Multiplexed and continuous microfluidic sensors using dynamic complex droplets

Barua, Baishali; Durkin, Tyler J.; Beeley, Isabel M; Gadh, Aakanksha; Savagatrup, Suchol

doi:10.1039/d3sm00074e

Cited by 7 publications

(30 citation statements)

References 72 publications

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“…41−44 Furthermore, each of these surfactants have also previously been used in systems comprising complex emulsions to stabilize the hydrocarbon oil (H-oil)/water or fluorocarbon oil (Foil)/water interface. 24,25,45,46 Additionally, their interactions with metal ions have been well studied. Specifically, charged surfactants form electrostatic complexes with oppositely charged species, leading to higher surface excess and improved surfactant effectiveness.…”

Section: ■ Experimental Designmentioning

confidence: 99%

“…61 A key point in these studies is that small quantitative changes in the interfacial tension are magnified into a more drastic conformational and optical change in the complex emulsions. [23][24][25][26]28,61 We calibrated the change in the emission intensity as a function of γ HW and initialized our sensing experiment at the highest emission intensity (at a ratio of 30% Triton X-100 and 70% Capstone FS-30) (Section S7). It is expected that the addition of metal ions to a monolayer of complex emulsions with modified BCP would reduce γ HW and decrease the overall emission of the droplets due to binding between the immobilized chelating groups and the free ions.…”

Section: Measurement Of the Interfacial Tension And The Effects Of Me...mentioning

confidence: 99%

“…22 We have previously reported the incorporation of a pH-sensitive BCP, polystyrene-block-poly-(acrylic acid) (PS-b-PAA), to prove the concept of a multiplexed sensing device. 24 Specifically, different types of complex emulsions (with or without PS-b-PAA at the interface) can produce distinct responses while sharing the same environment. Thus, we further sought to functionalize the liquid−liquid interfaces of complex emulsions with other interfacially bound selectors to realize multiplexed detection.…”

Section: ■ Introductionmentioning

confidence: 99%

“…We have shown previously that the pH-induced transition of PAA domains from compact globules to extended coils increases the surfactant effectiveness of BCP. 24,50 Thus, to test this hypothesis that such complexation occurs, we functionalized DFO onto a model system of single-blocked PAA (PAA-DFO). This model system was fully miscible in water, unlike BCP-DFO, and allowed for the characterization of the formation of DFO-Fe 3+ complex via UV−vis spectroscopy.…”

mentioning

confidence: 99%

“…We expected that the addition of Fe 3+ will transform the complex emulsions from a double emulsion (with high emission intensity) to an inverted emulsion (with low emission intensity) (Figure 6b), and thus we used the previously reported sensing mechanism (directional emission) to transduce this expected reduction in γ HW into reduction of the fluorescent emission intensity. 23,24,61 Figure 6c illustrates our transduction mechanism as a schematic of the emission intensity as a function of the difference between γ FW and γ HW and optical micrographs of complex droplets at each morphology (and resulting emission intensity). Figure 6d,e shows calibration curves of the emission intensity as a function of the Fe 3+ concentration in Milli-Q water and SGW, respectively.…”

mentioning

confidence: 99%

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Functionalized Amphiphilic Block Copolymers and Complex Emulsions for Selective Sensing of Dissolved Metals at Liquid–Liquid Interfaces

Durkin,

Barua,

Holmstrom

et al. 2023

Langmuir

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Increasing contamination in potable water supplies necessitates the development of sensing methods that provide the speed and selectivity necessary for safety. One promising method relies on recognition and detection at the liquid–liquid interface of dynamic complex emulsions. These all-liquid materials transduce changes in interfacial tensions into optical signals via the coupling of their chemical, physical, and optical properties. Thus, to introduce selectivity, it is necessary to modify the liquid–liquid interface with an interfacially stable and selective recognition unit. To this end, we report the synthesis and characterization of amphiphilic block copolymers modified with metal chelators to selectively measure the concentrations of dissolved metal ions. We find that significant reduction in interfacial tensions arises upon quantitative addition of metal ions with high affinity toward functionalized chelators. Furthermore, measurements from UV–vis spectroscopy reveal that complexation of the block copolymers with metal ions leads to an increase in surface excess and surfactant effectiveness. We also demonstrate selective detection of iron(III) cations (Fe3+) on the μM levels even through interference from other mono-, di-, or trivalent cations in complex matrices of synthetic groundwater. Our results provide a unique platform that couples selective recognition and modulation of interfacial behaviors and demonstrates a step forward in the development of the multiplexed sensing device needed to deconvolute the complicated array of contaminants that comprise real-world environmental samples.

