Micro-spherical porous biocompatible scaffolds and methods and apparatus for fabricating same
A microsphere, spherical technology, applied in other methods of inserting foreign genetic material, drug combinations, microcapsules, etc.
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Embodiment 1
[0244] Embodiment 1: Preparation of double-hole microspheres
[0245] Microspheres were prepared by the following method using a two-hole microsphere manufacturing apparatus. Briefly, 0.2 g of poly(DTE carbonate) was stirred and dissolved in a mixture of 3 mL of 1,4-dioxane and 0.3 mL of water to form a homogeneous solution in a storage vessel. The solution is then poured into the barrel of the syringe. Add 7 g of sodium chloride to the solution through a catheter connected to a syringe. Pressure is then applied to the syringe barrel to inject the solution droplets into the quench tower. As soon as the droplets enter the tower, they are quickly frozen and solidified, forming a double-pore structure. Next, residual salt and solvent are washed from the microspheres. Repeat the washing process several times until the silver nitrate test shows that no additional chloride ions are released into the water. The resulting microspheres were removed from the water and dried to co...
Embodiment 2
[0246] Example 2: Evaluation of Microsphere Morphology by SEM Scanning Electron Microscopy
[0247] SEM scanning electron microscopy was performed to evaluate the morphology of the microspheres. Briefly, samples were prepared by cryogenic rupture of microspheres in liquid nitrogen. A series of pressurization-depressurization cycles are performed on the microspheres to ensure that the pores are filled with water. Next, the samples are dried in a vacuum and mounted to metal mounts using adhesive labels. They were coated with silver using a sputter coater. Inspection at 15kV using Hitachi S450SEM.
[0248] Digital images obtained by SEM were analyzed for pore size with NIH Image 1.6 software. The image parameters evaluated included hole area, perimeter, major and minor axes of the ellipse. Adjustments were made to the digital images prior to evaluating the wells. Compare the numbered holes to the actual digital image to confirm hole locations. Certain well numbers that c...
Embodiment 3
[0249] Example 3: Evaluation of Pore Volume and Size Distribution
[0250] The microspheres were analyzed while the macroporous spacer material was still present within the polymer matrix. The pore volume and pore size distribution were determined by recording the volume of mercury entering the microspheres under different pressures with a mercury porosimeter. Fill pressures have been recorded up to 3,000 psia. This pressure corresponds to the energy required for mercury to enter pores of 0.06 μm or larger. Pore diameter and porosity values refer to equivalent cylindrical pores with a diameter of less than 310 μm.
[0251] These values are determined by the Washburn equation:
[0252] D=-(1 / P)4γcos f
[0253] where D is the pore diameter in microns; P is the applied pressure (psia); γ is the surface tension between the mercury and the scaffold surface (dynes / cm); and Φ is the contact angle.
[0254] Recommended values for surface tension and contact angle are: ...
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