Polyacrylamide nanoparticles as a delivery system in photodynamic therapy

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Photodynamic Therapy

Background:

• Nanoparticles offer targeted drug delivery via the enhanced permeability and retention effect, minimizing systemic toxicity.
• Photodynamic therapy (PDT) utilizes light-activated photosensitizers to generate reactive oxygen species (ROS) for cancer treatment, offering spatial control and reduced generalized toxicity.
• Overcoming cancer cell drug expulsion mechanisms is crucial for effective chemotherapy.

Purpose of the Study:

• To synthesize and characterize novel photodynamic nanoparticles (PCNP and PCNP-P) for enhanced ROS generation.
• To evaluate the efficacy of these nanoparticles in damaging colon adenocarcinoma cells (HT29) via light activation.
• To determine the necessity of nanoparticle internalization for inducing photodynamic damage.

Main Methods:

• Synthesis of polylysine-bound tetrasulfonato-aluminum phthalocyanine entrapped nanoparticles (PCNP) and PCNP coated with a porphyrin-based photosensitizer (PCNP-P).
• Characterization of nanoparticle size (45 ± 10 nm for PCNP, 95 ± 10 nm for PCNP-P).
• Assessment of nanoparticle uptake by HT29 cells using flow cytometry and confocal microscopy, followed by cell viability assays under light activation.

Main Results:

• Both PCNP and PCNP-P demonstrated the ability to damage HT29 cancer cells upon light activation.
• Photodynamic damage occurred both when nanoparticles were in the external media and after internalization.
• Effective damage was observed at both minimum (<5 min) and maximum (25 h) uptake times.

Conclusions:

• Photodynamic nanoparticles can induce significant cancer cell damage through light activation.
• Nanoparticle internalization is not strictly necessary for photodynamic damage; close association with the tumor cell is sufficient for singlet oxygen delivery.
• This finding has clinical implications for overcoming cancer cell drug resistance mechanisms.