Patent ID: 8586303

Claim:
A process for extracting from a candidate mixture of oligonucleotide molecules, whose members have unknown sequences, specific oligonucleotide molecules that bind to a preselected target, said specific molecules comprising one or more non-standard nucleotides having nucleobases independently selected from the group consisting of wherein said process comprises (a) obtaining a mixture of oligonucleotides having preselected regions containing, at positions that are not preselected, one or more of said non-standard nucleotide analogs, (b) contacting said mixture with said target, (c) separating the oligonucleotides in said mixture having a enhanced affinity to the target molecule relative to the candidate mixture from the remainder of the oligonucleotides in the candidate mixture; and (d) amplifying the separated oligonucleotides using the polymerase chain reaction, wherein R is the point of attachment to the oligonucleotide at position 1′ of the ribose or 2′-deoxyribose of said oligonucleotide.