Programmable DNA-responsive microchip for the capture and release of circulating tumor cells by nucleic acid hybridization

The detection and analysis of circulating tumor cells （CTCs） from patients＇ blood is important to assess tumor status; however, it remains a challenge. In the present study, we developed a programmable DNA-responsive microchip for the highly efficient capture and nondestructive release of CTCs via nucleic acid hybridization. Transparent and patternable substrates with hierarchical architectures were integrated into the microchip with herringbone grooves, resulting in greatly enhanced cell-surface interaction via herringbone micromixers, more binding sites, and better matched topographical interactions. In combination with a high-affinity aptamer, target cancer cells were specifically and efficiently captured on the chip. Captured cancer cells were gently released from the chip under physiological conditions using toehold-mediated strand displacement, without any destructive factors for cells or substrates. More importantly, aptamercontaining DNA sequences on the surface of the retrieved cancer cells could be further amplified by polymerase chain reaction （PCR）, facilitating the detection of cell surface biomarkers and characterization of the CTCs. Furthermore, this system was extensively applied to the capture and release of CTCs from patients＇ blood samples, demonstrating a promising high-performance platform for CTC enrichment, release, and characterization.

Advances in 3D bioprinting technology for liver regeneration

The liver is involved in over 500 biochemical reactions.Over the last couple of decades,liver diseases have become a major cause of morbidity and mortality in the world(1).Unfortunately,treatment options for patients with chronic liver disease remain limited.Due to the lack of highly sensitive and effective detection methods,most patients with liver cancer are already in an advanced stage when diagnosed(2).

Visually Intracellular Detection of Telomerase Activity Based on DNA Strand Displacement Reaction and Gold Nanoparticle Labeling

Telomerase,which is regarded as a common biomarker for early cancer diagnostics and a potential target for clinical therapies,has attracted considerable interests concerning its detection and monitoring.Herein,we propose a sensitive method by designing a gold nanoparticle(AuNP)probe for visually intracellular detection of telomerase activity.The AuNPs were functionalized with a telomer-ase substrate primer(SH-prime).A 6-carboxy-fluorescein(FAM)modified strand(FAM-probe)was attached to the surface of AuNP through its complementary stand(SH-attach).In the absence of telomerase,the fluorescence resonance energy transfer(FRET)from FAM to AuNPs results in efficient fluorescence quenching.In the presence of telomerase,SH-primers on AuNPs were extended with the repeat units(TTAGGGG)n.The extension sequence triggered the strand displacement of FAM-probe to restore the fluorescence signals.It is worth mentioning that the proposed strategy does not need to design complex hairpin structure and allows the meas-urement of telomerase in crude cell extracts down to 0.5 HeLa cells/μL in 2 h.In addition,the present sensing platform can be ap-plied to the visually intracellular detection of telomerase activity in living cells.