A bio-derived char-forming strategy for surface fireproofing: Functionalization of UV-curing flame-retardant coating with vinyl-modified tannic acid

Superhydrophilic and Antifriction Thin Hydrogel Formed under Mild Conditions for Medical Bare Metal Guide Wires

Medical guide wires play a crucial role in the process of intravascular interventional therapy. However, it is essential for bare metal guide wires to possess both hydrophilic lubricity and coating durability, avoiding tissue damage caused by friction inside the blood vessel during the interventional procedure. Additionally, it is still a huge challenge for diverse metal materials to bind with polymer coatings easily. Herein, we present a hydrogel coating scheme and its preparation method for various wires under mild conditions for environmental protection purposes. The preparation process involves surface pretreatment, including low-temperature heating and silanization, followed by a two-step dip coating and ultraviolet polymerization. The whole process leads to the formation of an interpenetrating cross-linked hydrogel network from the substrate to the surface section. This study confirms the superhydrophilicity and lubricity of three metal wires with the designed coating, especially reducing the friction significantly by ≥ 95%. The thin coating (average thickness <6.2 μm) demonstrates strong adhesion with various substrates and exhibits resistance to 25 or even 125 cycles of friction, indicating excellent stability and preventing easy detachment. The finally prepared composite nickel-titanium (NiTi) guide wire with stainless steel (SS) and platinum-tungsten (Pt-W) coils (overall diameter of ∼0.36 mm) shows satisfactory performance with a friction of 0.183 N for 25 cycles, meeting the clinical requirements (average friction ≤0.2 N) for interventional operation. These findings highlight the potential of this study in advancing the development of medical devices, particularly in the field of intravascular interventional therapy.