Construction of a photo-controlled fluorescent switching with diarylethene modified carbon dots

Photo-controlled fluorescent switching is of great utility in fluorescence sensors, reversible data storage, and logic circuit, based on their modifiable emission intensity and spectra. In this work, a novel photo-controlled reversible fluorescent switching system was constructed based on photochromic diarylethene (DT) molecular modified fluorescent carbon dots (CDs). The fluorescent CDs acted as fluorescent donors and the photochromic diarylethene molecular functioned as acceptors in this fluorescent switching system. The fluorescence modulation efficiency of the fluorescent switching was determined to be 97.1%. The result was attributable to Förster resonance energy transfer (FRET) between the CDs and the diarylethene molecular. The fluorescent switching could undergo 20 cycles without significant decay.

Bio-Mediated Synthesis of Nanoparticles for Fluorescence Sensors

The nature deeds alike a hefty “bio-laboratory” embracing of plants, algae, fungi, yeast etc. which are poised of biomolecules. These indeed befalling biomolecules must stood notorious to play an active role in the establishment of nanoparticles through diverse shapes and sizes thus acting as a driving force intended for the scheming of greener, safe and environmentally benign protocols for the synthesis of nanoparticles. The contemporary chapter targets the proportional biogenic synthesis and mechanisms of nanoparticles using biomolecules. The practice of biomolecules not only diminishes the price of synthesis but also curtails the need of using hazardous chemicals and arouses ‘green synthesis’. It also emphases on aspects of binding of biomolecules to nanoparticles and certain of the applications of the biosynthesized nanoparticles as sensor for cations, anions and also biosensors.

Live Cell Imaging of Enzymatic Turnover of an Adenosine 5′-Tetraphosphate Analog

The hydrolysis of nucleotides is of paramount importance as an energy source for cellular processes. In addition, the transfer of phosphates from nucleotides onto proteins is important as a post-translational protein modification. Monitoring the enzymatic turnover of nucleotides therefore offers great potential as a tool to follow enzymatic activity. While a number of fluorescence sensors are known, so far, there are no methods available for the real-time monitoring of ATP hydrolysis inside live cells. We present the synthesis and application of a novel fluorogenic adenosine 5′-tetraphosphate (Ap4) analog suited for this task. Upon enzymatic hydrolysis, the molecule displays an increase in fluorescence intensity, which provides a readout of its turnover. We demonstrate how this can be used for monitoring cellular processes involving Ap4 hydrolysis. To this end, we visualized the enzymatic activity in live cells using confocal fluorescence microscopy of the Ap4 analog. Our results demonstrate that the Ap4 analog is hydrolyzed in lysosomes. We show that this approach is suited to visualize the lysosome distribution profiles within the live cell and discuss how it can be employed to gather information regarding autophagic flux.