The systematic investigation of the interaction of a new class of molecular materials with proteins through structure-optical signaling relationship studies has led to the development of efficient fluorescent probes that can detect and quantify serum albumins in biofluids without causing any denaturation.

Plaques of amyloid fibrils composed of neuronal protein α-synuclein are one of the hallmarks of Parkinson’s disease, and their selective imaging is crucial to study the mechanism of its pathogenesis. However, the existing fluorescent probes for amyloids are efficient only in solution and tissue systems, and they are not selective enough for the visualization of amyloid fibrils in living cells. In this study, we present two molecular rotor-based probes RB1 and RB2. These thiazolium probes show affinity to α-synuclein fibrils and turn-on fluorescence response upon interactions. Because of its extended π-conjugation and high rotational degree of freedom, RB1 exhibits a 76 nm red-shift of absorption maxima and 112-fold fluorescence enhancement upon binding to amyloid fibrils. Owing to its strong binding affinity to α-synuclein fibrils, RB1 can selectively stain them in the cytoplasm of living HeLa and SH-SY5Y cells with high optical contrast. RB1 is a cell-permeable and noncytotoxic probe. Taken together, we have demonstrated that RB1 is an amyloid probe with an outstanding absorption red-shift that can be used for intracellular imaging of α-synuclein fibrils.

Here we present a set of fluorescent cages prepared by tethering fluorescent dyes to a photolabile group.

Selective staining of human serum albumin protein in gel electrophoresis over wide range of other protein(s) is extremely important because it contains more than 60% volume of serum fluid in human body. Given the nonexistence of suitable dye materials for selective staining of serum albumins in gel electrophoresis, we report a new class of easy synthesizable and low molecular weight staining agents based on 3-amino-N-alkyl-carbazole scaffold for selective staining of serum albumins in solid phase. A detailed structure-efficiency relationship (SER) study enabled us to develop two such potent functional molecular probes which stain both human and bovine serum albumin selectively in gel electrophoresis in the presence of other proteins and enzymes. The present gel staining process was found to be very simple and less time-consuming as compared to the conventional coomassie blue staining which in turn makes these probes a new class of serum albumin-specific staining materials in proteome research. Moreover, these molecular lumino-materials can detect serum albumins at subnanomolar level in the presence of broad spectrum of other proteins/enzymes in aqueous buffer (99.9% water, pH = 7.3) keeping the protein secondary structure intact. Our experimental and the docking simulation results show that these probes bind preferentially at 'binding site I' of both the serum proteins.

Pristine graphene, as the name suggests is the closest to graphite structurally among all the forms of graphene that are synthesized using different methods. High electronic conductivity, large surface area, and absence of defects make this perfect two-dimensional arrangement of sp2 hybridized carbon atoms a perfect support material for metal or metal oxide nanoparticles. We have introduced a quick and green route to synthesize CuO nanocomposites having pristine graphene as a support material by microwave assisted hydrothermal reaction. The nanocomposite exhibited very high catalytic activity in copper catalyzed azide-alkyne cycloaddition (CuAAC) reactions compared with reduced graphene oxide (RGO)-CuO nanocomposite and CuO nanoparticles. The presence of pristine graphene in the nanocomposite increases the catalytic activity due to its better conductivity and ability to adsorb reactants through π–π interaction than RGO. The pristine graphene-CuO nanocomposite showed very good recyclability with much less leaching of the metal from it. The CuAAC reactions could be completed in a short duration (1 h), at low reaction temperature (30 °C), using water as a “green” solvent with a small amount of the pristine graphene-CuO nanocomposite as catalyst (0.51 mol %) and sodium ascorbate as cocatalyst (1 mol %).

Successful integration of selenium unit into a newly designed cationic chemical architecture led to the development of a highly photostable molecular maker PA5 to be used in fluorescence microscopy as cellular nucleus staining agent for longer duration imaging under continuous laser illumination. Adaptation of a targeted single-atom modification strategy led to the development of a series of proficient DNA light-up probes (PA1-PA5). Further, their comparative photophysical studies in the presence of DNA revealed the potential of electron rich heteroatoms of chalcogen family in improving binding efficiency and specificity of molecular probes toward DNA. The findings of cell studies confirmed the outstanding cell compatibility of probe PA5 in terms of cell permeability, biostability, and extremely low cytotoxicity. Moreover, the photostability experiment employing continuous laser illumination in solution phase as well as in cell assay (both fixed and live cells) revealed the admirable photobleaching resistance of PA5. Finally, while investigating the phototoxicity of PA5, the probe was found not to exhibit light-induced toxicity even when irradiated for longer duration. All these experimental results demonstrated the promising standing of PA5 as a futuristic cell compatible potential stain for bioimaging and temporal profiling of DNA.

No abstract

Considering the fundamental and most desirable characteristics of energetic materials, a series of 1,2,3-triazole-based heterocyclic energetic motifs nicely tuned with nitrato (−ONO 2 ) functionality were synthesized by a microwave-assisted environmental friendly synthetic approach with good yields. Thermal stability and the nature of evolved gases on decomposition of structurally characterized energetic motifs were analyzed by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) analysis and Fourier transform infrared coupled with TGA–DSC. The explosiveness of these motifs was explored by calculation of enthalpy of formation and density employing density functional theory, and the detonation performances (detonation pressure and velocity) were explored using EXPLO5_V6.03. All of these compounds were calculated to have better oxygen balance (−36 to −52%) as compared to that of trinitrotoluene (−74%). Most of the nitrate ester derivatives were found to exhibit low impact sensitivities, high densities, good thermal stabilities, and promising detonation properties, and PN 3 was observed to be a superior candidate in terms of its energetic characteristics. Hence, the experimental and theoretical outcomes strongly reflect that the present approach of developing dendritic high energetic materials bearing green explosive characteristics might be a potential pathway for designing and synthesizing green explosives with desired characteristics.