Interacción de nanoestructuras de carbono o metálicas con (bio)moléculas y su aplicación al desarrollo de sensores

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Analitica y Análisis Instrumental . Fecha de lectura: 26-10-201

Gallium nanoparticles colloids synthesis for UV bio-optical sensors

F. Nucciarelli, I. Bravo, L. Vázquez, E. Lorenzo, J. L. Pau, "Gallium nanoparticles colloids synthesis for UV bio-optical sensors", SPIE Optics + Optoelectronics Proc. SPIE 10231 (16 May 2017) Copyright 2017 Society of Photo Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. Proceedings of the Optical Sensors Conference (Prague, Czech Republic) doi: https://doi.org/10.1117/12.2265883A new method for the synthesis of colloidal gallium nanoparticles (Ga NPs) based on the thermal evaporation of Ga on an expendable aluminum zinc oxide (AZO) layer is presented here. The growth of AZO layers was investigated on different substrates at room temperature and 300 °C. By means of physical evaporation process, nanoparticles were deposited with a distribution ranging from 10 nm to 80 nm in diameter. A study of their endurance in acidic environment was carried out in order to assure the NPs shape and size stability during the etching process. Smaller particles start to disappear between 1h and 2h immersion time in a pH=1 solution, while bigger particles reduce their dimension. The NPs were dispersed in tetrahydrofuran (THF) organic solvent and optically characterized, showing strong UV absorption with a band centered at 280 nm. The colloids size distribution of as-evaporated samples was compared with the distribution obtained in droplets of the solution after drop-casting. By Dipole Discrete Approximation simulations, a close relationship between the UV absorption and the NPs with diameter smaller than ∼40 nm was found. Because of the gallium oxide (Ga1-xOx) outer shell that surrounds the Ga NPs, an enhancement of their hydrophobicity occurs. Hence, the low agglomeration state between NPs in tetrahydrofuran allows to obtain narrow absorption band in the optical spectrumWe are also grateful to the international PROMIS project, framed in the Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 641899. This research is supported by the MINECO (CTQ2014-53334-C2-2-R and MAT2016-80394-R) and Comunidad de Madrid (NANOAVANSES ref. S2013/MIT-3029) Projec

Spectroelectrochemical operando method for monitoring a phenothiazine electrografting process on amide functionalized C-nanodots/Au hybrid electrodes

Phenothiazine derivatives are extensively explored dye molecules, which present interesting electrochemical and optical properties. In recent years, the possibility of transforming some phenothiazines in their aryl diazonium salt derivatives has been proved, what allows them to be electrochemically reduced and electrografted onto conductive surfaces. This is a smart way to modify these surfaces and enable them with specific functionalities. In order to better comprehend the electrografting process and consequently have a higher control of it, in this work we have carried out an exhaustive study by operando UV–Vis spectroelectrochemistry of the electrografting of a phenothiazine aryl diazonium salt onto amide carbon nanodots. As a model of phenothiazine dye we have chosen Azure A. The electrografting onto carbon nanodots has been stablished by comparison with the results obtained on bare gold electrodes in this novel study. The presence of carbon dots improves the reversibility of the electrochemical process as derived from the results obtained by operando UV–Vis spectroelectrochemistry. In addition, to asses that the electrochemical process studied corresponds to the electrografting, the results have been compared to those obtained for the simple Azure A adsorption. This study shows the advantages of obtaining simultaneously the electrochemical and the spectroscopic evolution of an electron-transfer process in a single experiment, in a particular electrochemical reaction. This work could be the starting point for the study of the electrografting on other nanomaterialsFunding from the Spanish Ministerio de Ciencia, Innovación y Universidades (project: CTQ2017-84309-C2-1-R) and Comunidad Autónoma de Madrid (NANOAVANSENS Program) is acknowledged. IMDEA Nanociencia acknowledges support from the 'Severo Ochoa' Programme for Centres of Excellence in R&D (Ministerio de Ciencia, Innovación y Universidades, Grant SEV-2016-0686

