A strip of tethered rhodamine carbon nanodots (C-dots) was designed for selective detection of Al(3+) ion using a Förster resonance energy transfer (FRET)-based ratiometric sensing mechanism. The probe consisted of rhodamine B moieties immobilized on the surface of water-soluble C-dots. Upon exposure to Al(3+), the rhodamine moieties showed a much enhanced emission intensity via energy transfer from the C-dots under excitation at their absorption wavelength. The detection mechanism was related to the Al(3+)-induced ring-opening of rhodamine on C-dots through the chelation of the rhodamine 6G moiety with Al(3+), leading to a spectral overlap of the absorption of C-dots (donor) and the emission of ring-opened rhodamine (acceptor). In addition, a paper-based sensor strip containing the tethered rhodamine C-dots was prepared for practical, versatile applications of Al(3+) sensing. The paper-based sensor could detect Al(3+) over other metal ions efficiently, even from a mixture of metal ions, with increased emission intensity at long-wavelength emission via FRET. Sensing based on FRET of C-dots is color-tunable, can be recognized with a naked eye, and may provide a new platform for specific metal-ion sensing.

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We discuss recent advances made in the development of NIR fluorescence-emitting small organic molecules for tumor imaging and therapy.

Recognition of glycans by proteins plays a crucial role in a variety of physiological processes in cells and living organisms.

An experimental and numerical study was performed to investigate the effects of interface debonding on the performance of piezoelectric (PZT) ceramic actuators for structural health monitoring (SHM) systems. Interface degradation of PZT actuators may occur over time during the in-service life of the structure compromising the performance and reliability of the SHM system. Energy losses and signal changes should be understood to guarantee the reliability of the SHM systems during the life-time of the structure. Here we present the first systematic study on the performance of PZT actuators with a partially degraded interface. The electro-mechanical coupling between PZT actuators and a hosting aluminium plate was found to vary with the interface debonding over a wide frequency range affecting the amplitude and phase of the actuator's signal. A signal delay and an amplitude decrease were observed for: increasing debonding area, different debond shape, and location underneath the PZT actuators. Changes were found to be dependent on the actuation frequency with respect to the PZT resonance frequency. A spectral element-based code integrated with a coupled electromechanical field solver was used to verify the experimental results by simulating the propagation of ultrasonic Lamb waves in an aluminum plate with built-in PZT sensors/actuators.