The selective immobilization of various biomolecules in well-defined area is important technique for the development of biosensors and biochips. Especially, the fabrication of protein micropatterns preserving their functional activity on the desired surface is critical issue for the development of medical diagnostic devices and basic protein studies. In this study, we have introduced a simple but reliable method of protein patterning on functionalized polyelectrolyte thin films (PEL) through consecutive layer-by-layer adsorption of polyelectrolytes via self-assembly technique and microcontact printing (μCP). For the selection of appropriate surface, several representative surfaces modified with various functional materials including aldehyde, epoxide, poly-L-lysine, amine, and self-assembled polyelectrolyte multilayers (PEL) were investigated. The PEL surface providing electrostatic interaction force showed most high functionality in point of homogeneous patterning of proteins with high density and preservation of inherent 3-dimensional structure of proteins. Immunoassay as a model system of protein-protein interaction showed good linearity, indicating the feasibility of a quantitative measurement of the concentration of target proteins in sample. Our proposed approach based on PEL constructed by self-assembly technique in aqueous solution is green chemistry and cost-effective method to generate stable 3-D thin film on surface. The demand for strict control over the positioning and the stable immobilization of several kinds of biomolecules in fabricated structures can result in many applications.
In here, we present the microfluidic approach to produce monodispersed microbeads that will contain viable cells. The utilization of microfludics is helpful to synthesize monodispersed alginate hydrogels and <i>in situ</i> encapsulate cell into the generating hydrogels in microfludic device. First, the condition of formation of hydrogels in multiphase flows including oil, CaCl<sub>2</sub>, and alginate was optimized. Based on the preliminary survey, microfludic device could easily manipulate the size of alginate beads having narrow size distribution. The microfluidic method manipulates the size of hydrogel microbeads from 30 to 200um with a variation less than 2%. For the proof of concept of cell entrapment, the live yeast expressing green fluorescence protein is successfully encapsulated in microfluidic device.
The patterning of biomolecules in well-defined microstructures is critical issue for the development of biosensors and biochips. However, the fabrication of microstructures with well-ordered and spatially discrete forms to provide the patterned surface for the immobilization of biomolecules is difficult because of the lack of distinct physical and chemical barriers separating patterns.
This study present rapid biomolecule patterning using micromolding in capillaries (MIMIC), soft-lithographic fabrication of PEG microstructures for prevention of nonspecific binding as a biological barrier, and self assembled polymeric thin film for efficient immobilization of proteins or cells. For the proof of concept, protein (FITC-BSA), bacteria (<i>E.coli</i> BL21-pET23b-GFP) were used for biomolecules patterning on polyelectrolyte coated surface within PEG microstructures.
The novel approach of MIMIC combined with LbL coating provides a general platform for patterning a broad range of materials because it can be easily applied to various substrates such as glass, silicon, silicon dioxide, and polymers.