Universal and naked-eye gene detection platform based on CRISPR/Cas12a/13a system

Colorimetric gene detection based on gold nanoparticles (AuNPs) is an attractive detection format due to its simplicity. Here, we report a new design for a colorimetric gene-sensing platform based on the CRISPR/Cas system that has improved specificity, sensitivity, and universality. CRISPR/Cas12a and CRISPR/Cas13a have two distinct catalytic activities and are used for specific target gene recognition. Programmable recognition of DNA by Cas12a/crRNA and RNA by Cas13a/crRNA with a complementary sequence activates the nonspecific trans-ssDNA or -RNA cleavage, respectively, thus degrading the ssDNA or RNA linkers which are designed as a hybridization template for the AuNP-DNA probe pair. Target-induced trans -ssDNA or RNA cleavage leads to a distance-dependent color change for the AuNP-DNA probe pair. In this platform, naked eye detection of transgenic rice, African swine fever virus (ASFV), and a miRNA can be completed within 1 hour. Our colorimetric gene-sensing method shows superior characteristics, such as probe universality, isothermal reaction conditions, on-site detection capability, and sensitivity that is comparable to that of the fluorescent detection; thus, this method represents a robust next generation gene detection platform.

Research on the Application of 20 Degrees Probe Pair in TOFD

The feasibility of the application of probes with refraction angle of 20 degrees is discussed, and application effects of the probe are verified by experimental testing. The result shows, for ultrasonic TOFD testing of small flaws in lower part of high-wall-thickness work-pieces, the probe pair with refraction angle of 20 degree is superior to 45 degrees.

A new mode to light up an adjacent DNA-scaffolded silver probe pair and its application for specific DNA detection

By fluorescence enhancement of a proximity-dependent DNA-scaffolded silver nanocluster probe pair and exonuclease III-mediated signal amplification, we present a new fluorescence turn-on mode and its application for specific DNA detection.

Spacer length, label moiety interchange and probe pair orientation in a homogeneous solid-phase hybridization assay utilizing lanthanide chelate complementation

We have studied parameters affecting DNA hybridization and lanthanide chelate complementation based signal formation in a separation-free solid-phase assay suitable for spatial multiplexing.

Theoretical analysis of crosstalk between oxygenated and deoxygenated haemoglobin in focal brain-activation measurements by near-infrared topography

The crosstalk between concentration changes in oxygenated haemoglobin and deoxygenated haemoglobin calculated by the modified Lambert-Beer law in near-infrared topography is theoretically investigated. The changes in intensity detected with probe pairs on the scalp caused by the concentration change in either oxygenated or deoxygenated haemoglobin induced by the focal brain activation is predicted by Monte Carlo simulation. The topographic images of the changes in oxygenated and deoxygenated haemoglobin are obtained from the changes in the intensity of light at two wavelengths detected by probe pairs to evaluate the crosstalk. The crosstalk slightly depends on the positional relationship between the probe arrangement and the focal brain activation and is minimised when the focal brain activation is located below a measurement point that is the midpoint between a probe pair. The 690-/830-nm wavelength pair is practically effective for reducing the crosstalk, especially the crosstalk from oxygenated haemoglobin to deoxygenated haemoglobin, in the NIR topography.