ABSTRACT
p-Nitrophenylphosphate (PNPP) is usually employed as the substrate for enzyme-linked immunosorbent assays. p-Nitrophenol (PNP), the product of PNPP, with the catalyst alkaline phosphatase (ALP), will passivate an electrode, which limits applications in electrochemical analysis. A novel anti-passivation ink used in the preparation of a graphene/ionic liquid/chitosan composited (rGO/IL/Chi) electrode is proposed to solve the problem. The anti-passivation electrode was fabricated by directly writing the graphene-ionic liquid-chitosan composite on a single-side conductive gold strip. A glassy carbon electrode, a screen-printed electrode, and a graphene-chitosan composite-modified screen-printed electrode were investigated for comparison. Scanning electron microscopy was used to characterize the surface structure of the four different electrodes and cyclic voltammetry was carried out to compare their performance. The results showed that the rGO/IL/Chi electrode had the best performance according to its low peak potential and large peak current. Amperometric responses of the different electrodes to PNP proved that only the rGO/IL/Chi electrode was capable of anti-passivation. The detection of cardiac troponin I was used as a test example for electrochemical immunoassay. Differential pulse voltammetry was performed to detect cardiac troponin I and obtain a calibration curve. The limit of detection was 0.05 ng/ml.
Subject(s)
Electrochemical Techniques/methods , Electrodes , Graphite , Immunoassay/methods , Ink , Microscopy, Electron, Scanning , Troponin I/bloodABSTRACT
Infantile liver failure syndrome type 1 (ILFS1) is a Mendelian disease due to biallelic mutations in the cytoplasmic leucyl-tRNA synthetase gene (LARS). This study aimed to report the clinical and molecular features of the first non-caucasian ILFS1 patient, providing reliable evidences for the definite diagnosis of ILFS1. The 2 years and 9 months old male patient was referred to the hospital with hepatosplenomegaly over 1 year. At age 17 months, he was found to have hepatosplenomegaly and anemia. Since then, he had been managed in different hospitals. The laboratory tests showed liver dysfunction, hypoproteinemia, coagulopathy and anemia, along with histologically-confirmed cirrhosis and fatty liver; however, the etiology remained undetermined. The subsequent SLC25A13 mutation analysis by means of prevalent mutation screening and Sanger sequencing only revealed a paternally-inherited mutation c.1658G>A, and no aberrant SLC25A13 transcripts could be detected from the maternal allele on cDNA cloning analysis, ruling out the possibility of citrin deficiency. Further target exome high-throughout sequencing of genes relevant to genetic liver diseases detected a paternal c.2133_2135del (p.L712del) and a maternal c.1183G>A (p.D395N) mutation in LARS gene. This finding was then confirmed by Sanger sequencing, and ILFS1 was thus definitely diagnosed. The child has been followed up till age 4 years, and his condition became stabilized.