A Microfluidic Device for Automated High Throughput Detection of Ice Nucleation of Snomax®

Roy, Priyatanu; House, Margaret L.; Dutcher, Cari S.

doi:10.3390/mi12030296

Cited by 16 publications

(12 citation statements)

References 84 publications

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“…Recently, advances in microfluidic measurements using devices made from a combination of glass and poly dimethylsiloxane (PDMS) have made it possible to perform IN experiments on a large number of particles using either static − or flow-based − approaches. PDMS, being permeable to water, has also led to the construction of trap-based devices where droplet dehydration and phase transitions can be observed over a long duration in a quasi-equilibrium manner to map out phase states of aerosols at different relative humidities (RHs). − A recent review by Roy et al lists different microfluidic devices for droplet-based studies.…”

Section: Introductionmentioning

confidence: 99%

Ice Nucleating Activity and Residual Particle Morphology of Bulk Seawater and Sea Surface Microlayer

Roy

Mael

Hill

et al. 2021

ACS Earth Space Chem.

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Ice nucleating particles (INPs) in sea spray aerosols (SSAs) are critical in estimating cloud radiative forcing and precipitation with implications in climate change. Laboratory experiments simulating the ocean-atmosphere environment are becoming increasingly popular for studying the nature of INPs in SSAs. Understanding the ice nucleating characteristics of bulk seawater and the sea surface microlayer (SSML) can provide valuable information about the emitted SSAs. Samples for this study were collected from a waveflume during a phytoplankton bloom and analyzed with complementary methods. The primary method used is a polydimethylsiloxane (PDMS)-based microfluidic static well array, designed and fabricated to trap droplets and measure the ice nucleation (IN) spectra of nanoliter-scale droplets of bulk seawater and SSML. Droplets were subsequently dehydrated in situ until efflorescence, and the dried residual particle morphology was correlated to the droplet IN temperature. Four distinct morphologies were found in the effloresced droplets, among which the aggregate and amorphous morphologies were present in larger amounts in the SSML compared to bulk. These particles also had a different IN spectra, nucleating ice at warmer temperatures than the single and fractal crystal morphologies. The microfluidic studies were complemented by micro-Raman spectroscopy and immersion freezing measurements of larger droplets assessing IN sensitivity to heat and organic carbon removal in an ice spectrometer (IS). This study highlights the compositional diversity of marine samples and paves the way for novel multiplexed microfluidic approaches to study the chemical and biological complexity behind the IN activity of aerosol liquid samples in an integrated platform.

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Section: Introductionmentioning

confidence: 99%

Ice Nucleating Activity and Residual Particle Morphology of Bulk Seawater and Sea Surface Microlayer

Roy

Mael

Hill

et al. 2021

ACS Earth Space Chem.

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“…In addition to merely determining the presence of biogenic INPs, this method has also been used by some researchers to quantify the abundance of biogenic INPs in their samples by evaluating the magnitude of the INA reduction (Christner et al, 2008;Joly et al, 2014;Joyce et al, 2019). The assumption that protein-bearing biological INPs associated with bacteria and fungi can lose at least some of their INA when sufficiently heated (up to 100 °C) has been confirmed via many previous studies (Lundheim, 2002;Roy et al, 2021) (see the review of Lundheim (2002) for an overview).…”

Section: Introductionmentioning

confidence: 93%

“…Bacterial ice nucleators' heat sensitivity is well characterised (Obata et al, 1989;Kunert et al, 2018), as is that of Snomax® (Tarn et al, 2018;Wex et al, 2015). The reduction in INA in bacteria upon heating has been associated with a change of the beta-helix structure to a beta-sheet structure, indicating denaturation of the ice-nucleating proteins of the bacteria (Roy et al, 2021). Lichens are symbiotic associations of fungi and algae and have been found to contain highly active INPs that are proteinaceous and likely originate from the fungal component (Moffett et al, 2015;Kieft and Ruscetti, 1990).…”

Section: Biological Inp Surrogatesmentioning

confidence: 99%

The sensitivity of the ice-nucleating ability of minerals to heat and the implications for the heat test for biological ice nucleators

