Publications

The electrochemical response of alpha/beta-peptides with (L-Ala-beta-Fpg)n sequence, where beta-Fpg refers to syn 3-amino-2-(2-fluorophenyl)-3-phenylpropanoic acid, has been investigated examining the effects of the peptide length (n = 1-3), the stereochemistry of the beta 2,3-diaryl-amino acid and their self-assembly. alpha/beta-Peptides have been deposited by drop-casting on a conducting polymer (CP) film, which is previously electropolymerized on a stainless steel conducting substrate. The current-potential response of the CP coated by the different studied peptides suggests that, for alpha/beta-peptides, the role played by the electron transport through intermolecular stacking of aromatic side groups prevails over peptide length and stereochemistry. In order to prove such a hypothesis, the experimental conditions used to achieve an ordered self-assembly are optimized for one of the alpha/beta-peptides. The achieved self-assembled structures, which consist of well-defined long microfibers, considerably improve the electrochemical response of the CP. Finally, the prepared alpha/beta-peptide-based electrodes are used to electrochemically detect the oxidation of nicotinamide adenine dinucleotide (NADH). The analytical parameters are better for electrodes with well-defined peptide microfibers than for uncoated CP, corroborating the importance of pi-pi stacking interactions in the response of alpha/beta-peptides.

JTD Keywords: Acid, Alpha/beta-peptides, Beta-peptides, Bioelectronics, Design, Electron-transfer, Foldamers, Nadh, Nadh detection, Nanomaterials, Self-assembly, Stacking interactions

Isotactic polypropylene (i-PP) nonabsorbable surgical meshes are modified by incorporating a conducting polymer (CP) layer to detect the adhesion and growth of bacteria by sensing the oxidation of nicotinamide adenine dinucleotide (NADH), a metabolite produced by the respiration reactions of such microorganisms, to NAD+. A three-step process is used for such incorporation: (1) treat pristine meshes with low-pressure O2 plasma; (2) functionalize the surface with CP nanoparticles; and (3) coat with a homogeneous layer of electropolymerized CP using the nanoparticles introduced in (2) as polymerization nuclei. The modified meshes are stable and easy to handle and also show good electrochemical response. The detection by cyclic voltammetry of NADH within the interval of concentrations reported for bacterial cultures is demonstrated for the two modified meshes. Furthermore, Staphylococcus aureus and both biofilm-positive (B+) and biofilm-negative (B-) Escherichia coli cultures are used to prove real-time monitoring of NADH coming from aerobic respiration reactions. The proposed strategy, which offers a simple and innovative process for incorporating a sensor for the electrochemical detection of bacteria metabolism to currently existing surgical meshes, holds considerable promise for the future development of a new generation of smart biomedical devices to fight against post-operative bacterial infections.

JTD Keywords: adhesion, bacteria metabolism, behavior, biocompatibility, conducting polymer, electrochemical sensor, hernia repair, in-vivo, liquid, nadh detection, plasma treatment, prevention, reinforcement, sensor, smart meshes, Bacteria metabolism, Bacterial infections, Conducting polymer, Electrochemical sensor, Humans, Nad, Nadh detection, Nanoparticles, Oxidation-reduction, Plasma treatment, Polymers, Polypropylene mesh, Smart meshes, Surgical mesh