“Open-Box” Approach to Measuring Fluorescence Quenching Using an iPad Screen and Digital SLR Camera

Abstract

Fluorescence quenching is an analytical technique and a common undergraduate laboratory exercise. Unfortunately, a typical quenching experiment requires the use of an expensive fluorometer that measures the relative fluorescence intensity of a single sample in a closed compartment unseen by the experimenter. To overcome these shortcomings, we designed an "open-box" fluorescence quenching method that uses an iPad screen as the excitation source and a digital singlelens reflex (SLR) camera as the detector. This setup enables a complete fluorescence quenching experiment to be performed and an accurate Stern−Volmer plot to be generated by analyzing a single image of six fluorescein samples and applying correction factors. The Stern−Volmer quenching constant (K SV ) calculated using this method was 9.62 ± 0.27 L mol −1 ; fluorometer value, 9.52 ± 0.40 L mol −1 ; literature values, 9.0 ± 0.2 L mol −1 and 9.608 L mol −1 . These results demonstrate that, in addition to allowing direct visualization of the chemical processes and simultaneous measurement of multiple samples, this simple method yields quantitative results comparable in accuracy to the more expensive fluorometer.

Using GFP-Tagged Escherichia coli to Investigate the Persistence of Fecal Bacteria in Vegetated Wetlands: An Experimental Approach

“…Unmodified digital single-lens reflex (DSLR) camera can be a successful tool for detecting fluorescence while being cost-effective, applicable to a wide range of studies and easy to use for the operators [56,57]. A DSLR camera Canon model Eos 7D (Canon Europe N.V., Amstelveen, The Netherlands) on a tripod with an amber filter on the front was used.…”

Glowing-in-the-Screen: Teaching Fluorescence with a Homemade Accessible Setup

“…Although the output colors on the smartphone screen do not directly reflect the detected light intensity, measurements are accurate enough to quantify fluorescence intensities and the quenching effect. These can be obtained using a color analysis application ( Color Grab for Android, Color Name for iPhone, or similar) which senses essentially three-color spectrographs, R, G, and B (see SI for more information). ,, …”

“…Usually, hands-on activities for fluorescence teaching are limited due to the high costs of instrumentation, supplies, and reagents needed . Moreover, modern instruments have become also “black boxes”, which does not easy learning the concepts of spectroscopy . Assays and experiments involving self-made equipment and newly accessible technology give an opportunity for students to grab complex topics and stimulate their curiosity …”

“…Following this line, many approaches in fluorescence portable devices have been described using light-emitting diodes (LED), optical filters, digital cameras, and smartphones, among other items, for teaching or research goals. − An interesting approach is an “open-box” fluorescence quenching method using an iPad screen as the excitation source and a digital camera as the detector, while other authors have introduced a setup prepared with a shoebox and a flashlight as an excitation source . Another report describes a homemade “fluorescence microscope” built up with a light-emitting diode (LED) and optical filters .…”

Approaching Diesel Fuel Quality in Chemistry Lab Classes: Undergraduate Student’s Achievements on Determination of Biodiesel Content in Diesel Oil Applying Solvatochromic Effect

“…In chemistry, digital image processing has been used as an alternative to conventional equipment, demonstrating multiple applications in the detection of colors in colorimetric reactions and processes. The low cost of this type of image processing technique and the potential to use mobile devices to capture the images make this a very attractive methodology, including in the teaching of chemistry and chemical engineering, as noted by several authors. − The digital images of colorimetry tests taken using smartphone cameras may be quantified in terms of the RGB color system using applications such as PhotoMetrix PRO − or Color Grab, , which can be downloaded free of charge.…”