Plasma‐Functionalized Isotactic Polypropylene Assembled with Conducting Polymers for Bacterial Quantification by NADH Sensing

Abstract

Rapid detection of bacterial presence on implantable medical devices is essential to prevent biofilm formation, which consists of densely packed bacteria colonies able to withstand antibiotic-mediated killing. In this work, a smart approach is presented to integrate electrochemical sensors for detecting bacterial infections in biomedical implants made of isotactic polypropylene (i-PP) using chemical assembly. The electrochemical detection is based on the capacity of conducting polymers (CPs) to detect extracellular nicotinamide adenine dinucleotide (NADH) released from cellular respiration of bacteria, which allows distinguishing prokaryotic from eukaryotic cells. Oxygen plasma-functionalized free-standing i-PP, coated with a layer (≈1.1 µm in thickness) of CP nanoparticles obtained by oxidative polymerization, is used as working electrode for the anodic polymerization of a second CP layer (≈8.2 µm in thickness), which provides very high electrochemical activity and stability. The resulting layered material, i-PP f /CP 2 , detects the electro-oxidation of NADH in physiological media with a sensitivity 417 µA cm −2 and a detection limit up to 0.14 × 10 −3 m, which is below the concentration of extracellular NADH found for bacterial cultures of biofilm-positive and biofilm-negative strains.

Preparation and Characterization of Functionalized Surgical Meshes for Early Detection of Bacterial Infections

“…Results obtained using a scan rate of 75 mV/s were similar to those displayed in Figure S7 for 100 mV/s, whereas results obtained using a scan rate of 25 mV/s were very similar to those depicted in Figure 8a,b, which were achieved using a scan rate of 50 mV/s. As it is reported, 47,48 the area of the voltammograms and j max increased with decreasing scan rate, this behavior being similar for the two functionalized meshes. Furthermore, the voltammograms became more symmetric, especially for the OMLP f /PHEDOT/PEDOT.…”

“…In the second regime, which extends from 1 to 6 mM, the sensitivity decreases slightly to 0.25 and 0.17 mA/(cm 2 ·mM) for OMLP f /PHEDOT/PEDOT and OME f /PHEDOT/PEDOT, respectively. As the final aim of the coated meshes is the detection of NADH from bacterial activity, the critical range is the first one, as the NADH concentration values reported from bacterial cultures are lower than 1 mM. , The presence of two linear regimes has been attributed to the complex geometry of the coated meshes, which affects the detection process with respect to simpler two-dimensional (2D) electrodes prepared by activating, functionalizing, and coating compact i-PP films . Thus, at high NADH concentrations, the access of the analyte molecules to the surface of film-shaped electrodes, which were found to exhibit a single linear regime, is much easier and robust than to the surface of complex mesh-shaped ( i.e.…”

“…In a recent study, the extracellular NADH, as determined by ultraviolet−visible (UV−vis) spectroscopy, was directly related to the quantity of bacteria in the medium, evidencing that such bioanalyte can be used to quantify the number of bacteria colonizing a mesh. 47 In this work, the NADH present in bacteria (S. aureus and both B+ and B− E. coli) culture media was detected by CV using OMLP f /PHEDOT/PEDOT and OME f /PHEDOT/ PEDOT as the working electrodes in an electrochemical sensor. Details of the experimental procedure are described in the Methods section.…”

Smart Design of Sensor‐Coated Surgical Sutures for Bacterial Infection Monitoring

“…[25] Accordingly, the NADH from eukaryotic cell respiration remains in the cytosolic pool, while the NADH from bacteria respiration migrates to the extracellular space and allows its detection in the surrounding environment without interference from eukaryotic cells. [22,26] These features were demonstrated in a previous study, [22] showing that the electrochemical signal associated with the oxidation of NADH increased with the growth of bacteria cultures while it remained constant with the proliferation of eukaryotic cells.…”

Multifunctional conductive hyaluronic acid hydrogels for wound care and skin regeneration

“…Indeed, other advanced features might include the rapid detection of infections coupled with the electrically controlled release of antibiotic drugs. 93,94…”