Graduation Semester and Year
Spring 2026
Language
English
Document Type
Thesis
Degree Name
Master of Science in Chemistry
Department
Chemistry and Biochemistry
First Advisor
Dr. Subhrangsu S Mandal
Abstract
This study focuses on the synthesis and investigation of NBD-based tryptophan derivatives for biological applications. The aim was to develop fluorescent probes to monitor tryptophan uptake and metabolism. Three compounds, NBD-tryptophan, NBD-tryptamine, and NBD- tryptophan methyl ester, were synthesized and characterized using ¹H NMR and HRMS. However, NBD-tryptophan showed low cellular uptake, which led to a shift in focus toward their photophysical properties. The pH-dependent behavior of these compounds was studied using UV–Visible spectroscopy. Fluorescence measurements were carried out using a microplate reader over a pH range of 1–12. The results showed clear changes in absorbance and fluorescence intensity with pH, and apparent pKa values were estimated. Structural differences, particularly the presence of electron-withdrawing groups such as the carboxyl group, affected the pKa and fluorescence behavior. NBD-tryptamine exhibited a higher pKa (10.1) compared to NBD-tryptophan (9.5) and NBD-tryptophan methyl ester (8.7), indicating that structural modifications influence protonation behavior. Overall, this study suggests that these compounds can act as pH-sensitive probes for biological applications.
Keywords
Tryptophan, Fluorescent Probes, Nitrobenzoxadiazole (NBD), Photophysical Properties, pH-Sensitive Probes, UV–Visible Spectroscopy, Cellular Uptake, BV2 Microglial Cells, Tryptophan Metabolism, Inflammation
Disciplines
Chemistry | Medicinal-Pharmaceutical Chemistry
License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Recommended Citation
Saha, Mandira, "FLUORESCENT TRYPTOPHAN DERIVATIVES FOR BIOLOGICAL APPLICATIONS" (2026). Chemistry & Biochemistry Theses. 1.
https://mavmatrix.uta.edu/chemistry_theses2/1