1,721,034 research outputs found
Recent advances in sustainable strategies for the integration of nanostructured sensing surfaces in electroanalytical devices
No full textNanomaterials (NMs) integration in electrochemical devices as conductive nanostructured freestanding transducers and sensing surfaces has emerged in the analytical scenario, toward on-demand device manufacturing and fully exploiting NMs' features. This review reports the advances in developing electroanalytical devices based on nanostructured sensing films/surfaces obtained via accessible/sustainable strategies. Various manufacturing approaches are discussed including emerging nanostructured film-transfer technologies and nanofilms' direct generation onto low-cost substrates. Additive manufacturing and printed electronics are also treated, focusing on straightforward strategies for printed device nano-structuring. Post-production nano-modifications of preexisting transducers/electrodes are not considered. This review outlines a critical overview concerning technological novelties to obtain nanofilm-based sensors, biosensors, and electroanalytical devices, and related analytical advancements. In particular, attention is paid to nanofilms 'manufacturing strategies' based on user-friendly technologies, focusing on approaches devoted to improving sustainability. The topics will be covered describing noteworthy advancements, giving technical/practical advice, pointing out limitations, and outlining future perspectives
Monitoring disinfection in the Covid-19 era. A reagent-free nanostructured smartphone-based device for the detection of oxidative disinfectants
No full textEco-Innovative Papers Integrating Nanostructured Graphenic Films. Toward Sustainable Multifunctional Integrated Sensors
No full text: Laser-induced conductive nanofilm (LIF) electronics have gained increasing attention for their versatility and ability to form high-performing graphenic nanopatterns. Most LIF-graphenic devices are realized on plastic/polymeric substrates, while paper devices rely mainly on graphitization approaches that give rise to fragile and low-performing sensors. Thus, the manufacturing of effective graphene LIF-based paper devices suitable for real applications is still an open issue. Herein, for the first time, laser-induced reduced graphene oxide (rGO) was integrated into different cellulosic substrates to fabricate complete nanostructured paper-based sensors capable of responding to different analytical needs. Different eco-innovative cellulosic substrates were investigated, including recycled papers and papers from textile and agro-industrial wastes and manufactured with fiber alternatives to trees. Paper sensors were serially manufactured via an accessible stencil printing approach, and the rGO film was easily integrated by pressure. The paper/rGO morphological, structural/chemical, and electrical/electrochemical features were deeply investigated. Each type of paper accommodates rGO differently, leading to unique graphene film formation and chemical rearrangements affecting electrochemistry. The latter appears influenced by the paper's ability to preserve the native exfoliated nature of the rGO-film, which is dominated by sp2 carbon domains. The multifunctional ability of paper-rGO sensors has been proven in various analytical applications. Reproducible data (RSD ≤ 7%), nano/micromolar limits of detection, and satisfactory recoveries (91-108%) were obtained when working with agri-food, biological, and pharmaceutical samples, proving the exploitability and high performance of paper-rGO sensors. Notably, for each application, a different paper-based sensor resulted in the best performance, proving that the cellulosic substrate directly affects the electrosensing ability
Flip-PAD integrating laser-scribed platinum-nanozyme for rapid smartphone-based colorimetric determination of ascorbic acid
No full textBackground: The development of portable easy-to-use devices to selectively determine antioxidants still represents an open issue; antioxidants, in fact, often coexist and have similar redox reactivity. In this framework, ensuring selective colorimetric reactivity in Paper-based Analytical Devices (PAD) for a single antioxidant compound is a challenge, and the selective determination still requires time-consuming and cumbersome methods. Results: A disposable paper-based device (Flip-PAD) for the rapid and selective colorimetric determination of ascorbic acid (AA) is proposed. The Flip-PAD is equipped with a platinum nanostructured (L-nPt) catalytic paper realized using a CO2 laser, able to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB); the selective inhibition of the reaction by AA gives the analytical signal. The L-nPt paper in the Flip-PAD is coupled with fiberglass loaded with TMB, and assembled in an array format to allow the simultaneous analysis of 5 samples in 1 min; a smartphone camera is used for the RGB signal acquisition. The L-nPt CO2-laser-based synthesis was carefully optimized to maximize the nanozyme (oxidase-mimicking) activity; TMB-catalytic conversion and AA-mediated inhibition were carefully studied via colorimetric, spectroscopic and microscopical analysis. The catalytic conversion of uncolored-TMB in blue-colored TMBox occurs in 1 min, with no additional reagent needed; the AA-induced TMB-catalytic conversion inhibition results in a dye conversion ‘switch-off’ employed as analytical signal. Significance: AA dose-response signal resulted linear from 31 to 250 mg kg−1 (R2 = 0.992), showing a LOD of 6 mg kg−1; analytical performance resulted constant over 6 weeks (RSD = 4 %). The Flip-PAD exploitability was proved for the AA determination in different foods and pharmaceutical samples, returning accurate (recoveries 92−114 %; relative error −11/+4 %) and reproducible (RSD ≤10 %; n = 3) data. The proposed laser-based approach opens new paths for PADs and nanostructured systems development
