Sharif Digital Repository

4-Hydroxy-2-mercapto-6-methylpyrimidine (MTU), is a drug from thiouracil antithyroid family which inhibits thyroid hormone synthesis and is generally used to remedy hyperthyroidism in gestation and liver disease. On the other hand, MTU has been applied to animals to gain higher weight . Since remaining of thyreostatic drugs in eatable animal tissues could be a risk to human health, their use in animal products was prohibited in the European Union in 1981.Based on these reasons, the need for an analytical procedure capable of determining MTU is of great importance. We report herein the development of a highly sensitive colorimetric method for the detection of MTU utilizing citrate capped gold... 

Spectrophotometric determination of arginine by aggregation of spherical Au nanoparticles Arginine has been classified as a ‘semi-essential’ or ‘conditionally-essential’ amino acid. This amino acid plays a crucial role in many biological path ways. Hence, its determination in biological body fluids such as blood plasma and urine is important for clinical diagnosis of various diseases. Herein we report the development of a sensitive colorimetric method for the determination of arginine based on aggregation of the citrate capped gold nanoparticles (Au NPs). Reaction contains replacement of citrate ions with guanidinium groups of arginine followed by establishing a chemical bond between amino... 

We report herein the development of a highly sensitive colorimetric method for detection of D- Penicillamine using citrate capped gold nano particles (Au-NPs) .This assay relies upon the distance-dependent of gold nanoparticles surface plasmonic resonance band of gold nanoparticles. By replacing the thiol-containg chelator drug, D-Penicillamine, with citrate on the gold nano particles surface, a new peak appearing at a longer wavelength intensifies and shifts further to the red from the original peak position which depends on ionic strength, D- Penicillamine and gold nanoparticles. The ratio intensities of absorbance at longer wavelength (630 nm) to original wavelength (521 nm) allow the... 

There is a growing interest in developing high-performance sensors monitoring fungicides, due to their broadly usage and their adverse effects on humans and wildlife. In the present study, a colorimetric probe has been proposed for detection of prothioconazole based on aggregation of unmodified silver nanoparticles (AgNPs). Under optimized condition, linear relationships between the concentration of prothioconazole and the absorbance ratio of A500/A395 were found over the range of 0.01 µg. mL-1 to 0.4 µg. mL-1 with Detection limit as low as 1.7 ng. mL-1. Furthermore, AgNPs color change from yellow to pink-orange in presence of prothioconazole, indicates highly sensitive naked-eye...