Hard shell gas-filled contrast enhancement particles for colour Doppler ultrasound imaging of tumors

Abstract

Hollow hard shell particles of 200 nm and 2 micron diameter with a 10 nm thick porous silica shell have been synthesized using polystyrene templates and a sol–gel process. The template ensures than the hollow particles are monodispersed, while the charged silica surface ensures that they remain suspended in solution for weeks. When filled with perfluorocarbon gas, the particles behave as an efficient contrast agent for colour Doppler ultrasound imaging in human breast tissue. The silica shell provides unique properties compared to conventional soft shell particles employed as ultrasound contrast agents: uniform size control, strong adsorption to tissue and cells immobilizing particles at the tissue injection site, a long imaging lifetime, and a silica surface that can be easily modified with biotargeting ligands or small molecules to adjust the surface charge and polarity.

Perfluorohexane‐Encapsulated Mesoporous Silica Nanocapsules as Enhancement Agents for Highly Efficient High Intensity Focused Ultrasound (HIFU)

“…[3] Later, additional boron and perfluoropentane (PFP) vapor were incorporated to strengthen shell robustness and scattering intensity. [4] More recently, a series of cell-level biological effects were also explored by using inorganic microcapsules as the ultrasound imaging agents. [5] In addition to these general inorganic microcapsules, capsules with mesopore channels in the shell could make it possible to encapsulate and sustainedly release guest molecules; these have been extensively investigated for applications in drug delivery.…”

A facile two-step etching method to fabricate porous hollow silica particles

“…Up to now, various synthetic techniques such as spray drying [14,20], interfacial polymerization [21,22], self-assembly [5,11], layer-by-layer (LBL) fabrication [23,24], and templating have been established for making hollow silica particles. Among these methods, the templating method is popular, which uses polymeric spheres [8][9][10][25][26][27], micelles [6,28], droplets [7,[29][30][31], and inorganic particles [3,16,19] as templates. These templating approaches involve multi-steps such as preparation of template, coating of the template particles to form silica shell, and removal of the template [32].…”

“…The synthesis of nano-or micro-sized hollow silica particles has attracted widespread attention in recent years due to their unique properties and numerous applications in the fields of catalysis [1,2], separation [3][4][5], cell-labeling [6,7], ultrasound imaging [8], photonic crystals [9], and drug delivery [10][11][12][13][14][15][16][17][18][19]. Up to now, various synthetic techniques such as spray drying [14,20], interfacial polymerization [21,22], self-assembly [5,11], layer-by-layer (LBL) fabrication [23,24], and templating have been established for making hollow silica particles.…”

Highly Uniform Perfluoropropane-Loaded Cerasomal Microbubbles As a Novel Ultrasound Contrast Agent

“…Moreover, to enhance backscattering signals between different tissues for better visualization of a specific tissue, microbubbles have been utilized because the compressibility of their gas cores is greater than that of normal tissues 3,4 . In addition to their gas cores, the sizes and shell materials of microbubbles have significant effects on the sensitivity and duration of ultrasound imaging [5][6][7][8] .…”