1,721,072 research outputs found
Enzyme-based amperometric biosensors: 60 years later ... Quo Vadis?
Full text linkEnzyme-based amperometric biosensors represent powerful tools for remote medicine and in situ analysis. Nowadays, billions of people are surrounded by enzyme-based amperometric biosensors even considering their relatively young age ... only 60 years! In this period, many researchers, dealing mostly with the same target molecules as in early times, have developed novel strategies to tackle electron transfer issues and to realise stable, sensitive, and selective biosensors. Besides marking 60 years from the first enzyme-based amperometric biosensor, this review aims at summarising the technological advancements in the field mainly considering three enzyme families: D-glucose oxidising enzymes, D-fructose oxidising enzymes and L-lactate oxidising enzymes. It is an overview of the past (previous five decades) and current advancements (2010-2020) from the electrode platform tailoring to the technological production and applications (e.g., in situ biosensors, Point-of-Care (PoC), wearable biosensors etc.) focused on few enzymes
Biosensors & enzymatic fuel cells based on direct electron transfer of dehydrogenases: characterization and applications
Full text linkIl lavoro svolto durante i tre anni di dottorato è stato indirizzato verso lo sviluppo di nuovi metodi di sintesi ed elettrosintesi di nanomateriali metallici o carboniosi per il miglioramento del trasferimento elettronico diretto tra l’enzima e l’elettrodo. Questo miglioramento si traduce in un notevole incremento della sensibilità, stabilità e selettività dei biosensori sviluppati nonché della potenza generata da una pila enzimatica a biocombustibile, (Biofuel Cell). La prima parte della tesi riguarda lo studio e l’ottimizzazione del trasferimento elettronico diretto della cellobiosio deidrogenasi (CDH), un enzima appartenente alle flavoemeossidoreduttasi, costituito da due subunità dotate rispettivamente di cofattore FAD (subunità I) e heme b (subunità II). In questa parte abbiamo sintetizzato nanoparticelle di oro e di argento con un nuovo metodo “green”, che impiega come
agente riducente la quercetina, un noto flavonoide presente in numerosi alimenti e bevande (es. tè, capperi, mirtilli, etc.). La reazione è stata condotta a temperatura ambiente e a pressione atmosferica senza ulteriore purificazione in quanto la quercetina
è nota avere un comportamento stabilizzante delle sospensioni colloidali. Le suddette nanoparticelle sono state impiegate nella costruzione di biosensori per la determinazione del lattosio e di una pila a biocombustibile glucosio/ossigeno.
Successivamente, abbiamo sviluppato un nuovo metodo per l’elettrodeposizione di nanoparticelle di oro in modo da ottenere una superficie nanostrutturata ordinata che ha portato allo sviluppo di un biosensore per la determinazione del glucosio nella saliva.
La seconda parte della tesi riguarda lo studio del meccanismo del trasferimento elettronico diretto della fruttosio deidrogenasi (FDH), con particolare attenzione rivolta all’influenza dei cationi monovalenti e bivalenti, all’influenza della forma delle
nanoparticelle sulla catalisi enzimatica, all’individuazione dei siti “heme” coinvolti nel trasferimento elettronico diretto attraverso l’accesso ad una porzione idrofobica dell’enzima, ed infine allo sviluppo di un biosensore per la determinazione del fruttosio
realizzato immobilizzando la FDH su elettrodi di oro altamente poroso.The aim of this thesis is the study and the enhancement of the direct electron transfer of two different dehydrogenases, by means of a proper nanostructuration of the electrodes, for biosensors and enzymatic fuel cells (EFCs) development. Cellobiose dehydrogenase (CDH) is an extracellular enzyme belonging to the oxidoreductase group. CDH contains two subunits: (a) subunit I is the dehydrogenase domain (DHCDH), similar to the domain of other oxidoreductases, which belongs to the glucose-methanol-choline (GMC) oxidoreductase superfamily with a flavin adenine dinucleotide (FAD) co-factor covalently bound to the enzyme structure; (b) subunit II is the cytochrome domain (CYTCDH), which contains a heme b and acts as a built-in mediator by shuttling the electrons to a modified electrode. Both subunits are connected through a flexible linker responsible of the modulation of the internal electron transfer (IET) rate by varying the experimental conditions, such as changes of pH and divalent cations the concentration. Fructose dehydrogenase (FDH) is a membrane-bound flavocytochrome oxidoreductase which also belongs to the hemoflavoproteins family. FDH is a heterotrimeric membrane-bound enzyme complex with a molecular mass of 146.4 kDa,
consisting of three subunits: (a) subunit I (DHFDH) is the catalytic domain with a covalently bound flavin adenine dinucleotide (FAD) cofactor, where D-(-)-fructose is involved in a 2H+/2e- oxidation to 5-dehydro-D-(-)-fructose; (b) subunit II (CYTFDH) acts as a built-in electron acceptor with three heme c moieties covalently bound to the enzyme scaffold and two of them involved in the electron transfer pathway; (c) subunit III is not involved in the electron transfer but plays a key role for the enzyme complex stability.
