sentences:  Once prepared, the randomized library is incubated with immobilized target to allow oligonucleotide-target binding.There are several considerations for this target incubation step, including the target immobilization method and strategies for subsequent unbound oligonucleotide separation, incubation time and temperature, incubation buffer conditions, and target versus oligonucleotide concentrations.Examples of target immobilization methods include affinity chromatography columns, nitrocellulose binding assay filters, and paramagnetic beads.