Hollow spherical nanoparticulate aggregates as potential ultrasound contrast agent: shell thickness characterization

Abstract

Objective: The objective of this work is to manufacture hollow spherical nanoparticulate aggregates for use as an ultrasound contrast agent by means of spray drying of nanoparticulate suspension at a fast drying rate. Methodology: Biocompatible PMMA-MeOPEGMA and silica nanoparticles are used as the model nanoparticles. The impacts of changing the nanoparticle concentration, pH, and spray drying operating condition on the size and shell thickness-to-particle radius (S/R) ratio, which governs the shell mechanical stability, are investigated. Results and conclusion: The results indicate that the hollow microspheres size varies between 2 and 10 μm having S/R ratio between 2% and 4%, where the smaller size particles exhibit a higher S/R ratio. The resultant S/R ratio is found to be more influenced by process parameters acting at the nanoparticle scale (e.g., suspension pH) than by the spray drying operating condition.

Keywords:

• Hollow aggregates
• nanoparticles
• shell thickness
• spray drying
• ultrasound contrast agent

Acknowledgments

A financial support from Nanyang Technological University's Start-Up Grant (Grant No. SUG 8/07) is gratefully acknowledged. The authors thank Selina Li for her contribution in the spray-drying experiment.

Declaration of interest : The authors report no conflicts of interest.