Colorimetric Determination of Tizanidine and Mercury (II) Based on Aggregation and Anti-aggregation of Gold Nanoparticles

, M.Sc. Thesis Sharif University of Technology Yahyazadeh, Ehsan (Author) ; Hormozi Nezhad, Mohammad Reza (Supervisor)

Abstract

In the first section of this research, we have developed a simple and rapid colorimetric method for determination of tizanidine using citrate capped gold nanoparticles. Under optimal conditions, the AuNPs easily aggregate upon addition of tizanidine and the solution color changes from red to gray. This color change was followed using a UV-Vis spectrophotometer. The detection limit was calculated to be 0.48 µM. The method was successfully applied for determination of tizanidine in Spalex© tablets. In the last section, the anti-aggregation effect of Hg(II) on the tizanidine-AuNPs system was utilized with the aim of developing a colorimetric method for detection of Hg(II). Addition of...

Spectrophotometric Determination of Copper Ions and Pamidronate Disodium Based on Changing the Surface Plasmon Resonance Band of Au Nanoparticles

, M.Sc. Thesis Sharif University of Technology Abbasi-Moayed, Samira (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)

Abstract

In recent years, metallic nanoparticles, specially gold and silver nanoparticles, have received great attention for biological and metal ions analysis, due to the surface plasmon resonance phenomena. Gold nanoparticles (AuNPs) have recently gained much interest in colorimetric probe based on aggregation or anti-aggregation of AuNPs, due to their simplicity and having high order of magnitude extinction coefficients, in addition to the dependence of surface plasmon resonance wavelength and intensity on the interparticles distances. In the first part of this thesis, a highly sensitive colorimetric method for detection of copper ions based on anti-aggregation of citrate capped AuNPs was...

Design of a Colorimetric Sensor Array Based on Aggregation of Gold Nanoparticles on the Surface of Probiotic Bacteria for Identification and Discrimination of Antiseptic Alcohols

, M.Sc. Thesis Sharif University of Technology Ghamsari, Mahdi (Author) ; Hormozinezhad, Mohammad Reza (Supervisor)

Abstract

The occurrence of the COVID-19 pandemic and the subsequent rising demand for purchasing alcohol-based sanitizers led to a remarkable prosperity in supplying these hygiene products. Hence, the development of a straightforward and efficient analytical strategy for discrimination of antiseptic alcohols including methanol, ethanol and isopropanol is of great importance. By exploiting the alcohol-sensitive membranes of probiotic bacteria, this research aims to develop a colorimetric sensor array for discriminating methanol, ethanol and isopropanol. In this design, the aggregation of citrate-capped gold nanoparticles (Au NPs) on the thiol-modified surface of two probiotic bacteria, including...

Design of an Optoelectronic Tongue Based on Anti-Aggregation of Gold Nanoparticles for Detection and Classification of Heavy Metal Ions

, M.Sc. Thesis Sharif University of Technology Najafzadeh, Fatemeh (Author) ; Hormozi-Nezhad, Mohammad Reza (Supervisor)

Abstract

The ﬁrst report of anti-aggregation-based sensor arrays is presented. The strategy is based on the competitive interaction of citrate-capped gold nanoparticles (AuNPs) and heavy metal ions (i.e., Hg(II), Ag(I), Fe(III), and Pb (II)) with three aggregation reagents (i.e., cysteine, melamine, and arginine). In the presence of aggregation reagent,the color and UV–vis spectra of AuNPs are changed indicating the aggregation ofAuNPs. Addition of the aggregation reagents which are ﬁrstly treated with the ions, causes AuNPs turn from the aggregation to the dispersion state. The anti-aggregation capability of ions towards various aggregation reagents is diﬀerent because of distinct stability...