ABSTRACT
A bio-inspired durable anti-biofilm coating was developed for industrial stainless steel (SS) surfaces. Two polymers inspired from the adhesive and cross-linking properties of mussels were designed and assembled from aqueous solutions onto SS surfaces to afford durable coatings. Trypsin, a commercially available broad spectrum serine protease, was grafted as the final active layer of the coating. Its proteolytic activity after long immersion periods was demonstrated against several substrata, viz. a synthetic molecule, N-α-benzoyl-DL-arginine-p-nitroanilide hydrochloride (BAPNA), a protein, FTC-casein, and Gram-positive biofilm forming bacterium Staphylococcus epidermidis.
Subject(s)
Anti-Bacterial Agents/chemistry , Biofilms , Biofouling/prevention & control , Green Chemistry Technology , Stainless Steel/chemistry , Staphylococcus epidermidis/drug effects , Anti-Bacterial Agents/pharmacology , Bacterial Adhesion/drug effects , Bacterial Load , Benzoylarginine Nitroanilide/chemistry , Biofilms/drug effects , Caseins/chemistry , Cross-Linking Reagents/chemistry , Dihydroxyphenylalanine/chemistry , Enzyme Activation , Fluoresceins/chemistry , Indoles/chemistry , Microbial Viability , Microscopy, Fluorescence , Polymers/chemistry , Proteolysis , Static Electricity , Surface Properties , Trypsin/chemistryABSTRACT
Poly(ε-caprolactone) (PCL) fibers ranging from 250 to 700 nm in diameter were produced by electrospinning a polymer tetrahydrofuran/N,N-dimethylformamide solution. The mechanical properties of the fibrous scaffolds and individual fibers were measured by different methods. The Young's moduli of the scaffolds were determined using macro-tensile testing equipment, whereas single fibers were mechanically tested using a nanoscale three-point bending method, based on atomic force microscopy and force spectroscopy analyses. The modulus obtained by tensile-testing eight different fiber scaffolds was 3.8±0.8 MPa. Assuming that PCL fibers can be described by the bending model of isotropic materials, a Young's modulus of 3.7±0.7 GPa was determined for single fibers. The difference of three orders of magnitude observed in the moduli of fiber scaffolds vs. single fibers can be explained by the lacunar and random structure of the scaffolds.
Subject(s)
Biocompatible Materials/chemistry , Polyesters/chemistry , Elastic Modulus , Electrochemical Techniques , Materials Testing , Microscopy, Atomic Force , Microscopy, Electron, Scanning , Stress, Mechanical , Tensile StrengthABSTRACT
A simple lift-off process was developed to rapidly fabricate nanopatterned photofunctional surfaces. Dye molecules of a perylene derivative (PDID) were adsorbed irreversibly on clean silicon through the holes of an electron-beam lithographied polymer mask. The subsequent removal of the mask in a proper solvent results in PDID nanosized regions of width as small as 30 nm for stripes and of diameter as small as 120 nm for dots. Numerical analyses of atomic force microscopy and laser-scanning confocal microscopy images show that the dye molecules are confined to the regions defined by the lithographic process, with the integrated fluorescence intensity being essentially proportional to the size of the nanofeatures. This demonstrates that a simple organic lift-off process compatible with clean-room technology, and not involving any chemical step, is able to produce photofunctional nanopatterned surfaces, even though the dye is not chemically bonded to the silicon surface.