Carbon nanodots based biosensors for gene mutation detection

This Accepted Manuscript will be available for reuse under a CC BY-NC-ND licence after 24 months of embargo periodAn electrochemical DNA biosensor based on a carbon nanodots (CDs) modified screen-printed gold electrode as a transducer is reported in this work. CDs were synthesized by thermal carbonization of ethyleneglycol bis-(2-aminoethylether)-N,N,N’,N’-tetraacetic acid (EGTA) and characterized by different techniques (DLS, TEM, FTIR, Raman). The electrode surface modification was accomplished by drop-casting a suspension of CDs. SEM analysis and cyclic voltammetry were used to characterize the resulting modified electrode. Synthetic 25-mer or 100-mer DNA capture probes, capable to hybridize with a specific sequence of the pathogen Helicobacter pylori or the cystic fibrosis transmembrane regulator (CFTR) gene were attached to the CDs-gold surface. A 25-bases synthetic fully complementary sequence or a single nucleotide polymorphism to the DNA capture probe and a 373-bases PCR amplicon of exon 11 of CFTR containing a sequence complementary to the capture probe, were employed as target. The hybridization event was electrochemically monitored by using safranine as redox indicator, which selectively binds to double stranded DNA (dsDNA). A detection limit of 0.16 nM was obtained for the 25-mer synthetic target DNA. The biosensor shows a very high reproducibility and selectivity, allowing to detect a single nucleotide polymorphism. It has been applied to the detection of F508del mutation in the CFTR geneThis work has been supported by the Comunidad Autónoma de Madrid NANOAVANSENS (project No. S2013/MIT-3029) and Spanish Ministerio de Economía, Industria y Competitividad through projects Nos. CTQ2015-71955-REDT (ELECTROBIONET) and CTQ2014-53334-C2-1-R. E. L. thanks the Fulbright scholarship-Salvador de Madariaga program from Spanish Ministerio de Economía, Industria y Competitividad. I. B. gratefully acknowledges the FPI-2012 Grant from Spanish Ministerio de Economía y Competitividad. R.W. gratefully acknowledges support by the European Union structural funds and the Comunidad de Madrid MAD2D-CM Program (S2013/MIT-3007), as well as by the Spanish Ministerio de Economía, Industria y Competitividad through project No. MAT2015-71879-

Fluorescent C-NanoDots for rapid detection of BRCA1, CFTR and MRP3 gene mutations

This is a post-peer-review, pre-copyedit version of an article published in Microchimica Acta. The final authenticated version is available online at: http://dx.doi.org/10.1007/s00604-019-3386-9The authors report on a fluorometric method for the rapid detection of BRCA1, CFRT and MRP3 gene mutations. These are associated with breast cancer, cystic fibrosis and autoimmune hepatitis diseases, respectively. Carbon nanodots with blue fluorescence (with excitation/emission maxima at 340/440 nm) were synthesized and characterized, and their interactions with DNA were investigated. Changes in the fluorescence intensity following interaction with ssDNA and dsDNA were used for specific DNA sequence of BRCA1, CFRT and MRP3 genes detection. The response to DNAs is linear up to 200 nM and the detection limit is 270 pM. The assay selectivity allows the detection of single gene mutations. Under optimum conditions, the assay can rapidly discriminate between wild type and mutated samplesCAM projects: TRANSNANOAVANSENS-CM (S2018/NMT-4349) and MAD2D-CM Program. MEIC projects: CTQ2017-84309-C2-1-R and MAT2015-71879-P. We thank the Confocal Microscopy and Flow Cytometry Services of CBMS

Enhanced Performance of Reagent-Less Carbon Nanodots Based Enzyme Electrochemical Biosensors

This work reports on the advantages of using carbon nanodots (CNDs) in the development of reagent-less oxidoreductase-based biosensors. Biosensor responses are based on the detection of H2O2, generated in the enzymatic reaction, at 0.4 V. A simple and fast method, consisting of direct adsorption of the bioconjugate, formed by mixing lactate oxidase, glucose oxidase, or uricase with CNDs, is employed to develop the nanostructured biosensors. Peripherical amide groups enriched CNDs are prepared from ethyleneglycol bis-(2-aminoethyl ether)-N,N,N′,N′-tetraacetic acid and tris(hydroxymethyl)aminomethane, and used as precursors. The bioconjugate formed between lactate oxidase and CNDs was chosen as a case study to determine the analytical parameters of the resulting L-lactate biosensor. A linear concentration range of 3.0 to 500 µM, a sensitivity of 4.98 × 10−3 µA·µM−1, and a detection limit of 0.9 µM were obtained for the L-lactate biosensing platform. The reproducibility of the biosensor was found to be 8.6%. The biosensor was applied to the L-lactate quantification in a commercial human serum sample. The standard addition method was employed. L-lactate concentration in the serum extract of 0.9 ± 0.3 mM (n = 3) was calculated. The result agrees well with the one obtained in 0.9 ± 0.2 mM, using a commercial spectrophotometric enzymatic kit

Reagent-Less and Robust Biosensor for Direct Determination of Lactate in Food Samples