The central target of the present thesis is the possibility to improve the electron transfer through the electrode nanostructuration, which can be realized by exploiting new nanomaterials as well as new nanostructuration methods (e.g. “green” synthesized metal nanoparticles, electrodeposition etc.). In the thesis much attention has been paid also to the understanding of the electron transfer pathway of FDH, which would be of fundamental interest in the near future for the development of highly sensitive biosensors and efficient EFCs. The biosensors realized and optimized in this thesis are prototypes of devices that, hopefully, will be commercially available on the market in the next future
Bioelectronic Large-Area Transistors for High-Performance Sensing
No full textBioelectronics, originating from Galvani’s eighteenth-century experiments,
blends biology, medicine, and electronics to create devices that can be
closely connected to biological systems. This review focuses on bioelectronic
large-area field-effect transistor (FET) sensing devices, emphasizing their
sensitivity, specificity, and reliability. The role of analytical chemistry in op-
timizing performance-level control is pivotal, and the review discusses key
performance metrics, including limit of identification (LOI), reliability and
selectivity. The assessment of the LOI level is addressed using examples of
FET-based bioelectronic sensors capable of detecting concentrations at least
in the picomolar range. Examples of sensors capable of detecting concen-
trations in the tens of zeptomolar range are also provided, demonstrating
that a single molecule in 0.1 mL can be reliably detected. Working at the
LOI also minimizes random errors, which can be as low as 1%. The review
also explores the use of molecularly imprinted polymers for highly selective
FET bioelectronic detections, noting their sustainability and robustness in
comparison to natural antibodies
Self-powered wearable biosensor based on stencil-printed carbon nanotube electrodes for ethanol detection in sweat
No full textHerein we introduce a novel water-based graphite ink modified with multiwalled carbon nanotubes, designed for the development of the first wearable self-powered biosensor enabling alcohol abuse detection through sweat analysis. The stencil-printed graphite (SPG) electrodes, printed onto a flexible substrate, were modified by casting multiwalled carbon nanotubes (MWCNTs), electrodepositing polymethylene blue (pMB) at the anode to serve as a catalyst for nicotinamide adenine dinucleotide (NADH) oxidation, and hemin at the cathode as a selective catalyst for H2O2 reduction. Notably, alcohol dehydrogenase (ADH) was additionally physisorbed onto the anodic electrode, and alcohol oxidase (AOx) onto the cathodic electrode. The self-powered biosensor was assembled using the ADH/pMB-MWCNTs/SPG||AOx/Hemin-MWCNTs/SPG configuration, enabling the detection of ethanol as an analytical target, both at the anodic and cathodic electrodes. Its performance was assessed by measuring polarization curves with gradually increasing ethanol concentrations ranging from 0 to 50 mM. The biosensor demonstrated a linear detection range from 0.01 to 0.3 mM, with a detection limit (LOD) of 3 +/- 1 mu M and a sensitivity of 64 +/- 2 mu W mM-1, with a correlation coefficient of 0.98 (RSD 8.1%, n = 10 electrode pairs). It exhibited robust operational stability (over 2800 s with continuous ethanol turnover) and excellent storage stability (approximately 93% of initial signal retained after 90 days). Finally, the biosensor array was integrated into a wristband and successfully evaluated for continuous alcohol abuse monitoring. This proposed system displays promising attributes for use as a flexible and wearable biosensor employing biocompatible water-based inks, offering potential applications in forensic contexts.Graphical AbstractA novel water-based graphite ink modified with multiwalled carbon nanotubes designed for the development of a wearable self-powered biosensor enabling alcohol abuse detection through sweat analysis
Photo-stimulated self-powered electrochemical system for DNA release
No full textThe DNA-release activated by light in the self-powered bioelectronic system has been studied. The system was composed of two connected electrodes: one photo-active electrode was modified with photosynthetic thylakoid membranes and another electrode was modified with O-2-reducing bilirubin oxidase and nanoparticles functionalized with molecules changing their charge upon pH variation. When the photo-electrode was illuminated, it produced current resulting in O-2 reduction and local pH change at the releasing electrode. The interfacial charge was changed from positive, when negatively charged DNA was loaded, to negative, when the DNA was repulsed and released
Synthesis and characterization of “green” metallic nanoparticles for electrochemical biosensors development
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Improved DET communication between cellobiose dehydrogenase and a gold electrode modified with a rigid self-assembled monolayer and green metal nanoparticles: the role of an ordered nanostructuration
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