Alginate/Chitosan Compact Polyelectrolyte Complexes: A Cell and Bacterial Repellent Material

Abstract

Ultracentrifugated compact polyelectrolyte complexes (uCoPECs) represent a new class of materials that are obtained by ultracentrifugation of solutions of polyanion/polycation complexes in the presence of salt. In the present study, two polysaccharides, chitosan and alginate, were used to form such complexes, thus providing a solid material uniquely composed of polysaccharides. The conditions for obtaining the uCoPEC material were optimized: the optimal salt concentration and polysaccharide concentrations were assessed, and the ultracentrifugation speed proved to be a key parameter to obtain compact and homogeneous materials. The Young's modulus, E, of the material was of the order of 12 MPa, which is the highest E value measured for a uCoPEC. The material contained nanometer-sized crystals of chitosan as indicated by X-ray diffraction. Most strikingly, this material proves to be totally cell-and bacteria-resistant. Immunological tests show that this uCoPEC does not induce any proinflammatory response. This makes it a suitable candidate for the development of biocompatible and antifouling biomaterials composed only of polysaccharides.

Bacteria-Resistant, Transparent, Free-Standing Films Prepared from Complex Coacervates

“…Our findings are consistent with experiments conducted on ultracentrifugated compact polyelectrolyte complexes formed from chitosan and alginate, which also demonstrated negligible killing of Staphylococcus aureus . 58 Charge-neutral polyelectrolyte complexes do not exhibit the antibacterial properties of their cationic polyelectrolyte components. Liquid complex coacervates have also been reported to be biocompatible with mammalian cells.…”

“…56,57 Another study described how ultracentrifugated compact PECs from chitosan and alginate resisted the adhesion of Staphylococcus aureus. 58 While this result is encouraging, there is a benefit to developing alternative processing strategies that are less energy intensive and can be performed at scale to enable the use of PECs as antifouling coatings.…”

Recent progress in the science of complex coacervation

“…In particular, a seminal report by Wang and Schlenoff demonstrated that solid precipitates and liquid coacervates could exist along a continuum of salt concentration ( Figure 10). 50 This idea of salt-driven plasticization, or 'salo- plasticity' has opened up a tremendous range of opportunities for using salt to process polyelectrolyte complex materials as liquid coacervates, and then solidify the materials by the removal of salt, and a range of accounts describing ultracentrifuged [190][191][192][193] or extruded materials, 194 spin-coated films, 195,196 3D printed structures, 197 and electrospun fibers 65,198,199 have been reported.…”

Compact polyelectrolyte hydrogels of gelatin and chondroitin sulfate as ion's mobile media in sustainable all-solid state electrochemical devices

“…This is a procedure analogous to that reported for the compaction of PECs constituted of alginate and chitosan which allows for the preparation of highly hydrated hydrogels in the presence of salt. 24,25 After centrifugation (compaction stage), and removing the supernatant, the precipitates from all the samples presented a hydrogel-like aspect as can be observed in Fig. 3.…”