Figure 4.

Schematic illustration of current strategies to improve the performance of targeted microbubbles (tMBs) in therapeutic applications. (A) Microbubble targeting can be achieved through electrostatic interactions or through the use of PEGylated lipids linked with conjugation groups such as thiol-maleimide, disulfide, DBCO-azide, folate or biotin. (B) Ligand–receptor targeting of drug, gene or cell-loaded MBs with antibodies, peptides or vitamins can improve delivery at the target site. (C) Dual targeting of loaded MBs with antibody-antibody, antibody-peptide, peptide-peptide, or peptide-vitamin conjugation can improve delivery efficiency and spatial targeting. (D) MBs conjugated with molecular or magnetic targeted carriers, such as nanoparticles, liposomes, and nanodroplets, can increase drug loading capacity and delivery efficiency at the target site.