Photo-Switchable Peroxidase/Catalase-Like Activity of Carbon Quantum Dots.

Nanozymes possess multi-enzyme activities over the natural enzymes, which produce multi-pathway synergistic effects for varies of biomedical applications. Unfortunately, their multi-enzyme activities are in fighting, significantly reducing the synergistic effects. Dynamic regulation of their multi-enzyme activities is the bottleneck for intelligent therapies. Herein, we construct a novel oxygen-nitrogen functionalized carbon quantum dots (O/N-CQDs) with peroxidase-like (Reactive oxygen species (ROS) producer) activity. Interestingly, the peroxidase-like activity can be reversibly converted to catalase-like (ROS scavenger) activity under visible light irradiation. It is found that both the peroxidase/catalase-like activity of O/N-CQDs can be precisely manipulated by the light intensity. The mechanism of switchable enzyme activities is attributed to the polarization of quinoid nitrogen in polyaniline (PANI) precursor retained on O/N-CQDs under visible light, which consumes the ROS to produce O2 and H2O. As a proof-of-concept demonstration, we are able to non-intrusively up and down regulate the ROS level in cells successfully by simply switching off and on the light respectively, potentially facilitating the precise medicine based on the development of the disease. Indeed, the photo-switchable peroxidase/catalase-like activity of O/N-CQDs opens a non-invasive strategy for better manipulations of the multi-activity of nanozymes, promising their wider and more intelligent biomedical applications.

3.0 T MRI is more recommended to detect acetabular labral tears than MR Arthrography: an updated meta-analysis of diagnostic accuracy.

BACKGROUND: This meta-analysis aimed to evaluate the current evidence on the diagnostic performance of MRI/MRA for detecting acetabular labral tears (ALT). METHODS: We systematically searched the PubMed, Embase, and Cochrane library until February 5, 2021, to identify original research studies reporting the diagnostic performance of MRI/MRA for the detection of ALT. Study methodological quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) tool. The summary sensitivity (Se) and specificity (Sp) of the studies were estimated using a bivariate model. We calculated the post-test probability to assess the clinical utility of MRI/MRA. Univariate meta-regression and subgroup analyses were performed to assess between-study heterogeneity. RESULTS: We included 22 studies (n = 1670 patients). The meta-analytic summary Se and Sp for MRI were 0.8 (95% CI 0.51-0.94) and 0.77 (95% CI 0.68-0.84), respectively, while for MRA they were 0.89 (95% CI 0.82-0.93) and 0.69 (95% CI 0.56-0.80). MRA showed a higher area under the summary receiver operating curve (SROC) (0.87 vs. 0.80) than MRI. MRI could increase the post-test probability to 0.78 and could decrease the post-test probability to 0.21, MRA could increase the post-test probability to 0.74 and could decrease the post-test probability to 0.14. Meta-regression analysis showed two significant factors affecting study heterogeneity: MR field strength and reference standard. After dividing the studies into two subgroups based on the MR field strength, we found that the Se values of 3.0 T MRI were very close to MRA (0.87 vs. 0.89), the Sp values of 3.0 T MRI were superior to MRA (0.77 vs. 0.69). CONCLUSIONS: Given that 3.0 T MRI could provide a non-invasive, fast and convenient method to recognize suspicious ALT cases, 3.0 T MRI is more recommended than MRA.