PSS/PDADMAC Saloplastics: Processing and Cytotoxicity Assessment

Details

Supervisors

Dupont, Christine ; Franco, Alexis

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

enBioprinting is an expanding field focused on fabricating tissue-like structures using materials that are both printable and compatible with living cells. In this context, two previous master’s theses from our laboratory laid the groundwork for the present study. These works focused on polyelectrolyte complexes (PECs), formed by mixing oppositely charged polymers, capable of adopting various physical states ranging from rigid solids to liquid solutions, with coacervates as intermediate viscoelastic phases. Their structure depends strongly on salt concentration, pH, and the used polymer pair. Alexis Franco first identified alginate/poly(diallyldimethylammonium chloride) (PDADMAC) as a promising PEC coacervate due to its extrusion properties. However, Jules Sigot later highlighted a major limitation: the coacervate’s loose network allowed PDADMAC to leach out, causing significant cytotoxicity and limiting its potential as a bioink. This raised a central question: Could a denser structure reduce PDADMAC release? This study builds on those findings by investigating a PEC system based on poly(styrenesulfonate) (PSS) and PDADMAC, selected for its ability to form saloplastics: dense materials that soften progressively with salt. Two processing methods were explored. Printing showed that the coacervate phase could form stable filaments extruded through a 500 µm needle and re-solidified by rinsing. Hot-pressing enabled the formation of transparent PEC films through high-temperature compression, offering promising potential for functionalization and opening new perspectives in sustainable packaging applications Rheological analyses confirmed the coacervate’s suitability for extrusion. PDADMAC detection study showed that densified saloplastics released up to 50 times less PDADMAC than alginate/PDADMAC coacervates. A431 cell assays showed no toxicity at the levels of PDADMAC released over a week (~1 µg/mL), while cytotoxic effects were only observed at much higher concentrations (~8 mg/mL). These results indicate that PSS/PDADMAC saloplastics are promising biomaterial candidates and open up new possibilities for biocompatible and transformable PECs, while also paving the way for broader applications such as recyclable packaging.