Unveiling the Assembly of Neutral Marine Polysaccharides into Electrostatic-Driven Layer-by-Layer Bioassemblies by Chemical Functionalization

Abstract

Marine-origin polysaccharides, in particular cationic and anionic ones, have been widely explored as building blocks in fully natural or hybrid electrostatic-driven Layer-by-Layer (LbL) assemblies for bioapplications. However, the low chemical versatility imparted by neutral polysaccharides has been limiting their assembly into LbL biodevices, despite their wide availability in sources such as the marine environment, easy functionality, and very appealing features for addressing multiple biomedical and biotechnological applications. In this work, we report the chemical functionalization of laminarin (LAM) and pullulan (PUL) marine polysaccharides with peptides bearing either six lysine (K6) or aspartic acid (D6) amino acids via Cu(I)-catalyzed azide-alkyne cycloaddition to synthesize positively and negatively charged polysaccharide-peptide conjugates. The successful conjugation of the peptides into the polysaccharide’s backbone was confirmed by proton nuclear magnetic resonance and attenuated total reflectance Fourier-transform infrared spectroscopy, and the positive and negative charges of the LAM-K6/PUL-K6 and LAM-D6/PUL-D6 conjugates, respectively, were assessed by zeta-potential measurements. The electrostatic-driven LbL build-up of either the LAM-D6/LAM-K6 or PUL-D6/PUL-K6 multilayered thin film was monitored in situ by quartz crystal microbalance with dissipation monitoring, revealing the successful multilayered film growth and the enhanced stability of the PUL-based film. The construction of the PUL-peptide multilayered thin film was also assessed by scanning electron microscopy and its biocompatibility was demonstrated in vitro towards L929 mouse fibroblasts. The herein proposed approach could enable the inclusion of virtually any kind of small molecules in the multilayered assemblies, including bioactive moieties, and be translated into more convoluted structures of any size and geometry, thus extending the usefulness of neutral polysaccharides and opening new avenues in the biomedical field, including in controlled drug/therapeutics delivery, tissue engineering, and regenerative medicine strategies.

Acidochromic Free-Standing Multilayered Chitosan-Pyranoflavylium/Alginate Membranes toward Food Smart Packaging Applications

“…The analytes were attached to a metal stub using double-sided carbon conductive tape to provide electrical contact. A Polaron E5000 sputter coater was then used to sputtered coat the analytes with a coating of conductive carbon (Quorum Technologies, Laughton, UK) …”

“…A Polaron E5000 sputter coater was then used to sputtered coat the analytes with a coating of conductive carbon (Quorum Technologies, Laughton, UK). 29 2.11. pH-Sensing Properties in Food Spoilage Model-Like Solutions. The biocompatible free-standing membranes were split into 1.5 cm 2 pieces and submerged in buffer solutions for 24 h. Buffer solutions of pH 4 and 5 were prepared using citric acid-phosphate buffer and pH 6, 7, and 8 buffer solutions were prepared using a sodium phosphate buffer.…”

“…However, the higher increase in both Δf 7 /7 and ΔD 7 after the deposition of ALG, reveals the stiffer nature of CHT-Pyflav layers in comparison with ALG. 27,29,32 Thicker and robust self-standing multilayered membranes encompassing (CHT-Pyflav/ALG) 400 layers were produced on an automatic dipping robot by repeating the alternate immersion of polypropylene substrates into 1 mg.mL −1 oppositely charged aqueous solutions of CHT-Pyflav and ALG in 0.1 M acetate buffer at pH 5.5, followed by air drying and easy detachment (Figure 4b).…”

“…Several benefits are provided by this technology over casting-produced biomembranes, including the ability to control and regulate layer growth, presenting more uniform, highly reproducible membranes, and the possibility to incorporate rationally designed building blocks. Because membranes are produced in mild conditions, this technology is advantageous for use in sustainable chemistry and the food industry. − …”

Unveiling the Potential of Marine Biopolymers: Sources, Classification, and Diverse Food Applications

“…Although marine collagens are both fibrillar and nonfibrillar, they have higher viscosities than corresponding bovine forms and lower gelling and melting temperatures than mammalian collagen. Compared to mammals, fish collagen has labile cross-connections that make it more susceptible to heat [ 94 ]. The majority of fish collagens have been discovered to include two chains, which are typically referred to as α-1 and -2 [ 95 ].…”