Digital photography for the analysis of fluorescence responses

Schwaebel, Thimon; Trapp, Oliver; Bunz, Uwe H. F.

doi:10.1039/c2sc21412a

Cited by 31 publications

(27 citation statements)

References 37 publications

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“…15 Therefore, the RGB values of an emission color differ somewhat, depending on the camera adjustments. The following adjustments can be made on most cameras: white balance, shutter speed, film sensitivity, focal aperture, data format (RAW files or JPEG files), and color space (i.e.…”

Section: Discussionmentioning

confidence: 99%

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores

Schwaebel

Lirag

Davey

et al. 2013

JoVE

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Molecular cruciforms are X-shaped systems in which two conjugation axes intersect at a central core. If one axis of these molecules is substituted with electron-donors, and the other with electron-acceptors, cruciforms' HOMO will localize along the electron-rich and LUMO along the electron-poor axis. This spatial isolation of cruciforms' frontier molecular orbitals (FMOs) is essential to their use as sensors, since analyte binding to the cruciform invariably changes its HOMO-LUMO gap and the associated optical properties. Using this principle, Bunz and Miljanić groups developed 1,4-distyryl-2,5-bis(arylethynyl)benzene and benzobisoxazole cruciforms, respectively, which act as fluorescent sensors for metal ions, carboxylic acids, boronic acids, phenols, amines, and anions. The emission colors observed when these cruciform are mixed with analytes are highly sensitive to the details of analyte's structure and - because of cruciforms' charge-separated excited states - to the solvent in which emission is observed. Structurally closely related species can be qualitatively distinguished within several analyte classes: (a) carboxylic acids; (b) boronic acids, and (c) metals. Using a hybrid sensing system composed from benzobisoxazole cruciforms and boronic acid additives, we were also able to discern among structurally similar: (d) small organic and inorganic anions, (e) amines, and (f) phenols. The method used for this qualitative distinction is exceedingly simple. Dilute solutions (typically 10(-6) M) of cruciforms in several off-the-shelf solvents are placed in UV/Vis vials. Then, analytes of interest are added, either directly as solids or in concentrated solution. Fluorescence changes occur virtually instantaneously and can be recorded through standard digital photography using a semi-professional digital camera in a dark room. With minimal graphic manipulation, representative cut-outs of emission color photographs can be arranged into panels which permit quick naked-eye distinction among analytes. For quantification purposes, Red/Green/Blue values can be extracted from these photographs and the obtained numeric data can be statistically processed.

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Section: Discussionmentioning

confidence: 99%

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores

Schwaebel

Lirag

Davey

et al. 2013

JoVE

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“…The color differences are small at pH>7. The data were analyzed by MANOVA leading to autocorrelation plots (Figures S8 and S9 in the Supporting Information), which at pH 7, acidified to pH 1 and regenerated to pH 7 showed blacked diagonal squares, and corners (Figure S10 in the Supporting Information), the system should work as a reversible pH sensor.…”

Section: Figurementioning

confidence: 99%

Immobilized Poly(aryleneethynylene) pH Strips Discriminate Different Brands of Cola

Bender

Bojanowski

Seehafer

et al. 2018

Chemistry A European J

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Fluorescent, water-soluble poly(p-aryleneethynylene)s (PAE) were immobilized on commercially available nylon membranes by using a slot plotter, creating fluorescent, barcode-like sensor strips. Digital imaging by using a standard digital camera, before and after immersion of the strips in buffers of different pH, displays a unique color for each pH value. Statistical evaluation, multivariate analysis of variance (MANOVA) and principal component analysis (PCA), of the acquired data revealed that the immobilized PAEs are superior to the identical fluorophores when dissolved. The pH sensor array discriminates 20 different brands of commercial-cola soft drinks through differences in pH and colorant-PAE interactions.

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“…The angle between the support surface and the axis of the light source was 30° ( Figure 1B-(ii)). [34][35][36][37][38][39][40][41][42] In fact, the camera of smartphone can be used as an optical sensor in chemical assays. This time, no light source was used ( Figure 1B-(iii)).…”

Section: Detection and Data Treatmentmentioning

confidence: 99%

Fusion of microlitre water-in-oil droplets for simple, fast and green chemical assays

Chiu

Urban

2015

Analyst

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A simple format for microscale chemical assays is proposed. It does not require the use of test tubes, microchips or microtiter plates. Microlitre-range (ca. 0.7-5.0 μL) aqueous droplets are generated by a commercial micropipette in a non-polar matrix inside a Petri dish. When two droplets are pipetted nearby, they spontaneously coalesce within seconds, priming a chemical reaction. Detection of the reaction product is accomplished by colorimetry, spectrophotometry, or fluorimetry using simple light-emitting diode (LED) arrays as the sources of monochromatic light, while chemiluminescence detection of the analytes present in single droplets is conducted in the dark. A smartphone camera is used as the detector. The limits of detection obtained for the developed in-droplet assays are estimated to be: 1.4 nmol (potassium permanganate by colorimetry), 1.4 pmol (fluorescein by fluorimetry), and 580 fmol (sodium hypochlorite by chemiluminescence detection). The format has successfully been used to monitor the progress of chemical and biochemical reactions over time with sub-second resolution. A semi-quantitative analysis of ascorbic acid using Tillman's reagent is presented. A few tens of individual droplets can be scanned in parallel. Rapid switching of the LED light sources with different wavelengths enables a spectral analysis of multiple droplets. Very little solid waste is produced. The assay matrix is readily recycled, thus the volume of liquid waste produced each time is also very small (typically, 1-10 μL per analysis). Various water-immiscible translucent liquids can be used as the reaction matrix: including silicone oil, 1-octanol as well as soybean cooking oil.

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Digital photography for the analysis of fluorescence responses

Cited by 31 publications

References 37 publications

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores

Immobilized Poly(aryleneethynylene) pH Strips Discriminate Different Brands of Cola

Fusion of microlitre water-in-oil droplets for simple, fast and green chemical assays

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