Ultrasound-driven fabrication of hybrid magnetic tryptophan nanoparticles

Abstract

A facile sonochemical method to fabricate magnetic tryptophan-iron oxide hybrid nanoparticles was established in this study. First, superparamagnetic iron oxide nanoparticles (SPIONs) of an average size of 5 nm were synthesised using hydrothermal processes, followed by surface modification using tryptophan to improve their colloidal stability. Then, the surface-modified iron oxide nanoparticles were subjected to 490 kHz ultrasound treatment in tryptophan solution to fabricate magnetic tryptophan nanoparticles (MTNs) with an average size of 167 ± 29 nm. A comprehensive analysis of the synthesised nanocomposite was performed to describe the possible mechanism of MTNs formation. We show that high-frequency ultrasound transforms tryptophan into hydroxylated, oligomeric, and hybrid SPIONs-Trp products, forming magnetic tryptophan hybrid nanoparticles. These hybrid MTNs showed fluorescence properties that could be utilised to probe the dissolution of MTNs inside the cells. In addition, MTNs also exhibited sensitivity in magnetic resonance imaging (MRI) analysis which could be further exploited for diagnostic applications.