Covalent Micropatterning of Poly(dimethylsiloxane) by Photografting through a Mask

Abstract

A new photografting method to micropattern a covalent surface modification on poly(dimethylsiloxane) (PDMS) provides advantages in simplicity and efficiency. To accomplish the entire process on the benchtop, the PDMS was initially treated with benzophenone dissolved in a water/acetone mixture. This process permitted limited diffusion of the photoinitiator into the PDMS surface. Polymerization of acrylic acid was initiated by exposure of the benzophenone-implanted PDMS to UV radiation through a photomask with a thin aqueous layer of acrylic acid sandwiched between the PDMS and photomask. This procedure resulted in patterned poly(acrylic acid) (PAA) on the PDMS surface. In the modified regions, PAA and PDMS formed an interpenetrating polymer network extending 50 microm into the PDMS with an X-Y spatial resolution of 5 microm. The carboxyl groups of the PAA graft could be derivatized to covalently bond other molecules to the patterned PAA. Two bioanalytical applications of this micropatterned surface were demonstrated: (1) a guide for cell attachment and growth and (2) a substrate for immunoassays. 3T3 cells were shown to selectively localize to modified surface regions where they could be cultured for up to 7 days. Additionally, the micropatterned surface was used to immobilize either protein A or antibody for heterogeneous immunoassays.

Photopatternable PEDOT:PSS/PEG hybrid thin film with moisture stability and sensitivity

“…Benzophenone serves as a PI to crosslink the PEGDA molecules, which first diffuses into the porous PDMS surface to form photoreactive areas. Wang et al 40 visualized the diffusion of benzophenone into a PDMS surface and polymerization inside the PDMS layer using a fluorescent dye when photopatterning poly (acrylic acid) on PDMS. Other groups have also reported a similar photoinduced grafting approach to patterning PEGDA onto a PDMS surface 41 .…”

“…Subsequently, a thicker layer of PEDOT:PSS can be transferred onto the crosslinked PEG substrate, and, therefore, an increased electrical conductivity, which is supposedly proportional to the thickness of the PEDOT:PSS layer 39 , is expected to be measured from the hybrid PEDOT:PSS/PEG film. As previous publications stated [40][41][42] , the hybrid structure only polymerizes under UV exposure when the diffusion of PEGDA penetrates into the PEDOT:PSS layers. Thus, it is reasonable to approximate the PEGDA diffusion length as the thickness of the conductive PEDOT:PSS/PEG complex, which can be directly calculated from the measured film conductance.…”

Scaffold fabrication in a perfusion culture microchamber array chip by O2 plasma bonding of poly(dimethylsiloxane) protected by a physical mask

“…27 Briefly, a microarray of poly͑acrylic acid͒ ͑PAA͒ as a base polymer for ECM immobilization was grafted on a PDMS plate ͑width: 25.0 mm, length: 76.0 mm, thickness: 1 mm͒ by micropatterned UVinduced graft polymerization through a photomask with a transparent pattern corresponding to the 8 ϫ 8 array. 28 Collagen and fibronectin were subsequently immobilized on the PAA microarray by a dehydration-condensation reaction through a microfabricated stencil with through-holes corresponding to the 8 ϫ 8 array. This procedure resulted in identical spots of collagen and fibronectin in an arrangement that precisely matched the 8 ϫ 8 array.…”

Non-Calcium Inorganic Materials Fabrication by Surface-Immobilized Organic Molecular Template

“…A photomask which can effectively control irradiation path on the surface was simply applied during the photografting polymerization of AA on the surface. As a result, patterned PAA polymer brush could be obtained (Wang et al, 2005) and then region-selective fabrication of the above ZnO QD/PAA nanocomposite hybrid could be easily achieved. As shown in Figure 41, the pattern of PAA/ZnO QD composite film could form on the underlying substrate in a large area (5 mm 2 ), which is especially appealing in macroelectronics (Morin et al, 2007;Forrest, 2004;Henzie et al, 2006;Reuss et al, 2006).…”