensitive surfaces.
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