Search

DNA-based nanomachines have aroused tremendous interest because of their potential applications in bioimaging, biocomputing, and diagnostic treatment. Herein, we constructed a novel exonuclease III-propelled and signal-amplified stochastic DNA walker that autonomously walked on a spherical particle-based 3D track through a burnt-bridge mechanism, during which nanosurface energy transfer (NSET) occurred between the fluorescent dye modified on hairpin DNA and the surface of gold nanoparticles (AuNPs). As a proof of concept, this stochastic DNA walker achieves prominent detection performance of HIV DNA in the range of 0.05–1.2 nM with a detection limit of 12.7 pM and satisfactory recovery in blood serum, showing high promise in biosensing applications with complicated media.

Fluorescent labeled single-stranded DNA (ssDNA) molecules physisorbed on graphene oxide (GO) have been extensively explored as a useful sensing platform. However, this approach faces challenges when applied to complex biological samples due to heavy nonspecific desorption of nontarget molecules from GO. To overcome this problem, we introduced a capture DNA (cDNA) fragment with a poly adenine (poly-A) extension into the physisorption system that greatly reduces nonspecific desorption and false positive signal due to strong binding between poly-A and GO. Fluorescence from the dye can be effectively quenched by BHQ, which thus provides a second guarantee of anti-interference to avoid possible nonspecific poly-A DNA displacement. As a proof of concept, we have successfully developed a novel DNA-adsorbing GO nanocomplex probe (DNA-GO nanocomplex probe). This probe has a high anti-interference capability and low background due to the presence of both GO and black hole quencher (BHQ) as a dual-quencher that reduces the background in live cell imaging due to resonance energy transfer (RET). We then employed the DNA-GO nanocomplex probe for simultaneous detection of miR-630 and miR-21 and also for simultaneous in situ dynamic monitoring of intracellular miR-630 and miR-21 in apoptotic cells. We discovered that miR-630 expression was up-regulated during the first 120 min. This simple but powerful protocol has great potential in precise detection and imaging of various substances in complex biological samples with improved accuracy.

Nitrite (NO2−) is one of the important pollutants in food and the environment, which can seriously endanger the health of human beings. Therefore, detecting nitrite in food, environmental and biological samples is very significant for health monitoring. Herein, polymer carbon dots (PCDs) doped with nitrogen and phosphorus were prepared by polymerization of ascorbic acid (AA) and polyethylenimine (PEI) with phosphoric acid, and exhibited excellent stability, adjustable fluorescence emissions and good biocompatibility. It was found that the PCDs presented a sensitive response to nitrite (NO2−), and they were successfully applied for NO2− analysis in water and milk samples, and the dynamic monitoring of nitrite entry into Hep-2 cells.

Multi-centric solid-pseudopapillary neoplasm (SPN) of the pancreas is a rare tumor: only 4 cases are reported in the literature. The clinical and pathological features have not yet been fully clarified. We report 3 cases of multi-centric SPN and discuss their clinical presentations and histological and immunohistochemical features, comparing with solitary SPN. Among the total of 7 cases, 6 were female and 1 was male. Patients had nonspecific symptoms at presentation. Tumors were often large and well demarcated with cystic degeneration and clear margin between lumps. Histologically, characteristic pseudopapilla was formed with uniform cells surrounding the delicate blood vessels. Tumor cells were positive for vimentin, synaptophysin, progesterone receptor, and CD10 and demonstrated nuclear localization of β-catenin. The prognosis of patients was excellent after complete surgical resections. Multi-centric SPN shares similar clinical and pathological features to solitary SPN.

To determine the contents of thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) in pancreatic cancer to provide a basis for the clinical use of capecitabine in pancreatic cancer patients.The contents of TP and DPD in pancreatic cancer and adjacent normal tissues from 20 patients were determined by ELISA and the TP to DPD ratios in the cancer and adjacent normal tissue were compared.TP content was 5- to 283-fold higher in tumor tissue (mean 74-fold) than in the adjacent normal tissue (P0.01). DPD in the cancer tissue increased significantly. So did the TP to DPD ratio, when compared to that in normal pancreatic tissue (P0.01).The increased TP to DPD ratio in pancreatic cancer suggests that capecitabine could be activated by the cancer, these capable of selectively kill the tumor cells.