In a paper published online in advance in Nucleic Acids Research this week, researchers at Illumina describe their approach to "make individual or pools of purified 5' biotin-functionalized oligonucleotides," which they say is "based on 5'-hexa-His phase tag purification, followed by exchange of the hexa-His tag for a functional group using reversible reaction chemistry." The Illumina team reports cases in which it prepared "5'-biotin, 95-mer, oligonucleotide pools of [greater tha