Phosphonium Polyelectrolyte Complexes for the Encapsulation and Slow Release of Ionic Cargo.

Area of Science:

• Polymer Science
• Materials Science
• Biomaterials

Background:

• Polyelectrolyte complexes (PECs) form hydrogel networks for cargo encapsulation and release.
• Traditional PECs often exhibit rapid release (hours to days) and weak mechanical properties.
• Developing robust hydrogels with tunable, sustained release profiles is crucial for drug delivery applications.

Purpose of the Study:

• To prepare and characterize novel polyelectrolyte complexes (PECs) using sodium hyaluronate (HA) and various polyphosphoniums.
• To investigate the influence of polyphosphonium structure and salt concentration on PEC properties, including swelling, rheology, and self-healing.
• To evaluate the encapsulation efficiency and sustained release of anionic molecules from the developed PECs and assess their cytotoxicity.

Main Methods:

• Synthesis of four distinct polyphosphonium polymers.
• Formation of PEC hydrogel networks through polyelectrolyte complexation with sodium hyaluronate.
• Compaction of PECs via ultracentrifugation.
• Characterization of PECs using composition analysis, swelling tests, rheological measurements, and self-healing assays.
• Encapsulation and in vitro release studies of anionic molecules (fluorescein, diclofenac, ATP).
• Cytotoxicity assessment using C2C12 mouse myoblast cells.

Main Results:

• The polyphosphonium-HA PECs exhibited predominantly gel-like behavior with relaxation times > 40 s and self-healing within 2-18 hours.
• High encapsulation capacities (up to 16 wt %) were achieved for anionic molecules like fluorescein and diclofenac.
• Sustained release of fluorescein and diclofenac over 60 days was observed, attributed to combined hydrophobic and ionic interactions within the dense PEC network.
• Cytotoxicity varied depending on the polyphosphonium structure and PEC properties.

Conclusions:

• Polyphosphonium-HA networks provide a versatile platform for the loading and sustained release of ionic drugs.
• The physical and biological properties of these networks can be effectively tuned by modifying the polyphosphonium structure.
• These findings highlight the potential of these novel PECs for advanced drug delivery systems.