Tuning the Surface Properties of Poly(Allylamine Hydrochloride)-Based Multilayer Films

Abstract

The layer-by-layer (LbL) method of polyelectrolyte multilayer (PEM) fabrication is extremely versatile. It allows using a pair of any oppositely charged polyelectrolytes. Nevertheless, it may be difficult to ascribe a particular physicochemical property of the resulting PEM to a structural or chemical feature of a single component. A solution to this problem is based on the application of a polycation and a polyanion obtained by proper modification of the same parent polymer. Polyelectrolyte multilayers (PEMs) were prepared using the LbL technique from hydrophilic and amphiphilic derivatives of poly(allylamine hydrochloride) (PAH). PAH derivatives were obtained by the substitution of amine groups in PAH with sulfonate, ammonium, and hydrophobic groups. The PEMs were stable in 1 M NaCl and showed three different modes of thickness growth: exponential, mixed exponential-linear, and linear. Their surfaces ranged from very hydrophilic to hydrophobic. Root mean square (RMS) roughness was very variable and depended on the PEM composition, sample environment (dry, wet), and the polymer constituting the topmost layer. Atomic force microscopy (AFM) imaging of the surfaces showed very different morphologies of PEMs, including very smooth, porous, and structured PEMs with micellar aggregates. Thus, by proper choice of PAH derivatives, surfaces with different physicochemical features (growth type, thickness, charge, wettability, roughness, surface morphology) were obtained.

Rational Mitomycin Nanocarriers Based on Hydrophobically Functionalized Polyelectrolytes and Poly(lactide-co-glycolide)

“…The aforementioned compounds comprise both ionizable groups, for example, carboxylic acid or styrenesulfonate moieties, and shorter or longer hydrophobic side chains. 38 Charged groups are responsible for stabilization by repulsive electrostatic forces, while hydrophobic side chains can anchor to the surfaces of hydrophobic nanoparticles and provide additional attractive interactions between polyelectrolytes and core-forming materials. Conversely, these side chains can also sterically stabilize the charged particles, further increasing the stability of the particles.…”

“…Considering these drawbacks, a unique class of HF-PEs were carefully studied as stabilizing materials for PLGA nanoparticles as mitomycin carriers. The aforementioned compounds comprise both ionizable groups, for example, carboxylic acid or styrenesulfonate moieties, and shorter or longer hydrophobic side chains . Charged groups are responsible for stabilization by repulsive electrostatic forces, while hydrophobic side chains can anchor to the surfaces of hydrophobic nanoparticles and provide additional attractive interactions between polyelectrolytes and core-forming materials.…”

Layer-by-Layer Cell Encapsulation for Drug Delivery: The History, Technique Basis, and Applications

“…The extent of lateral heterogeneity of branched PAMAM films was also quantified with atomic force microscopy at molecule-scale [151]. For films of linear materials, although their statistical features can be obtained via atomic force microscopy, detailed delineation of saturated multilayers of attached linear materials is still lacking [152]. In the meantime, it was acknowledged that PAMAM-PSS films were heterogeneous, examined by direct force measurement [153].…”

Exploring the Mechanical and Chemical Properties of Cross-Linked Poly(allylamine)-hyaluronic Acid Multilayer Films Using a Chemometric Unmixing Approach

“…31,32 The authors of these works evidenced that the swelling ratio of this type of hydrogel is related to the total number of layers and the pH of the assembly solution. 31,33 They also suggested that the swelling behavior of PAH-HA hydrogels can be tuned by controlling the ionic strength, thus allowing interesting applications, especially for the controlled release of active drugs, membrane filtration, and biomaterial coatings. 33−35 Investigating the mechanical properties can provide insight into intermolecular interactions in the materials and is thus of fundamental interest.…”

“…As HA and PAH exhibit opposite charge, they can be associated according to the LbL process to produce multilayered hydrogels . Previous works highlighted that these materials, in the absence of any chemical cross-linking, are highly sensitive to pH and ionic strength. , The authors of these works evidenced that the swelling ratio of this type of hydrogel is related to the total number of layers and the pH of the assembly solution. , They also suggested that the swelling behavior of PAH-HA hydrogels can be tuned by controlling the ionic strength, thus allowing interesting applications, especially for the controlled release of active drugs, membrane filtration, and biomaterial coatings. − Investigating the mechanical properties can provide insight into intermolecular interactions in the materials and is thus of fundamental interest . However, mechanical measurements on PEMs and hydrogels can be complex and experimentally challenging, especially when the thickness of these materials is of a few micrometers .…”