Xuelian Shen,Zhuqing Song,Erjiao Xu,Jun Zhou,Fei Yan
Neuromodulation by ultrasound (US) has recently drawn considerable attention due to its great advantages in noninvasiveness, high penetrability across the skull and highly focusable acoustic energy. However, the mechanisms and safety from US irradiation still remain less understood. Recently, documents revealed Piezo1, a mechanosensitive cation channel, plays key role in converting mechanical stimuli from US through its trimeric propeller-like structure. Here, we developed a Piezo1-targeted microbubble (PTMB) which can bind to the extracellular domains of Piezo1 channel. Due to the higher responsiveness of bubbles to mechanical stimuli from US, significantly lower US energy for these PTMB-binding cells may be needed to open these mechanosensitive channels. Our results showed US energy at 0.03 MPa of peak negative pressure can achieve an equivalent level of cytoplasmic Ca 2+ transients which generally needs 0.17 MPa US intensity for the control cells. Cytoplasmic Ca 2+ elevations were greatly reduced by chelating extracellular calcium ions or using the cationic ion channel inhibitors, confirming that US-mediated calcium influx are dependent on the Piezo1 channels. No bubble destruction and obvious temperature increase were observed during the US exposure, indicating cavitation and heating effects hardly participate in the process of Ca 2+ transients. In conclusion, our study provides a novel strategy to sensitize the response of nerve cells to US stimulation, which makes it safer application for US-mediated neuromodulation in the future.
In this study, a colorimetric detection system for Cr(III) was established by leveraging the laccase-mimicking activity of two-dimensional Cu-based metal-organic frameworks (Cu-MOFs) modified with polydopamine (PDA) nanomaterials (Cu-MOF@PDA), through which Cr(III) specifically inhibits the catalytic performance. The Cu-MOF@PDA composite exhibited significant laccase-mimicking activity, enabling the oxidation of 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP), leading to the generation of a red-colored compound. Notably, the laccase-like activity of Cu-MOF@PDA was substantially enhanced under ultrasonic (US) stimulation. Free-radical trapping experiments revealed that the levels of singlet oxygen ( 1 O 2 ) and hydroxyl radicals ( OH) were markedly increased, while the electron transfer rate was accelerated, thereby boosting catalytic efficiency under US exposure. The research confirmed that Cr(III) binds to Cu-MOF@PDA, leading to the suppression of its catalytic activity. A strong linear correlation (R 2 = 0.995) was observed between the absorbance at 505 nm and Cr(III) concentrations ranging from 0.67 to 54.17 μg/L, with a low detection limit (LOD) of 0.26 μg/L (S/N = 3). The developed approach was effectively utilized for the analysis of Cr(III) and total Cr in cigarette tipping paper samples, yielding highly satisfactory results.
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