Ultrasound-Responsive Nanodroplet-Based Targeted Therapy via Conversion to Microbubbles.

Ultrasound-based therapy is appealing as it can be used via a wireless approach at remote parts of the body including the brain. Microbubbles are commonly used in such therapy due to their highly sound-responsive property. However, the larger size of microbubbles limits selective targeting in vitro/in vivo. Here, we report the design of nanodroplets of 70-130 nm in size that can be easily converted to microbubbles via ultrasound exposure. The advantage of this approach is that smaller nanodroplets can be used for cell/subcellular targeting, and next, they can be used for therapy by converting to microbubbles. More specifically, folate/dopamine-terminated perfluorohexane nanodroplets are designed that are loaded with a molecular drug. These nanodroplets are used for selective cell targeting, followed by ultrasound-induced microbubble conversion that is associated with drug release and intracellular reactive oxygen species generation. This approach has been used for selective cell therapy applications. The designed nanodroplet and approach can be used for the enhanced therapeutic performance of existing drugs.

Weakly coordinating tert-amide assisted Rh(III)-catalyzed C4-cyanation of indoles: application in photophysical studies.

A rhodium(III)-catalyzed indole C4-selective cyanation is described using the bench-stable, user-friendly electrophilic cyanation agent N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) as a coupling partner. A suitably positioned weakly coordinating tert-amide group was utilized for this site selectivity. The developed protocol proceeded with a broad scope. [Cp*Rh(MeCN)3][SbF6]2 was found to be an effective Rh(III) catalyst for this transformation. An initial study was carried out to know the photophysical properties of the C4-cyanated indole frameworks.

A PET and ESIPT-communicated ratiometric, turn-on chromo-fluorogenic sensor for rapid and sensitive detection of sarin gas mimic, diethylchlorophosphate.

Fast and precise identification of toxic G-series nerve agents in the solution and vapor phase is urgently needed to save human beings from unwanted wars and terrorist attacks, which is challenging to execute practically. In this article, we have designed and synthesized a sensitive and selective phthalimide-based chromo-fluorogenic sensor, DHAI, by a simple condensation process that shows ratiometric and turns on chromo-fluorogenic behavior towards Sarin gas mimic diethylchlorophosphate (DCP) in liquid and vapor phases, respectively. A colorimetric change, from yellow to colorless, is observed in the DHAI solution due to the introduction of DCP in daylight. A remarkable cyan color photoluminescence enhancement is noticed in the presence of DCP in the DHAI solution, which is observable to the naked under a portable 365 nm UV lamp. The mechanistic aspects of the detection of DCP by employing DHAI have been revealed by time-resolved photoluminescence decay analysis and 1H NMR titration investigation. Our probe DHAI exhibits linear photoluminescence enhancement from 0 to 500 µM with a detection limit of nanomolar range from non-aqueous to semi-aqueous media. For practical utility, a DHAI-stained test kit employing Whatman-41 filter paper has been fabricated and used as a portable and displayable photonic device for on-site detection of Sarin gas surrogate, DCP. Also, a dip-stick experiment has been demonstrated to identify the vapor of Sarin gas mimics DCP colorimetrically and fluorometrically. The concentrations of DCP in various water samples have been evaluated with the help of a standard fluorescence curve for real sample analysis.

Recent reports on the synthesis of γ-butenolide, γ-alkylidenebutenolide frameworks, and related natural products.

γ-Butenolides are fundamental frameworks found in many naturally occurring compounds, and they exhibit tremendous biological activities. γ-Butenolides also have proven their potential as useful synthetic intermediates in the total synthesis of natural compounds. Over the years, many γ-butenolide natural products have been isolated, having exocyclic γ-δ unsaturation in their structure. These natural products are collectively referred to as γ-alkylidenebutenolides. Considering the different biological profiles and wide-ranging structural diversity of the optically active γ-butenolide, the development of synthetic strategies for assembling such challenging scaffolds has attracted significant attention from synthetic chemists in recent times. In this report, a brief discussion will be provided to address isolation, biogenesis, and current state-of-the-art synthetic protocols for such molecules. This report aims to focus on synthetic strategies for γ-butenolides from 2010-2020 with a particular emphasis on γ-alkylidenebutenolides and related molecules. Metal-mediated catalytic transformation and organocatalysis are the two main reaction types that have been widely used to access such molecules. Mechanistic considerations, enantioselective synthesis, and practical applications of the reported procedures are also taken into consideration.

Fabrication of a GUMBOS-based acid-base indicator: smart probe for sensing acids and bases in any solvent.

This report outlines the synthesis of an ionic liquid-based pH-responsive indicator to sense acids or bases in non-polar as well as polar solvents. Herein, we have assembled a new ionic liquid (IL) comprised of a group of uniform materials based on organic salts (GUMBOS) by attaching a quaternary phosphonium ionic liquid with a very common acid-base indicator, methyl orange, via simple ion-exchange reaction. This integrated IL-based indicator is highly soluble in less polar solvents and exhibits good sensitivity toward the presence of acids/bases in those media. Furthermore, this indicator has been exploited in determining the dissociation constants of several acids in non-aqueous aprotic solvents by overlapping indicator method and hence this report provides essential information toward the understanding of many fundamental chemical reactions. This report has further scope for the synthesis of novel aqueous suspended nanomaterials, i.e., the nanoparticles derived from GUMBOS (nanoGUMBOS) by a simple flash nano-precipitation method. The nanomaterial has been well characterized by different spectroscopic and microscopic studies. The obtained nanoparticles also exhibit substantial pH-responsive behaviors in aqueous medium and show better susceptibility as compared to the free organic indicator. Thus, this report explores detailed studies on the IL-based indicator in sensing the acidity/basicity of various media.