Folate receptor-targeted ultrasonic PFOB nanoparticles: Synthesis, characterization and application in tumor-targeted imaging

Abstract

Abstract. In this study, we aimed to determine an effective strategy for the synthesis of folate receptor (FR) targetednanoparticles (FRNPs). The nanoparticles used as ultrasound contrast agents (UCAs) were composed of a liquid core of perfluorooctyl bromide (PFOB) liposome and a targeted shell chemically conjugated with folic acid (FA) and polyethylene glycol (PEG). This was done in order to avoid recognition and clearance by the mononuclear phagocyte system [also known as the reticuloendothelial system (RES)] and enhance the targeting capability of the nanoparticles to tumors overexpressing folate receptor (FR). The FRNPs exhibited an average particle size of 301±10.8 nm and surface potential of 39.1±0.43 mV. Subsequently, in vitro, FRNPs labeled with FITC fluorescence dye were visibly uptaken into the cytoplasm of FR-overexpressing cancer cells (Bel7402 and SW620 cells), whereas the A549 cells expressing relatively low levels of FR just bound with few FRNPs. These results demonstrated that FRNPs have a high affinity to FR-overexpressing cancer cells. Additionally, in in vivo experiments, FRNPs achieved a greater enhancement of tumor ultrasound imaging and a longer enhancement time in FR-overexpressing tumors and the Cy7-labeled FRNPs exhibited a relatively high tumor-targeted distribution in FR-overexpressing tumors. Targeted ultrasound and fluorescence imaging revealed that FRNPs have the ability to target FR-overexpressing tumors and ex vivo fluorescence imaging was then used to further verify and confirm the presence of FRNPs in tumor tissues with histological analysis of the tumor slices. On the whole, our data demonstrate that the FRNPs may prove to be a promising candidate for the early diagnosis for FR-overexpressing tumors at the molecular and cellular levels.

Internalization of Methotrexate Conjugates by Folate Receptor-α

“…Real-time qPCR data analysis revealed higher expression levels of FRα in the KB cancer cell line and negligible levels in the MDA-MB-435S cell line ( Figure 3A). 11 Although posttranscriptional regulation can occur, previous studies showed that the level of protein expression of FR 31,32 and RFC 33,34 in several cancer cell lines is directly proportional to mRNA levels.…”

Enhanced antitumor efficacy in colon cancer using EGF functionalized PLGA nanoparticles loaded with 5-Fluorouracil and perfluorocarbon

“…Free PLGA/PVA polymers were separated by centrifugation at 3,000 rpm for 15 min. The PLGA NPs were modified with EGF using N'-ethylcarbodiimide hydrochloride (EDC) [19].…”

Perfluorooctylbromide nanoparticles for ultrasound imaging and drug delivery

“…Based on the experimental results, the authors predicted that the FR-mediated PFOB NPs are more promising agents for tumor-targeted US imaging. 71 In a subsequent study, 72 the researchers injected their FR-mediated PFOB NPs along with an immobilized probe into mice via the tail vein and set the ultrasonography parameters to an MI of 0.7 and a gain of 80%. Between 20 and 160 minutes after injection, the images from FR-overexpressing tumors displayed a higher intensity value than those from tumors expressing low levels of FR.…”

“…Thus, the FR-mediated PFOB NPs achieved specific enhanced imaging of FR-overexpressing tumors and a longer duration of effective enhanced US imaging. 72 The abovementioned alternative approaches to applying PFOB NPs in ultrasonography are summarized in Table 2.…”

“…136 Nevertheless, the question remains: how do we design PFOB NPs to achieve therapeutic functions coupled with diagnostic functions via ultrasonography? Importantly, in recent years, two laboratories 63,72 have designed targeted PFOB NPs that successfully enhanced tumor US imaging in vivo. The most recently reported success in the application of targeted PFOB NPs with a lipid coating to targeted US imaging has inspired a substantial number of subsequent studies on achieving therapeutic functions coupled with diagnostic functions via ultrasonography.…”