ArticleProceedings of the National Academy of Sciences of the United States of America2018
Aerosol microdroplets exhibit a stable pH gradient.
Article in Proceedings of the National Academy of Sciences of the United States of America, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 57 papers.
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Who cites it
57 citing papers in PubMed.
- Size-Dependent Reaction Pathways in Multiphase SOEnvironmental science & technology letters · 2026Article
- Evolution of the Composition and pH of Single Aqueous Aerosols Produced from Bulk Aqueous Sulfite Solutions.The journal of physical chemistry. A · 2026Article
- Influence of Carbon Dioxide and pH on Influenza Virus in Sessile Saliva Droplets.Environmental science & technology · 2026Article
- Highly efficient production of nitrite and nitrate from air at the gas-water interface of nanobubbles.Science advances · 2026Article
- Electric fields at hydrophobic water interfaces: spectroscopic evidence, physical origin, and implications on reactivity.Chemical Society reviews · 2026Review
- Size Dependent Uncatalyzed Sulfite Oxidation in Aqueous Microdroplets.Environmental science & technology · 2025Article
- Electric field-driven interfacial reduction of metal ions in microdroplets: gold, silver, and nickel.Chemical science · 2025Article
- Surface-Enhanced Raman Spectroscopy (SERS) Based Biological and Environmental 2D and 3D Imaging.ACS environmental Au · 2025Review
- Measurements of Surrogate Respiratory Sessile Droplet pH and Implications for Exhaled Respiratory Aerosol and Airborne Disease Transmission.ACS central science · 2025Article
- Accelerated Synthesis of Pyrazoles Mediated by Water Microdroplets.ACS sustainable chemistry & engineering · 2025Article
- Nonenzymatic Hydration of Phosphoenolpyruvate: General Conditions for Hydration in Protometabolism by Searching Across Pathways.Angewandte Chemie (International ed. in English) · 2025Article
- Aerosol Fluorescent Labeling via Probe Molecule Volatilization.Analytical chemistry · 2024Article
- Unlocking the electrochemical functions of biomolecular condensates.Nature chemical biology · 2024Review
- Double-Layer Distribution of Hydronium and Hydroxide Ions in the Air-Water Interface.ACS physical chemistry Au · 2024Article
- Review of factors affecting virus inactivation in aerosols and droplets.Journal of the Royal Society, Interface · 2024Review
- Busting the myth of spontaneous formation of HChemical science · 2024Article
- Seasonal influenza viruses decay more rapidly at intermediate humidity in droplets containing saliva compared to respiratory mucus.Applied and environmental microbiology · 2024Article
- Aqueous microdroplets promote C-C bond formation and sequences in the reverse tricarboxylic acid cycle.Nature ecology & evolution · 2023Article
- Nanobubble Reactivity: Evaluating Hydroxyl Radical Generation (or Lack Thereof) under Ambient Conditions.ACS ES&T engineering · 2023Article
- Stability of Aerosolized SARS-CoV-2 on Masks and Transfer to Skin.Environmental science & technology · 2023Article
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Abstract
Suspended aqueous aerosol droplets (<50 µm) are microreactors for many important atmospheric reactions. In droplets and other aquatic environments, pH is arguably the key parameter dictating chemical and biological processes. The nature of the droplet air/water interface has the potential to significantly alter droplet pH relative to bulk water. Historically, it has been challenging to measure the pH of individual droplets because of their inaccessibility to conventional pH probes. In this study, we scanned droplets containing 4-mercaptobenzoic acid-functionalized gold nanoparticle pH nanoprobes by 2D and 3D laser confocal Raman microscopy. Using surface-enhanced Raman scattering, we acquired the pH distribution inside approximately 20-µm-diameter phosphate-buffered aerosol droplets and found that the pH in the core of a droplet is higher than that of bulk solution by up to 3.6 pH units. This finding suggests the accumulation of protons at the air/water interface and is consistent with recent thermodynamic model results. The existence of this pH shift was corroborated by the observation that a catalytic reaction that occurs only under basic conditions (i.e., dimerization of 4-aminothiophenol to produce dimercaptoazobenzene) occurs within the high pH core of a droplet, but not in bulk solution. Our nanoparticle probe enables pH quantification through the cross-section of an aerosol droplet, revealing a spatial gradient that has implications for acid-base-catalyzed atmospheric chemistry.
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