Applications of the electrostatic layer-by-layer self-assembly technique in biomedical engineering

The electrostatic layer-by-layer (LbL) self-assembly technique has shown broad applications in biomedical engineering including: 1) Controlled Drug Release: Furosemide microcrystals have been encapsulated with polyions to control the release of the drug in aqueous solutions. The release of furosemide was slowed (up to 300 times) after encapsulation. 2) Artificial cells: Platelets were coated with polyions, nanoparticles, or antibodies through LbL self-assembly, and targeting of anti-IgG shelled platelets based on antigen-antibody recognition was demonstrated. 3) Biocompatible Nanofilms: Nanofilms of gelatin, Poly-D-lysine, collagen, fibronectin, laminin, hyaluronic acid, or heparin were coated on a PDMS substrate through LbL assembly. A film thickness could be controlled with nanometer accuracy by varying the number of layers. The film was hydrophilic and biocompatible for cell adhesion and growth. 4) Micropatterning: Micropatterning of microspheres and nanospheres was achieved on PDMS substrate through LbL assembly. Cell adhesion on micropatterns was observed. 5) Bio/Nano-Reactors: Multiple layers of nanoparticles were coated on 420 nm diameter nanospheres and then glucose oxidase (GOx) multilayers were fabricated to form high surface area colloidal biocatalysts. The GOx catalytic activity of the biocolloids increased proportionally with the number of silica layers. Biocolloids also exhibited magnetic properties.