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Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the world, which can lead to considerably high mortality rate. It was reported that the prognosis is extremely poor and survival is often measured in months once CRC metastases become clinically evident. Therefore, the development of effective approach for metastatic CRC cells detection and imaging may potentially be significant and helpful for CRC prognosis and treatment. Therefore, we proposed a sensitive and specific approach for high-metastatic CRC LoVo cells detection and imaging by using terminal deoxynucleotidyl transferase (TdT)-initiated molecule beacons (MBs) arrayed fluorescent aptamer probes (denoted as TMAP). In this approach, the aptamer W3 targeting high-metastatic CRC LoVo cells was elongated to form W3-poly A at the 3′-hydroxyl terminus with repeated A bases in the presence of TdT and dATP. The MBs designed with poly T sequence in the loop were then hybridized with the poly A in the aptamer W3. The TMAP was easily constructed without the need of aptamer modification. It was demonstrated that this approach could specifically detect and image the high-metastatic CRC LoVo cells from the mixture of high-metastatic CRC LoVo cells and non-metastatic HCT-8 cells. Compared with 6-carboxyfluorescein (6-FAM) labeled aptamer W3, the TMAP was demonstrated to have a much stronger fluorescence signal on the target cells, realizing a 4-fold increase in signal-to-background ratio (SBR). Determination by flow cytometry allowed for detection of as low as 23 CRC LoVo cells in 200 μL cell culture medium. The high sensitivity and the capability for using in complicate biological samples imply that this approach holds considerable potential for metastatic CRC detection and therapy. Image 1 • TMAP was developed for specific detection and imaging of metastatic CRC cells. • TMAP could identify target LoVo cells with excellent binding affinity and specificity. • TMAP could specifically distinguish between the metastatic LoVo cells and non-metastatic HCT-8 cells in mixed cells samples. [ABSTRACT FROM AUTHOR]

Abstract Anterior gradient protein 2 homolog (AGR) is a potential tumor biomarker and plays an important role in tissue development and regeneration. The intracellular detection of AGR is rarely reported. By conjugating the AGR aptamer with a cytosine base sequence as Ag cluster template, a highly fluorescent probe (MA@AgNCs) was synthesized for targeting intracellular AGR. The MA@AgNCs display a maximum fluorescence peak at 565 nm, and possess an excellent quantum yield (QY = 87.43%), small size, great biocompatibility, low toxicity, and good stability. Moreover, the as synthesized MA@AgNCs show high specificity on recognizing breast cancer cells. Graphical abstract Scheme 1 The sketch of synthesis process and fluorescence cell imaging. fx1 Highlights • The MA@AgNCs shows high quantum yield, excellent stability, and good thermostability with negligible cytotoxicity. • The MA@AgNCs imaged the AGR protein in MCF-7 cells with good selectivity between MCF-7 and Hela cells. [ABSTRACT FROM AUTHOR]

Mucin 1 (MUC1) overexpression in tumor cells is related to various cancers, including breast, stomach, and lung cancer. MUC1 detection and imaging are important for cancer localization in tissue sections to support histopathological diagnosis. In this study, we developed a simple, enzyme-free MUC1 detection and in situ imaging method. Three hairpin probes, Apt-trigger, HP1-FAM, and HP2, were designed for MUC1 recognition and hybridization chain reaction (HCR). The Apt-trigger probe was composed of two sequences: the MUC1 aptamer and HCR trigger sequence. The 5' end of the HP1-FAM probe was modified with a FAM signal molecule. In the presence of MUC1, the aptamer sequence is activated and bound to MUC1, which opens the hairpin structure. Then, the trigger sequence gets exposed and, complementary to HP1-FAM, triggers a continuous HCR process. This method was successfully used to detect MUC1 of 200 pM–25 nM and MUC1 in situ imaging in specific cells, such as human breast carcinoma (MCF-7) and human colon cancer (HT-29) cells. A simple, enzyme-free detection and in situ imaging method for MUC1 was developed. This method was not only successfully used for MUC1 detection, but also its in situ imaging in specific cells. [Display omitted] • A simple, enzyme-free detection and in situ imaging method for MUC1 was developed. • An aptamer conformational switch was used for MUC1 recognition. • The hybridization chain reaction (HCR) was used for signal amplification. • This approach has potential applications in the detection and in situ imaging of various proteins. [ABSTRACT FROM AUTHOR]

Targeted imaging of cancer cells is crucial for early diagnosis. Mucin is a transmembrane protein that is overexpressed by cancer cells and is considered a cancer target. Specific recognition of mucin by aptamers has been receiving increasing attention in recent years. In this study, we use DNA MUC1 aptamer as a protective agent and target molecule in the synthesis of ultra-small fluorescent gold nanoclusters (MUC1-AuNCs) via a simple one-step method. MUC1-AuNCs exhibited red fluorescence emission with excellent stability over a wide pH range and under strong illumination. Confocal images showed that the synthesized MUC1-AuNCs efficiently targeted mucin overexpressing 4T1 cancer cells, but were not observed in 293T normal cells. Furthermore, the MUC1-AuNCs had a 5667 ns lifetime and 235 nm Stokes shifts and markedly eliminated background interference, suggesting they are a promising fluorescent probe for cell-targeted labeling and imaging. Image 1 • Luminescent gold nanoclusters were synthesized by thiolated MUC1 DNA aptamer as template. • The MUC1-AuNCs demonstrate good stability, low toxicity and specific cancer cell targeting properties. • The MUC1-AuNCs with long fluorescence lifetimes and large stokes shift can reduce background interference. [ABSTRACT FROM AUTHOR]