Modified DNA aptamers incorporated with amino-acid like side chains or drug-like ligands can offer unique advantages and enhance specificity as affinity ligands. Thy-1 membrane glycoprotein (THY1 or CD90) was previously identified as a biomarker candidate of neovasculature in pancreatic ductal adenocarcinoma (PDAC). The current study developed and evaluated modified DNA X-aptamers targeting THY1 in PDAC. The expression and glycosylation of THY1 in PDAC tumor tissues were assessed using immunohistochemistry and quantitative proteomics. Bead-based X-aptamer library that contains 10⁸ different sequences was used to screen for high affinity THY1 X-aptamers. The sequences of the X-aptamers were analyzed with the next-generation sequencing. The affinities of the selected X-aptamers to THY1 were quantitatively evaluated with flow cytometry. Three high affinity THY1 X-aptamers, including XA-B217, XA-B216 and XA-A9, were selected after library screening and affinity binding evaluation. These three X-aptamers demonstrated a high binding affinity and specificity to THY1 protein and the THY1 expressing cell lines, using THY1 antibody as a comparison. The development of these X-aptamers provides highly specific and non-immunogenic affinity ligands for THY1 binding in the context of biomarker development and clinical applications. They could be further exploited to assist molecular imaging of PDAC targeting THY1.

与氨基酸样侧链或药物样配体结合的修饰 DNA 适体可以提供独特的优势并增强作为亲和配体的特异性。Thy-1 膜糖蛋白（THY1 或 CD90）先前被确定为胰腺导管腺癌 (PDAC) 中新血管系统的候选生物标志物。目前的研究开发并评估了针对 PDAC 中 THY1 的修饰 DNA X 适体。使用免疫组织化学和定量蛋白质组学评估 PDAC 肿瘤组织中 THY1 的表达和糖基化。包含 10 ^{8个基于磁珠的 X 适体库}不同的序列用于筛选高亲和力的 THY1 X 适体。X-适体的序列通过二代测序进行分析。用流式细胞术定量评估所选 X 适体对 THY1 的亲和力。在文库筛选和亲和力结合评估后，选择了三种高亲和力 THY1 X 适体，包括 XA-B217、XA-B216 和 XA-A9。使用 THY1 抗体作为比较，这三个 X 适体对 THY1 蛋白和表达 THY1 的细胞系表现出高结合亲和力和特异性。在生物标志物开发和临床应用的背景下，这些 X 适体的开发为 THY1 结合提供了高度特异性和非免疫原性亲和配体。它们可以进一步用于辅助 PDAC 靶向 THY1 的分子成像。