Artificial biomembranes stabilized over spin coated hydrogel scaffolds. Crosslinking agent nature induces wrinkled or flat surfaces on the hydrogel

• Hydrogel films, deposited through spin coating technique, were used as scaffold for artificial biomembranes.
• DPPC bilayer (artificial membrane model) was deposited over hydrogel films using Langmuir–Blodgett technique.
• Wrinkled or flat surfaces were spontaneously formed in the top of hydrogel layers according to crosslinking agent nature.
• DPPC phase and phase transitions were detected using ellipsometry and AFM techniques.
• Hydrogel-cushioned biomembranes maintain their stability in time under uncomfortable conditions.

Hydrogel films possess the ability of retain water and deliver it to a phospholipid bilayer mainly composed by DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine); moisture of the medium favors the stability of an artificial biomembrane when it is subjected to repetitive heating cycles. This hypothesis is valid when the hydrogel film, used as scaffold, present a flat surface morphology and a high ability for water releasing. On the other hand, when the sample presents a wrinkle topography (periodic undulations), free lateral molecular movement of the bilayer becomes lower, disfavoring the occurrence of clear phases/phase transitions according to applied temperature.Hydrogel films were prepared using HEMA (hydroxyethylmetacrylate), different crosslinking agents and initiators. This reaction mixture was spread over hydrophilic silicon wafers using spin coating technique. Resultant films were then exposed to UV light favoring polymeric chain crosslinking and interactions between hydrogel and substrate; this process is also known to generate tensile stress mismatch between different hydrogel strata, producing out-of-plane net force that generate ordered undulations or collapsed crystals at surface level. DPPC bilayers were then placed over hydrogel using Langmuir–Blodgett technique. Surface morphology was detected in order to clarify the behavior of these films. Obtained data corroborate DPPC membrane stability making possible to detect phases/phase transitions by ellipsometric methods and Atomic Force Microscopy due to their high hydration level. This system is intended to be used as biosensor through the insertion of transmembrane proteins or peptides that detect minimal variations of some analyte in the environment; artificial biomembrane stability and behavior is fundamental for this purpose.

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