Rapidly and simultaneously quantifying multiple biomarkers of L-tyrosine hydroxylase deficiency by using paper microfluidic devices and smartphone-based analysis system

L-tyrosine hydroxylase (TH) is a critical enzyme and involved in the conversion of L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA) in the human body. TH deficiency is a rare autosomal recessive disorder which results in cerebral catecholamine deficiency and causes symptoms of depression, movement disorders, and impaired development. L-DOPA is the common precursor of catecholamine neurotransmitters, therefore how to rapidly and precisely determine the ratio of L-DOPA to L-tyrosine in the bio-matrix is important to the clinical diagnosis of disorder. To response the demand, a low-cost, user-friendly, and on-site detection system is developed herein, which includes a wax-printing paper microfluidics as reaction platform, surface modification with sodium periodate for improving detection performance, an additive manufactured enclosed case for maintaining identical detection environment, and an IOS application (APP) to drive smartphone's imaging to facilitate high-throughput quantification of multiple biomarkers simultaneously. Multiple experiments were conducted to understand the detection limit, detection range, shelf-life, and specificity of this quantification system even with a complex bio-matrix such as artificial urine or Fetal Bovine Sera (FBS). The experiment results showed that L-DOPA, L-tyrosine, and creatinine can be easily and rapidly quantified with high reliability and repeatability, demonstrating an efficient tool for routine checkup of patients with TH deficiency.