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    Home > Chemicals Industry > New Chemical Materials > York University "Chemistry·Science" self-assembled low molecular weight gelling agent injection microgel beads

    York University "Chemistry·Science" self-assembled low molecular weight gelling agent injection microgel beads

    • Last Update: 2021-09-23
    • Source: Internet
    • Author: User
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    【Abstract】 Recently, the David K.
    Smith research team of York University reported the preparation of hybrid self-assembled microgels by combining low molecular weight gelling agent (LMWG) DBS-CONHNH2 and natural polysaccharide calcium alginate polymer gelling agent (PG) Beads
    .
    Due to the fragility of self-assembled networks and the difficulty of maintaining any applied shape, LMWG-based microgel formulations are extremely rare
    .
    The hybrid beads contain interpenetrating LMWG and PG networks, and are obtained by an emulsion method, and can prepare spherical gel particles with a controllable size in the range of mm or μm
    .
    Related papers are published on "Chemical Science" with the title Self-assembled low-molecular-weight gelator injectable microgel beads for delivery of bioactive agents
    .
    Microgels based on LMWG/alginate can be easily prepared with reproducible diameters of <1μm (approximately 800 nm)
    .
    They are stable in water for several months at room temperature and can be injected through a syringe
    .
    The rapid assembly of LMWG during cooling plays a positive role in helping to control the diameter of the microgel beads
    .
    These LMWG microbeads retain the ability of the parent gel to deliver the biologically active molecule heparin, and enhance the growth of human mesenchymal stem cells in the cell culture medium
    .
    Therefore, this microgel may have future applications in tissue repair
    .
    This method of manufacturing LMWG microgels is a platform technology that can potentially be applied to various LMWGs with different functions, so it has a wide range of potentials
    .
    [Main picture see analysis] Fig.
    1 The chemical structure of sodium alginate and DBS-CONHNH2, and the vials prepared by emulsion method from left to right, DBS-CONHNH2/sodium alginate in millimeter beads and microgel beads Image of gel
    .
    Figure 2.
    Schematic diagram of preparation of DBS-CONHNH2/alginate gel beads and microgels by emulsion method
    .
    Heat the mixture of DBS-CONHNH2 (0.
    3% wt/vol) and alginate (0.
    5% wt/vol) until the LMWG is completely dissolved
    .
    In order to obtain hybrid gel beads, the hot solution was added dropwise to paraffin oil (2a)
    .
    Then the gel drop was collected by filtration (3a) and transferred to a CaCl 2 solution (5.
    0% wt/vol) to crosslink the alginate (4a)
    .
    Alternatively, in order to obtain microgels, the hot solution of DBS-CONHNH2/alginate is added dropwise to the mixture of paraffin oil and Span80 under stirring (2b)
    .
    After 1 hour, add CaCl2 (5.
    0% wt/vol) and stir the emulsion for another 20 minutes (3b)
    .
    The sample was then transferred to a Falcon tube, and the microgel particles were purified by washing with petroleum ether, ethanol and water multiple times and centrifugation cycles (4b)
    .
    Finally, the sample is transferred to a sample bottle and sonicated to help disperse the particles (5b)
    .
    Figure 3(a) is a schematic diagram of the spatial arrangement of two gelling agents in the gel beads
    .
    (B and c) Optical microscope of cross-section of gel beads embedded in resin and colored with toluidine blue (scale bar 500 μm)
    .
    (D) SEM of the entire gel bed, (e) gel bead surface and (f) cross section (scale bars of 500, 10 and 1 μm)
    .
    Figure 4 (a) SEM images of DBS-CONHNH2/alginate two-component microgel and (b) alginate microgel
    .
    The image on the left is newly prepared, and the image on the right is the image after 30 days
    .
    Scale bars: 1μm ((a) left) and 5μm ((a) right, (b) left and right)
    .
    Figure 5 DLS measurement volume distribution of DBS-CONHNH2/alginate two-component microgel (blue) and only alginate microgel (red) prepared with different rotation speeds
    .
    Figure 6 (Left) The average diameter of the DBS-CONHNH2/alginate two-component microgel prepared by mixing at a speed of 1350 rpm before and after injection via a syringe
    .
    (Right) Photo of DBS-CONHNH2/alginate two-component microgel injected through a syringe
    .
    Figure 7 shows the percentage of DBS-CONHNH2 visualized by 1H NMR after heating at 90°C for different times in the NMR spectrometer, so it is in the liquid mobile phase
    .
    The schematic diagram shows the thermally induced decomposition of the LMWG network in the LMWG/PG hybrid gel beads
    .
    Figure 8 Percentage of heparin released over time in 10 mM Tris-HCl/150 mM NaCl buffer: DBS-CONHNH2/alginate multi-component gel in vial (red triangle), gel beads (green square) and Microgel beads (blue circle)
    .
    Figure 9 (1) Schematic diagram of a gel loaded with heparin in a cross-well
    .
    (2) The results of dark blue metabolic activity determination on different gels containing 0.
    1 mg heparin on days 0, 3 and 6
    .
    (3) Exposure to heparin released from DBS-CONHNH2 gel (a and b, respectively), DBS-CONHNH2/alginate gel (c and d, respectively), heparin released from the gel (0.
    1 mg) mg) Fluorescence microscope images of cells stained with calcein AM on day 3 and day 6 beads (e and f, respectively) and microgels (g and h, respectively)
    .
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