Information-Based Design of Polymeric Drug Formulation Additives

Area of Science:

• Polymer Chemistry
• Materials Science
• Drug Delivery

Background:

• Peptide-poly(ethylene glycol) (PEG) conjugates are used to solubilize photosensitizers such as meta-tetra(hydroxyphenyl)chlorin (m-THPC).
• Designing synthetic analogs that mimic the functionalities of peptide-PEG conjugates is crucial for developing advanced drug delivery systems.

Purpose of the Study:

• To design and synthesize tailor-made alternating copolymers that mimic the functionalities of a peptide-PEG blueprint for m-THPC solubilization.
• To investigate the impact of copolymer composition, functional segment length, and side chain modification on m-THPC hosting and release properties.

Main Methods:

• Synthesis of styrene (S) or 4-vinylbenzyl-phthalimide (VBP) and maleic anhydride (MA) based alternating copolymers via controlled radical polymerization.
• Post-polymerization modification of MA units with isobutylamine to yield isobutylamide-carboxyl functional units (iBuMA).
• Systematic variation of functional segment degree of polymerization (DPn = 2, 4, 6) and side chain functionalization (iBuMA, iPrMA, MeMA).

Main Results:

• The P[S-alt-iBuMA]6-PEG copolymer exhibited superior m-THPC payload capacity and release rates compared to the parent peptide-PEG conjugate.
• Alterations in side chain functionality (iBuMA, iPrMA, MeMA) significantly affected payload capacity, with reductions up to 78%.
• Mimicking amino acid substitutions (Leu4 to Val/Ala) in the copolymer structure led to a substantial decrease in drug loading (92%).

Conclusions:

• Tailor-made alternating copolymers effectively mimic peptide-PEG functionalities for photosensitizer solubilization.
• The synthesized P[S-alt-iBuMA]6-PEG demonstrates enhanced performance in hosting and releasing m-THPC, outperforming the parent conjugate.
• Copolymer side chain structure critically influences drug loading capacity, highlighting the importance of precise molecular design in drug delivery applications.