Dry native protein assays on 3D and 2D substrates by non-contact Laser-Induced-Forward Transfer LIFT process

Laser-Induced-Forward Transfer (LIFT) is a non-contact method for transferring bioactive substances such as proteins in a microstructured way from a transfer layer on a LIFT target to more or less any surface of a 2D or 3D solid work piece. The quality of the biological transfer layer on the target, i.e. its homogeneity and the bioactivity of the ingredients to be transferred, is crucial for the efficiency of the process and quality of the transferred pattern. Here, aqueous trehalose solutions containing green fluorescent protein (GFP) or the ECM protein laminin type 1 were used in a spin-coating/drying process to render dry thin native protein trehalose films on titanium-coated COP foils. The homogeneity of the layer thicknesses was characterized by spectroscopic ellipsometry and the homogeneity of the GFP distribution within the layer was monitored by fluorescence scan analysis. After application of the LIFT process, the transferred proteins were tested in their bioac tivity by fluorescence scan analyses and cell assays.