Publications

The development of smart biomedical devices as efficient tools in early diagnosis and therapy monitoring has recently witnessed unprecedented growth, becoming an emerging field in biomedical engineering. Sponges for endoluminal vacuum therapy, which are intended for transmitting negative pressure as trigger for tissue regeneration and for draining infections in anastomotic leakages, are massively used implants with very complex geometry and high risk of infection. In this work, commercial polyurethane (PU) sponges have been converted into smart biomedical devices by incorporating an electrochemical sensor to monitor the growth of bacteria. Such innovative approach, which allows to track the tissue healing process avoiding further infection development, has been performed applying a three-step process: 1) activation of PU using low pressure oxygen plasma; 2) incorporation of conducting polymer (CP) nanoparticles (NPs) at the surface of the activated PU by chemical oxidative polymerization; and 3) formation of a homogeneous electroactive coating using the CP NPs obtained in 2), as growth nuclei in an electrochemical polymerization. The functionalized PU sponge is able to monitor the bacteria growth in the surrounding media by detecting the concentration of nicotinamide adenine dinucleotide (NADH) from respiration reactions in the cytosol (i.e. bacteria do not have mitochondria). Conversely, respiration in normal eukaryotic cells takes place in the mitochondria, whose double membrane is not permeable to NADH. The sensing performance of the CP-coated PU sponges (limit of detection: 0.06 mM; sensitivity: 1.21 mA/cm2) has been determined in the lab using NADH solutions, while a proof of concept have been conducted using Escherichia coli bacteria cultures.

JTD Keywords: Conducting polymer, Desig, Electrochemical coating, Esophageal cancer, Nadh, Pedot, Polyurethane functionalization, Selective detection, Sponge functionalizatio

In addition of a key catecholamine neurotransmitter, dopamine is is the metabolite predominantly produced by specific types of tumors (e.g. paragangliomas and neuroblastomas), which cannot be diagnosed using conven-tional sensitive tests. Within this context, development of flexible electrochemical sensors to monitor dopamine levels in physiological fluids for the early diagnosis and control of diseases related to abnormal levels of such compound, is necessary. In this work, a flexible self-supported membrane, which acts directly as electrode, has been developed to detect dopamine. The membrane consists of three nanoperforated polylactic acid (PLA) layers, which provide flexibility and mechanical integrity, separated by two layers of an electroactive copolymer, which are obtained by electrochemical copolymerization of 3,4-ethylenedioxythiophene and aniline. The sensitivity and detection limit provided by the electroactive copolymer, which is accessible to dopamine molecules through the nanoperforations of the PLA outer layers, is 1.846 mu A/(cm2.mu M) and 1.7 mu M, respectively, in a urea-rich environments that mimics urine. These values allow us to propose the self-standing flexible electrodes devel-oped in this study for the detection of dopamine in patients affected by paragangliomas and neuroblastomas tumors, which typically present dopamine concentrations between 2 and 7 mu M.

JTD Keywords: 4-ethylenedioxythiophene), Conducting polymer, Electrochemical sensor, Electrodes, Hydrogels, Poly(3, Polyaniline, Polylactic acid, Selective detection, Sensors, Supercapacitors

We describe a multi-tasking flexible system that is able to release a wide spectrum antibiotic (levofloxacin, LVX) under electrostimulation and act as a pH sensor for detecting bacterial infections. Combining anodic polymer-ization with plasma polymerization processes we engineered dual pH-and electro-responsive polymeric systems. Particularly, the manufactured devices consisted on a layer of poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHEDOT) loaded with the LVX antibiotic and coated with a plasma polymer layer of poly(acrylic acid) (PAA). The PHEDOT acted as conductive and electro-responsive agent, while the PAA provided pH responsiveness, changing from a compact globular conformation in acid environments to an expanded open coil conformation in alkaline environments. The assembly between the PHEDOT layer and the PAA coating affected the electro-chemical response of the former, becoming dependent on the pH detected by the latter. The conformational change experienced by the PAA layer as a function of the pH and the redox properties of PHEDOT were leveraged for the electrochemical detection of bacteria growth and for regulating the release of the LVX antibiotic, respectively. The effectiveness of the system as a stimulus-responsive antibiotic carrier and pH sensor was also investigated on strains of Escherichia coli and Streptococcus salivarius.

JTD Keywords: Conducting polymer, Delivery, Drug delivery, Electrostimulation, Levofloxacin, Ph sensor, Plasma, Poly(acrylic acid), Selective detection

When danger is perceived, the human body responds to overcome obstacles and survive a stressful situation; however, sustained levels of stress are associated with health disorders and diminished life quality. Hence, stress biomarkers are monitored to control stress quantitatively. Herein, a porous sensor (4l-COP/p) composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-ethylenedioxythiophene-co-N-methylpyrrole) (COP), which is prepared in a four-layered fashion to detect dopamine (DA) and serotonin (5-HT), is presented. Specifically, the detection is conducted in phosphate-buffered saline (PBS), as well as artificial urine and sweat, by applying cyclic voltammetry. The limit of detection values obtained are as low as 5.7 x 10(-6) and 1.4 x 10(-6) m for DA and 5-HT, respectively, when assessed individually in artificial urine. When mixed in PBS, 4l-COP/p detects both biomarkers with a resolution of 0.18 V and a sensitivity of 40 and 30 mu A mm(-1) for DA and 5-HT, respectively. Additionally, by theoretical calculations, the interaction pattern that each stress biomarker establishes with the PEDOT outer layer is elucidated. Whereas DA interacts with the pi-system of PEDOT, 5-HT forms specific hydrogen bonds with the conducting polymer chains. The resolution value obtained depends upon such interactions. Overall, 4l-COP/p electrodes display potential as stress sensing devices for healthcare technologies.

JTD Keywords: Artificial body fluids, Boron-doped diamond, Cortisol, Cyclic voltammetry, Dopamine, Multilayered films, Paper, Saliva, Selective detection, Sensor, Sensors, Serotonin, Serum