PEG Mono-layer Detection on Crosslinked Oxide Chips

Below are the results of my recent crosslinking efforts. PEG with 1.5% crosslinker was exposed to UV light at varying times through a bar  printer/transparency mask measuring 100/200. In theory this corresponds to 100 micron PEG bars and 200 micron openings. In practice the results are much less neat. The table shows HUVEC cell attachment to the TPM coated porous oxide membranes with PEG crosslinked onto them. The membrane chips were photo-crosslinked, washed with PBS for 2 minutes each, placed in a small petri dish PEG side up(membrane touching the bottem of the plate), and sterilized under UV light for 30 minutes prior to cell attachment.

It can be seen that after 4 hours, each of the conditions seems to show minimal cell attachment. However after 78 hours, there is a lack of cell growth and proliferation on any of the chips. This could be a result of PEG residual material on the membrane, between the bars, which can be seen in some of the pictures. There was also no cell growth on the plate, outside of the chips.

Chips were exposed for 100 ms, 200 ms, 300 ms, and 400 ms and imaged at 10x at phase and bright field. I did this experiment to try and determine at what point does a PEG mono-layer start to form between the bars. There is no clear conclusion because: a) the cells did not proliferate long term and b) it seem that the mono-layer forms before the bars even fully form. This suggests that the mask is not strong enough the keep the light from shining through the black ink.

I also chose two different imaging techniques to determine if one was better or worse at allowing the detection of that PEG mono-layer between the bars. It appears the bright field may give a slight advantage.