▁obtained ▁from ▁reconst itution ▁experiments ▁with ▁isolated ▁S - layer ▁sub un its ▁on ▁cell ▁surfaces ▁from ▁which ▁they ▁had ▁been ▁removed ▁( hom olog ous ▁re attach ment ) ▁or ▁on ▁those ▁of ▁other ▁organ isms ▁( h eter olog ous ▁re attach ment ). ▁ ▁In ▁vit ro ▁assembly ▁ ▁S - layer ▁prote ins ▁have ▁the ▁natural ▁cap ability ▁to ▁self - ass emble ▁into ▁regular ▁mon om ole cular ▁arrays ▁in ▁solution ▁and ▁at ▁interfaces , ▁such ▁as ▁solid ▁supports , ▁the ▁air - water ▁interface , ▁li pid ▁films , ▁li pos om es , ▁em uls om es , ▁nan oc aps ules , ▁nan op articles ▁or ▁micro ▁be ads . ▁S - layer ▁cry stal ▁growth ▁follows ▁a ▁non - class ical ▁path way ▁in ▁which ▁a ▁final ▁ref old ing ▁step ▁of ▁the ▁S - layer ▁protein ▁is ▁part ▁of ▁the ▁lattice ▁formation . ▁ ▁Application ▁ ▁Native ▁S - layer ▁prote ins ▁have ▁already ▁been ▁used ▁three ▁dec ades ▁ago ▁in ▁the ▁development ▁of ▁b ios ens ors ▁and ▁ult ra fil tr ation ▁memb ran es . ▁Sub sequently , ▁S - layer ▁fusion ▁prote ins ▁with ▁specific ▁functional ▁ ▁domains ▁( e . g . ▁en zym es , ▁lig ands , ▁m im ot op es , ▁ant ib od ies ▁or ▁ant ig ens ) ▁allowed ▁to ▁investigate ▁completely ▁new ▁strateg ies ▁for ▁functional izing ▁surfaces ▁in ▁the ▁life ▁sciences , ▁such ▁as ▁in ▁the ▁development ▁of ▁novel ▁aff