Mussel-inspired and Click Chemistry Engineered Surface Strategies for Constructing Efficient Antibacterial Coating

It is an advanced surface modification technology that can provide the highly effective antibacterial properties to the substrate material surfaces of the blood contact devices without altering the physical properties of the substrate material by constructing a coating with antibacterial peptide (ABP) molecules on the surface of substrate material. Current substrates for blood contact devices have poor antibacterial properties and are at risk of local or systemic infection after use. In this paper, we investigated the highly effective antibacterial properties of ABP coatings based on mussel-inspired and click chemistry constructs. As a substrate material for the study, 316L stainless steel was prepared as a disc of 1 cm diameter and 2 mm thickness, smoothed and polished with sandpaper and cleaned with anhydrous ethanol and distilled water, and finally the samples were dried. Firstly, the samples were immersed in Tris-base buffer (10 mM, pH=8.5) containing dopamine (1 mg/mL) and hexanediamine (2.44 mg/mL) at 25 ℃ for 24 hours. The material with deposits on the surface was then washed by ultrasonication with distilled water and dried under nitrogen to obtain a dopamine-hexanediamine (DA/HD) base coating. Then, the dried DA/HD coated samples were immersed in a PBS buffer solution of NHS-N3 (1 mg/mL) and submerged for 24 hours at 25 ℃. The material was then ultrasonically washed with distilled water and removed and dried with nitrogen to obtain the azidized DA/HD coating (N3 coating). Finally, the N3 coating was immersed in a PBS buffered solution of DBCO-ABP (1 mg/mL) for 24 hours at 25 ℃. The material was then washed ultrasonically with distilled water and removed and dried with nitrogen to obtain the ABP coating. Broad-spectrum applicability of DA/HD coatings was analyzed by preparing DA/HD coatings on a variety of different material surfaces and performing amine groups density measurements. The thickness of the coating was calculated through Cauchy model analysis with an ellipsometric polarisation spectrometer (M-2000V). The hydrophile of the material was determined with a water contact angle goniometer (DSA 100). The structural composition of the coating was analyzed with Fourier infrared absorption spectroscopy (Nicolet 5700) and X-ray photoelectron spectroscopy (K-Alpha). The number of ABP molecules grafted on the surface of the N3 coating was quantified in real time with a dissipative quartz crystal microbalance (Q-sense). The surface morphology of the specimens was observed with a scanning electron microscope (JSM-6390). Finally, the antimicrobial performance of ABP coatings was evaluated by antimicrobial experiments of E. coil and S. epidermidis and comparison of antimicrobial rates of various antimicrobial coatings. Dopamine (DA), which contained an adhesion-capable catechol structure, and hexanediamine (HD), which had a polyamine chemical structure, were mixed in a certain ratio to construct a DA/HD substrate coating on the surface of the material in a simple one-step molecular self-assembly. The N3 coating was obtained by introducing azide group on the surface of the DA/HD coating through the amide reaction between the abundant amino groups on the surface of the DA/HD coating and the azidized NHS (NHS-N3). The ABP coating was obtained by grafting ABP on the surface of the N3 coating by click reaction. The successful preparation of DA/HD coatings with a high amine groups density on a wide range of different material surfaces demonstrated the broad spectrum applicability of DA/HD coatings. The results of WCA, FTIR, XPS, QCM-D and ellipsometric polarisation spectroscopy confirmed that ABP coatings based on DA/HD substrate coatings were successfully prepared, the ABP graft on the ABP coating was as high as 352.7 ng/cm2. The results of surface antibacterial experiments and comparison of antimicrobial rates of various antimicrobial coatings showed that the ABP coating was highly effective against both E. coli and S. epidermidis with antibacterial rates of (89.0±9.9)% and (97.3±1.7)% respectively. The DA/HD coating has a broad spectrum of applicability. ABP coatings with highly effective antibacterial properties is successfully prepared on the surface of the substrate after modification. The coating is in direct contact with bacteria and is able to provide highly effective inhibition of Gram-negative and positive bacteria by disrupting the bacterial film. © 2023 Chongqing Wujiu Periodicals Press. All rights reserved.