Figure 4: Depictions of receptor attachment via biotin-avidin/streptavidin methodologies. Initially, biotin is physically or covalently immobilized above an appropriate solid support [79] and then further modified with multivalent avidin or streptavidin. A biotin labeled antibody (a) or a biotin labeled aptamer (b) is then attached. The high affinity constant between biotin and avidin or streptavidin facilitates stable film formation.