A third-generation hydrogen peroxide biosensor based on horseradish peroxidase cross-linked to multi-wall carbon nanotubes

Hydrogen Peroxide Detection by Super-Porous Hybrid CuO/Pt NP Platform: Improved Sensitivity and Selectivity

A super-porous hybrid platform can offer significantly increased number of reaction sites for the analytes and thus can offer advantages in the biosensor applications. In this work, a significantly improved sensitivity and selectivity of hydrogen peroxide (H₂O₂) detection is demonstrated by a super-porous hybrid CuO/Pt nanoparticle (NP) platform on Si substrate as the first demonstration. The super-porous hybrid platform is fabricated by a physiochemical approach combining the physical vapor deposition of Pt NPs and electrochemical deposition of super-porous CuO structures by adopting a dynamic hydrogen bubble technique. Under an optimized condition, the hybrid CuO/Pt biosensor demonstrates a very high sensitivity of 2205 µA/mM·cm² and a low limit of detection (LOD) of 140 nM with a wide detection range of H₂O₂. This is meaningfully improved performance as compared to the previously reported CuO-based H₂O₂ sensors as well as to the other metal oxide-based H₂O₂ sensors. The hybrid CuO/Pt platform exhibits an excellent selectivity against other interfering molecules such as glucose, fructose, dopamine, sodium chloride and ascorbic acid. Due to the synergetic effect of highly porous CuO structures and underlying Pt NPs, the CuO/Pt architecture offers extremely abundant active sites for the H₂O₂ reduction and electron transfer pathways.

Detección electroquímica de peróxido de hidrógeno usando peroxidasa de pasto Guinea (Panicum maximum) inmovilizada sobre electrodos serigrafiados de puntos cuánticos

Los biosensores electroquímicos son herramientas analíticas de rápida y confiable respuesta que han adquirido especial interés en los últimos años gracias a la posibilidad de integrar biomoléculas con electrodos hechos a base de materiales nanométricos. En este trabajo se desarrolló un biosensor electroquímico para detección de peróxido de hidrógeno (H2O2) usando peroxidasa de pasto Guinea (PPG) inmovilizada sobre electrodos serigrafiados de puntos cuánticos (ESPC). La PPG fue aislada y parcialmente purificada a partir de hojas de pasto Guinea con una actividad específica de 602 U mg-1. Posteriormente, la PPG fue inmovilizada sobre la superficie del ESPC mediante adsorción física y el estudio del comportamiento electroquímico fue llevado a cabo mediante voltamperometría cíclica y cronoamperometría. La PPG reveló una pareja bien definida de señales redox a 17 mV/-141 mV correspondientes al proceso redox del grupo hemo (Fe2+/Fe3+) de las peroxidasas. La reducción bioelectrocatalítica del peróxido de hidrógeno se observó a un potencial redox de -645 mV vs Ag. Este proceso fue controlado por difusión de las especies en la superficie del electrodo en un rango de velocidad de barrido lineal de 50-500 mV/s. La cronoamperometría permitió la construcción de curvas de calibración entre la corriente de reducción y la concentración del H2O2 para la determinación de parámetros analíticos como sensibilidad, rango lineal y nivel mínimo de detección. El desarrollo de este biosensor amperométrico se convierte en un paso preliminar para la construcción de un dispositivo portátil y de respuesta rápida para el análisis de H2O2 en muestras de interés ambiental y biomédico.

Peroxidases-assisted removal of environmentally-related hazardous pollutants with reference to the reaction mechanisms of industrial dyes

Environmental protection is one of the most important challenges for the humankind. Increasing number of emerging pollutants resulting from industrial/human-made activities represents a serious menace to the ecological and environmental equilibrium. Industrial dyes, endocrine disrupters, pesticides, phenols and halogenated phenols, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and other xenobiotics are among the top priority environmental pollutants. Some classical remediation approaches including physical, chemical and biological are being employed, but are ineffective in cleaning the environment. Enzyme-catalyzed transformation reactions are gearing accelerating attention in this context as potential alternatives to classical chemical methods. Peroxidases are catalysts able to decontaminate an array of toxic compounds by a free radical mechanism resulting in oxidized or depolymerized products along with a significant toxicity reduction. Admittedly, enzymatic catalysis offers the hallmark of high chemo-, regio-, and enantioselectivity and superior catalytic efficiency under given reaction environment. Moreover, enzymes are considered more benign, socially acceptable and greener production routes since derived from the renewable and sustainable feedstock. Regardless of their versatility and potential use in environmental processes, several limitations, such as heterologous production, catalytic stability, and redox potential should be overcome to implement peroxidases at large-scale transformation and bio-elimination of recalcitrant pollutants. In this article, a critical review of the transformation of different types of hazardous pollutants by peroxidases, with special reference to the proposed reaction mechanisms of several dyes is presented. Following that major challenges for industrial and environmental applications of peroxidases are also discussed. Towards the end, the information is also given on miscellaneous applications of peroxidases, concluding remarks and outlook.

Peroxidase(s) in environment protection

Industrial discharges of untreated effluents into water bodies and emissions into air have deteriorated the quality of water and air, respectively. The huge amount of pollutants derived from industrial activities represents a threat for the environment and ecologic equilibrium. Phenols and halogenated phenols, polycyclic aromatic hydrocarbons (PAH), endocrine disruptive chemicals (EDC), pesticides, dioxins, polychlorinated biphenyls (PCB), industrial dyes, and other xenobiotics are among the most important pollutants. Peroxidases are enzymes that are able to transform a variety of compounds following a free radical mechanism, thereby yielding oxidized or polymerized products. The peroxidase transformation of these pollutants is accompanied by a reduction in their toxicity, due to loss of biological activity, reduction in the bioavailability, or the removal from aqueous phase, especially when the pollutant is found in water. The review describes the sources of peroxidases, the reactions catalyzed by them, and their applications in the management of pollutants in the environment.

Sensitive detection of endocrine disrupters using ionic liquid--single walled carbon nanotubes modified screen-printed based biosensors

Simple and low cost biosensor based on screen-printed electrode for sensitive detection of some alkylphenols was developed, by entrapment of HRP in a nanocomposite gel based on single-walled carbon nanotubes (SWCNTs) and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF(6)]) ionic liquid. Raman and FTIR spectroscopy, CV and EIS studies demonstrate the interaction between SWCNTs and ionic liquid. The nanocomposite gel, SWCNT-[BMIM][PF(6)] provides to the modified sensor a considerable enhanced electrocatalytic activity toward hydrogen peroxide reduction. The HRP based biosensor exhibits high sensitivity and good stability, allowing a detection of the alkylphenols at an applied potential of -0.2V vs. Ag/AgCl, in linear range from 5.5 to 97.7 μM for 4-t-octylphenol and respectively, between 5.5 and 140 μM for 4-n-nonylphenol, with a response time of about 5s. The detection limit was 1.1 μM for 4-t-octylphenol, and respectively 0.4 μM for 4-n-nonylphenol (S/N=3).