Binding of Targeted Semiconducting Photothermal Polymer Nanoparticles for Intraperitoneal Detection and Treatment of Colorectal Cancer

Abstract

Nanoparticles offer many promising advantages for improving current surgical regimens through their ability to detect and treat disseminated colorectal cancer (CRC). Hybrid Donor-Acceptor Polymer Particles (HDAPPs) have recently been shown to fluorescently detect and thermally ablate tumors in a murine model. Here, HDAPPS were functionalized with hyaluronic acid (HA) to improve their binding specificity to CT26 mouse CRC cells using HA to target the cancer stem cell marker CD44. In this work, we compared the binding of HA functionalized HDAPPs (HA-HDAPPs) in in vitro, ex vivo, and in vivo environments. The HA-HDAPPs bound to CT26 cells 2-fold more in vitro and 2.3-fold higher than un-functionalized HDAPPs ex vivo. Compared to intraoperative abdominal perfusion, intraperitoneal injection prior to laser stimulation for nanoparticle heat generation provides a superior modality of HA-HDAPPs delivery for CRC tumor selectivity. Photothermal treatment of disseminated CRC showed that only HA-HDAPPs delivered via intraperitoneal injection had a reduction in the tumor burden, and these nanoparticles also remained in the abdomen following resolution of the tumor. The results of this work confirm that HA-HDAPPs selectively bind to disseminated CRC, with ex vivo tumors having bound HA-HDAPPs capable of photothermal ablation. HA-HDAPPs demonstrated superior binding to tumor regions compared to HDAPPs. Overall, this study displays the theranostic potential of HDAPPs, emphasizing their capacity to detect and photothermally treat disseminated CRC tumors.

Semiconducting polymer nanoparticles for photothermal ablation of colorectal cancer organoids

“…Optical characterization of both HDAPPs and HA-HDAPPs shows their characteristic photothermal excitation and fluorescent emission within the biologically optimal NIR window 22 . In addition to the benefit of NIR-availability, both HDAPPs and HA-HDAPPs are non-cytotoxic, colloidally stable in aqueous solutions, and reproducibly heat and fluoresce, serving as an ideal theranostic for tumor imaging and ablation 22 , 24 . HA-HDAPPs demonstrated increased binding potential relative to non-targeted HDAPPs with a 1 h binding incubation; however, there was insufficient binding of HA-HDAPPs (a maximum of 2 × 10 9 NP) to achieve ablation, leading to the negative results in Supplementary Figure S9 .…”

“…To target the CD44 receptor, HDAPPs were coated with 60 kDa hyaluronic acid through layer-by-layer electrostatic deposition by modifying our published protocol in accordance with other work, using chitosan as an intermediate layer between the HDAPPs and HA 24 , 40 , 50 . First, 350 μL HDAPPs were added to a 5 mL solution of chitosan (3 mg/mL) in 2% acetic acid (filtered with 0.22 μm filter) and stirred for 1 h, followed by centrifugation to remove nanoparticle aggregates.…”

“…Heat generated by HDAPPs, HA-HDAPPs, BSe NPs, or HA-BSe NPs was determined by exposing 100 μL nanoparticle dilutions in water (5.225 × 10 11 , 2.5 × 10 11 , 1 × 10 11 , 5 × 10 10 , and 1 × 10 10 NP/mL) to 800 nm continuous wave laser at 5 W for 36 s (used for 2D culture) or 60 s (used for organoids) with a 1 cm 2 spot size (K-Cube, Summus Medical Laser), according to our previous publications 22 , 24 , 51 . Solution temperatures before and after exposure were recorded using a Neoptix Nomad fiber optic thermometer.…”

“…1 22 . Termed Hybrid Donor–Acceptor Polymer Particles (HDAPPs), our group has demonstrated the capacity of HDAPPs to reproducibly heat by photoexcitation within the NIR window, generate fluorescence emission with minimal photobleaching within the NIR window (825 nm), remain colloidally stable to indefinite time points, and show minimal cytotoxicity, even up to 1 mg/ml 22 – 24 . The combination of these characteristics into a single targetable nanoparticle platform demonstrates the utility of HDAPPs as a photothermal theranostic for both detection and ablation of CRC.…”

“…Although systemic delivery of chemotherapy is used for disseminated CRC, the blood peritoneal barrier can impede delivery, and thus intraperitoneal perfusion of chemotherapy is often employed. We have shown that HDAPPs can be delivered similarly, using intraperitoneal perfusion that overcomes the biological limitation and improves delivery to the tumor, to serve as a theranostic modality for CRC treatment 24 . However, anisotropic diffusion of nanoparticles within the tumor microenvironment may be a major barrier to therapeutic success, and it is this limitation that the current work has sought to illucidate 26 .…”