Electrically Triggered Fluorescein and Dexamethasone Release from Conducting Polymer Hydrogels

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Drug Delivery Systems

Background:

• Conventional drug administration faces limitations in spatial and temporal control.
• Existing controlled drug delivery systems rarely offer a beneficial mechanical environment for cells.
• Conducting polymer hydrogels present a potential avenue for advanced drug delivery platforms.

Purpose of the Study:

• To investigate the drug release characteristics of poly(N-isopropylacrylamide)/polypyrrole (pNIPAM/PPy) conducting polymer hydrogels.
• To evaluate the controlled release of fluorescein and dexamethasone from pNIPAM/PPy hydrogels.
• To assess the potential of pNIPAM/PPy hydrogels for on/off drug delivery applications.

Main Methods:

• Electropolymerization of polypyrrole (PPy) onto pNIPAM hydrogels.
• Comprehensive drug release studies using fluorescein as a model drug and dexamethasone.
• Cyclic voltammetry and scanning electron microscopy (SEM) for material characterization.
• Modulation of drug release by electrical stimulation (constant reduction, pulsed potential).

Main Results:

• Fluorescein release was successfully initiated by constant reduction and tunable by electropolymerization charge.
• pNIPAM/PPy hydrogels demonstrated multiple cycles of fluorescein depletion and reloading.
• Dexamethasone release required a biphasic pulsed potential, showing minimal passive leaching and multi-day, multi-triggerable release.
• Material characterization indicated that pNIPAM presence and drug doping affected PPy structure without preventing release.

Conclusions:

• pNIPAM/PPy conducting polymer hydrogels are a promising platform for on/off drug delivery.
• The nondegrading matrix, minimal passive drug leaching, and reloadable drug payload offer significant advantages.
• These hydrogels provide a suitable mechanical environment for interfacing with living cells, enhancing their therapeutic potential.