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5921080 
Journal Article 
Cysteine-stabilized silver nanoparticles as a colorimetric probe for the selective detection of cysteamine 
Diamai, S; Negi, DPS 
2019 
1 
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
ISSN: 1386-1425
EISSN: 1873-3557 
215 
203-208 
English 
30826579 
The purpose of the present research was to design a method for the colorimetric determination of cysteamine. We have employed cysteine-stabilized silver nanoparticles (AgNPs) as a probe. The addition of cysteamine resulted in the quenching of the 400 nm surface plasmon resonance (SPR) band of the AgNPs. It was accompanied by the appearance of a new absorption band at 560 nm. The colour of the colloidal AgNPs changed from yellow to dark brown within a few seconds. The change in colour of the AgNPs was due to their aggregation induced by the addition of cysteamine. Significantly, other biomolecules such as arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutathione, glycine, methionine and 6-mercaptopurine did not cause any change in the colour of the AgNPs. The limit of detection (LOD) of the method was 0.37 μM. The mechanism of the aggregation of the AgNPs induced by cysteamine has also been described. The method has been applied for the detection of cysteamine in human blood serum.