Titanium alloys are common materials in the manufacturing of dental and orthopedic implants. Although these materials exhibit excellent biocompatibility, corrosion in response to biological fluids can impact prosthesis performance and longevity. In this work, a PEGylated metal binding peptide (D-K122-4-PEG), derived from bacteria Pseudomonas aeruginosa, was applied on a titanium (Ti) alloy, and the corrosion resistance of the coated alloy specimen was investigated in simulated chloride-containing physiological fluids by electrochemical impedance spectroscopy and micro-electrochemical measurements, surface characterization, and biocompatibility testing. Compared to uncoated specimen, the D-K122-4-PEG-coated Ti alloy demonstrates decreased corrosion current density without affecting the natural passivity. Morphological analysis using atomic force microscopy and scanning electron microscopy confirms a reduction in surface roughness of the coated specimens in the fluids. The D-K122-4-PEG does not affect the binding of HEK-293T cells to the surface of unpolished Ti alloy, nor does it increase the leukocyte activation properties of the metal. D-K122-4-PEG represents a promising coating to enhance the corrosion resistance of Ti alloys in physiological fluids, while maintaining an excellent biocompatibility.
Peptide-based biocoatings for corrosion protection of stainless steel biomaterial in a chloride solution.
Cheng YF, Feng Y, Liu T, Muruve DA, Hassett DJ, Irvin RT
Mater Sci Eng C Mater Biol Appl. 2016 Nov 1;68:695-700. doi: 10.1016/j.msec.2016.06.053. Epub 2016 Jun 16.
In this work, PEGylated D-amino acid K122-4 peptide (D-K122-4-PEG), derived from the type IV pilin of Pseudomonas aeruginosa, coated on 304 stainless steel was investigated for its corrosion resistant properties in a sodium chloride solution by various electrochemical measurements, surface characterization and molecular dynamics simulation. As a comparison, stainless steel electrodes coated with non-PEGylated D-amino acid retroinverso peptide (RI-K122-4) and D-amino acid K122-4 peptide (D-K122-4) were used as control variables during electrochemical tests. It was found that the D-K122-4-PEG coating is able to protect the stainless steel from corrosion in the solution. The RI-K122-4 coating shows corrosion resistant property and should be investigated further, while the D-K122-4 peptide coating, in contrast, shows little to no effect on corrosion. The morphological characterizations support the corrosion resistance of D-K122-4-PEG on stainless steel. The adsorption of D-K122-4 molecules occurs preferentially on Fe2O3, rather than Cr2O3, present on the stainless steel surface.
Peptide-Mediated PEGylation of Polysulfone Reduces Protein Adsorption and Leukocyte Activation
The exposure of blood to bioincompatible materials used for dialysis triggers leukocyte activation and protein adsorption. We describe a single-step, postmanufacturing method for surface modification to create biomaterials used in medical devices and dialysis with altered surface characteristics. Peptides derived from the receptor-binding domain of the type IV pilin of Pseudomonas aeruginosa were synthesized using L and D-amino acids to generate L-K122-4, enantiomer D-K122-4, and D-retroinverso RI-K122-4 peptides. L-K122-4, D-K122-4, and RI-K122-4 peptides, but not control peptides, bound durably to the surfaces of materials used in medical devices and dialysis including silicone and polysulfone. D-K122-4 enantiomeric peptides were protease resistant on polysulfone and could remain bound to the surface for up to 28 days. To demonstrate that K122-4 peptides could be used to modify material surfaces, D-K122-4 peptide was conjugated to polyethylene glycol (D-K122-4-PEG) and applied to polysulfone. When compared with untreated material, D-K122-4-PEG reduced the surface adsorption of albumin or immunoglobulin G to polysulfone. In coincubation experiments, although uncoated polysulfone induced pro-interleukin-1β cytokine expression in leukocytes, cellular activation was prevented when leukocytes were incubated with D-K122-4-PEG-modified polysulfone. These data demonstrate the proof of principle that K122-4 peptides can be applied to modify the surface characteristics of materials used for dialysis.
The Pseudomonas aeruginosa type IV pilin receptor binding domain functions as an adhesin for both biotic and abiotic surfaces
Giltner CL, van Schaik EJ, Audette GF, Kao D, Hodges RS, Hassett DJ, Irvin RT
Pseudomonas aeruginosa readily binds to stainless steel and other abiotic surfaces, causing major problems in both the medical and food industries. In this study, we show that P. aeruginosa binds to abiotic surfaces in a concentration-dependent, saturable manner during the initial stages of biofilm formation. P. aeruginosa type IV pili mediate binding to stainless steel as a pilus-deficient strain does not bind to steel, purified type IV pili bound in a concentration-dependent, saturable manner, and purified pili competitively inhibited whole cell binding. PAK pili can also bind polystyrene and polyvinylchloride in a concentration-dependant and saturable manner. As an antibody specific for the C-terminal pilin receptor binding domain inhibited adherence to abiotic surfaces, the role of the C-terminal receptor binding domain in mediating binding to steel surfaces was examined. A synthetic peptide of the PAK pilin epithelial cell receptor binding domain [PAK(128-144)ox] bound directly to steel with high affinity. The interaction of pili with steel was specifically inhibited by this peptide with an apparent Ki of approximately 0.2 nM and effectively inhibited the binding of viable homologous and heterologous P. aeruginosa strains to steel with an apparent Ki of approximately 4 nM. A single point mutation (K130I) in the PAO receptor binding domain was observed to abolish binding to stainless steel while binding to human buccal epithelial cells was enhanced. Therefore, the C-terminal receptor binding domain appears to have evolved for binding a variety of surfaces.