Micropatterning of Proteins on 3D Porous Polymer Film Fabricated by Using the Breath‐Figure Method

Abstract

Micropatterning of proteins provides a power tool for studying the interactions between proteins, antibodies, and other biomolecules, [1,2] which can find applications in many fields such as biology, biosensor technology, biomedical devices, and tissue engineering. [3][4][5] Most micropatterning techniques are based on conventional photoresist lithography, soft lithography, and pin spotting. [6][7][8][9][10] Both photoresist-lithography and pin-spotting techniques require high-tech equipment such as mask aligners, electron (e)-beam writers, or pin spotters, and well-trained people to operate them. Conversely, soft lithography uses a polydimethylsiloxane (PDMS) stamp or stencil as a template to create a pattern of proteins or cells on the substrate, which is more convenient.[11] However, fabrication of a PDMS stamp or stencil still relies on photolithography. Furthermore, for most of the work carried out so far, 2D patterns of proteins were generated by using soft-lithography techniques on substrates with planar surfaces. Very recently it has been reported that porous polymer films with well-ordered honeycomb structures can be prepared by using a breath-figure method, a templating method based on evaporative cooling and subsequent water-droplet templating to form an ordered array of breath figures. [12][13][14][15] A variety of polymers and block polymers such as polystyrene (PS), a-D-glucose, b-cyclodextrin and cellulose derivatives, dendronized polymethacrylate block polymer, and linear poly(ethylene oxide) block polymer have been used to fabricate such films. [16][17][18] Nanoparticles, such as gold, silver, and CdSe, are added into the porous films for different applications. [19][20][21] In this work, a porous polymer film was used as a template to guide the patterning of proteins and a 3D pattern of proteins was achieved. A big challenge was how to attach proteins to the designated regions of the polymer film, because most of the polymers used in the breath-figure method are hydrophobic and do not have functional chemical groups for conjugating proteins.A schematic drawing is given in Figure 1 to show how proteins can be patterned by using the porous film as the template. PS and a small amount of amino-terminated PS (PS-mNH 2 ) were dissolved in chloroform. The mixed polymer solution was spread on a glass slide to form a film. PS-mNH 2 is an amphiphilic linear polymer, bearing a hydrophilic amino group at one end and a long hydrophobic alkyl group at the other end, which could be used as a surfactant to be self-assembled at the interfaces between water droplets and waterimmiscible PS solution. During the formation of breath figures, the hydrophobic alkyl group of the amphiphilic PS-mNH 2 was oriented towards the hydrophobic phase (PS) in the solution and the hydrophilic amino group was oriented towards the water droplet. After the water droplets were removed, pores were formed with an amino-terminated pore surface. The surface property of the pores in such a film was different from that of a pure PS film whe...

Microwells with Patterned Proteins by a Self‐Assembly Process Using Honeycomb‐Structured Porous Films

“…A multistep synthesis, which included the protection of the surface against protein adsorption, resulted in a regular protein pattern. [15] In another work, a copolymer with biotin moieties distributed randomly along the backbone does allow streptavidin binding on the surface, but not localized within the pore. [16] Here we propose a simple one-step approach that does not require additional surface modification but does nevertheless direct the functionality of the polymer towards the pore interior.…”

Droplet condensation on polymer surfaces: A review

“…This application can be used as a non-lithographic method for 3D protein micropatterning, which is important in tissue engineering, and protein-and cell-based biosensors. 162 Zander et al transferred arrays of pillars (inverse pores) to polymeric films by using them as templates to obtain textured silicone pillars and breath figure templating was proposed as a new technique for fabrication of hydrophobic surfaces, providing a low cost alternative to customary techniques. 163 Hernandez-Guerrero et al applied graft copolymerization and used PS-PHEMA based honeycomb membranes and a thermoresponsive polymer, PNIPPAm, inside the pores to form a membrane to be used in fibroblast cell attachment.…”

Fabrication of macroporous protein-containing films through the reverse emulsions approach featuring β-cyclodextrin-conjugated PEG-PLGA copolymers

“…Using this method, a variety of biomolecules have been successfully employed for the fabrication of functional porous films, especially macroporous biohybrid films. Zhang et al prepared an amino-terminated surface and immobilized proteins to the surface of the pores to form a pattern of proteins [18] . Stenzel et al fabricated honeycomb-patterned porous films using poly(styreneblock-acrylic acid) and then attached proteins inside the pores by linking the amino groups of the proteins to the carboxyl groups [19] .…”