Thermo-stable hollow magnetic microspheres: preparation, characterization and recyclable catalytic applications

Abstract

Thermo-stable hollow magnetic microspheres are prepared by layer-by-layer (LbL) assembly on a uniform melamineformaldehyde resin microsphere template coated by silica and calcination for burning off organic resin. Trypsin is immobilised by their coated polydopamine layer, and nanogolds are assembled onto microspheres by LbL method for catalytic applications. The morphologies and hollow structures are observed by scanning electron microscope and transmission electron microscope. The characteristics are investigated by Fourier transfer infrared spectra, thermogravimetric analysis and vibrating sample magnetometer. Meanwhile, the catalytic characteristics of nanogolds and trypsin are evaluated by ultraviolet-visible spectra. The prepared hollow thermo-stable magnetic microspheres are narrowdispersed with relatively low coefficient of variation, and their size ranging from 0.5 μm to 5.0 μm and saturation magnetization (4-30 emu·g -1 ) can be regulated by different conditions. Combined with magnetic separation and calcination activation or regeneration, these microspheres can also be reused for over 20 times for nanogold catalyst and over 32 times for trypsin catalyst reconjugation without any significant loss in catalytic activity, indicating their considerable potential for recyclable catalytic applications. in our previous research, and importantly, MF organic template could simply be removed by calcination. Recently, MF microspheres with various diameters in the range of 0.5-5.0 μm were synthesised in our research. 23 The size could easily be changed by altering the

Magnetically Responsive Enzyme and Hydrogen-bonded Organic Framework Biocomposites for Biosensing

“…After the tests, we switched the flow from the analyte solution to deionized water to wash the chip and the biocomposite and, after the removal of the magnet, the particles were collected at the outlet of the chip (Figure 4d) and analyzed. XRD and SEM analysis confirmed that the crystal structure and morphology of the biocomposites were preserved (Figure S10,11,16). These proof-of-concept experiments demonstrated not only that magnetically responsive and biocatalytically active BioHOF-1 biocomposites can be positioned and localized in microfluidic devices during the sensing activity, but also that subsequently the BioHOF-1 biocomposite can be re-collected.…”

“…[10][11][12][13][14] We note that, on a laboratory scale, the combination of enzymes and magnetic responsiveness has been successfully applied to the synthesis of fine chemicals, biosensing, and lab-on-a-chip devices. [10,[15][16][17][18] As a result, enzyme immobilization in magnetically active porous materials is a fervent research field. [2,19,20] investigation and design of enzyme@HOF systems for biocatalysis and biosensing applications.…”

Insights into Sustainable Glucose Oxidation Using Magnetically Recoverable Biocatalysts

“…They are time and energy consuming and result in catalyst losses. Magnetically recoverable catalysts allow for easy magnetic separation, leading to energy conservation, and cheaper and more pure target products. − In a number of cases, iron oxide nanoparticles (NPs), giving magnetic properties to the catalyst, may enhance the catalytic activity via an electron transfer , or due to changes in the reaction mechanism, favoring target molecules. , The immobilization of enzymes on magnetic NPs or magnetic supports is an upcoming trend as well. − …”

Multifunctional magnetic-responsive hydrogels to engineer tendon-to-bone interface

“…[1], [91], [92] For example under the influence of an electromagnetic field (EMF), the release of an anticancer drug, doxorubicin, co-encapsulated with magnetic nanoparticles (Fe3O4) in polylactide spheres was prolonged without a burst effect which ensures minimal exposure for the healthy cells, and locally increases drug release. [93] Another work [94] reported the feasibility of the encapsulation of hybrid chitosan/hyaluronic acid nanoparticles by spray drying into microspheres with an aerodynamic diameter of approximately 2.6 µm for lung delivery. The homogeneously distribution of MNPs in this carrier resulted in a dry powder with appropriate aerodynamic properties.…”

“…The homogeneously distribution of MNPs in this carrier resulted in a dry powder with appropriate aerodynamic properties. [94] Magnetic alginate microspheres have also been used in another study to deliver neuron growth factor [1] in a control manner assisted by the application of EMF targeting PC12 cells, a cell line derived from a rat 18 pheochromocytoma. [56] The NGF release in combination with the magnetic field was able to promote cellular differentiation of these cells towards neuronal regeneration.…”