Comparison of Mobile Phone and CCD Cameras for Electrochemiluminescent Detection of Biogenic Amines.

Biogenic amines are an important and widely studied class of molecules due to their link to the physiological processes of food-related illnesses and histamine poisoning. Electrochemiluminescent (ECL) detection offers an inexpensive and portable analytical method of detection for biogenic amines when coupled with recent advancements in low-cost carbon-based electrodes and a smartphone camera. In this work, a mobile phone camera was evaluated against a piece of conventional instrumentation, the charge-coupled device, for the detection of ECL from the reaction of biogenic amines with the luminescent compound tris(2,2'-bipyridyl)ruthenium(II). Assisted by a 3D-printed light-tight housing, the mobile phone achieved limits of detection of 127, 425 and 421 µM for spermidine, putrescine, and histamine, respectively. The mobile phone's analytical figures of merit were lesser than the CCD camera but were still within the range to detect contamination. In an exploration of real-world samples, the mobile phone was able to determine the contents of amines in skim milk on par with that of a CCD camera.

Micromolded Carbon Paste Microelectrodes for Electrogenerated Chemiluminescent Detection on Microfluidic Devices.

Micromolded carbon paste electrodes are easily fabricated, disposable, and can be integrated into microfluidic devices to fabricate inexpensive sensors and biosensors. In this work, carbon paste microelectrodes were fabricated in poly(dimethylsiloxane) using micromolding techniques and were coupled to a microfluidic channel to fabricate electrogenerated chemiluminescent (ECL) sensors. ECL was generated using both the tris(2,2'-bipyridyl)ruthenium(II)-tripropylamine system and the hydrogen peroxide and luminol system. For each of these ECL systems, the sensor fabrication method was optimized, along with key experimental parameters (applied voltage, solution flow rate, buffer species and luminol concentration). The limit of detection (S/N = 3) for TPrA was ~2.4 µM with a linear range of 10-100µM. For hydrogen peroxide the LOD was ~11 µM and the electrodes gave a linear response between 30 µM and 200 µM hydrogen peroxide. Electrodes containing glucose oxidase were fabricated using this new method, demonstrating that glucose could be indirectly detected via generation of hydrogen peroxide by the enzymatic reaction at the micromolded biosensor.

A review of electrogenerated chemiluminescent biosensors for assays in biological matrices.

Electrogenerated chemiluminescence (ECL) is the production of light via electron transfer reactions between electrochemically produced reagents. ECL-based biosensors use specific biological interactions to recognize an analyte and produce a luminescent signal. Biosensors fabricated with novel biorecognition species have increased the number of analytes detected. Some of these analytes include peptides, cells, enzymes and nucleic acids. ECL biosensors are selective, simple, sensitive and have low detection limits. Traditional methods use ruthenium complexes or luminol to generate ECL. Nanomaterials can be incorporated into ECL biosensors to improve efficiency, but also represent a new class of ECL emitters. This article reviews the application of ruthenium complex, luminol and nanomaterial-based ECL biosensors to making measurements in biological matrices over the past 4 years.

Chemistry: a bridge to discovery.

American Chemical Society Regional Meetings are a convenient and economical route for students, faculty and industry representatives to come together and communicate scientific findings and ideas. This year the 47th American Chemical Society Midwest Regional Meeting was held in Omaha (NE, USA) and included a special symposium on 'New frontiers in bioanalysis'.

Use of microelectrodes for electrochemiluminescent detection in microfluidic devices.

Microfluidic devices allow for fast detection with little reagent consumption. They also offer portability and the ability to mimic biological systems. Currently, many microfluidic devices are a hybrid of the microchip components, such as flow channels and wells, and larger instrumentation. There is a need to develop miniaturized detectors for lab-on-a-chip applications. Electrochemical detection methods have the advantage of ease of miniaturization. The electrochemical method, electrochemiluminescence, has the potential to be miniaturized and incorporated into a lab-on-a-chip device. As in other electrochemical methods, electrochemiluminescence is straightforward to miniaturize, but also possesses the sensitivity of a fluorescence detection method. In our laboratory, we have been developing carbon ink microelectrodes as the working electrode for a miniaturized electrochemiluminescence system. Since the signal is proportional to the electrode area, the challenge has been to maximize the signal-to-noise ratio and maintain low detection limits as the electrode size decreases.

Electrogenerated chemiluminescence: an oxidative-reductive mechanism between quinolone antibiotics and tris(2,2'-bipyridyl)ruthenium(II).

The cyclic voltammetry and electrogenerated chemiluminescent (ECL) reactions of a series of quinolone and fluoroquinolone antibiotics were investigated in a flow injection analysis (FIA) system. 7-Piperazinyl fluoroquinolone antibiotics were found to participate as a coreactant in an oxidative-reductive ECL mechanism with tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) as the luminescent reagent. The reaction mechanism was investigated in order to understand and optimize the processes leading to light emission. The optimal conditions included a solution pH approximately 7 at a flow rate of 3.0 mL min(-1) with no added organic modifier and application of 1.2V vs. a Pt quasi-reference electrode (QRE). Fluoroquinolones containing a tertiary distal nitrogen on the piperazine ring, such as enrofloxacin and ofloxacin, reacted to produce more intense ECL than those with a secondary nitrogen, such as ciprofloxacin and norfloxacin. The method linear range, precision, detection limits, and sensitivity for the detection of enrofloxacin and ciprofloxacin were compared to that of tripropylamine. The method was applied to the determination of the ciprofloxacin content in a pharmaceutical preparation. The assay is discussed in terms of its analytical figures of merit, ease of use, speed, accuracy and application to pharmaceutical samples.