{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T06:12:40Z","timestamp":1790143960089,"version":"4.0.1"},"reference-count":31,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T00:00:00Z","timestamp":1790121600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Bioeng. Biotechnol."],"abstract":"\n Background<\/jats:title>\n Fluorescence imaging of breast cancer is often limited by high background signals from conventional \u201calways-on\u201d probes. The nucleolin-targeting AS1411 aptamer provides a promising recognition element for tumors with elevated nucleolin expression, including triple-negative breast cancer (TNBC). This study aimed to develop a target-activated molecular probe to enable high-contrast detection of nucleolin-overexpressing breast tumors.<\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n An activatable probe (AAFP-AS1411) based on the AS1411 aptamer was engineered by hybridizing fluorescent AS1411 with a quencher strand to generate a target-responsive \u201cOFF-to-ON\u201d fluorescence response. Its preferential fluorescence response and concentration-dependent behavior were evaluated\n in vitro<\/jats:italic>\n using flow cytometry, fluorescence spectroscopy, and confocal microscopy.\n In vivo<\/jats:italic>\n tumor-associated fluorescence,\n ex vivo<\/jats:italic>\n tissue fluorescence distribution, and preliminary acute safety were evaluated in MDA-MB-231 tumor-bearing mice.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n AAFP-AS1411 exhibited low background interference and preferential fluorescence activation in MDA-MB-231 TNBC cells compared with MCF-10A cells, with reduced signals following sequence mismatch or competitive blocking.\n In vivo<\/jats:italic>\n , preferential tumor-associated fluorescence was observed, with the strongest signal detected at 6\u00a0h post-injection.\n Ex vivo<\/jats:italic>\n analysis showed higher fluorescence in tumor tissue than in the examined major organs. No evident acute toxicity was observed at the tested dose of 2\u00a0nmol per mouse and the 24-h time point based on hematological, biochemical, and histopathological assessments.\n <\/jats:p>\n <\/jats:sec>\n \n Conclusion<\/jats:title>\n \n AAFP-AS1411 enabled preferential, high-contrast fluorescence imaging in the tested MDA-MB-231 TNBC model across\n in vitro<\/jats:italic>\n ,\n in vivo<\/jats:italic>\n , and\n ex vivo<\/jats:italic>\n experiments. These findings provide proof-of-concept support for further evaluation of activatable AS1411-based probes for molecular imaging of nucleolin-overexpressing TNBC.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fbioe.2026.1934598","type":"journal-article","created":{"date-parts":[[2026,9,23]],"date-time":"2026-09-23T05:55:52Z","timestamp":1790142952000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["A target-activated AS1411 aptamer probe for in vivo and ex vivo imaging of nucleolin-overexpressing triple-negative breast cancer"],"prefix":"10.3389","volume":"14","author":[{"given":"Juntao","family":"Tan","sequence":"first","affiliation":[{"name":"Jiangxi Province Key Laboratory of Breast Diseases, Nanchang People\u2019s Hospital\/The Affiliated Nanchang People\u2019s Hospital of Nanchang Medical College","place":["Nanchang, Jiangxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zixi","family":"Hu","sequence":"additional","affiliation":[{"name":"Clinical Laboratory Center, The First Affiliated Hospital of Guilin Medical University","place":["Guilin, Guangxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Da","family":"Huang","sequence":"additional","affiliation":[{"name":"Jiangxi Province Key Laboratory of Breast Diseases, Nanchang People\u2019s Hospital\/The Affiliated Nanchang People\u2019s Hospital of Nanchang Medical College","place":["Nanchang, Jiangxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lu","family":"Chen","sequence":"additional","affiliation":[{"name":"Jiangxi Province Key Laboratory of Breast Diseases, Nanchang People\u2019s Hospital\/The Affiliated Nanchang People\u2019s Hospital of Nanchang Medical College","place":["Nanchang, Jiangxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Liangliang","family":"Min","sequence":"additional","affiliation":[{"name":"Jiangxi Province Key Laboratory of Breast Diseases, Nanchang People\u2019s Hospital\/The Affiliated Nanchang People\u2019s Hospital of Nanchang Medical College","place":["Nanchang, Jiangxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kui","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Tumor Functional Genomics and Precision Prevention and Treatment, Guilin Medical University","place":["Guilin, Guangxi, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhihua","family":"Li","sequence":"additional","affiliation":[{"name":"Jiangxi Province Key Laboratory of Breast Diseases, Nanchang People\u2019s Hospital\/The Affiliated Nanchang People\u2019s Hospital of Nanchang Medical College","place":["Nanchang, Jiangxi, China"]},{"name":"Department of Breast Surgery, Nanchang People\u2019s Hospital\/The Affiliated Nanchang People\u2019s Hospital of Nanchang Medical College","place":["Nanchang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,23]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"2010","DOI":"10.3390\/cancers15072010","article-title":"Aptamer-based strategies to boost immunotherapy in TNBC","volume":"15","author":"Agnello","year":"2023","journal-title":"Cancers (Basel)"},{"key":"B2","doi-asserted-by":"publisher","first-page":"235","DOI":"10.1038\/nmat4476","article-title":"A small-molecule dye for NIR-II imaging","volume":"15","author":"Antaris","year":"2016","journal-title":"Nat. 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