Tracking Sulfonated Polystyrene Diffusion in a Chitosan/Carboxymethyl Cellulose Layer-by-Layer Film: Exploring the Internal Architecture of Nanocoatings

Abstract

Since chitosan presents the ability to interact with a wide range of molecules, it has been one of the most popular natural polymers for the construction of layer-by-layer thin films. In this study, depth-profiling X-ray photoelectron spectroscopy (XPS) was employed to track the diffusion of sulfonated polystyrene (SPS) in carboxymethyl cellulose/chitosan (CMC/Chi) multilayers. Our findings suggest that the CMC/Chi film does not constitute an electrostatic barrier sufficient to block diffusion of SPS, and that diffusion can be controlled by adjusting the diffusion time and the molecular weight of the polymers that compose the CMC/Chi system. In addition to monitoring the diffusion, it was also possible to observe a process of preferential interaction between Chi and SPS. Thus, the nitrogen N 1s peak, due to functional groups found exclusively in chitosan chains, was the key factor to identifying the molecular interactions involving chitosan and the different polyanions. Accordingly, the presence of a strong polyanion such as SPS shifts the N 1s peak to a higher level of binding energy. Such results highlight that understanding the fundamentals of polymer interactions is a major step to fine-tuning the internal architecture of LbL structures for specific applications (e.g., drug release).

Effect of Multilayer Termination on Nonspecific Protein Adsorption and Antifouling Activity of Alginate-Based Layer-by-Layer Coatings

“…Marine biofouling, the accumulation and growth of animals, plants, and microorganisms on surfaces which are in contact with aqueous environments, causes severe economic and ecological issues such as high fuel consumption, high operational and maintenance costs, an increased greenhouse effect, biocorrosion, and the translocation of nonindigenous species. − Since numerous commonly used antifouling coatings are toxic and environmentally harmful, nontoxic alternatives are investigated and developed to control and prevent marine biofouling without polluting the environment. − To identify new chemistries that are worth exploring for polymer formulations, monolayer systems or grafted macromolecules are frequently used. − Another facile method to directly apply charged biomacromolecules to surfaces is layer-by-layer (LbL) deposition in which oppositely charged macromolecules are alternately assembled on surfaces. − The resulting coatings provide functional materials with defined compositions, structures, and surface properties and are well suited for studies exploring interactions with cells, bacteria, or fouling organisms. − Besides electrostatic interactions, hydrophobic interactions, charge-transfer interactions, host–guest interactions, coordinative interactions, hydrogen bonding, or covalent bonding can also be exploited as a driving force for the formation of LbL coatings. − Fine tuning of the properties of the coatings can be achieved by tailoring the charge density, addition of salts, and choice of solvents. − Depending on the choice of macromolecules, LbL coatings can respond to water, ions, pH, and temperature by swelling, morphological reorganization, changes in mechanical properties, or an alteration of their permeability. ,,− Polyelectrolyte multilayers (PEMs) are applied in different fields where resistance against the nonspecific adsorption (NSA) of proteins and antibacterial properties is required, especially in biomedical applications. ,,−…”

Materials with Hierarchical Porosity Enhance the Stability of Infused Ionic Liquid Films

“…We employ the LbL process to create layers of SiO 2 nanoparticles to enhance the nanoporosity of a surface. ,− To this end, we created negative charges on the surface by means of plasma treatment. Subsequently, the substrate was immersed in a 0.1% w/w solution of PDADMAC as a positively charged polyelectrolyte.…”

“…In addition to introducing chemical functionalities to a surface, the LbL method allows the creation of nanoscale surface topographies. ,,− To this end, one of the polymeric species is replaced by a colloidal dispersion, which is subsequently adsorbed to build up a particulate coating held together by a polymeric “glue” provided by the oppositely charged polymer. Upon calcination, a nanoporous coating results.…”

Interplay of the Assembly Conditions on Drug Transport Mechanisms in Polyelectrolyte Multilayer Films

“…6 An analytical approach to methodically design and optimize polymer-based coatings for the efficient delivery of specific drugs is highly necessary because of the diversity of possibilities for physical and chemical interactions between drugs and selected polymeric materials, 7−9 in addition to the interaction of biomaterial accordingly to the environmental stimuli. 10 Amongst the methods used for the film assembly, 11,12 the layer-by-layer (LbL) technique has emerged as one of the most popular strategies for the self-assembly of polyelectrolyte multilayers (PEM) through the interaction of oppositely charged species, 13 enabling one to tune the surface properties based on the assembly conditions, 14 the sequence of building block deposition, 15 or the postassembly treatment. 16 Several features make the LbL films attractive for drug delivery, including the control of the drug loading and release processes, the ability to functionalize surfaces with diverse geometry and chemistry, the use of mild chemical conditions for handling sensitive therapeutic molecules, and the simple and scalable processing.…”