Responsive soft-nanoarchitectures as novel substrates with tunable mechanical properties

C. VON BILDERLING; GIUSSI, JUAN M.; ELIANA M. MAZA; CORTEZ, M. LORENA; MIJANGOS, CARMEN; L. I. PIETRASANTA; AZZARONI, OMAR

San Luis

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

SAB

The design of responsive surfaces with tunable mechanical properties, such as stiffness or adhesion,holds interesting potential for applications in biomedical research, tissue engineering and cell adhesionmanipulation. Nano/micro hydrogels are colloidal architectures that can incorporate large amounts ofwater thus changing their mechanical properties in response to specific stimuli such as temperature, pH,salt concentration or solvent nature. Poly (N-isopropylacrylamide) (PNIPAm) is one of the most studiedthermoresponsive polymers: at 32°C PNIPAm-based architectures in aqueous solution experiment adrastic deswelling due to their lower critical solution temperature (LCST).In this work, we present novel substrates designed and fabricated with two kinds of PNIPAm basedthermosensitive nanoarchitectures: spheres and pillars. Nanomechanical properties of the substrateswere characterized by Quantitative Nanoscale Mechanical- Atomic Force Microscopy (QNM-AFM).PNIPAm nanospheres (microgels) containing a pH sensitive monomer, were LBL assembed withpoly(diallyldimethylammonium chloride) (PDADMAC). Microgel based films were found to decoupleconflicting properties: they exhibit an increase in hydrophobicity, stiffness and adhesion properties uponswitching the temperature from below to above the LCST, while the permeability of redox probesthrough the film remained unchanged.PNIPAm based nanopillars surfaces were also investigated, showing an abrupt change in wettability,topological and mechanical properties when increasing the temperature above the LCST. Interestingly,these surface properties were amplified through the incorporation of Fe 3 O 4 nanoparticles. Theincorporation of magnetic nanoparticles into the nanopillars sharply increased their stiffness andhydrophobicity above the LCST, whether their magnetic response resulted proportional to the amountof incorporated nanoparticles.