Fig. 2

Characterisation of the LH aptamer. a Nitrocellulose membrane-based SELEX method for LH aptamer generation. The LH aptamer selection was performed by 20 rounds of binding, partitioning, eluting, amplification and ssDNA generation steps. Nitrocellulose membrane filtration was used to partition the LH-bound sequence in the LH selection rounds and FSH-bound sequences in the FSH counter selection round. Thirty-eight clones of the last-round library were sequenced. b Affinity study of the B23 aptamer. The concentration–response curve of B23 is shown in black. Two blue lines indicate the negative controls, one is the response of truncated B23 against FSH (red) and the other is the response of a random sequence against LH (blue). Means ± s.d. from three independent experiments are shown (n = 3). c Specificity study of B23 via ELONA and EMSA. The red column represents the colourimetric response of adding 1 μM B23 onto the LH plate and the blue columns represent the response of adding 5 μM of B23 to other nonspecific proteins. The gel image shows the specificity study of B23 using EMSA. The blue dots represent the negative controls of the experiment with 1 μM of B23 and 5 μM FSH, 1 μM of B23 and 5 μM HSA and a random sequence with 5 μM LH. The rest of the lanes show 1 μM of B23 with a series of LH concentration ranging from 0 to 5000 nM. Means ± s.d. from three independent experiments are shown (n = 3). c, d Circular dichroism (CD) of B23 before and after adding 5 μM of LH. The red dashed line represents the change after binding, a negative peak at 240 nm increased and a positive peak at 280 nm decreased. Source data are provided as a Source Data file