Positively charged calcium phosphate/polymer nanoparticles for photodynamic therapy

Area of Science:

• Biomedical Engineering
• Materials Science
• Photochemistry

Background:

• Nanoparticle surface charge impacts cellular uptake.
• Positive nanoparticle charge is hypothesized to enhance cell membrane penetration.
• Developing effective delivery systems for photodynamic therapy (PDT) agents is crucial.

Purpose of the Study:

• To engineer positively charged nanoparticles for improved PDT.
• To evaluate the efficacy of novel nanoparticles loaded with 5,10,15,20-tetrakis(3-hydroxyphenyl)-porphyrin (mTHPP) for PDT.
• To compare the PDT activity and toxicity of nanoparticle-delivered mTHPP with the free dye.

Main Methods:

• Synthesized calcium phosphate nanoparticles with an inner carboxymethyl cellulose (CMC) shell and a poly(ethyleneimine) (PEI) outer shell.
• Loaded the PEI shell with the photoactive dye mTHPP.
• Tested the photodynamic activity and dark toxicity of the nanoparticles against HT29, HIG-82, and J774A.1 cells.
• Utilized aqueous dispersion for cell treatment.

Main Results:

• The modified nanoparticles exhibited a reversed positive charge.
• High photodynamic activity and low dark toxicity were observed in HIG-82 and J774A.1 cells at 2 microM mTHPP concentration.
• The killing efficiency of the nanoparticle formulation was comparable to the pure mTHPP dye.
• The nanoparticle formulation allowed for aqueous dispersion, unlike the alcoholic solution required for the pure dye.

Conclusions:

• Positively charged nanoparticles effectively deliver photoactive dyes for photodynamic therapy.
• This nanoparticle system demonstrates high therapeutic efficacy with minimal dark toxicity.
• The aqueous nanoparticle formulation presents a significant advantage over alcohol-based delivery of free dyes for PDT.