Fabrication of Crescent Shaped Microparticles for Particle Templated Droplet Formation.

Crescent-shaped hydrogel microparticles are shown to template uniform volume aqueous droplets upon simple mixing with aqueous and oil media for various bioassays. This emerging "lab on a particle" technique requires hydrogel particles with tunable material properties and dimensions. The crescent shape of the particles is attained by aqueous two-phase separation of polymers followed by photopolymerization of the curable precursor.

A Nanometric Probe of the Local Proton Concentration in Microtubule-Based Biophysical Systems.

We show a double-functional fluorescence sensing paradigm that can retrieve nanometric pH information on biological structures. We use this method to measure the extent of protonic condensation around microtubules, which are protein polymers that play many roles crucial to cell function. While microtubules are believed to have a profound impact on the local cytoplasmic pH, this has been hard to show experimentally due to the limitations of conventional sensing techniques.

Ultrasensitive Picomolar Detection of Aqueous Acids in Microscale Fluorescent Droplets.

We report on a fluorescent-droplet-based acid-sensing scheme that allows limits of detection below 100 pM for weak acids. The concept is based on a strong partitioning of acid from an aqueous phase into octanol droplets. Using salicylic acid as a demonstration, we show that at a high concentration, the acid partitions into the organic phase by a factor of 260, which is approximately consistent with literature values.

Reactions of an anionic chelate phosphane/borata-alkene ligand with [Rh(nbd)Cl], [Rh(CO)Cl] and [Ir(cod)Cl].

Borata-alkenes can serve as anionic olefin equivalent ligands in transition metal chemistry. A chelate ligand of this type is described and used for metal coordination. Deprotonation of the MesP(CH)B(CF) frustrated Lewis pair in the α-CH[B] position gave the methylene-bridged phosphane/borata-alkene anion.

An Ultrasensitive Fluorescent Paper-Based CO Sensor.

We demonstrate a versatile and easily fabricated paper-based CO sensor. The sensor consists of a specially designed fluorescent color-shift chromophore infused into standard filter paper. The emission color of the resulting fluorescent paper changes upon exposure to CO due to the formation of carbonic acid, which underlies the sensing mechanism.