Preparation of Uniform Microspheres Using a Simple Fluidic Device and Their Crystallization into Close-Packed Lattices

Department of Biomedical Engineering, Washington University, St. Louis, Missouri 63130, USA.
Small (Impact Factor: 8.37). 02/2009; 5(4):454-9. DOI: 10.1002/smll.200801498
Source: PubMed


The preparation of uniform raspberry-like microspheres using a simple fluidics device and their crystallization into close-packed lattices was investigated. The spheres was developed by stable Oil-in-Water (O/W) or Water-in-Oil (W/O) emulsions and scanning Electron Microscopy (SEM) of close packed lattices was done. Various types of microfluidic devices have been developed to generate microparticles with diverse morphologies such as spheres, rods, disks and ellipsoids. The device provided precise control over the formation of emulsion droplets, leading to the production of uniform microspheres in size ranging from 30 to 250 μm. The technique provided a powerful strategy for the scalable and continuous production of microspheres from both organic and inorganic materials actively sought for encapsulation of drugs, dyes, and tissue engineering.

12 Reads
  • Source
    • "By modifying our previous method, we fabricated inverse opal scaffolds with cubic-close packed lattices of gelatin microspheres as templates [8] [25]. Fig. 2, A and B, show SEM images of a typical lattice of gelatin microspheres and the corresponding inverse opal scaffold of PLGA, respectively. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Visualizing cells in three-dimensional (3D) scaffolds has been one of the major challenges in tissue engineering. Most current imaging modalities either suffer from poor penetration depth or require exogenous contrast agents. Here, we demonstrate photoacoustic microscopy (PAM) of the spatial distribution and temporal proliferation of cells inside three-dimensional porous scaffolds with thicknesses over 1 mm. Specifically, we evaluated the effects of seeding and culture methods on the spatial distribution of melanoma cells. Spatial distribution of the cells in the scaffold was well-resolved in PAM images. Moreover, the number of cells in the scaffold was quantitatively measured from the as-obtained volumetric information. The cell proliferation profile obtained from PAM correlated well with what was obtained using the traditional 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay.
    Full-text · Article · Nov 2010 · Biomaterials
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A technique for fabricating chitosan inverse opal three-dimensional scaffolds characterized by a biodegradable material, uniform pore size, well-controlled interconnectivity, and nanofibrous texture on the wall surface, was described. A uniform poly(caprolactone) (PCL) microsphere, prepared using a simple fluidic device, was used as a template. The results show that by placing the ccp lattice formed from the PCL microspheres, in an oven heated at 45°C for 50 min, a robust ccp lattice in the form of a pellet without changing the surface morphology of the microspheres could be obtained. The open and ordered pore structure throughout the scaffold allows cells to easily penetrate into the scaffold, facilitate the exchange of nutrient and metabolite waste, and promote in vivo vascularization.
    Full-text · Article · Aug 2009 · Advanced Materials
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Poly(d,l-lactide-co-glycolide) (PLGA) microbeads with a hollow interior and porous wall are prepared using a simple fluidic device fabricated with PVC tubes, glass capillaries, and a needle. Using the fluidic device with three flow channels, uniform water-in-oil-in-water (W-O-W) emulsions with a single inner water droplet can be achieved with controllable dimensions by varying the flow rate of each phase. The resultant W-O-W emulsions evolve into PLGA microbeads with a hollow interior and porous wall after the organic solvent in the middle oil phase evaporates. Two approaches are employed for developing a porous structure in the wall: emulsion templating and fast solvent evaporation. For emulsion templating, a homogenized, water-in-oil (W/O) emulsion is introduced as the middle phase instead of the pure oil phase. Low-molecular-weight fluorescein isothiocyanate (FITC) and high-molecular-weight fluorescein isothiocyanate-dextran conjugate (FITC-DEX) is added to the inner water phase to elucidate both the pore size and their interconnectivity in the wall of the microbeads. From optical fluorescence microscopy and scanning electron microscopy images, it is confirmed that the emulsion-templated microbeads (W-W/O-W) have larger and better interconnected pores than the W-O-W microbeads. These microstructured microbeads can potentially be employed for cell encapsulation and tissue engineering, as well as protection of active agents.
    Full-text · Article · Sep 2009 · Advanced Functional Materials
Show more