Daily

Tarn

Whale

et al. 2021

Preprint

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Abstract. Ice-nucleating particles (INPs) are atmospheric aerosol particles that can strongly influence the radiative properties and precipitation onset in mixed-phase clouds by triggering ice formation in supercooled cloud water droplets. The ability to distinguish between INPs of mineral and biological origin in samples collected from the environment is needed to better understand their distribution and sources, but this is challenging. A common method for assessing the relative contributions of mineral and biogenic INPs in samples collected from the environment (e.g., aerosol, rainwater, soil) is to determine the ice-nucleating ability (INA) before and after heating, where heat is expected to denature proteins associated with biological ice nucleants. The key assumption is that the ice nucleation sites of biological origin are denatured by heat, while those associated with mineral surfaces remain unaffected; we test this assumption here. We exposed atmospherically relevant mineral samples to wet heat (INP suspensions warmed to above 90 °C) or dry heat (dry samples heated to 250 °C) and assessed the effects on their immersion mode INA using a droplet freezing assay. K-feldspar, thought to be the dominant mineral-based atmospheric INP type where present, was not significantly affected by wet heating, while quartz, plagioclase feldspars and Arizona test Dust (ATD) lost INA when heated in this mode. We argue that these reductions in INA in the aqueous phase result from direct alteration of the mineral particle surfaces by heat treatment rather than from biological or organic contamination. We hypothesise that degradation of active sites by dissolution of mineral surfaces is the mechanism in all cases due to the correlation between mineral INA deactivation magnitudes and their dissolution rates. Dry heating produced minor but repeatable deactivations in K-feldspar particles but was generally less likely to deactivate minerals compared to wet heating. We also heat tested proteinaceous and non-proteinaceous biogenic INP proxy materials and found that non-proteinaceous samples (cellulose and pollen) were relatively heat resistant. In contrast, the proteinaceous ice-nucleating samples were highly sensitive to wet and dry heat, as expected, although their activity remained non-negligible after heating. We conclude that, while INP heat tests have the potential to produce false positives, i.e., deactivation of a mineral INA that could be misconstrued as the presence of biogenic INPs, they are still a valid method for qualitatively detecting proteinaceous biogenic INP in ambient samples, so long as the mineral-based INA is controlled by K-feldspar.

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“…Amongst existing microfluidic platforms designed for studying ice nucleation, there are two common approaches for droplet generation and cooling: dynamic flow-through devices (Roy et al, 2021a;Stan et al, 2009;Tarn et al, 2020Tarn et al, , 2021 and static droplet arrays (Brubaker et al, 2019;Edd et al, 2009;Reicher et al, 2018;Roy et al, 2021b). The flow-through approach is beneficial for analysing high numbers of droplets (between 10 3 and 10 4 ; Tarn et al, 2020) and is therefore particularly suitable for detecting low concentrations of INPs suspended in water or an aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

The Microfluidic Ice Nuclei Counter Zürich (MINCZ): a platform for homogeneous and heterogeneous ice nucleation

et al. 2022

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Abstract. Ice nucleation in the atmosphere is the precursor to important processes that determine cloud properties and lifetime. Computational models that are used to predict weather and project future climate changes require parameterizations of both homogeneous nucleation (i.e. in pure water) and heterogeneous nucleation (i.e. catalysed by ice-nucleating particles, INPs). Microfluidic systems have gained momentum as a tool for obtaining such parameterizations and gaining insight into the stochastic and deterministic contributions to ice nucleation. To overcome the shortcomings of polydimethylsiloxane (PDMS) microfluidic devices with regard to temperature uncertainty and droplet instability due to continuous water adsorption by PDMS, we have developed a new instrument: the Microfluidic Ice Nuclei Counter Zürich (MINCZ). In MINCZ, droplets with a diameter of 75 µm are generated using a PDMS chip, and hundreds of these droplets are then stored in fluoropolymer tubing that is relatively impermeable to water and solvents. Droplets within the tubing are cooled in an ethanol bath. We validate MINCZ by measuring the homogeneous freezing temperatures of water droplets and the heterogeneous freezing temperatures of aqueous suspensions containing microcline, a common and effective INP in the atmosphere. We obtain results with a high accuracy of 0.2 K in measured droplet temperature. Pure water droplets with a diameter of 75 µm freeze at a median temperature of 237.3 K with a standard deviation of 0.1 K. Additionally, we perform several freeze–thaw cycles. In the future, MINCZ will be used to investigate the freezing behaviour of INPs, motivated by a need for better-constrained parameterizations of ice nucleation in weather and climate models, wherein the presence or absence of ice influences cloud optical properties and precipitation formation.

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A Microfluidic Device for Automated High Throughput Detection of Ice Nucleation of Snomax®

Cited by 16 publications

References 84 publications

Ice Nucleating Activity and Residual Particle Morphology of Bulk Seawater and Sea Surface Microlayer

Ice Nucleating Activity and Residual Particle Morphology of Bulk Seawater and Sea Surface Microlayer

The sensitivity of the ice-nucleating ability of minerals to heat and the implications for the heat test for biological ice nucleators

The Microfluidic Ice Nuclei Counter Zürich (MINCZ): a platform for homogeneous and heterogeneous ice nucleation

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