A novel bi-layer sensing structure is proposed for trace BTEX detection, where an insulated CeO2 catalyst is coated onto the top-surface of a conventional ZnO sensing layer.

Programming ultrasensitive and stimuli-responsive DNAzyme-based probes that contain logic gate biocomputation hold great potential for precise molecular imaging. In this work, a DNA computationmediated DNAzyme platform that can be activated by 808 nm NIR light and target c-MYC was designed for spatiotemporally controlled ultrasensitive AND-gated molecular imaging. Particularly, the sensing and recognition function of the traditional DNAzyme platform was inhibited by introducing a blocking sequence containing a photo-cleavable linker (PC-linker) that can be indirectly cleaved by 808 nm NIR light and thus enables the AND-gated molecular imaging. According to the responses toward three designed SDz, nPC-SDz, and m-SDz DNAzyme probes, the fluorescence recovery in diverse cell lines (MCF-7, HeLa, and L02) and inhibitor-treated cells was investigated to confirm the ANDgated sensing mechanism. It is worth noting that thanks to the strand displacement amplification and the ability of gold nanopyramids (Au NBPs) to enhance fluorescence, the fluorescence intensity increased by ∼7.9 times and the detection limit decreased by nearly 40.5 times. Moreover, false positive signals can be also excluded due to such AND-gated design. Furthermore, such a designed "AND-gate" sensing manner can also be applied to spatiotemporally controlled ultrasensitive in vivo molecular imaging, indicating its promising potential in precise biological molecular imaging.

Signal amplification strategies with spatiotemporally high sensitivity can provide more accurate information and hold great promise for improving the accuracy of disease diagnosis. Herein, a 808 nm near-infrared (NIR) light-activated plasmon enhanced fluorescence-catalytic hairpin assembly (PEF-CHA) signal amplification strategy was proposed for spatiotemporally controllable precise imaging of miRNA in vitro and in vivo with ultrasensitivity. The proposed 808 nm NIR light-activated PEF-CHA signal amplification strategy is constructed through combining up-conversion photocontrol and PEF technologies with CHA. It is worth noting that the laser irradiation-induced overheating effect could be effectively alleviated by using Nd 3+ -sensitized upconversion nanoparticles (UCNPs) to convert 808 nm NIR light to ultraviolet (UV) light, which is almost nondestructive to cells or tissues. In addition, nonspecific activation as well as false positive signals can be effectively avoided. Moreover, the detection limit can be reduced by approximate 38 times thanks to the high sensitivity of the proposed strategy. Furthermore, we demonstrate that the 808 nm NIR light-activated PEF-CHA signal amplification strategy can be expanded to sensitive and activatable imaging of intratumoral miRNAs in living mice, showing feasible prospects for precise biological and medical analysis.

Arsenic contamination in groundwater and river has become a major problem around the world, which may cause severe environment pollution and human health problem. In this study, a cost-efficient adsorbentred mud porous beads (RPB), using red mud – a kind of alumina industry by-product, was synthesized for adsorptive removal of arsenic(V) from aqueous solution. Kinetic studies showed that chemisorption mainly governed the adsorption process. The experimental data was fitted well by Langmuir isotherm, and the equilibrium adsorption capacity for arsenic of 11.758 mg/g at pH = 7 condition. The effect of pH showed that the pHpzc of RPB was 6.0 and at pH = 6 the removal rate reached nearly 100%. The removal rate decreased from 91.3% to 79.0% with the increasing of initial concentration of arsenic from 2.5 to 20 mg/L. The adsorption performance from column studies illustrated that the velocity of flow and the initial concentration influenced the breakthrough time of the column. This study would facilitate the use of red mud, which can be fabricated into RPB, acting as a valuable adsorbent for removing arsenic in aqueous solution.

Nanogap antennas with strong electromagnetic fields of the “hot spot” in the gap region of two adjacent particles that can significantly improve the optical properties of fluorophores hold great potential for ultrasensitive bioanalysis. Herein, a DNA computation-mediated self-assembly of Au NBP dimer-based plasmonic nanogap antennas was designed for imaging of intracellular correlated dual disease biomarkers. It is worth noting that with the benefit from the electromagnetic fields of the “hot spot” in the gap region and strand displacement amplification, the fluorescence intensity can be enhanced ∼14.7-fold by Au NBP dimer-based plasmonic nanogap antennas. In addition, the AND-gate sensing mechanism was confirmed through monitoring the response of three designed nAP-PH1, m-PH1, and PH1 probes, the fluorescence recovery in different cell lines (Hela and L02), and inhibitor-treated cells, respectively. Furthermore, thanks to the “dual keys” activation design, such an “AND-gate” sensing manner can be used for ultrasensitive correlated multiplexed molecular imaging, demonstrating its feasible prospect in correlated multiplexed molecular imaging.