Chemical modifications of inert organic monolayers with oxygen plasma for biosensor applications

Plasma surface modification of polymers for sensor applications

Polymeric sensors play an increasingly important role in monitoring the environment we live in, providing relevant information for a host of applications.

Controlled oxidation, biofunctionalization, and patterning of alkyl monolayers on silicon and silicon nitride surfaces using plasma treatment

A new method is presented for the fast and reproducible functionalization of silicon and silicon nitride surfaces coated with covalently attached alkyl monolayers. After formation of a methyl-terminated 1-hexadecyl monolayer on H-terminated Si(100) and Si(111) surfaces, short plasma treatments (1-3 s) are sufficient to create oxidized functionalities without damaging the underlying oxide-free silicon. The new functional groups can, e.g., be derivatized using the reaction of surface aldehyde groups with primary amines to form imine bonds. In this way, plasma-treated monolayers on silicon or silicon nitride surfaces were successfully coated with nanoparticles, or proteins such as avidin. In addition, we demonstrate the possibility of micropatterning, using a soft contact mask during the plasma treatment. Using water contact angle measurements, ellipsometry, XPS, IRRAS, AFM, and reflectometry, proof of principle is demonstrated of a yet unexplored way to form patterned alkyl monolayers on oxide-free silicon surfaces.

Controlling and manipulating supported phospholipid monolayers as soft resist layers for fabricating chemically micropatterned surfaces

Chemically micropatterned surfaces have broad applications in many fields. In this paper, we report a new method for preparing chemically micropatterned surfaces by controlling and manipulating supported phospholipid monolayers as soft resist layers with molecular-level precision. First, we introduce self-assembled supported phospholipid monolayers on solid surfaces and use a microcontact lift-up process to create micropatterned phospholipid monolayers (with micrometer resolution) on the surface. Next, the micropatterned phospholipid monolayers can function as "soft" resist layers to protect underlying solid substrates and create either positive or negative chemically micropatterned surfaces during subsequent treatments. Unlike traditional "hard" resist layers which can only be removed by using harsh chemical treatments, this novel soft resist layer only comprises a single layer of compact phospholipid; therefore, it can be easily removed by water rinsing after the preparation of micropatterns. This method is also versatile. It can be applied to prepare a protein microarray or silver patterns on solid substrates.