Publications

Skin is a barrier that protects us against physical, chemical and biological agents. However, any damage to the skin can disrupt this barrier and therefore compromise its function leading to sometimes catastrophic consequences like sepsis. Thus, methods to detect early signs of infection are necessary. In this work, we have developed a straightforward method for producing 2D nanomembranes with regularly spaced 1D metallic nanostructures integrating sensing capabilities to pH and NADH (nicotinamide adenine dinucleotide), which are critical analytes revealing infection. To achieve this, we have successfully fabricated a bilayered nanomembrane combining a pH-responsive polyaniline (PANI) layer and a nanoperforated poly(lactic acid) (PLA) layer containing gold nanowires (Au NWs) as NADH sensing element. SEM, FTIR, Raman and AFM techniques revealed the formation of the bilayered PANI/PLA nanomembrane and the successful incorporation of the Au NWs inside the nanoperforations. The resulting bilayered nanomembrane showed significant flexibility and conformability onto different substrates due to the softness of the polymers and the ultrathin thickness with stiffness values similar to human skin. These nanomembranes also exhibited remarkable electrochemical sensing performance towards pH and NADH detection. Thus, the nanomembrane displayed linearity with good sensitivity (47 mVpH-1) in the critical pH range 4-10 and fast response time (10 s). On the other hand, PANI/PLA-Au nanomembranes also allowed the quantitative sensing of NADH with a limit of detection of 0.39 mM and a sensitivity of 1 mu A cm-2 mM-1 in the concentration range 0-5 mM.

JTD Keywords: Bilayered nanomembranes, Biomimetic membranes, Free-standing films, Gold nanowires, Nad, Nanoparticles, Pani, Ph and nadh sensor, Pla, Polyaniline

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