A novel dual-targeted ultrasound contrast agent provides improvement of gene delivery efficiency in vitro.

Ultrasound-targeted microbubble destruction (UTMD) has become a novel gene/drug delivery method in cancer therapeutic application. However, the gene transfection efficiency mediated by UTMD is still unsatisfactory. Here, we introduced iRGD/CCR2 dual-targeted cationic microbubbles (MBiRGD/CCR2) which was modified with PEI-600 and coated with iRGD peptides and anti-CCR-2 antibodies. It showed that MBiRGD/CCR2 had a 25.83 ± 1.57 mV surface zeta potential and good stability. The experiments in vitro showed MBiRGD/CCR2 had higher binding efficiency with both bEnd.3 cells and MCF-7 cells than that of iRGD or CCR2 single-targeted cationic microbubbles (MBiRGD or MBCCR2) (P < 0.05 for both). Agarose gel electrophoresis assay showed that MBiRGD/CCR2 can effectively load pGPU6/GFP/Neo-shAKT2 plasmid DNA. Compared with the plain MBs (MBcontrol) or single-targeted cationic MBs including MBiRGD and MBCCR2 (P < 0.05 for all), the dual-targeted cationic MBiRGD/CCR2 groups had higher gene transfection efficiency under US exposure. It showed that the dual-targeted cationic MBiRGD/CCR2 has a potential value to be used as an ultrasound imaging probe for ultrasound image-guided tumor gene therapy.