Self-made ultrasound/fluorescent bi-functional contrast agent for rabbit's normal lymph node imaging / 中国医学科学院学报

<p><b>OBJECTIVE</b>To prepare a lymph node-targeted ultrasound/fluorescence bi-functional imaging contrast agents, and observe its effectiveness both on contrast-enhanced ultrasound (CEUS) and vivo near infrared fluorescence (NIR) imaging through animal experiments.</p><p><b>METHODS</b>The chimeric lymph node-targeted ligand (phosphatidylserine) and near-infrared fluorescent substance were assembled to form bi-functional contrast microbubbles. The morphology and size distribution were detected by optical microscope and Malvern potential tests. Five normal New Zealand white rabbits were subcutaneously injected with the prepared contrast agent in bilateral footpads, and the imaging effectiveness of lymph nodes and lymphatic vessel were observed by CEUS and NIR technique. Then blue dye was subcutaneously injected at the same site, and the rabbits were sacrificed for lymph nodes pathological examination.</p><p><b>RESULTS</b>Lipid ultrasound microbubbles,with a mean size of 3-5 Μm in diameter, appeared to be uniform in distribution and regular in configuration. The images of inflow lymphatic vessel and relevant lymph node were quickly showed up after the subcutaneous injection by CEUS, which was identical to the result detected by NIR. Biopsy confirmed that all the blue-stained lymph nodes could be displayed by NIR.</p><p><b>CONCLUSIONS</b>The self-made bi-functional contrast agent has a good imaging ability in CEUS and NIR imaging. It may be a better agent as lymph node tracer.</p>

Preparation of polyelectrolyte multilayer film-coated microbubble ultrasound contrast agent / 中国医学科学院学报

<p><b>OBJECTIVE</b>To prepare polyelectrolyte multilayer film-coated microbubble ultrasound contrast agent (UCA) and evaluate its effects in contrast imaging on normal rabbit's liver parenchyma.</p><p><b>METHODS</b>Perfluorocarbon (PFC) -containing microbubble UCA (ST68-PFC) were prepared by sonication-based on surfactants (Span 60 and Tween 80). Subsequently, the resulting ST68-PFC microbubbles were coated using oppositely charged polylysine (PLL) and alginate (Alg) by microbubble-templated layer-by-layer self-assembly technique via electrostatic interaction. The enhancement effects in contrast imaging on normal rabbit's liver parenchyma were assessed.</p><p><b>RESULTS</b>The obtained microbubble UCA exhibited a narrow size distribution. The polyelectrolytes were successfully assembled onto the surface of ST68-PFC microbubbles. In vivo experiment showed that polyelectrolyte multilayer film-coated UCA effectively enhanced the imaging of rabbit's liver parenchyma.</p><p><b>CONCLUSIONS</b>The novel microbubble UCA obtained via layer-by-layer self-assembly, when enabling more functions, has no obvious difference in enhancement effects compared with the premodified microbubbles. The polymers with chemically active groups (such as amino group and carboxyl group) can be used as the outermost layer for the attachment of targeting ligands to microbubbles, which allows the selective targeting of the microbubbles to desired sites.</p>