Unveiling the effect of bovine serum albumin on the packaging performance of medical silicone rubber coating for implantable electronic devices

Abstract

Silicone rubber encapsulation materials utilized in implantable electronic devices must withstand a complex biofluidic environment and incorporate a diverse array of inorganic and organic components. Nevertheless, the impact of proteins on the reliability of these encapsulation materials has not been extensively investigated. This study presents a thorough examination of the mechanisms through which proteins influence the performance of silicone rubber encapsulation materials. Initially, it was observed that bovine serum albumin (BSA) adsorbs in an elliptical particulate form, a process facilitated by the presence of peptide bonds (-CO-NH-) and α-helical structures, which are functional groups inherent to medical silicone rubber coatings. Additionally, the geometric dimensions of BSA are marginally larger than the microscopic pores of the coating, effectively obstructing water passage through the silicone rubber by blocking these pores. This blockage is crucial for enhancing the encapsulation properties of the coatings, as it significantly inhibits water transport. However, as the coating undergoes cracking, its encapsulation capacity is compromised, allowing for the diffusion of BSA to the T2 copper surface. At this juncture, BSA occupies the adsorption sites of the cathodic reactant O₂, thereby effectively inhibiting the corrosion of the metal.