Layer‐by‐layer films based on catechol‐modified polysaccharides produced by dip‐ and spin‐coating onto different substrates

Abstract

Layer‐by‐layer films based on chitosan and hyaluronic acid were produced by dip‐ and spin‐coating techniques onto glass, 316L stainless steel and titanium. These natural polymers were modified with catechol groups, in order to build coatings with improved adhesive properties. Polymeric coatings were exclusively composed by both modified polymers whereas the multifunctional coatings combined an inorganic phase of bioactive glass nanoparticles with the polymeric layers to confer bioactivity. Ultraviolet–visible spectroscopy demonstrated that both polymers were successfully synthesized. Fourier transform infrared imaging was used as an innovative way to analyze the layer interdiffusion in these coatings. Their morphology was analyzed by scanning electron microscopy and atomic force microscopy, and their wettability was evaluated by water contact angle measurements. Major differences were found in the structure and surface properties of the coatings assembled either by dip‐ or spin‐coating. The spin‐coated films onto glass were smoother, with a more homogeneous structure and lower interdiffusion of polyelectrolytes layers, when compared with the dip‐coated ones. Furthermore, it was concluded that the intrinsic surface roughness of stainless steel and titanium substrates had great influence on the surface morphology and wettability of the coatings obtained from both layer‐by‐layer methodologies.

Recent Progress of Layer‐by‐layer Assembly, Free‐Standing Film and Hydrogel Based on Polyelectrolytes

“…[ 17 ] The stability of these coatings has been further enhanced with catechols. [ 18 ] Their introduction also made it possible to incorporate copper particles through a coordination bond. In this way, coatings were obtained to gradually release heparin and nitrogen oxide (NO).…”

Polyelectrolyte Gels: Fundamentals, Fabrication and Applications

“…PE gels that are classified as natural are typically based on materials obtained from the natural world. The natural biopolymers that are commonly observed as major constituents in PE gels include polymers such as CHT, HA and heparin (HEP) [ 22 , 23 ]. These glycosaminoglycans (GAGs) are naturally found in the ECM at various locations, particularly the connective, neural and epithelium tissue.…”

“…As two adhesive charges were present, C-HA was chosen as the ending layer due to C-CHT being selected as the stable precursor layer for the deposition of the assembly. The study further demonstrated how a higher content of catechol groups improves the wetting contact angle that aids in a stronger bond formation in wet environments, showing potential for tissue engineering [ 22 ].…”

“…The multilayered system was comparative to the bioactive C-CHT system. It also demonstrated how obtaining an even number of multilayers within the adhesive component at the topmost layer boosts the overall adhesion capabilities of the polyelectrolytic multilayer [ 22 ]. The study demonstrated how the difference in odd- and even-numbered multilayers effects adhesion capabilities not only from their adhesive nature but also their structure, as shown in Figure 12 .…”

“…A promising approach to address this is PE gels, where they can be modulated in a facile manner through ionic functionalization, allowing enhancement in mechanical stability, durability and degradability [ 164 ]. Moreover, as the constituents used to develop PE gels typically attain properties originating from biological tissue [ 22 , 23 ], they can match biological motions at the molecular level from their stimuli-responsive behaviour [ 165 ]. Thus, PE gels are gaining further attention as a candidate for tissue engineering applications, where they can address specific properties required by the targeted tissue.…”