Lactic acid is a relevant analyte in the food industry, since it affects the flavor, freshness, and storage quality of several products, such as milk and dairy products, juices, or wines. It is the product of lactose or malo-lactic fermentation. In this work, we developed a lactate biosensor based on the immobilization of lactate oxidase (LOx) onto N,N′-Bis(3,4-dihydroxybenzylidene) -1,2-diaminobenzene Schiff base tetradentate ligand-modified gold nanoparticles (3,4DHS–AuNPs) deposited onto screen-printed carbon electrodes, which exhibit a potent electrocatalytic effect towards hydrogen peroxide oxidation/reduction. 3,4DHS–AuNPs were synthesized within a unique reaction step, in which 3,4DHS acts as reducing/capping/modifier agent for the generation of stable colloidal suspensions of Schiff base ligand–AuNPs assemblies of controlled size. The ligand—in addition to its reduction action—provides a robust coating to gold nanoparticles and a catalytic function. Lactate oxidase (LOx) catalyzes the conversion of l-lactate to pyruvate in the presence of oxygen, producing hydrogen peroxide, which is catalytically oxidized at 3,4DHS–AuNPs modified screen-printed carbon electrodes at +0.2 V. The measured electrocatalytic current is directly proportional to the concentration of peroxide, which is related to the amount of lactate present in the sample. The developed biosensor shows a detection limit of 2.6 μM lactate and a sensitivity of 5.1 ± 0.1 μA·mM−1. The utility of the device has been demonstrated by the determination of the lactate content in different matrixes (white wine, beer, and yogurt). The obtained results compare well to those obtained using a standard enzymatic-spectrophotometric assay kit

Reagent-Less and Robust Biosensor for Direct Determination of Lactate in Food Samples

Lactic acid is a relevant analyte in the food industry, since it affects the flavor, freshness, and storage quality of several products, such as milk and dairy products, juices, or wines. It is the product of lactose or malo-lactic fermentation. In this work, we developed a lactate biosensor based on the immobilization of lactate oxidase (LOx) onto N,N′-Bis(3,4-dihydroxybenzylidene) -1,2-diaminobenzene Schiff base tetradentate ligand-modified gold nanoparticles (3,4DHS–AuNPs) deposited onto screen-printed carbon electrodes, which exhibit a potent electrocatalytic effect towards hydrogen peroxide oxidation/reduction. 3,4DHS–AuNPs were synthesized within a unique reaction step, in which 3,4DHS acts as reducing/capping/modifier agent for the generation of stable colloidal suspensions of Schiff base ligand–AuNPs assemblies of controlled size. The ligand—in addition to its reduction action—provides a robust coating to gold nanoparticles and a catalytic function. Lactate oxidase (LOx) catalyzes the conversion of l-lactate to pyruvate in the presence of oxygen, producing hydrogen peroxide, which is catalytically oxidized at 3,4DHS–AuNPs modified screen-printed carbon electrodes at +0.2 V. The measured electrocatalytic current is directly proportional to the concentration of peroxide, which is related to the amount of lactate present in the sample. The developed biosensor shows a detection limit of 2.6 μM lactate and a sensitivity of 5.1 ± 0.1 μA·mM−1. The utility of the device has been demonstrated by the determination of the lactate content in different matrixes (white wine, beer, and yogurt). The obtained results compare well to those obtained using a standard enzymatic-spectrophotometric assay kit

Gallium nanoparticles colloids synthesis for UV bio-optical sensors

Paper presented at the SPIE Optics + Optoelectronics, held in Prague (Czech Republic) on April 24-27th 2017.A new method for the synthesis of colloidal gallium nanoparticles (Ga NPs) based on the thermal evaporation of Ga on an expendable aluminum zinc oxide (AZO) layer is presented here. The growth of AZO layers was investigated on different substrates at room temperature and 300 °C. By means of physical evaporation process, nanoparticles were deposited with a distribution ranging from 10 nm to 80 nm in diameter. A study of their endurance in acidic environment was carried out in order to assure the NPs shape and size stability during the etching process. Smaller particles start to disappear between 1h and 2h immersion time in a pH=1 solution, while bigger particles reduce their dimension. The NPs were dispersed in tetrahydrofuran (THF) organic solvent and optically characterized, showing strong UV absorption with a band centered at 280 nm. The colloids size distribution of as-evaporated samples was compared with the distribution obtained in droplets of the solution after drop-casting. By Dipole Discrete Approximation simulations, a close relationship between the UV absorption and the NPs with diameter smaller than ~40 nm was found. Because of the gallium oxide (Ga1-xOx) outer shell that surrounds the Ga NPs, an enhancement of their hydrophobicity occurs. Hence, the low agglomeration state between NPs in tetrahydrofuran allows to obtain narrow absorption band in the optical spectrum