The potential of genetic alphabet expansion technologies using artificial extra base pairs (unnatural base pairs) has been rapidly expanding and increasing. We present that the hydrophobic unnatural base, 7-(2-thienyl)imidazo[4,5-b]pyridine (Ds), which acts as a fifth letter in a DNA library, provides a series of high-affinity DNA aptamers with versatile binding specificities and activities to cancer cells. These Ds-containing DNA aptamers were generated by a method called cell-ExSELEX to target three breast cancer cell lines: MCF7, MDA-MB-231, and T-47D. Aptamer 14A-MCF7, which targets MCF7 cells, specifically binds to MCF7 cells, but not other cancer cell lines. Aptamer 07-MB231, which targets MDA-MB-231 cells, binds to a series of metastatic bone and lung cancer cell lines. Aptamer 05-MB231 targets MDA-MB-231 cells, but it also binds to all of the cancer and leukemia cell lines that we examined. None of these aptamers bind to normal cell lines, such as MCF10A and HUVEC. In addition, aptamers 14A-MCF7 and 05-MB231 are internalized within the cancer cells, and aptamer 05-MB231 possesses anti-proliferative properties against most cancer cell lines that we examined. These aptamers and the generation method are broadly applicable to cancer cell imaging, biomarker discovery, cancer cell profiling, anti-cancer therapies, and drug delivery systems.

使用人工额外碱基对（非自然碱基对）的遗传字母扩展技术的潜力正在迅速扩大和增加。我们提出疏水性非天然碱，7-（2-噻吩基）咪唑并[4,5- b在DNA文库中充当第五个字母的]吡啶（Ds）提供了一系列具有多种结合特异性和对癌细胞活性的高亲和力DNA适体。这些含Ds的DNA适体是通过称为cell-ExSELEX的方法产生的，可靶向三种乳腺癌细胞系：MCF7，MDA-MB-231和T-47D。靶向MCF7细胞的适体14A-MCF7特异性结合MCF7细胞，但不与其他癌细胞系结合。靶向MDA-MB-231细胞的适体07-MB231与一系列转移性骨和肺癌细胞系结合。适体05-MB231靶向MDA-MB-231细胞，但它也与我们检查过的所有癌细胞和白血病细胞系结合。这些适体均不结合正常细胞系，例如MCF10A和HUVEC。另外，适体14A-MCF7和05-MB231被内化在癌细胞中，适体05-MB231具有针对我们所研究的大多数癌细胞系的抗增殖特性。这些适体和产生方法广泛适用于癌细胞成像，生物标志物发现，癌细胞概况分析，抗癌疗法和药物递送系统。