YES, we do!
BSI offers the custom synthesis of single-stranded circular oligo nucleotides.
Custom synthesis is achieved using chemical solid phase, solution phase and enzymatic synthesis methods. Small circular single-stranded oligonucleotides (<28 base pairs {bp}) can be chemically synthesized using solution and solid-phase methods from partially protected linear precursor molecules whereas longer circular oligos (>28 bp) are relatively easy to synthesize using both methods, chemical and enzymatic.
Circular oligonucleotides are covalently closed singular DNA or RNA strands that are resistant to degradation by many cellular DNA and RNA decay machineries since these recognize the ends of linear RNAs to function.