Novel solid inks based on beeswax, graphite and graphene applied to the fabrication of paper-based sensor for galactose determination.

In this study, we present for the first time a simple and novel method for the fabrication of paper-based electrochemical sensors. The device development was carried out in a single stage with a standard wax printer. Hydrophobic zones were delimited with commercial solid ink, while electrodes were generated using new composite solid inks of graphene oxide/graphite/beeswax (GO/GRA/beeswax) and graphite/beeswax (GRA/beeswax). Subsequently, the electrodes were electrochemically activated by applying an overpotential. Various experimental variables for the GO/GRA/beeswax composite synthesis and electrochemical system obtention were evaluated. The activation process was examined by SEM, FTIR, cyclic voltammetry, electrochemical impedance spectroscopy and contact angle measurement. These studies showed morphological and chemical changes in the electrode active surface. As a result, the activation stage considerably improved the electron transfer on the electrode. The manufactured device was successfully applied for galactose (Gal) determination. This method presented a linear relation in the Gal concentration range from 84 to 1736 µmol L-1, with a LOD of 0.1 µmol L-1. The variation within and between-assay coefficients were 5.3% and 6.8%, respectively. The strategy here exposed for paper-based electrochemical sensors design is an unprecedented alternative system and represents a promising tool for mass production of economic analytical devices.

Kosakonia radicincitans and Cryptococcus laurentii controlled Penicillium expansum rot and decreased patulin production at 4 and 25 °C.

In the present work, we evaluated the effects of a mixture of biocontrol agents against two toxigenic strains of Penicillium expansum isolated in Argentine Patagonia from pome fruits. The two strains, INTA-5 and INTA-10, were previusly selected among ten strains coming from the Alto Valle (Rio Negro-Argentina) for their high production of patulin. For the biocontrol, Kosakonia radicincitans, Cryptococcus laurentii, and Rhodosporidium fluviale were tested in vitro experiments on Potato Dextrose Agar (PDA) dishes against the INTA-5 and INTA-10 strains. The bacterium K. radicincitans and the yeast C. laurentii were selected to be used in a mixture due to their capacity to control the fungus and reduce the mycotoxin severely. In vitro assays with the mixture showed a high antagonism against P. expansum INTA-5 and INTA-10, at 21 d of incubation at 25 °C and a patulin reduction of 98%. The mixture of microorganisms was also effective in apples stored at 25 °C for 10 d and 4 °C for 30 d. At cold storage, the mixture controlled moderately the development of rot and decreased patulin concentration. At 25 °C, the pathogen's optimal growth temperature, the mixture of Biological Control Agent (BCAs) assured both the control of rot and decrease of patulin concentration. The combination of two microorganisms, with different requirements and abilities, resulted in a mix with a strong antagonism against P. expansum with the capability to decrease the patulin concentration. Treatment with the selected mixture could be a good option for controlling strains with different behaviours and in different environmental conditions.

First steps in the formulation of praziquantel nanosuspensions for pharmaceutical applications.

Praziquantel (PZQ), a broad spectrum anthelmintic drug, cannot be found in acceptable dosage forms for elderly patients, paediatric patients, and for veterinary use. In fact, very little has been done up to now in the formulation of liquid dosage forms, being they always formulated for parenteral administration. To beat this important challenge, it was accomplished a comprehensive analysis of the influence of two elementary physicochemical aspects, i.e. surface thermodynamic and electrokinetic properties, on the colloidal stability of PZQ nanosuspensions. The hydrophobic character of the drug, intensely determining the flocculation curves, was confirmed by the thermodynamic characterization. The electrophoretic characterization, in combination with the sedimentation and relative absorbance versus time curves, highlighted that the electrical double layer thickness and the surface charge can play an essential role in the stability of the pharmaceutical colloid. Finally, it was demonstrated that controlling the pH values and the incorporation of electrolytes can help in formulating PZQ aqueous nanosuspensions with appropriate stability and redispersibility behaviours for pharmaceutical use.

Electrochemical microfluidic immunosensor based on TES-AuNPs@Fe3O4 and CMK-8 for IgG anti-Toxocara canis determination.

We report a microfluidic immunosensor for the electrochemical determination of IgG antibodies anti-Toxocara canis (IgG anti-T. canis). In order to improve the selectivity and sensitivity of the sensor, core-shell gold-ferric oxide nanoparticles (AuNPs@Fe3O4), and ordered mesoporous carbon (CMK-8) in chitosan (CH) were used. IgG anti-T. canis antibodies detection was carried out using a non-competitive immunoassay, in which excretory secretory antigens from T. canis second-stage larvae (TES) were covalently immobilized on AuNPs@Fe3O4. CMK-8-CH and AuNPs@Fe3O4 were characterized by transmission electron microscopy, scanning electron microscopy, energy dispersive spectrometry, cyclic voltammetry, electrochemical impedance spectroscopy, and N2 adsorption-desorption isotherms. Antibodies present in serum samples immunologically reacted with TES, and then were quantified by using a second antibody labeled with horseradish peroxidase (HRP-anti-IgG). HRP catalyzes the reduction from H2O2 to H2O with the subsequent oxidation of catechol (H2Q) to p-benzoquinone (Q). The enzymatic product was detected electrochemically at _100 mV on a modified sputtered gold electrode. The detection limit was 0.10 ng mL-1, and the coefficients of intra- and inter-assay variation were less than 6%, with a total assay time of 20 min. As can be seen, the electrochemical immunosensor is a useful tool for in situ IgG antibodies anti-T. canis determination.

Paper surface modification strategies employing N-SBA-15/polymer composites in bioanalytical sensor design.