Determination of Pesticides in Wheat Flour Using Microextraction on Packed Sorbent Coupled to Ultra-High Performance Liquid Chromatography and Tandem Mass Spectrometry
No full textAn ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC–MS/MS) method for multiclass analysis of pesticide and fungicide residues in wheat flour based is presented. An efficient and rapid cleanup based on microextraction by packed sorbent (MEPS) has been developed in order to have a good enrichment factor together with a low matrix effect. The target analytes were 25 pesticides widely used in wheat, with different physico-chemical characteristics and different mechanism of action: acetylcholinesterase inhibitors such as organophosphorus, carbamates, neonicotinoids, and inhibitors of ergosterol such as imidazoles and triazoles. MEPS was shown to be successful with reduction of the amount of solvent required and possibility of automation of the cleanup procedure. The whole method was then validated according to the SANCO/12571/2013 guidelines, proving its suitability as confirmation method for the selected analytes
Integrating electrochemical sensors in circular economy: biochar-film sensors based on paper industry waste for agri-food by-product valorization
No full textSustainable nanostructured paper sensors (PS) have been developed to detect bioactive compounds in plant-derived agri-food by-products. These sensors comprise 100 % recycled fibers-paper and pulp industry-derived biochar and are produced using accessible, cost-effective technologies. In detail, black liquor-derived biochar (BH) was nano-dispersed in water using an ultrasound-assisted liquid phase exfoliation-like approach, avoiding solvents. Self-standing BH-sensing nanofilms were formed directly on cellulosic membranes and integrated into stencil-printed complete electrochemical sensors manufactured on recycled paper. The biochar-based paper sensors (BH-PS) were optimized, characterized, and then employed to analyze bioactive phenols present in agri-food waste and derivatives, including cocoa and coffee husks, exhausted coffee powder, and olive leaves and artichoke production waste-based supplements. BH-PS demonstrated robust performance, yielding dose-response curves for representative bio-compounds such as caffeic acid, catechin, chlorogenic acid, and oleuropein. These showed excellent linearities (R2 ≥ 0.9946) and detection limits ranging from 0.03 to 0.6 μM. The sensors were successfully used to quantify biomolecules in agri-food wastes and derivatives, with results comparable to conventional photometric assays (r ≥ 0.99; relative error vs. AuNPs assay: -3 % to +14 %). The method produced quantitative and reproducible recoveries for all samples (97–114 %; RSD ≤ 13 %, n = 3). Finally, the superior sustainability of the BH-PS was validated using the White Analytical Chemistry framework, achieving a significantly higher score (94 %) compared to traditional colorimetric and chromatographic methods (60–80 %). This work demonstrates a circular economy model, utilizing plant-derived waste exclusively to fabricate integrated paper sensors, that were then applied to determine high-value bioactive compounds in plant-derived agri-food by-products
Press-transferred carbon black nanoparticles on board of microfluidic chips for rapid and sensitive amperometric determination of phenyl carbamate pesticides in environmental samples
No full textThe authors describe a strategy for rapid and sensitive determination of phenyl carbamate pesticides in environmental samples. It consists of the following steps: (a) Enrichment and clean-up of the analytes using a C18 microtip based procedure; (b) alkaline hydrolysis of the carbamates (carbofuran, isoprocarb and carbaryl) to form phenol derivatives; and (c) fast separation and amperometric detection in a microfluidic chip (MCs). The microchips were fabricated by using press-transferred carbon black nanoparticles (CB-NPs) as electrochemical sensing nanomaterial. The excellent electrochemical behavior of the CB-NPs coupled to the microchip warrants good separation and allows for the voltammetric determination (best at a working voltage of +0.70 V vs Ag/AgCl) of the carbamates within < 6 min. The authors also describe a rapid procedure for the clean-up and enrichment of the carbamates from real samples by using a C18 microtip. The procedure allowed a 10-fold enrichment of the analytes, and this led to a detection limits in ̴the 0.7 to 1.2 μM concentration range. The assay was applied to samples of river, lake and irrigation water that were spiked with carbamates at 50 and 100 μM levels. Recoveries are in the 87 to 108 % range, and RSDs (n = 3) in the 5 to 11 % range. The exploitation of the such nanomaterials coupled to microfluidics and microextraction procedures for real sample analysis in our preception represents a most viable tool for the analysis of complex real samples, for on-site environmental monitoring, and for rapid diagnosis. [Figure not available: see fulltext.
