Stable, nanometer‐thick oxygen‐containing plasma polymer films suited for enhanced biosensing

Abstract

Stable surface functionalization is required in many applications such as in biosensing. For this purpose, hydrocarbon‐based plasma polymer films (PPFs) were investigated by controlling cross‐linking and film structure at the nanoscale, while functional groups were incorporated using a CO2/C2H4 low pressure plasma. In particular, an oxygen‐rich termination layer of 1 nm (top layer) was gradually deposited onto a more cross‐linked PPF (base layer) with varying thickness (<20 nm) yielding highly stable yet functional a‐C:H:O films as compared to conventional oxygen‐rich PPFs. Such stabilized nano‐layers provided a homogeneous functionalization of Au‐coated (flat) biochips as used for immunosensing as well as of nanostructured Au‐coated surfaces explored for enhanced biosensing. The used periodic grating coated by the highly stable a‐C:H:O nano‐layer can be adjusted to the required environmental refractive index range yielding a distinct sensitivity enhancement for biosensing.

Plasma Processing of Low Vapor Pressure Liquids to Generate Functional Surfaces

“…For longer storage times WCA values increased gradually up to 60°–70°, most probably due to the diffusion of siloxanes from the silicone backing. But the samples did not loose their hydrophilicity even after several months which makes them superior to optimized functional plasma polymer films [ 88 ]. Other groups using different methods to prepare samples equipped with PEG also reported contact angles staying below 50°–70° after storage periods of several weeks [ 89 , 90 ].…”

Top‐down approach to attach liquid polyethylene glycol to solid surfaces by plasma interaction

“…However, the surfaces remain highly hydrophilic. We could also show that this high degree of functionalization can even be maintained for at least several months, superior to optimized functional plasma polymer films . Hence, covalent attachment of liquid molecules to plasma‐produced films can be assumed, providing them with specific functionalities.…”

pH-Responsive Chitosan/Alginate Polyelectrolyte Complexes on Electrospun PLGA Nanofibers for Controlled Drug Release

“…The negative surface charge of PLGA was insufficient to generate robust electrostatic interactions with CHI. To solve this issue, the nanofibers were submitted to a plasma gradient to lower the charge of the mesh as described in previous work [ 41 ].…”

“…Plasma coating of PLGA electrospun nanofibers: In order to introduce an oxygen-containing functional hydrocarbon layer onto the surface of the electrospun nanofibers, an ultrathin plasma coating (≤20 nm) was used as described in previous reports [ 39 , 40 , 41 ]. The coating comprises a vertical chemical gradient by changing the power and gas flow rate during the plasma deposition process in order to enhance adhesion, stability, and surface functionality [ 42 ].…”