OPTIMIZATION OF GOLD-FUNCTIONALIZED SURFACES AND MULTILAYER COATINGS FOR THE CAPTURE OF CIRCULATING TUMOR CELLS

Multilayer films fabricated using the Layer-by-Layer (LbL) technique have emerged as a promising approach in biotechnological applications due to their ability to precisely control physicochemical and functional properties. In the context of biosensing for tumor cell detection, the use of natural polyelectrolytes such as chitosan (CHI), a cationic polymer, and hyaluronic acid (HA), an anionic polymer, is particularly relevant. When alternately deposited, these polymers form biocompatible films capable of promoting cell adhesion. This strategy is especially promising for the diagnosis and prognosis of cancer, due to the specific interaction between HA and the CD44 receptor, which is commonly overexpressed in circulating tumor cells (CTCs) [1,2]. To improve the performance of electrodes in biosensing platforms, gold functionalization has been employed to enhance electrical conductivity, facilitating electron transfer and improving the sensitivity, selectivity, and stability of the system [3]. The incorporation of metallic nanoparticles with high surface area further contributes to enhanced electrochemical and electrocatalytic properties. In this study, titanium alloy electrodes (Ti6Al4V) were functionalized with gold nanoparticles, followed by the deposition of CHI/HA films via the LbL technique, aiming at CTC detection. Electrochemical characterization by cyclic voltammetry revealed increased conductivity of the electrodes after gold functionalization compared to the bare metal. The gold nanoparticles showed homogeneous distribution, spherical morphology, and an average diameter of 15 nm. Atomic force microscopy (AFM) analysis indicated an increase in surface roughness and the formation of polymeric islands following film deposition. Cell adhesion assays using PC3 cells (prostate cancer cell line) demonstrated significantly higher adhesion on electrodes coated with CHI/HA films, highlighting the effectiveness of the polyelectrolytes in surface modification for cell capture.In conclusion, the combination of gold nanoparticle functionalization and CHI/HA multilayer film deposition proved to be a promising strategy for the development of biosensors aimed at the detection and capture of CTCs. The results obtained provide a solid foundation for advancing sensitive and effective platforms for the early diagnosis of cancer.