Upconversion Luminescence-Activated DNA Nanodevice for ATP Sensing in Living Cells

Designer DNA nanodevices have attracted extensive interest for detection of specific targets in living cells. However, it still remains a great challenge to construct DNA sensing devices that can be activated at desired time with a remotely applied stimulus. Here we report a rationally designed, synthetic DNA nanodevice that can detect ATP in living cells in an upconversion luminescence-activatable manner. The nanodevice consists of a UV light-activatable aptamer probe and lanthanide-doped upconversion nanoparticles which acts as the nanotransducers to operate the device in response to NIR light. We demonstrate that the nanodevice not only enables efficient cellular delivery of the aptamer probe into live cells, but also allows the temporal control over its fluorescent sensing activity for ATP by NIR light irradiation in vitro and in vivo. Ultimately, with the availability of diverse aptamers selected in vitro, the DNA nanodevice platform will allow NIR-triggered sensing of various targets as well as modulation of biological functions in living systems

Near-Infrared-Light Mediated Ratiometric Luminescent Sensor for Multimode Visualized Assays of Explosives

The development of a portable and easy-to-use device for the detection of explosives with high sensitivity and selectivity is in high demand for homeland security and public safety. In this study, we demonstrate miniaturized devices depending on the upconversion ratiometric luminescent probe for point-of-care (POC) assay of explosives with the naked-eye. When the PEI-coated upconversion nanoparticles (UCNPs) selectively bonded to 2,4,6-trinitrotoluene (TNT) explosives by the formation of Meisenheimer complex, the formed of UCNP–Meisenheimer complexes show turned visible multicolor upconversion luminescence (UCL) on account of TNT-modulating Förster resonance energy transfer process under near-infrared excitation. With UCL emission at 808 nm as internal standard and ratiometric UCL at 477 nm to that at 808 nm (<i>I</i>₄₇₇/<i>I</i>₈₀₈) as output signal, the probe can simultaneously meet the accuracy for TNT explosives quantitative analysis. In addition, this easy-to-use visual technique provides a powerful tool for convenient POC assay of rapid explosives identification

Highly Sensitive Wearable Pressure Sensors Based on Three-Scale Nested Wrinkling Microstructures of Polypyrrole Films

Pressure sensors have a variety of applications including wearable devices and electronic skins. To satisfy the practical applications, pressure sensors with a high sensitivity, a low detection limit, and a low-cost preparation are extremely needed. Herein, we fabricate highly sensitive pressure sensors based on hierarchically patterned polypyrrole (PPy) films, which are composed of three-scale nested surface wrinkling microstructures through a simple process. Namely, double-scale nested wrinkles are generated via in situ self-wrinkling during oxidative polymerization growth of PPy film on an elastic poly­(dimethylsiloxane) substrate in the mixed acidic solution. Subsequent heating/cooling processing induces the third surface wrinkling and thus the controlled formation of three-scale nested wrinkling microstructures. The multiscale nested microstructures combined with stimulus-responsive characteristic and self-adaptive ability of wrinkling morphologies in PPy films offer the as-fabricated piezoresistive pressure sensors with a high sensitivity (19.32 kPa^–1), a low detection limit (1 Pa), an ultrafast response (20 ms), and excellent durability and stability (more than 1000 circles), these comprehensive sensing properties being higher than the reported results in literature. Moreover, the pressure sensors have been successfully applied in the wearable electronic fields (e.g., pulse detection and voice recognition) and microcircuit controlling, as demonstrated here

Highly Sensitive Wearable Pressure Sensors Based on Three-Scale Nested Wrinkling Microstructures of Polypyrrole Films

Pressure sensors have a variety of applications including wearable devices and electronic skins. To satisfy the practical applications, pressure sensors with a high sensitivity, a low detection limit, and a low-cost preparation are extremely needed. Herein, we fabricate highly sensitive pressure sensors based on hierarchically patterned polypyrrole (PPy) films, which are composed of three-scale nested surface wrinkling microstructures through a simple process. Namely, double-scale nested wrinkles are generated via in situ self-wrinkling during oxidative polymerization growth of PPy film on an elastic poly­(dimethylsiloxane) substrate in the mixed acidic solution. Subsequent heating/cooling processing induces the third surface wrinkling and thus the controlled formation of three-scale nested wrinkling microstructures. The multiscale nested microstructures combined with stimulus-responsive characteristic and self-adaptive ability of wrinkling morphologies in PPy films offer the as-fabricated piezoresistive pressure sensors with a high sensitivity (19.32 kPa^–1), a low detection limit (1 Pa), an ultrafast response (20 ms), and excellent durability and stability (more than 1000 circles), these comprehensive sensing properties being higher than the reported results in literature. Moreover, the pressure sensors have been successfully applied in the wearable electronic fields (e.g., pulse detection and voice recognition) and microcircuit controlling, as demonstrated here

Heterodimers Made of Upconversion Nanoparticles and Metal–Organic Frameworks

Creating nanoparticle dimers has attracted extensive interest. However, it still remains a great challenge to synthesize heterodimers with asymmetric compositions and synergistically enhanced functions. In this work, we report the synthesis of high quality heterodimers composed of porphyrinic nanoscale metal–organic frameworks (nMOF) and lanthanide-doped upconversion nanoparticles (UCNPs). Due to the dual optical properties inherited from individual nanoparticles and their interactions, absorption of low energy photons by the UCNPs is followed by energy transfer to the nMOFs, which then undergo activation of porphyrins to generate singlet oxygen. Furthermore, the strategy enables the synthesis of heterodimers with tunable UCNP size and dual NIR light harvesting functionality. We demonstrated that the hybrid architectures represent a promising platform to combine NIR-induced photodynamic therapy and chemotherapy for efficient cancer treatment. We believe that such heterodimers are capable of expanding their potential for applications in solar cells, photocatalysis, and nanomedicine

Determinative Surface-Wrinkling Microstructures on Polypyrrole Films by Laser Writing

We report a simple and efficient laser-writing strategy to fabricate hierarchical nested wrinkling microstructures on conductive polypyrrole (PPy) films, which enables us to develop advanced functional surfaces with diverse applications. The present strategy adopts the photothermal effect of PPy films to mimick the formation of hierarchical nested wrinkles observed in nature and design controlled microscale wrinkling patterns. Here, the PPy film is grown on a poly­(dimethylsiloxane) (PDMS) substrate via oxidation polymerization of pyrrole in an acidic solution, accompanied by in situ self-wrinkling with wavelengths of two different scales (i.e., λ₁ and λ₂). Subsequent laser exposure of the PPy/PDMS bilayer induces a new surface wrinkling with a larger wavelength (i.e., λ₃). Owing to the retention of the initial λ₁ wrinkles, we obtain hierarchical nested wrinkles with the smaller λ₁ wrinkles nested in the larger λ₃ ones. Importantly, we realize the large-scale path-determinative fabrication of complex oriented wrinkling microstructures by controlling the relative motion between the bilayer and the laser. Combined with the induced changes in surface color, surface-wrinkling microstructures, and conductivity in the PPy films, the laser-writing strategy can find broad applications, for example, in modulation of surface wetting properties and fabrication of microcircuits, as demonstrated in this work