Control of cell adhesion by thermal annealing of natural polyelectrolyte multilayers: mimicking the extracellular matrix with surfaces with gradients in their physicochemical properties

PASQUALE, M.A.; AZZARONI, O.; PIETRASANTA, LÍA I.; MUZZIO, N.E.; MOYA, SERGIO E.

La Plata

Congreso; XLVII Reunión anual de La Sociedad Argentina Biofísica (SAB); 2018

Cell adhesion plays a key role in many physiological and pathological processes, and is a fundamental issue in the design of new materials for cell biology studies and medical devices. Moreover, materials with gradients in their physicochemical properties better mimic the complexity and functionalities of the extracelullar matrix. Polyelectrolyte multilayers (PEMs) assembled by the layer by layer technique are a versatile approach to functionalize a biomaterial surface. Though PEMs assembled from natural polyelectrolytes are very appealing for biological and medical applications, they display poor cell adhesion as they are soft materials. We present a novel strategy for the enhancement of cell adhesion on natural PEMs based on thermal annealing. Poly-L-lysine and alginate multilayers are assembled and heated at 37ºC for three days. The changes in the physicochemical properties of the PEMs are assesed by means of the quartz crystal microbalance, atomic force microscopy, zeta potential and contact angle. The adhesion of different immortalized cell lines on nonannealed and annealed PEMs is studied. After the annealing the films become more compact and smoother, with an increase in the Young´s modulus of one order of magnitud. Furthermore, PEMs become more hydrophobic and the surface charge decreases from around zero for nonannealed PEMs to -14 mV for annealed ones. The protein deposition on PEMssignificantly changes as well. Cell spreading and focal contact formation isremarkably improved on the annealed PEMs. Based on the impact on PEM properties and cell adhesion caused by the thermal annealing, a temperature gradient is applied to induce a spatial variation of PEM properties resulting in a gradient on cell adhesion. Thermal annealing offers a friendly and simple method for enhancing cell adhesion without changing the composition and biocompatibility of PEMs, with potential applications in cell studies and tissue engineering.