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Section: ■ Experimental Designmentioning

confidence: 99%

Section: Measurement Of the Interfacial Tension And The Effects Of Me...mentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Functionalized Amphiphilic Block Copolymers and Complex Emulsions for Selective Sensing of Dissolved Metals at Liquid–Liquid Interfaces

Durkin,

Barua,

Holmstrom

et al. 2023

Langmuir

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Morphology‐Directed Light Emission from Fluorescent Janus Colloids for Programmable Chemical‐To‐Optical Signal Transduction

Frank

Nagelberg

Baryzewska

et al. 2023

Advanced Optical Materials

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Materials capable of dynamically and reversibly altering their emission are relevant for numerous optical applications. Here, the anisotropic morphology‐directed light emission from fluorescent Janus emulsion droplets, an intrinsically chemo‐responsive material platform, is investigated. Informed by experimental observations of morphology‐dependent optical confinement of internally emitted light within the higher refractive index phases, ray‐tracing is used to predict and fine‐tune the droplets’ optical properties and their ability to concentrate light. Theoretical prediction and closely matching experimental results show that the collection of incident light and the confinement of emitted light in the internal droplet phase due to total internal reflection both contribute to the droplets’ anisotropic light emission profile. A novel ratiometric dual‐angle fluorescence detection approach that exploits the gravitational alignment of the droplets is implemented to quantify the morphology‐dependent large‐scale chemically‐induced modulation of the anisotropic emission of droplet layers. Relevant emulsion design parameters are systematically examined to enhance the signal‐to‐noise ratio, and a second emitter is co‐compartmentalized inside the droplets to amplify the anisotropic light confinement via an absorption–emission cascade. Preferential excitation of dyes in proximity to the internal droplet interface enhances the collected light intensity, demonstrating that dye‐loaded Janus emulsion droplets function as stimuli‐responsive, tunable, fluorescent optical elements.

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Innovative Real‐Time Flow Sensor Using Detergent‐Free Complex Emulsions with Dual‐Emissive Semi‐Perfluoroalkyl Substituted Α‐Cyanostilbene

Rakesh,

Tu,

Chang

et al. 2023

Advanced Science

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In this study, the potential of complex emulsions is investigated as transducers in sensing applications. Complex emulsions are stabilized without external detergents by developing a novel α‐cyanostilbene substituted with PEG and semi‐perfluoroalkyl chain (CNFCPEG). CNFCPEG exhibits unique variable emission properties depending on its aggregation state, allowing dual blue and green emissions in complex emulsions with hydrocarbon‐in‐fluorocarbon‐in‐water (H/F/W) morphology. The green excimer emissions result from the self‐assembly of CNFCPEG at the fluorocarbon/water interface, while the blue emission observed is due to aggregation in the organic phase. A novel flow‐injection method is developed by incorporating complex emulsions with CNFCPEG into multiple‐well flow chips (MWFC). Iodine is successfully detected in a mobile aqueous solution by monitoring morphology changes. The findings demonstrate that self‐stabilized complex emulsions with MWFC hold great promise for real‐time sensing without costly instruments.

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Multiplexed and continuous microfluidic sensors using dynamic complex droplets

Abstract: The combination of emissive complex droplets and PDMS microfluidic devices offers a promising framework for real-time, continuous, and multiplexed sensing platform.

Cited by 7 publications

References 72 publications

Functionalized Amphiphilic Block Copolymers and Complex Emulsions for Selective Sensing of Dissolved Metals at Liquid–Liquid Interfaces

Functionalized Amphiphilic Block Copolymers and Complex Emulsions for Selective Sensing of Dissolved Metals at Liquid–Liquid Interfaces

Morphology‐Directed Light Emission from Fluorescent Janus Colloids for Programmable Chemical‐To‐Optical Signal Transduction

Innovative Real‐Time Flow Sensor Using Detergent‐Free Complex Emulsions with Dual‐Emissive Semi‐Perfluoroalkyl Substituted Α‐Cyanostilbene

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