7 Bio-microelectromechanical Systems (BioMEMS) …
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path and communicating with the outlet. The dry reagents were stored in the device
in the right portion and a solvent traveled between the inlet and the outlet inside the
reaction vessel. As the solvent passed through the channel, the dry reagents were
dissolved and transferred to the reaction vessel. The optical characteristics of the
reaction mixture within the reaction vessel were analyzed by BL-CL measurement.
This measurement method was used for endotoxin and β-glucan detection. A main
concern in fabrication and reagent storage of this device was the deterioration of the
reagent containing biological compounds over time. It was, therefore, recommended
to use the dissolved reagents immediately after preparation.
7.4 Alternative BioMEMS for Biochemiluminescence
Detection
Roda et al. (2004) for the first time, reported the use of a smartphone to image and
quantify BL-CL coupled bio-specific enzymatic reactions to detect analytes in biological fluids. By using low-cost 3D printing technology, the authors fabricated a smartphone accessory and a minicartridge for hosting bio-specific reactions (Fig. 7.1). The
device consisted of two main parts: a phone adapter with a dark box and lens holder
and a cartridge for the bioassays, specifically designed to match an iPhone 5S. This
accessory played a dual role of acting as a dark box for shedding from ambient light
and hosting the minicartridge, which could be customized according to the target
chemical reactions and diagnostic needs. The disposable mini-cartridge contained
a blood separator pad holder, with a LF1 glass fiber filter, connected to a reaction
chamber where a nitrocellulose disk supporting the specific enzymes was placed. A
separate reservoir for BL/CL reagents was connected via microfluidics to the reaction
chamber in order to prevent premature mixing. Two assays were conducted in this
device: (i) Total Bile Acid Smartphone-Based Assay (SmartBA), a bioluminescence
assay for measurement of total bile acids (BA) using 3α-hydroxyl steroid dehydrogenase co-immobilized with bacterial luciferase system and a chemiluminescence
substrate; (ii) and Total Cholesterol Smartphone-Based Assay (SmartChol), for total
cholesterol measurement using cholesterol esterase/cholesterol oxidase coupled with
the luminol–H 2 O 2 −horseradish peroxidase (HRP).
In SmartBA, converted groups from BA 3αhydroxyl group, in the presence of
bacterial luciferase, reacts with decanal and oxygen to produce flavin mononucleotide
(FMN), decanoic acid, and light. The light intensity was proportional to BA concentration in the initial reaction. The smartphone camera was used to image and quantify
the light produced by BL-CL reactions and to amplify analyte-specific enzymatic
reactions. Due to the design of the device, no accidental release of the reagents could
occur even when turning the minicartridge upside down.
The SmartChol assay was based on coupled enzymatic reactions in two steps.
Firstly, esterification of cholesterol hydrolysis was done by cholesterol esterase
and cholesterol oxidation by cholesterol oxidase. Secondly, the CL detection of
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path and communicating with the outlet. The dry reagents were stored in the device
in the right portion and a solvent traveled between the inlet and the outlet inside the
reaction vessel. As the solvent passed through the channel, the dry reagents were
dissolved and transferred to the reaction vessel. The optical characteristics of the
reaction mixture within the reaction vessel were analyzed by BL-CL measurement.
This measurement method was used for endotoxin and β-glucan detection. A main
concern in fabrication and reagent storage of this device was the deterioration of the
reagent containing biological compounds over time. It was, therefore, recommended
to use the dissolved reagents immediately after preparation.
7.4 Alternative BioMEMS for Biochemiluminescence
Detection
Roda et al. (2004) for the first time, reported the use of a smartphone to image and
quantify BL-CL coupled bio-specific enzymatic reactions to detect analytes in biological fluids. By using low-cost 3D printing technology, the authors fabricated a smartphone accessory and a minicartridge for hosting bio-specific reactions (Fig. 7.1). The
device consisted of two main parts: a phone adapter with a dark box and lens holder
and a cartridge for the bioassays, specifically designed to match an iPhone 5S. This
accessory played a dual role of acting as a dark box for shedding from ambient light
and hosting the minicartridge, which could be customized according to the target
chemical reactions and diagnostic needs. The disposable mini-cartridge contained
a blood separator pad holder, with a LF1 glass fiber filter, connected to a reaction
chamber where a nitrocellulose disk supporting the specific enzymes was placed. A
separate reservoir for BL/CL reagents was connected via microfluidics to the reaction
chamber in order to prevent premature mixing. Two assays were conducted in this
device: (i) Total Bile Acid Smartphone-Based Assay (SmartBA), a bioluminescence
assay for measurement of total bile acids (BA) using 3α-hydroxyl steroid dehydrogenase co-immobilized with bacterial luciferase system and a chemiluminescence
substrate; (ii) and Total Cholesterol Smartphone-Based Assay (SmartChol), for total
cholesterol measurement using cholesterol esterase/cholesterol oxidase coupled with
the luminol–H 2 O 2 −horseradish peroxidase (HRP).
In SmartBA, converted groups from BA 3αhydroxyl group, in the presence of
bacterial luciferase, reacts with decanal and oxygen to produce flavin mononucleotide
(FMN), decanoic acid, and light. The light intensity was proportional to BA concentration in the initial reaction. The smartphone camera was used to image and quantify
the light produced by BL-CL reactions and to amplify analyte-specific enzymatic
reactions. Due to the design of the device, no accidental release of the reagents could
occur even when turning the minicartridge upside down.
The SmartChol assay was based on coupled enzymatic reactions in two steps.
Firstly, esterification of cholesterol hydrolysis was done by cholesterol esterase
and cholesterol oxidation by cholesterol oxidase. Secondly, the CL detection of