Tailormade Microfluidic Devices Through Photochemical Surface Modification

Abstract

A new pathway for the generation of polymer‐based microfluidic devices with tailor‐made surface chemistry is described. A simple photochemical process is used to covalently bind polymer molecules to the surfaces of microchannels fabricated by hot embossing. The substrates for the embossing process have the format of a compact disk (CD). CDs from polymethylmethacrylate and polyethylene‐co‐norbornene were chosen due to their good optical properties. Thin films of polymers containing photoactive benzophenone units were deposited onto the surface of the thus generated devices. These films were subsequently irradiated with UV light leading to the surface‐attachment of ultrathin polymer networks. In contrast to their unmodified peers, the obtained, modified microfluidic channels coated with hydrophilic, photoattached layers can be filled in a straightforward manner with water by capillary forces. Channels coated by thin films of poly(ethyloxazoline) show complete resistance to non‐specific protein binding. Generation of hydrophobic patches inside the modified microfluidic channels using benzophenone‐containing fluoropolymers allows the generation of passive microfluidic valves to direct fluid motion in these CD‐based devices.magnified image

Poly(2-oxazoline) functionalized surfaces: from modification to application

“…Samuel et al attached benzophenone to the linear poly(ethylene imine) (LPEI) units of partially hydrolyzed PEtOx (PHPEtOx) (Scheme 3b). 36 The resulting copolymer of PEtOx, LPEI and poly(2-benzophenone-2-oxazoline) (PBPOx) was immobilized through the PBPOx units onto a poly(methyl methacrylate) (PMMA) film which was deposited on a gold coated lanthanum surface.…”

“…The fibrinogen repellency of PEtOx coatings was also reported by Samuel et al who photoimmobilized PHPEtOx-co-PBPOx on the surface of a microfluidic device via the benzophenone units attached to the polymer backbone. 36 Even when stored for several weeks in PBS buffer solution, the PEtOx coating remained stable and protein repellent. Lind et al produced micropatterned electronic devices for cell-capturing purposes (Fig.…”

Surface Grafted Antimicrobial Polymer Networks with High Abrasion Resistance

“…The electron-deficient oxygen abstracts a hydrogen atom from a neighboring C–H group, followed by the combination of two newly created carbon radicals and subsequent generation of a new C–C bond. This photochemistry has been used to permanently attach polymer films to a broad selection of C–H surfaces in many different applications, such as microfluidic devices, , biosensors, , patterned sheets, , and even organic semiconductors . Because of these advantages, we previously developed an antimicrobial copolymer containing hydrophobic N -alkyl and benzophenone moieties on a polyethylenimine backbone (AmBP) and covalently grafted the copolymer to various plastic and textile surfaces via photo-cross-linking .…”

Highly efficient Suzuki cross-coupling reaction within an open channel plastic microreactor immobilized with palladium complexes

“…The COC plates and the microchips were fabricated through easily operational and inexpensive hot-embossing technique reported previously (Tsao and DeVoe 2009;Steigert et al 2007;Pu et al 2007). The inner surface of microchannel was modified by photographting (Mair et al 2006;Bedair and Oleschuk 2006;Rohr et al 2003;Samuel et al 2010). The benzophenone-mediated photografting process generates a very thin layer of branched and cross-linked DMAPMA polymer architecture that is rich of dimethylamino groups on the substrate surface, which is ideal for anchoring palladium complex and providing proper microenvironment for Suzuki reaction.…”