Reaction Acceleration in Electrospray Droplets: Size, Distance, and Surfactant Effects

Marsh, Brett M.; Iyer, Karthik A.; Cooks, R. Graham

doi:10.1007/s13361-019-02264-w

Cited by 72 publications

(104 citation statements)

References 43 publications

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“…The observed acceleration of chemical reaction rates in microdroplets, and in many cases their transformation from positive to negative Gibbs free energy changes (Δ G ), has implications for chemistry across many areas, including basic kinetics, aerosols in both the laboratory and atmosphere, prebiotic chemistry, synthetic routes and industrial processes [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. Here, we discuss in more detail how Δ G is influenced by the processes determining the rate of a reaction when it is taking place in and on a microdroplet, as contrasted to its value in the bulk liquid or gas.…”

Section: Introductionmentioning

confidence: 99%

Gibbs Free Energy and Reaction Rate Acceleration in and on Microdroplets

Tuck

2019

Entropy

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Recent observations show that many reactions are accelerated in microdroplets compared to bulk liquid and gas media. This acceleration has been shown to feature Gibbs free energy changes, ΔG, that are negative and so reaction enabling, compared to the reaction in bulk fluid when it is positive and so reaction blocking. Here, we argue how these ΔG changes are relatable to the crowding enforced by microdroplets and to scale invariance. It is argued that turbulent flow is present in microdroplets, which span meso and macroscales. That enables scale invariant methods to arrive at chemical potentials for the substances involved. G and ΔG can be computed from the difference between the whole microdroplet and the bulk medium, and also for individual chemical species in both cases, including separately the microdroplet’s surface film and interior, provided sufficiently fine resolution is available in the observations. Such results can be compared with results computed by quantum statistical mechanics using molecular spectroscopic data. This proposed research strategy therefore offers a path to test its validity in comparing traditional equilibrium quantum statistical thermodynamic tests of microdroplets with those based on scale invariant analysis of both their 2D surface and 3D interior fluid flows.

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Section: Introductionmentioning

confidence: 99%

Gibbs Free Energy and Reaction Rate Acceleration in and on Microdroplets

Tuck

2019

Entropy

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“…eaction-rate acceleration in micron-sized droplets (microdroplets) was first observed by mass spectrometrists during the processes of desorption electrospray ionization (DESI) 1 and also by electrospray ionization (ESI) 2,3 . Microdroplets can be generated by a number of setups including microfluidics 4 , surface drop-casting 5 , theta-tip capillaries 6,7 , paper spray 8,9 , or other different spray-based ionization methods 10,11 .…”

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confidence: 99%

Ultrafast enzymatic digestion of proteins by microdroplet mass spectrometry

2020

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Enzymatic digestion for protein sequencing usually requires much time, and does not always result in high sequence coverage. Here we report the use of aqueous microdroplets to accelerate enzymatic reactions and, in particular, to improve protein sequencing. When a room temperature aqueous solution containing 10 µM myoglobin and 5 µg mL −1 trypsin is electrosonically sprayed (−3 kV) from a homemade setup to produce tiny (∼9 µm) microdroplets, we obtain 100% sequence coverage in less than 1 ms of digestion time, in sharp contrast to 60% coverage achieved by incubating the same solution at 37°C for 14 h followed by analysis with a commercial electrospray ionization source that produces larger (∼60 µm) droplets. We also confirm the sequence of the therapeutic antibody trastuzumab (∼148 kDa), with a sequence coverage of 100% for light chains and 85% for heavy chains, demonstrating the practical utility of microdroplets in drug development.

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“…44 (ii) The reaction scale suffers from the small volumes of the droplets (chosen because small volumes provide high acceleration factors). 20,29,41,[45][46][47] (iii) Large amounts of solvent are wasted which is undesirable from green chemistry considerations. 48 To address the yield and scale issues, microdroplet collection experiments have been performed.…”

Section: Introductionmentioning

confidence: 99%

High-yield gram-scale organic synthesis using accelerated microdroplet/thin film reactions with solvent recycling

et al. 2020

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A closed system has been designed to perform microdroplet/thin film reactions with solvent recycling capabilities for gram-scale chemical synthesis. Claisen-Schmidt, Schiff base, Katritzky and Suzuki coupling reactions show acceleration factors relative to bulk of 15 to 7700 times in this droplet spray system. These values are much larger than those reported previously for the same reactions in microdroplet/thin film reaction systems. The solvent recycling mode of the new system significantly improves the reaction yield, especially for reactions with smaller reaction acceleration factors. The microdroplet/thin film reaction yield improved on recycling from 33% to 86% and from 32% to 72% for the Katritzky and Suzuki coupling reactions, respectively. The Claisen-Schmidt reaction was chosen to test the capability of this system in gram scale syntheses and rates of 3.18 g per h and an isolated yield of 87% were achieved.

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Reaction Acceleration in Electrospray Droplets: Size, Distance, and Surfactant Effects

Cited by 72 publications

References 43 publications

Gibbs Free Energy and Reaction Rate Acceleration in and on Microdroplets

Gibbs Free Energy and Reaction Rate Acceleration in and on Microdroplets

Ultrafast enzymatic digestion of proteins by microdroplet mass spectrometry

High-yield gram-scale organic synthesis using accelerated microdroplet/thin film reactions with solvent recycling

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