Nanocomposite Microcontainers with High Ultrasound Sensitivity

Abstract

A water suspension of nanocomposite microcapsules with embedded ZnO nanoparticles in the capsule shell is reported. The microcapsule morphology is characterized by confocal microscopy, TEM, SEM, and AFM before and after ultrasound treatment. A remarkably high capsule sensitivity to ultrasound is evidenced, and it is observed to grow with increasing number of ZnO nanoparticle layers in the nanocomposite shell. This effect is correlated with the mechanical properties of microcapsules measured with AFM.

Composite silica nanoparticle/polyelectrolyte microcapsules with reduced permeability and enhanced ultrasound sensitivity

“…One reasonable explanation for the increased sensitivity is that the incorporation of SiO2 nanoparticles increased the density gradient across the water/shell interface and consequently improved the absorption of acoustic energy. 29 Another possible explanation is the modification of the shell's mechanical properties. It was known that the concentration of nanoparticles in the capsule shell could affect the capsule stability.…”

“…28 Such stimuli, however, have limited use in biological and medical systems due to the short penetration depth relating to laser and microwave, and the large side effect associated with changing pH and temperature. 29 In contrast, ultrasound, which is already employed as diagnostics and therapeutic method for many diseases (i.e., prostate cancer), is promising due to its long penetration depth and non-invasive nature. 30 There is, however, very limited investigation on the ultrasonic effect on capsule release.…”

Bifunctional ultraviolet/ultrasound responsive composite TiO2/polyelectrolyte microcapsules

“…The strong response to ultrasound might be attributed to the increased density gradient across the water/shell interface, the enhanced of the shell stiffness, and the decreased shell elasticity, all of which would improve the absorption of acoustic energy, leading to the increased ultrasound responsiveness. 5,11,[38][39][40][41] Despite of these two types of stimuli response, TiO 2 /PAH/PSS hybrid capsules also displayed a different response to the pH of the environment compared to the pure PAH/PSS capsules. We know from other work that LbL microcapsules composed of weak PEs are generally sensitive to the pH of the environment.…”

Theranostic Multilayer Capsules for Ultrasound Imaging and Guided Drug Delivery

“…33 The improved US sensitivity of PSS/PAH multilayer capsules was achieved by lowering the capsule stiffness via embedding ZnO within the PSS/PAH capsule wall; ZnO-(PAH/PSS) 2 capsules totally ruptured after 9 s of US at 40 W (30 W/cm 2 ). 34 However, those studies involved high-power US in the range of tens to hundreds of watts. Lower power diagnostic US is more desirable in chemotherapy to avoid tissue damage and related side effects.…”