Aptamer: tdBroccoli
Target: RNA Mimic of Green Fluorescent Protein (Fluorophores, coupled with fluorescence-activated cell sorting (FACS); Escherichia coli
Type of nucleic acid: ssRNA
Sequence: 5'GCCCGGAUAGCUCAGUCGGUAGAGCAGCGGAGACGGUCGGGUCCAUCUGAGACGGUCGGGUCCAGAUAUUCGUAUCUGUCGAGUAGAGUGUGGGCUCAGAUGUCGAGUAGAGUGUGGGCUCCGCGGGUCCAGGGUUCAAGUCCCUGUUCGGGCGCCA3'
Sequence length: 157
GC content: 0.6114649681528662
Affinity: Not reported
Pool type: 5'GAGACGCAACTGAATGAA-N26-CTGCTTCGGCAG-N26-TCCGTAACTAGTCGCGTCAC-3'
Pool random region: 26
Binding buffer/conditions: 40 mM HEPES pH 7.4, 100 mM KCl, 1 mM MgCl2, and 0.1% DMSO.
Divalent salt: MgCl
Buffer type: Other Buffers
pH: 7.4
Molecular weight of target: Not reported 
Post-SELEX modifications: Dimeric Broccoli by Modification of the Terminal Stem-Loop of Broccoli. We inserted the cyclic diGMP-binding aptamer14 into the stem region of tBroccoli
cylci diGMP-binding aptamer 14 is from paper below
Kellenberger C. A.; Wilson S. C.; Sales-Lee J.; Hammond M. C. J. Am. Chem. Soc. 2013, 135, 4906. 
insert a second Broccoli aptamer into the Broccoli terminal stem

Truncation T2 region, mutation (Analysis revealed that most of the improved variants acquired mutations stabilizing this terminal stem-loop either by enhanced base-pairing or by introduction of the stable tetraloop GAAA.28 This suggests that specific terminal stem-loop sequences improve aptamer folding in vivo.
We decided to combine the mutations that shorten the aptamer while preserving its fluorescence. This generated 29-1-3-1. This aptamer exhibited similar overall colony fluorescence as 29-1
Application as quoted in the referenced paper: Detection: " Genetically encoded fluorescent ribonucleic acids (RNAs) have diverse applications, including imaging RNA trafficking and as a component of RNA-based sensors that exhibit fluorescence upon binding small molecules in live cells. tRNA-independent tagging for mammalian cell imaging, in vivo imaging; Reduced magnesium dependence contributes to a nearly 100% increase in brightness in E. coli and allows robust imaging of tagged RNA in mammalian cells without the need for additional magnesium in media. Additionally, unlike Spinach2, Broccoli does not require the use of a tRNA scaffold to promote its folding in vivo. Thus, selection of aptamers in living cells results in variants that exhibit properties allowing them to function well in cells without the need for extensive in vitro mutagenesis."
Additional information: Modification of the Terminal Stem-Loop of Broccoli. Purified single stranded DNA library was then used in a PCR reaction to gently amplify the library and to create double stranded DNA templates for RNA in vitro synthesis.
The middle fixed region in pool indicates a fixed region which is predicted to form a stable tetraloop and which was previously shown to facilitate  the formation of structured aptamers during SELEX.
we created a library of 29-1-T2 mutants using a “doping” strategy similar to the mutagenesis approach originally described by Bartel et al.27 Briefly, a DNA library is synthesized so that each encoded aptamer resembles the parent aptamer, however every nucleotide has a certain and controlled probability of being converted into one of the other three nucleotides. Parent sequence (used as library) was 5'GAGACGGUCGGGUCCAGCACAAAAAUGUUGCUGUUGAGUAGAGUGUGGGCUC3'

This dimeric Broccoli (dBroccoli) exhibits almost twice the fluorescence as the monomeric Broccoli, as demonstrated by comparing 1 pmol of in vitro transcribed tBroccoli and tdBroccoli (dBroccoli in tRNA scaffold) in polyacrylamide gel electrophoresis (PAGE) gel 
Reference (2014,J Am Chem Soc): Filonov, G. S., Moon, J. D., Svensen, N., & Jaffrey, S. R. (2014). Broccoli: rapid selection of an RNA mimic of green fluorescent protein by fluorescence-based selection and directed evolution. Journal of the American Chemical Society, 136(46), 16299–16308. https://doi.org/10.1021/ja508478x