Polyelectrolyte–Surfactant Complexes As a Formulation Tool for Drug Delivery

Abstract

Aqueous polyelectrolyte−surfactant complexes (PESCs) are very rich with respect to their properties and the structures formed by them. By design they normally contain hydrophobic micellar surfactant aggregates complexed by long polyelectrolyte chains, thereby combining the formation of small hydrophobic domains given by the surfactant with large-scale structuring due to the presence of the polyelectrolyte chain. In addition, they contain highly polar regions of surfactant head groups in contact with polyelectrolyte, forming a shell around the micellar aggregates, which often also possesses a certain hydrophobic character. Accordingly, the ability for solubilization of waterinsoluble compounds of different sorts is particularly versatile in PESCs. Their solubilization sites with very different polarities and hydrophobic characters make them very flexible in adapting to the requirements of a given drug molecule. This renders them attractive for potential applications in drug delivery. In addition, modification of the rheological properties via self-assembly and network formation can be very important in PESC applications. In the following, we discuss the structures of PESCs and their properties, with a focus on the solubilization properties. Subsequently, examples are described where PESCs have been employed in the context of drug solubilization and delivery. These comprise examples with individual aggregates, cross-linked hydrogels, and ones taking advantage of the high solubilization capacity of microemulsions.

Role of Polyanions and Surfactant Head Group in the Formation of Polymer–Colloid Nanocontainers

“…surfactant–PE nanostructures may be of interest as carriers due to the ease of their formation. According to the literature data, including our studies, mixed systems based on amphiphiles and PE can be used as nanocontainers for the delivery of hydrophobic substances, specifically medicines [ 3 , 11 , 12 , 13 , 27 , 28 ]; Polymer–surfactant complexes are biomimetic systems, and their study makes it possible to simulate the interaction of charged amphiphiles with natural biopolymers (nucleic acids, proteins, polysaccharides) and lipids [ 29 , 30 ], factors of enzyme catalysis [ 31 ], etc. Moreover, they may be considered the simplest models for studying membrane–drug interactions (e.g., antimicrobial preparations exert their effects by interacting with biological membranes) [ 32 ].…”

“…surfactant–PE nanostructures may be of interest as carriers due to the ease of their formation. According to the literature data, including our studies, mixed systems based on amphiphiles and PE can be used as nanocontainers for the delivery of hydrophobic substances, specifically medicines [ 3 , 11 , 12 , 13 , 27 , 28 ];…”

“…Interactions between surfactants and PEs in the bulk solution and at the water–air interface have been systematically studied by many research groups, including ours [ 4 , 7 , 8 , 9 , 10 ]. Meanwhile, these systems continue to attract the attention of researchers, with the variety of self-assembling nanostructures such as micelles, vesicles, polyelectrolyte capsules, nanolayers, nano- and microparticles involved [ 11 , 12 , 13 , 14 ]. This research activity emphasizes the urgency of the study of surfactant–PE systems, which is based on the following reasons: The formation of surfactant–PE complexes is contributed by a variety of noncovalent intermolecular interactions, including hydrophobic effect, hydrogen bonds, Van der Waals, and electrostatic forces.…”

Aggregation and Gelation Behavior of Stereocomplexed Four-Arm PLA-PEG Copolymers Containing Neutral or Cationic Linkers

“…This approach may successfully facilitate the preparation of stable particles, but it can also lead to a reduced hydrophilicity and/or biodegradability. As an alternative, enhanced stability can also be achieved by dynamic polymer–polymer interactions such as polyelectrolyte interactions [ 19 , 20 ], stereocomplexation [ 21 , 22 ], and hydrogen bonding [ 23 ] in either the core or the shell of polymeric micelles. Moreover, it was shown that replacing the hydrolytically labile ester bond between the PLA and PEG blocks with amide groups has a significant effect on gel stability [ 24 ].…”

Tuning Properties of Polyelectrolyte-Surfactant Associates in Two-Phase Microfluidic Flows

“…Self-organization in polyelectrolyte-surfactant solutions causes the formation of functional nanoscale systems [2,6], which are used in nanotechnology [7,8] and medicine [4,9]. Polyelectrolyte-surfactant complexes are demanded for template synthesis of materials [10,11], target drug delivery systems [4,7,12,13], and fabrication of soft matter with smart stimuli-responsive capabilities [5,14].…”