Self-assembly of DNA-hyperbranched aggregates catalyzed by a dual-targets recognition probe for miRNAs SERS detection in single cells.

MicroRNAs (miRNAs) are very important for the early diagnosis and prognosis of tumors. In this work, we achieved the simultaneous detection of microRNA-155 (miR-155) and microRNA-21 (miR-21) with a dual target recognition probe (DRP) based on the nonlinear hybridization chain reaction (HCR). The multi-branched DNA products, three-dimensional multi-hotspot DNA dendrimers (3DmhD) were used in the amplification of the target miRNAs signal. The DRP is constructed with a core of gold nanocages (AuNCs), modified by nucleic acid probes and labeled with Raman signaling molecules ROX and Cy3. Experiments demonstrated that DRP could activate the multi-branched DNA reaction and generate 3DmhD in the presence of miR-155 and miR-21, which can achieve effective amplification of miR-21 and miR-155. When Surface Enhanced Raman Scattering (SERS) analysis was performed on 3DmhD, the multi-hot spot effect of 3DmhD significantly enhanced the signals of ROX and Cy3, allowing ultra-sensitive detection of miR-21 and miR-155 in vitro. To our delight, DRP also exhibited sensitive specificity and significant signal amplification for intracellular miRNAs. These results revealed that DRP has the potential to screen tumor cells by analyzing the expression levels of intracellular miRNAs.

Combination of microfluidic chips and biosensing for the enrichment of circulating tumor cells.

It has been reported that more than 90% of cancer patients are died from cancer metastasis. Circulating tumor cells (CTCs) could detach from solid tumors to form new lesions via blood transport and play an important role in cancer metastasis and progression. As part of the liquid biopsy, the investigation and analysis toward CTCs are of great importance for prognosis assessment and tumor precision medical treatment. Unfortunately, the enrichment of circulating tumor cells has been a huge challenge due to the fact that CTCs are very rare and vulnerable. Thus, a number of effective strategies have been developed for the enrichment of CTCs. This paper discusses the advantages and disadvantages of label-free and label-based methods commonly used in the isolation of CTCs. In particular, we systematically review the most recent advances in the combination of microfluidic chips and biosensing for the enrichment of circulating tumor cells. Finally, we put forward the current barriers that need to be overcome and developmental trends in the CTCs research.

Ultrasensitive Dual-Signal Detection of Telomerase and MiR-21 Based on Boolean Logic Operations.

Telomerase and micro-RNAs (miRNAs) are simultaneously upregulated in a variety of tumor cells and have emerged as promising tumor markers. However, sensitive detection of telomerase and miRNAs in situ remains a great challenge due to their low expression levels. Here, we designed a Boolean logic "AND" signal amplification strategy based on functionalized ordered mesoporous nanoparticles (FOMNs) to achieve ultrasensitive detection of telomerase and miR-21 in living tumor cells. Briefly, the strategy uses telomerase as an input to enable the release of DNA3-ROX-BHQ hairpins by making the wrapping DNA1 form a DNA-a hairpin with the joint participation of dNTPs. Subsequently, DNA2-Ag, DNA3-ROX-BHQ, and the second input miR-21 participated in hybridization chain reaction to amplify fluorescence and Raman signals. Experimental results showed the intensity of output dual signals relevant to the expression levels of telomerase and miR-21. The Ag nanoparticles (AgNPs) not only enhanced the fluorescence signals but also allowed to obtain more sensitive Raman signals. Therefore, even if expression of tumor markers is at a low level, the FOMN-based dual-signal logic operation strategy can still achieve sensitive detection of telomerase and miR-21 in situ. Furthermore, FOMNs can detect miR-21 expression levels in a short time. Consequently, this strategy has a potential clinical application value in detection of tumor markers and the assessment of tumor treatment efficacy.