Reaction of t-butylcalix[8]arene (BCA[8]) as an A8-type monomer with hexamethylene diisocyanate as a B2-type monomer was examined to afford only soluble polymers in high yields. Analysis by 1H NMR, IR, MALDI-TOF mass spectroscopy, and AFM indicated that the synthesized polymers consist of nanoscale-gel-shaped structures that contain fixed holes and cavities. We designated this class of polymers as botryosin, after the Greek word botrys, meaning a bunch of grapes. Examination of host–guest chemistry of the synthesized polymers revealed complexation with alkali metal ions.

The mechanism underlying the bioinertness of nonfouling self-assembled monolayers was investigated with protein adsorption experiments, platelet adhesion tests, and surface force measurements with an atomic force microscope. Our force measurements revealed strong repulsion operating between nonfouling SAMs in the range of 4 to 6 nm in PBS buffer solution. In addition, we found that the protein-adsorbing and cell-adhering SAMs did not exhibit such repulsion. We concluded that the repulsion originated from structured interfacial water molecules. Considering the correlation among the above results, we propose that the structured interfacial water with a thickness of 2 to 3 nm (half of the range of the repulsion observed in the surface force measurements) plays an important role in deterring proteins and cells from adsorption or adhesion.

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