A novel liquid crystal sensing platform for highly selective UO22+ detection based on a UO22+-specific DNAzyme.

A label-free and selective sensor was established for uranyl ion (UO22+) detection based on a UO22+-dependent DNAzyme and liquid crystals (LCs). In the presence of UO22+, the substrate chains can be cleaved at the rA site by the DNAzyme strands. The cleaved products released from the DNAzyme strand will hybridize with the capture probes that are fixed on the LC sensing substrate to form double strands. The formation of double strands would disturb the original orientation and induce the rearrangement of liquid crystal molecules, resulting in the polarization images changing from uniform black to bright. Attributed to the specificity of the DNAzyme and the optical signal of the LC, a highly selective and label-free method was established with a detection limit of 25 nM. This approach showed satisfactory analytical performance and offered an inspiring platform for detecting other radioactive elements.

[Relationship between spinal function and the severity of spinal cord injury by needle puncture].

OBJECTIVE: To observe the changes in spinal cord pathophysiology, motor function and electrophysiology after spinal cord injuries induced by punctures with different needles, and explore a new means for studying spinal neurotoxicity of local anesthetics. METHODS: A total of 144 SD rats were randomly allocated into the sham-operated group (n=36) and 3 spinal cord injury groups (n=36) with the L4-5 segment of the dura mater of the spinal cord punctured using 29G, 25G, and 21G needles. The BBB scores before surgery were recorded, and at 8 h, 24 h, 72 h, 1 week, and 2 weeks after the surgery, the motor evoked potential (MEP), spinal cord pathology and the BBB scores were examined. RESULTS: In the control group, the rats showed normal BBB score, spinal function and microstructure. Spinal cord puncture with 29G needle did not cause obvious pathologies of the spinal cord, whereas puncture with 21G needle resulted in marked changes in the motor function, electrophysiology and histology of the spinal cord, which showed significant improvements at 2 weeks postoperatively. CONCLUSION: Puncture with a 29G needle causes less injuries and minimal functional changes of the spinal cord, which can serve as a new means for studying spinal neurotoxicity of local anesthetics.