A Concise Synthetic Approach to Highly Reactive Click-to-Release Trans-Cyclooctene Linkers.

An increase in the click-to-release reaction rate between cleavable trans-cyclooctenes (TCO) and tetrazines would be beneficial for drug delivery applications. In this work, we have developed a short and stereoselective synthesis route towards highly reactive sTCOs that serve as cleavable linkers, affording quantitative tetrazine-triggered payload release. In addition, the fivefold more reactive sTCO exhibited the same in vivo stability as current TCO linkers when used as antibody linkers in circulation in mice.

Improved Sensitivity of Ultrasound-Based Subharmonic Aided Pressure Estimation Using Monodisperse Microbubbles.

Objectives: Subharmonic aided pressure estimation (SHAPE) has been shown effective for noninvasively measuring hydrostatic fluid pressures in a variety of clinical applications. The objective of this study was to explore potential improvements in SHAPE sensitivity using monodisperse microbubbles.

Methods: Populations of monodisperse microbubbles were created using a commercially available microfluidics device (Solstice Pharmaceuticals).

Bioorthogonal Tetrazine Carbamate Cleavage by Highly Reactive -Cyclooctene.

The high rate of the 'click-to-release' reaction between an allylic substituted -cyclooctene linker and a tetrazine activator has enabled exceptional control over chemical and biological processes. Here we report the development of a new bioorthogonal cleavage reaction based on -cyclooctene and tetrazine, which allows the use of highly reactive -cyclooctenes, leading to 3 orders of magnitude higher click rates compared to the parent reaction, and 4 to 6 orders higher than other cleavage reactions. In this new pyridazine elimination mechanism, wherein the roles are reversed, a -cyclooctene activator reacts with a tetrazine linker that is substituted with a methylene-linked carbamate, leading to a 1,4-elimination of the carbamate and liberation of a secondary amine.

One-Step Microfluidic Coating of Phospholipid Microbubbles with Natural Alginate Polymer as a Delivery System for Human Epithelial Lung Adenocarcinoma.

In this study, the neoplastic drug frequently used in the treatment of lung cancer, carboplatin is loaded to microbubbles via a microfluidic platform. In order to increase the drug loading capacity of microbubbles, carboplatin is encapsulated into alginate polymer layer. The phospholipid microbubbles (MBs) are synthesized by MicroSphere Creator, which is connected with T-junction and micromixer for the treatment with CaCl solution to provide gelation of the alginate coated phospholipid microbubbles (AMBs).

Fluorogenic Bifunctional trans-Cyclooctenes as Efficient Tools for Investigating Click-to-Release Kinetics.

The inverse electron demand Diels-Alder pyridazine elimination reaction between tetrazines and allylic substituted trans-cyclooctenes (TCOs) is a key player in bioorthogonal bond cleavage reactions. Determining the rate of elimination of alkylamine substrates has so far proven difficult. Here, we report a fluorogenic tool consisting of a TCO-linked EDANS fluorophore and a DABCYL quencher for accurate determination of both the click and release rate constants for any tetrazine at physiologically relevant concentrations.