Bioinspired Low-Friction and High-Stability Hydrophilic Coatings for Capsule Endoscopy Surfaces

Area of Science:

• Biomaterials Science
• Surface Chemistry
• Gastroenterology Devices

Background:

• Polycarbonate (PC) capsule endoscopes (CEs) suffer from high friction, biofouling (protein adsorption, bacterial adhesion), and unstable surface modifications, compromising clinical use and patient safety.
• Existing surface modification strategies often lack robust adhesion and long-term stability, limiting their effectiveness for biomedical applications.

Purpose of the Study:

• To develop a robust, bioinspired composite coating for PC-based capsule endoscopes (CEs) to overcome limitations of friction and biofouling.
• To enhance the safety and functionality of CEs through advanced surface modification.

Main Methods:

• A one-step oxidative co-deposition method was used to graft poly(sulfobetaine methacrylate) (PSBMA) onto PC substrates via a polydopamine (PDA) interlayer, creating PC-PDA&PSB composite coatings.
• Characterization techniques included XPS, SEM, and AFM to verify coating deposition and morphology.
• Performance was evaluated through contact angle measurements, friction coefficient tests, protein adsorption assays (BSA/BFG), stability tests (pH 1.5 PBS), and in vitro cytocompatibility assessments (CCK-8, Live/Dead staining).

Main Results:

• The PC-PDA&PSB coating exhibited a low water contact angle (14.3 ± 3.1°) and an ultralow coefficient of friction (<0.05).
• The coating achieved over 80% suppression of protein adsorption and demonstrated sustained stability in acidic conditions (pH 1.5 PBS for 14 days).
• In vitro studies confirmed non-cytotoxicity, with cell viability exceeding 80%, meeting ISO 10993-5 standards.

Conclusions:

• The bioinspired PDA and zwitterionic polymer composite coating effectively enhances the lubricity and antifouling properties of PC substrates.
• This scalable surface modification strategy overcomes adhesion issues associated with zwitterionic polymers alone, improving CE safety and performance.
• The developed coating shows significant potential for application in capsule endoscopes and other biomedical devices requiring enhanced slippery and fouling-resistant surfaces.