Optimizing ultrasound molecular imaging of secreted frizzled related protein 2 expression in angiosarcoma
Fig 1
SFRP2-targeted and control ultrasound contrast agents were designed with NeutrAvidin™.
(A) Sulfhydryl-activated lipid solution was formulated by incorporating a thiol functionalized PEG-lipid (DSPE-PEG2000-thiol) at 0.2 mole percent in our lipid solution. Thiol-activated contrast agent was prepared by shaking the lipid solution in 3 ml glass vials containing perfluorobutane gas (see Methods for details). (B) NeutrAvidin™ functionalized contrast agent was prepared by forming a covalent crosslink between maleimide-activated NeutrAvidin™ and thiol-activated contrast agent. We estimated the thiol content of our sulfhydryl-activated contrast agent and tested 3 and 10-fold molar excess of maleimide-activated NeutrAvidin™. (C) Anti- SFRP2 targeted or control anti-chicken IgY targeted microbubbles were prepared by adding a 3-fold molar excess of either biotinylated SFRP2 antibodies or biotinylated antibody to chicken IgY to NeutrAvidin™ functionalized, ultrasound contrast agents.