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Dehydrogenase based reagentless biosensor for monitoring phenylketonuria
David J Weiss1, Megan Dorris, Amanda Loh
1Department of Chemistry, University of Colorado at Colorado Springs, 1420 Austin Bluffs Parkway, Colorado Springs, CO 80918, United States. dweiss@uccs.edu <dweiss@uccs.edu>
Insights
This study introduces a novel sensor for detecting phenylalanine in urine, offering a reagentless, dehydrogenase-based method for monitoring Phenylketonuria (PKU). This advancement provides a simpler, safer alternative to blood tests for managing PKU.
Area of Science:
- Biomedical Engineering
- Analytical Chemistry
- Biochemistry
Background:
- Phenylketonuria (PKU) is a metabolic disorder requiring lifelong phenylalanine monitoring.
- Current clinical analysis primarily relies on blood tests, which can be invasive.
- Urine analysis presents a simpler, safer, and painless alternative for detecting phenylalanine.
Purpose of the Study:
- To develop and characterize the first reagentless dehydrogenase-based sensor for phenylalanine determination in human urine.
- To establish an alternative analytical method for PKU management.
- To investigate the electrochemical behavior of a novel carbon paste electrode composition.
Main Methods:
- Fabrication of a carbon paste electrode incorporating nicotinamide adenine dinucleotide (NAD+), phenylalanine dehydrogenase (PDH), uricase, and 3,4-dihydroxybenzaldehyde (3,4-DHB).
- Electrochemical characterization using cyclic voltammetry to assess sensor response to NADH and phenylalanine.
- Analysis of phenylalanine in human urine samples.
Main Results:
- The sensor demonstrated a limit of detection for phenylalanine at 0.5mM (S/N=3).
- The electrochemical behavior of the incorporated electron mediator (3,4-DHB) within the carbon paste electrode was investigated.
- The sensor successfully determined phenylalanine concentrations in human urine.
Conclusions:
- A novel reagentless dehydrogenase-based sensor for phenylalanine in urine has been successfully developed.
- This sensor offers a promising alternative for non-invasive PKU monitoring.
- The findings contribute to the field of biosensor development for metabolic disease diagnostics.
Abstract:
Phenylketonuria (PKU) is a disease characterized by an inability to metabolize the amino acid l-phenylalanine. The resulting buildup leads to brain damage and ultimately mental retardation in children if their phenylalanine intake is not carefully controlled. The National Institutes of Health recently suggested that people with PKU monitor their phenylalanine levels throughout their life and be put on a low phenylalanine diet. As an alternative approach to analysis using blood, this paper describes the first reagentless dehydrogenase based sensor for the determination of phenylalanine in human urine. The clinical range of phenylalanine in human urine is 20-60mM for people with PKU. Although most clinical analysis is performed using blood, urine was chosen due to its high concentrations of phenylalanine in phenylketonurics, as well as its simple, safe, and painless collection. The sensor is comprised of a carbon paste electrode with nicotinamide adenine dinucleotide (NAD(+)), phenylalanine dehydrogenase (PDH), uricase, and an electron mediator, 3,4-dihydroxybenzaldehyde (3,4-DHB), all mixed into the paste. The electron mediator reacts with the electrode surface to produce two redox species, which catalytically oxidize NADH. The behavior of the electron mediator mixed into a carbon paste electrode has not been previously investigated. Cyclic voltammetry was used to characterize the sensor's response to NADH, and with the addition of PDH and NAD(+) to the paste, its response to phenylalanine in human urine. The limit of detection for phenylalanine is 0.5mM (S/N=3).
