Quartz Crystal Microbalance with Dissipation monitoring (QCM-D): a non invasive technique to study cell-surface interactions

The Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) is an ultrasensitive mechanical sensing device capable of providing real-time, non-invasive measurements of changes in resonance frequency and energy dissipation responses due to cells immobilization onto the sensor surface. Most of its applications in cell research have been limited to the study of adhesive interaction between cells and the substrate surface and the evaluation of the effect of external stimuli on the adherent cells. The aim of this thesis work was to further exploit the capabilities of the QCM-D to study cell adhesion on different substrates. Firstly, it was introduced the mechanism of cell adhesion on the QCM-D sensor surface characterized by a three-phase response profile: cells adsorption, attachment and spreading, and remodelling. A state of art of QCM-D was also presented in order to show the biological applications of this technique, in particular the use of QCM-D to study cell adhesion on surfaces that are used in medical implants. The experimental section presented in the final chapter was used to evaluate the effectiveness of scaffold functionalization protocol ,adopted in a previous work, by reproducing each functionalization step on the gold sensor surface . The gold sensor surface was coated with Polycaprolactone (PCL) using the electrospinning technique to continue the previous work , in which in vitro models of human cardiac fibrotic tissue based on 2D and 3D bioartificial Polycaprolactone (PCL) scaffolds were produced. Bidimensional scaffold were fabricated by electrospinning technique because of its ability in mimicking closely the hierarchical properties of the extracellular matrix (ECM) of the native tissue. Gelatin (G) was grafted on the scaffold surface by a two-step mussel-inspired strategy. At first 3,4-Dihydroxy-D,L-phenylalanine (DOPA) was polymerized on PCL scaffold (PCL-polyDOPA) and then G was grafted (PCL-polyDOPA/G). At last , a future experiment was set to monitor cell adhesion on the sensor surface coated with PCL and functionalized with poly-DOPA and Gelatine. This experiment should give informations about other aspects of cellular behaviour, such as cell morphology, cell signaling, all of which can potentially be applied to medical diagnosis and pharmaceutical development.