Gene biomarkers of circulating tumor DNA (ctDNA) in liquid biopsies have been explored for use in the precise diagnosis of tumors. There is a great clinical need to realize the ultrasensitive detection of gene biomarkers in ctDNA. Here we reported that an ultrasensitive label-free biosensor was developed for the detection of the gastric cancer-related PIK3CA gene of ctDNA in peripheral blood. The polymeric L-arginine and graphene oxide-wrapped gold nanostars (rGO-AuNSs) were prepared and deposited on the glass electrode. The capturing DNA probes for the PIK3CA gene were prepared and successfully immobilized on the rGO-AuNS-modified electrode surface via π−π interaction among the rGO-AuNS composites and DNA probes. The resultant electrochemical sensor was effectively applied to detect the PIK3CA gene of ctDNA via the hybridization between the capturing DNA probe and ctDNA, the result of which showed that the biosensor exhibited desirable sensitivity, stability, and a wider dynamic response in a ctDNA concentration range from 1.0 × 10 −20 to 1.0 × 10 −10 M (R 2 = 0.997). Moreover, the low limit of detection of 1.0 × 10 −20 M (S/N = 3) indicates the biosensor owns satisfactory detection sensitivity. Fourteen PIK3CA genes and two PIK3CA gene mutations were detected in 60 clinical ctDNA samples of gastric cancer patients by using the developed biosensor. In conclusion, this ultrasensitive label-free electrochemical biosensor possesses a significant application prospect in the detection of the PIK3CA gene in ctDNA and in early screening for gastric cancer in the near future.
How to develop near-infrared second window (NIR-II, 1000–1700 nm) fluorescent nanoprobes with a uniform size, strong fluorescence signal and good biosafety owns great clinical requirement. Herein we reported that a two photon fluorescent nanoprobe was developed via encapsulating
NIR-II-fluorescent molecules into DSPE-PEG, which was effectively endocytosized by cancer cells, and achieved strong NIR-II fluorescence imaging in cancer cells and cancer cell-beard mice models. Prepared NIR-II-fluorescent nanoprobe exhibited rapid metabolism and excellent biocompatibility.
In conclusion, the prepared two photon nanoprobe owns good biosafety, and clinical translational prospect in NIR-II fluorescent imaging of tumour in vivo in near future.
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