No abstract

Functionalization of carbon nanodots (C-dots) with quinoline derivatives enables a highly sensitive and specific nanosensor for Zn2+ sensing in aqueous solution and Zn2+ imaging in vivo.

Obtaining tunable photoluminescence (PL) with improved emission properties is crucial for successfully implementing fluorescent carbon nanodots (fCDs) in all practical applications such as multicolour imaging and multiplexed detection by a single excitation wavelength. In this study, we report a facile hydrothermal approach to adjust the PL peaks of fCDs from blue, green to orange by controlling the surface passivation reaction during the synthesis. This is achieved by tuning the passivating reagents in a step-by-step manner. The as-prepared fCDs with narrow size distribution show improved PL properties with different emission wavelengths. Detailed characterization of fCDs using elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy suggested that the surface chemical composition results in this tunable PL emission. Surface passivation significantly alters the surface status, resulting in fCDs with either stronger surface oxidation or N element doping that ultimately determine their PL properties. Further experiments suggested that the as-prepared orange luminescent fCDs (O-fCDs) were sensitive and specific nanosensing platforms towards Fe(3+) determination in a complex biological environment, emphasizing their potential practical applications in clinical and biological fields.

No abstract

Recent developments in the rational design and the controlled assembly of nanoscale building blocks have resulted in functional devices such as nano-optoelectronics, novel contrast probes for molecular imaging, and nanosensors. In the present study, we designed and synthesized a hybrid nanomaterial consisting of [Ru(bpy)3](2+)-encapsulated silica nanoparticles (SiNPs) and gold nanoparticles (AuNPs) through peptide-bridged assembly in a controllable way. A peptide that contains recognition sequence DEVD specific for active caspase-3 cleavage was employed to bring SiNPs and AuNPs into close proximity through specific molecular recognition. A FRET system with SiNPs as energy donors and AuNPs as energy acceptors has been thus developed and applied for caspase-3 detection. A change in distance between the two building blocks resulted in a change in FRET efficiency, causing a ratiometric change in emission. Caspase-3 triggers the cleavage of the peptide links between the two nanoparticles and releases AuNPs from the nanohybrids, inducing the activation of SiNPs to the "ON" state. The fluorescence turn-on response is specific to caspase-3 and allows the detection of caspase-3 as low as 0.05 U mL(-1) (∼6 pM).