Desarrollo de nuevas plataformas electroquímicas y ópticas lab-on-a-chip para detección de contaminantes y biomarcadores
- Autores: Andrzej Chałupniak
- Directores de la Tesis: Arben Merkoçi (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Giuseppe Palleschi (presid.), Cesar Fernandez Sanchez (secret.), Adaris López Marzo (voc.)
- Programa de doctorado: Programa de Doctorado en Biotecnología por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TESEO
- Resumen
The detection of hazardous contaminants requires special attention due to their possible toxicity, low concentration in real samples and, in most cases, an impossibility to perform detection by using such a specific approach as immunoassay. One of the approaches taking an important step towards easier detection of hazardous compounds is the use of Lab-on-a-chip platform.
In Chapter 3, a novel, miniaturized microfluidic platform for the simultaneous detection and removal of polybrominated diphenyl ethers (PBDEs) was developed. The platform consists of a polydimethylsiloxane (PDMS) microfluidic chip for the immunoreaction step, a PDMS chip with an integrated screen-printed electrode (SPCE) for detection, and a PDMS-reduced graphene oxide (rGO) chip for physical adsorption and subsequent removal of PBDE residues. The detection was based on competitive immunoassay-linked binding between PBDE and PBDE modified with horseradish peroxidase (HRP-PBDE) followed by the monitoring of enzymatic oxidation of o-aminophenol (o-AP) by using square wave anodic stripping voltammetry (SW-ASV). PBDE was detected with good sensitivity and a limit of detection similar to that obtained with a commercial colorimetric test (0.018 ppb), but with the advantage of using lower reagent volumes and a reduced analysis time. In order to design a detection system suitable for toxic compounds such as PBDEs, a reduced graphene oxide–PDMS composite has been developed and optimized to obtain increased adsorption (based on both the hydrophobicity and π–π stacking between rGO and PBDE molecules) compared to those of non-modified PDMS. This system can be easily applied to detect any analyte by using the appropriate immunoassay and it supports operation in such complex matrices as seawater.
In Chapter 4, a LOC device for the simultaneous preconcentration and detection of heavy metals was developed. This device consists of a screen-printed carbon electrode, a PDMS chip, and a GO-PDMS chip. The GO-PDMS chip was fabricated and the most crucial factors were optimized, including the concentration of GO and the concentration of the curing agent. It was found that the adsorption ability is inversely proportional to the PDMS catalyser (curing agent) concentration in the composite and proportional to the GO concentration. The mechanism of adsorption is based on surface complexation, where oxygen active groups of negative charge can bind with such bivalent metals as Pb. The highest adsorption was obtained in pH=7.
The GO-PDMS has a relatively big large adsorption capacity, as even the samples >500 ppb are nearly fully adsorbed, taking into account that such a concentration is very high.
The desorption process was optimized as well. Thanks to this, previously adsorbed metals can be released and detected in square wave anodic stripping voltammetry. The limit of detection of this technique (using screen-printed electrodes) was 0.5 ppb for Pb. This means that by using a preconcentration GO-PDMS platform, a lower amount of Pb can be quantified because preconcentrated samples showed a current up to 30 times higher than that of non-preconcentrated one.
This platform can be used for improved heavy metal sensing and also for its removal.
