Real-time detection of errors in oligonucleotide synthesis

Abstract

Fluorophores are used during the synthesis of oligonucleotides to achieve real-time quality control of the synthesis process. Fluorescence may indicate successful addition of individual nucleotides to a growing oligonucleotide strand or removal of a blocking group. The oligonucleotides may be created by enzymatic synthesis using terminal deoxynucleotidyl transferase (TdT). The synthesis is performed on an addressable array so that oligonucleotides with different sequences are created in parallel on different regions of the array. The oligonucleotide sequences are predetermined and the locations of synthesis on the array are controlled. Observed fluorescence is compared to expected locations of fluorescence as determined by the oligonucleotide sequences and the arrangement on the array. Thus, the fidelity of oligonucleotide synthesis is checked as synthesis proceeds. If a variation is found, a mitigating action is taken such as repeating addition of a species of nucleotide or repeating a deblocking step.