title: A review of integrating electroactive polymers as responsive systems for specialized drug delivery applications.
abstract: Electroactive polymers (EAPs) are promising candidate materials for the design of drug delivery technologies, especially in conditions where an "on-off" drug release mechanism is required. To achieve this, EAPs such as polyaniline, polypyrrole, polythiophene, ethylene vinyl acetate, and polyethylene may be blended into responsive hydrogels in conjunction with the desired drug to obtain a patient-controlled drug release system. The "on-off" drug release mechanism can be achieved through the environmental-responsive nature of the interpenetrating hydrogel-EAP complex via (i) charged ions initiated diffusion of drug molecules; (ii) conformational changes that occur during redox switching of EAPs; or (iii) electroerosion. These release mechanisms are not exhaustive and new release mechanisms are still under investigation. Therefore, this review seeks to provide a concise incursion and critical overview of EAPs and responsive hydrogels as a strategy for advanced drug delivery, for example, controlled release of neurotransmitters, sulfosalicyclic acid from cross-linked hydrogel, and vaccine delivery. The review further discusses techniques such as linear sweep voltammetry, cyclic voltammetry, impedance spectroscopy, and chronoamperometry for the determination of the redox capability of EAPs. The future implications of the hydrogel-EAP composites include, but not limited to, application toward biosensors, DNA hybridizations, microsurgical tools, and miniature bioreactors and may be utilized to their full potential in the form of injectable devices as nanorobots or nanobiosensors.
authors.affiliation: Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.
authors.forename: Viness
authors.initials: V
authors.lastname: Pillay
authors.forename: Tong-Sheng
authors.initials: TS
authors.lastname: Tsai
authors.forename: Yahya E
authors.initials: YE
authors.lastname: Choonara
authors.forename: Lisa C
authors.initials: LC
authors.lastname: du Toit
authors.forename: Pradeep
authors.initials: P
authors.lastname: Kumar
authors.forename: Girish
authors.initials: G
authors.lastname: Modi
authors.forename: Dinesh
authors.initials: D
authors.lastname: Naidoo
authors.forename: Lomas K
authors.initials: LK
authors.lastname: Tomar
authors.forename: Charu
authors.initials: C
authors.lastname: Tyagi
authors.forename: Valence M K
authors.initials: VM
authors.lastname: Ndesendo
mesh_terms: D000818:Animals; D003692:Delayed-Action Preparations / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000379:methods; D004553:Electric Conductivity; D055664:Electrochemical Techniques; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D003692:Delayed-Action Preparations; D020100:Hydrogels; D011108:Polymers
keywords: drug delivery; electroactive polymers; electroresponsive hydrogel; interpenetrating polymer networks; “on-off” drug release mechanisms