Theoretical and Experimental Optimization of the Graft Density of Functionalized Anti-Biofouling Surfaces by Cationic Brushes

Abstract

Diseases and complications related to catheter materials are severe problems in biomedical material applications, increasing the infection risk and medical expenses. Therefore, there is an enormous demand for catheter materials with antibacterial and antifouling properties. Considering this, in this work, we developed an approach of constructing antibacterial surfaces on polyurethane (PU) via surface-initiated atom transfer radical polymerization (SI-ATRP). A variety of cationic polymers were grafted on PU. The biocompatibility and antifouling properties of all resulting materials were evaluated and compared. We also used a theoretical algorithm to investigate the anticoagulant mechanism of our PU-based grafts. The hemocompatibility and anti-biofouling performance improved at a 86-112 μg/cm² grafting density. The theoretical simulation demonstrated that the in vivo anti-fouling performance and optimal biocompatibility of our PU-based materials could be achieved at a 20% grafting degree. We also discuss the mechanism responsible for the hemocompatibility of the cationic brushes fabricated in this work. The results reported in this paper provide insights and novel ideas on material design for applications related to medical catheters.

Keywords: anti-biofouling; catheter; cationic brushes; graft density; hemocompatibility; polyurethane.

Figure 1

Model showing interactions between the calcium-binding epidermal growth factor (cbEGF)-like domain and polyurethane (PU) in the presence of water. The red dots represent Ca²⁺ complexed with an EGF-like domain. The green dots are Cl⁻. The black dots are Na⁺. Pink represents water molecules.

Figure 2

Number of hydrogen bonds in the cbEGF-like domain-acryl-oxy-ethyl-trimethyl-ammonium chloride (DAC)-g-PU surface as a function of the grafting degree.

Figure 3

Fourier transform infrared (FTIR) spectra of pure and modified PU prepared in this work.

Figure 4

X-ray photoelectron spectra (XPS) survey (A,C) and high-resolution C1s (B,D,E) spectra of PU (A,B) and PU-Br (C,D,E) samples.

Figure 5

Water contact angle (WCA) data for various PU samples.

Figure 6

Protein adsorption by PU grafted with methacryl-oxy-oxyethyl-trimethyl-ammonium chloride (DMC), DAC, and DMDAAC canyon brushes possessing different grafting densities (20, 40, and 60%). The error bars represent the standard deviation from the average value calculated using three measurements.

Figure 7

(A) Hemolysis rate of the PU grafted with DMC, DAC, and DMDAAC cationic brushes and possessing different grafting densities. (B) Recalcification time of cationic brushes possessing different grafting densities. The values represent the average of three measurements. The error bars are standard deviations from the average.

Figure 8

Scanning electron microscope (SEM) micrographs of bacteria accumulation on PU (A,D), PU-PDAC (B,E), and PU-PDMDAAC (C,F).

Figure 9

Zeta potential in the water of different PU composites.