Quick and Cheap Colorimetric Quantification of Proteins Using 96-Well-Plate Images

Abstract

Students quantified the protein content in beer, milk, powdered milk, and whey protein using the Bradford assay. The assay was carried out using absorbance measured at 595 nm (standard method) and 96-well-plate images (proposed method). They built analytical curves using bovine serum albumin (BSA) and casein and determined that protein type affected the Bradford assay. They also determined figures of merit such as the limit of detection (LOD), the limit of quantification (LOQ), linear working range, sensitivity, precision (standard deviation, F-test), and accuracy (percent error, t test). In addition, an interference test was carried out using nitrogen-rich compounds, organic bases, and amino acids, and it was shown that the Bradford assay was not affected by these compounds. Student learning outcomes were assessed by a final test using Microsoft Forms. As a learning model, students can determine the protein content in various food samples using just sample dilution, without the need for intricate sample preparation procedures.

A Fluorometer-Free Experimental Course for Fluorescence Analysis Based on Smartphone and Image/Data-Processing Software Using a Synthetic Sensor

“…More straightforwardly, when the fluorescence photograph of a sample exhibited a “deeper color” (a higher RGB value), we can deduce that this sample possessed a higher fluorescence intensity, which suggested that RGB values of the fluorescence photograph can be regarded as the fluorescence intensity. There are some literatures introducing the simple method to measure RGB values using imaging software after acquiring the photograph of the samples by smartphone. ,,− Based on this method, fluorescence intensity can be measured in a lively and fluorimeter-free manner. , Comparing with colorimetric analysis, fluorescence analysis exhibited a higher sensitivity (as shown in Figure a, b). Meanwhile, because an extra excitation light was needed, which must be evenly irradiated on all samples, measuring the fluorescence intensity, based on the smartphone and image processing software, requires more restrictions on the position of excitation light and the camera of smartphone, and a more detailed design.…”

“…Obviously, new approaches are desired to make the education of fluorescence assay more interesting and lively and, meanwhile, available to most students over the world. Fortunately, the RGB value, which can be simply measured using image processing software (such as ImageJ) after acquiring the photograph by smartphones, , can be regarded as the fluorescence intensity because of their linear relationship . Based on this strategy, some ingenious homemade devices were designed for undergraduate teaching of basic fluorescence, which can directly exhibit the fluorescence intensity change between different samples. , However, the conception of chemical reaction-based fluorescent sensors and the detection mechanisms were not included.…”

Whey Protein Analysis Using the Lowry Assay and 96-Well-Plate Digital Images Acquired Using Smartphones

“…Normally, colorimetric assays were carried out using spectrophotometers. However, nowadays, digital images obtained using electronic devices such as smartphones and scanners have been widely used instead of spectrophotometers. − For example, Na + , F – , Fe 3+ , − Cu 2+ , , NO 2 – , NO 3 – , tyrosinase, glucose, proteins, ,, food dyes, − reducing compounds, and pharmaceuticals − were quantified using digital images.…”

Digital Image Colorimetry Smartphone Determination of Acetaminophen

“…Table shows some examples of the application of the smartphone as a teaching aid in the analytical, forensic, and environmental sciences, principally using the RGB color model; however, other color models and Apps have been attempted. Previous publications in this Journal have highlighted their application for developing the understanding of the science behind analytical systems such as fluidics, kinetics, − spectroscopy and digital color, − and fluorescence, − along with the possibility of undertaking experiments outside of the laboratory at home. − Previously, using such an approach, it has been shown possible to colorimetrically determine a number of different drugs using the camera on a smartphone. − It has been shown possible to determine the concentration of the drug in sample solutions following the construction of a calibration curve. In this student laboratory practical, the possibility of utilizing such an approach for the determination of acetaminophen and its quantification of unknown samples is described.…”