Multimodality imaging and photothermal experiments of nanoparticles by iron (Ⅱ) phthalocyanine-based targeted to breast cancer

Abstract

Objective To prepare a novel nanoparticle carrying iron(Ⅱ) phthalocyanine (FePc) coupled with aptamer AS1411 for targeting human breast cancer MCF-7 cells and evaluate its physicochemical properties, targeting ability to MCF-7 cells, photoacoustic/ultrasonic multimodal imaging capabilities, photothermal performance, photoinduced phase transitions in vitro and multimodal imaging performance in vivo. Methods FePc-encapsulated non-targeted nanoparticles (PLGA@FePc@PFP) were prepared by a two-step phacoemulsification method, and the targeted nanoparticles (AS1411-PLGA@FePc@PFP NPs) were prepared by combining the aptamer AS1411 modified with NH2 and the PLGA@FePc@PFP nanoparticles using the carbodiimide method. The physicochemical properties of AS1411-PLGA@FePc@PFP NPs were detected, and laser confocal microscopy and flow cytometry were used to evaluate the binding between AS1411 and the nanoparticles. CCK-8 assay was used to detect the cytotoxicity of AS1411-PLGA@FePc@PFP; laser confocal microscopy was used to observe the in vitro targeting ability of the nanoparticles; photoacoustic and ultrasonic imagers were used to test their imaging performance and targeting ability both in vitro and in vivo. Near-infrared laser (660 nm) and thermal imagers were used to test the in vitro photothermal conversion abilities of the nanoparticles, and the changes of the nanoparticles after laser irradiation were observed under an optical microscope. The temperature change of AS1411-PLGA@FePc@ PFP in tumor-bearing nude mice was detected in response to 660 nm laser irradiation. Results AS1411-PLGA@FePc@PFP was successfully prepared, which had an average diameter of 208.03±8.96 nm with a narrow particle size distribution, a mean zeta potential of -10.8±1.14 mV, and a FePc encapsulation rate of (83.96±1.61)%. The results of CCK-8 assay showed that the nanoparticles at varying concentrations had no obvious cytotoxicity. Flow cytometry showed an efficient binding of AS1411 with the nanoparticles had a binding rate of (93.31±2.58)%. Laser confocal analysis showed that there were significantly more nanoparticles around MCF-7 cells in the targeted group than in the non-targeted group. Laser irradiation caused the temperature of the nanoparticles carrying FePc to increase rapidly with time, and the phase change of the nanoparticles was observed under an optical microscope, suggesting good photothermal conversion ability of the nanoparticles. Photoacoustic imaging results showed that compared with nanoparticles without FePc, AS1411-PLGA@FePc@PFP produced strong photoacoustic signals, and the signal intensity showed a positive linear correlation with the nanoparticle concentration. Ultrasound and imaging results showed FePc in AS1411-PLGA@FePc@PFP achieved good photothermal conversion in a concentration-dependent manner for enhancing the effect of ultrasound imaging. In the tumor-bearing nude mice, the photoacoustic signal values in the xenograft were 1.26±0.06 and 0.30±0.01 at 6 h after tail vein injection of AS1411-PLGA@FePc@PFP and PLGA@FePc@PFP, respectively, showing a significant difference in their signal intensity (P < 0.05); in vivo ultrasound/contrast imaging also demonstrated a significant difference in the signal value after laser irradiation between the targeted group and the non-targeted group (P < 0.05). After laser irradiation, the tumor temperature in the targeted nanoparticle group was 50.53±0.56 ℃, as compared with 40.63±0.78 ℃ in the non-targeted group. Conclusion A multimodal molecular probe AS1411-PLGA@FePc@PFP for breast cancer has been successfully prepared, which has a good photothermal effect and can be potentially used for photoacoustic/ultrasound multimodal imaging of breast cancer.

Keywords

• iron(ⅱ) phthalocyanine
• poly(latic-co-glycolic acid)
• aptamer as1411
• breast cancer
• photoacoustic/ultrasonic imaging
• photothermal conversion capacity