Simple oil-in-water emulsion led to structural complexity at both the surface and interior of the PLGA microsphere. A golf ball-like dimpled surface comes from the heteroaggregation of volatile nonsolvent colloid originating from the inside of the organic droplet as supported by in situ optical microscopy. The internal porous structure and encapsulation of hydrophobic agent inside the microparticle implies its potential application as a drug carrier.

We demonstrate the new fabrication of uniform polymer microparticles exhibiting not only an internal porous structure but also a golf-ball-like dimple pattern on the surface. The method provides a simple route for engineering the physical aspects of microparticles and can also be applied to various polymers that have been a continuous challenge in microparticle engineering. The final appearance of the porous structure interior of the microparticles was determined by the selection of amorphous or semicrystalline polymers. Materials and methods MaterialsPolymers used to fabricate golf-ball-shaped microparticles are poly(D,L-lactide-co-glycolide) (PLGA, D,L-lactide: glycolide ¼ 65:35, h inh : 0.55-0.75 dl g À1 in HFIP, Lactel), poly(methyl

Fabrication of physically engineered colloids and their application to the biological fields is emerging importance because of their potential to provide an enhanced performance without altering the chemical properties of biomaterials used. A facile approach is reported to fabricate sub-10-μm-sized PLGA microparticle with small dimples covering the surface by droplet imprinting. Optical and magnetic resonance bioimaging agents are easily co-encapsulated inside the microparticles to obtain a bi-modal imaging agent. Cell internalization efficacy of dimpled particles in DC 2.4 cell is enhanced compared with conventional smooth round-shaped colloids. Our result indicates that morphology-controlled microparticles show promise as a cell labeling with improved cell interaction.

Crack-free three-dimensional (3D) colloidal silica crystals are fabricated on an elastomeric polydimethylsiloxane (PDMS) stamp via the lift-up method. A surface relief structure is fabricated on the PDMS substrate to enable the formation of colloidal crystal assemblies that cannot be achieved on a plane PDMS substrate owing to the hydrophobic nature of its surface. Four samples of uniform silica particles having different sizes are prepared for colloidal crystal assembly on PDMS substrates with various relief patterns. This strategy not only provides a means for the assembly of crack-free colloidal crystals on a soft hydrophobic surface via the lift-up method but enables the transfer of the crack-free colloidal crystals onto a curved surface.

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