All cellular processes are the results of synchronized actions of several intracellular biochemical pathways. Recent emphasis is to visualize such pathways using appropriate small molecular reagents, dye-labeled proteins, and genetically encoded fluorescent biosensors that produce a luminescence ON response either on selective binding or on reacting with an analyte that is produced through a specific biochemical/ enzymatic transformation. Studying such enzymatic processes by probing the fluorescence response as the read-out signal is expected to provide important insights into crucial biochemical transformations induced by an enzyme in its native form. Many of such studies are extended for monitoring enzymatic transformations under in vitro or in vivo condition. A few of the recent reports reveal that such molecular probes are even capable of quantifying abnormal levels of enzymes in real-time and is linked to the key area of clinical diagnostics and chemical biology. A synchronized analysis of all such reports helps in developing a rationale for designing purpose-built molecular probes or chemodosimeters as well as newer reagents for studying crucial enzymatic process or quantification of the respective enzyme. In this review, an attempt will be there to highlight several recent bioimaging reagents and studies that have provided insights into crucial biochemical or enzymatic transformations.

Protein kinase C (PKC) is an important constituent of the signaling pathways involved in apoptosis. We report here that like staurosporine, withaferin A is a potent inhibitor of PKC. In Leishmania donovani, the inhibition of PKC by withaferin A causes depolarization of DW m and generates ROS inside cells. Loss of DW m leads to the release of cytochrome c into the cytosol and subsequently activates caspase-like proteases and oligonucleosomal DNA cleavage. Moreover, in treated cells, oxidative DNA lesions facilitate the stabilization of topoisomerase I-mediated cleavable complexes, which also contribute to DNA fragmentation. However, withaferin A and staurosporine cannot induce cleavable complex formation in vitro with recombinant topoisomerase I nor with nuclear extracts from control cells. Taken together, our results indicate that inhibition of PKC by withaferin A is a central event for the induction of apoptosis and that the stabilization of topoisomerase I-DNA complex is necessary to amplify apoptotic process.

Separation membranes with higher molecular weight cut‐offs are needed to separate ions and small molecules from a mixed feed. The molecular sieving phenomenon can be utilized to separate smaller species with well‐defined dimensions from a mixture. Here, the formation of freestanding polyimine nanofilms with thicknesses down to ≈14 nm synthesized via self‐assembly of pre‐synthesized imine oligomers is reported. Nanofilms are fabricated at the water–xylene interface followed by reversible condensation of polymerization according to the Pieranski theory. Polyimine nanofilm composite membranes are made via transferring the freestanding nanofilm onto ultrafiltration supports. High water permeance of 49.5 L m‐2 h−1 bar−1 is achieved with a complete rejection of brilliant blue‐R (BBR; molecular weight = 825 g mol−1) and no more than 10% rejection of monovalent and divalent salts. However, for a mixed feed of BBR dye and monovalent salt, the salt rejection is increased to ≈18%. Membranes are also capable of separating small dyes (e.g., methyl orange; MO; molecular weight = 327 g mol−1) from a mixed feed of BBR and MO. Considering a thickness of ≈14 nm and its separation efficiency, the present membrane has significance in separation processes.

Two-photon active graphene quantum dots (GQDs) are obtained from extracts of the neem root.

Functional nanocarriers were synthesized using an in situ inverse miniemulsion polymerization employing thiol-isocyanate reactions at the droplet interface to encapsulate hydrophilic payloads. The morphology of the nanocarriers is conveniently tunable by varying the reaction conditions and the dispersions are easily transferable to the aqueous phase.