  From viruses to nanoparticles, constructs functionalized with multiple
ligands display peculiar binding properties that only arise from multivalent
effects. Using statistical mechanical modelling, we describe here how
multivalency can be exploited to achieve what we dub range selectivity, that
is, binding only to targets bearing a number of receptors within a specified
range. We use our model to characterise the region in parameter space where one
can expect range selective targeting to occur, and provide experimental support
for this phenomenon. Overall, range selectivity represents a potential path to
increase the targeting selectivity of multivalent constructs.