Press-Printed Conductive Carbon Black Nanoparticle Films for Molecular Detection at the Microscale
No full textCarbon black nanoparticle (CBNP) press-transferred film-based transducers for the molecular detection at the microscale level were proposed for the first time. Current-sensing atomic force microscopy (CS-AFM) revealed that the CBNP films were effectively press-transferred, retaining their good conductivity. A significant correlation between the morphology and the resistance was observed. The highest resistance was localized at the top of the press-transferred film protrusions, whereas low values are usually obtained at the deep crevices or grooves. The amount of press-transferred CBNPs is the key parameter to obtain films with improved conductivity, which is in good agreement with the electrochemical response. In addition, the conductivity of such optimum films was not only Ohmic; in fact, tunneling/hopping contributions were observed, as assessed by CS-AFM. The CBNP films acted as exclusive electrochemical transducers as evidenced by using two classes of molecules, that is, neurotransmitters and environmental organic contaminants. These results revealed the potential of these CBNP press-transferred films for providing new options in microfluidics and other related micro- and nanochemistry applications
Integrated 3D-Printed Microfluidic Device for Immunocapture and Electrochemical Assessment of Transferrin Saturation in Point-of-Care Stroke Diagnostics
No full text: A 3D-printed electrochemical microfluidic device (3D-EMD) was developed to assess the transferrin saturation (TSAT) biomarker in ischemic stroke patients. The all-in-one 3D-EMD integrates a strategically engineered immunoassay module for the direct and selective isolation of transferrin (Tf) from unpretreated clinical samples, unaffected by sample coloration, with an interchangeable electrochemical sensor for the simultaneous detection of Tf and Tf-bound iron. Both modules are interconnected through microfluidic channels whose flow is regulated by a cylindrical rotary valve. The analytical workflow enables magnetic bead-based direct Tf immunocapture and simultaneous electrochemical detection of Tf and Tf-bound iron via square wave voltammetry, allowing TSAT assessment within 60 min using only 50 μL of sample. Validation with certified reference materials demonstrated excellent accuracy (Er ≤ 5%) and precision (RSD ≤ 4%). Application to human serum from ischemic stroke patients showed strong correlation (r = 0.87) and agreement (slope 0.9 ± 0.3; intercept 6 ± 10; p < 0.05) with the urea-PAGE reference method, which typically requires up to 18 h. Overall, the 3D-EMD constitutes an elegant, fully integrated dual-functionality platform that seamlessly combines customizable sample preparation with online electrochemical detection in a single device. This configuration enables direct serum analysis and supports clinical decision-making in time-critical conditions. The device shows strong potential as a rapid point-of-care testing candidate for ischemic stroke and as a next-generation platform for broader clinical diagnostics
Micro-solid-phase extraction (μ-SPE) of organophosphorous pesticides from wheat followed by LC-MS/MS determination
No full textA rapid, selective and effective method of extraction, clean-up and concentration of organophosphorous pesticides from wheat followed by electrospray (ESI) LC-MS/MS analysis was developed. The μ-SPE (micro-solid-phase extraction) procedure resulted in good analytical performance and reduced at the same time matrix effects, analysis time and solvent consumption. Limits of detection (LODs) and quantification (LOQs) were in the range of 0.3–10 and 1–30 μg kg−1, respectively, with good reproducibility (RSD ≤ 13.8) and recoveries between 75% and 109%. Coefficients of determination (r2) were greater than 0.996 for the studied pesticides. Despite the reduced sorbent bed mass of μ-SPE tips (4.2 mg), the analytical data showed that no saturation phenomena occurs in the tested range of concentration both for single compounds and mixtures. Several real samples were analysed and the concentrations of the selected pesticides were found to be below the respective maximum residue limit (MRLs). © 2016 The Author(s). Published by Taylor & Francis
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