Fabrication of nano- to micron-sized patterns using zeolites: Its application in BSA adsorption

• Direct attachment of zeolites was combined with lithographic approaches.
• Substrates that retain two different zeolite types were fabricated.
• 3D differentiated areas on a single surface were created without further modification.
• FITC conjugated BSA was adsorbed on differentiated areas of a single surface.

Nano to micron-sized zeolite A (Z-A) and silicalite (Z-SIL) patterns were generated using the combinations of electron beam lithography (EBL) or photolithography (PL) with direct attachment method to be able to generate differentiated areas on a single surface in a cheap and facile way. The possibility to generate minimum sized zeolite patterns on top of zeolite monolayers was investigated by using EBL to understand the capability of the system for the first time. Also generation of large scale zeolite patterns on top of a different zeolite monolayer was investigated by using PL allowing the generation of differentiated surfaces for various potential applications such as selective adsorption studies. With this combination, it was shown that creating 3D zeolite architectures of different types with a perfect control in all dimensions was possible without the using any chemical linker. In order to test the potential different behaviors that zeolites of different properties are offering in the adsorption of biomolecules, zeolite patterned surfaces developed by PL were subjected to adsorption studies with bovine serum albumin (BSA). Irrespective of zeolite type, BSA always preferred the patterned regions rather than the underlying zeolite monolayers. It can be speculated that the obtained difference in roughness values facilitates the protein to be selectively adsorbed onto surfaces with increased roughness, i.e., the patterned regions. Moreover, we observed ∼2-fold fluorescence intensity difference between Z-SIL and Z-A patterns, which were subjected to FITC-BSA solution. Hydrophobic interactions and charge repulsion are considered as two critical forces responsible for the observed adsorption differences.

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