In this work, different paper surface modification strategies were compared to obtain an amine functionalized SBA-15 (N-SBA-15) composite for paper-based device development. The synthesized N-SBA-15 was characterized by N2 adsorption-desorption isotherm, and infrared spectroscopy (FTIR), and it was incorporated to different polymer matrices (κ-carrageenan (CA), polyvinyl alcohol (PVA) and polyethylenimine (PEI)) for the development of the composite modified paper-based device. The retention, interactions, and morphology of the obtained composites were investigated by absorbance measurement, FTIR and scanning electron microscopy (SEM), respectively. To demonstrate the applicability of the modified paper-based device, ascorbic acid (AA) quantification was carried out. Horseradish peroxidase (HRP) was immobilized onto the modified paper surface. HRP in the presence of H2O2 catalyzes the oxidation of 10-acetyl-3,7-dyhidroxyphenoxazine (ADHP) to highly fluorescent resorufin, which was measured by LIF detector. Thus, when AA was added to the solution, it decreases the relative fluorescence signal proportionally to the AA concentration. The linear range from 50 nmol L-1 to 1500 nmol L-1 and a detection limit of 15 nmol L-1 were obtained for AA quantitation. The obtained results allowed us to conclude that N-SBA-15/PEI composite could be considered an excellent choice for the paper-based device modification procedure due to its inherent simplicity, low cost, and sensitivity.

EGFR detection in extracellular vesicles of breast cancer patients through immunosensor based on silica-chitosan nanoplatform.

In the present work, we designed a microfluidic electrochemical immunosensor with enough sensibility and precision to quantify epithermal growth factor receptor (EGFR) in plasma extracellular vesicles (EVs) of plasma from breast cancer patients. The sensor employs SiNPs coated with chitosan (SiNPs-CH) as reaction's platform, based on the covalently immobilization of monoclonal anti-EGFR on SiNPs-CH retained in the central channel (CC) of the microfluidic device. The synthetized SiNPs-CH were characterized by UV-visible spectroscopy (UV-visible), energy dispersive spectrometry (EDS), Nanoparticle Tracking Analysis (NTA) and transmission electron microscopy (TEM). EGFR was quantified by a direct sandwich immunoassay measuring through a horseradish peroxidase (HRP)-conjugated anti-EGFR. The enzymatic product (benzoquinone) was detected by reduction at - 100 mV on a sputtering gold electrode. The measured current was directly proportional to the level of EGFR in human serum samples. The linear range was from 0 ng mL-1 to 50 ng mL-1. The detection limit was 1.37 pg mL-1, and the within- and between-assay coefficients of variation were below 6.25%. Finally, plasma samples from 30 early breast cancer patients and 20 healthy donor were analyzed by the novel method. EGFR levels in EVs (EVs-EGFR) were significantly higher than in the healthy control group (p = 0.002) and also, more sensitivity and specificity than normal serum markers like CEA and CA15.3 has been observed. EVs-EGFR concentration correlates with EGFR tumor status (p = 0.0003) as well as it correlate with the tumor size and pathological grade. To conclude, plasma EVs are suitable for proteomic characterization of cancer disease, as long as the employed method has sufficient sensitivity, like the case of immune-electrochemical nanosensors with incremented reaction surface.

Novel electrochemical sensing platform based on a nanocomposite of PVA/PVP/RGO applied to IgG anti- Toxoplasma gondii antibodies quantitation.

This article describes the development of a new electrochemical platform composed by a polymer mixture and graphene oxide (GO). The working electrode of a screen-printed carbon electrode (SPCE) was modified with nanocomposite constituted by poly-vinyl alcohol (PVA), poly-vinylpyrrolidone (PVP) and GO, which was electrochemically reduced to obtain PVA/PVP/RGO/SPCE. The interactions and morphology of the PVA/PVP/GO nanocomposite were investigated by SEM, FTIR and UV-Vis. SEM images indicated an excellent dispersion of the GO sheets in the polymer matrix. Besides, FTIR and visible UV studies revealed strong interactions between polymer mixture and GO sheets. According to electrochemical studies, the new platform increased the electroactive surface area by a factor of 20.46 compared to the unmodified SPCE. Also, the PVA/PVP/RGO/SPCE had a fast electron kinetics transfer process with a value of ks = 9.6 s-1. The modified electrode was applied to the determination of IgG anti-T. gondii antibodies for the serological diagnosis of toxoplasmosis. The IgG anti-T. gondii antibodies quantification showed a detection limit of 0.012 U mL-1, and the coefficients of variation intra-day and inter-day assays were lower than 4.5% and 6.2%, respectively. The electrochemical platform proved to be a sensitive and easily applicable tool applied to the serological diagnosis of toxoplasmosis. Therefore, the developed nanocomposite represents an excellent alternative for the electrochemical biosensor fabrication.

Serological diagnosis of Toxoplasmosis disease using a fluorescent immunosensor with chitosan-ZnO-nanoparticles.

This article describes a microfluidic LIF immunosensor for the quantitative determination of anti-Toxoplasma gondii IgG (anti-T. gondii) specific antibodies. The serological detection of these antibodies plays a crucial role in the clinical diagnosis of toxoplasmosis. Zinc oxide nanoparticles (ZnO-NPs) obtained by wet chemical procedure were covered with chitosan and then used to conjugate T-gondii antigens into the central microfluidic channel. Serum samples containing anti-T-gondii IgG antibodies were injected into the immunosensor where they interact immunologically with T. gondii antigens. Bound antibodies were quantified by the addition of anti-IgG antibodies labeled whit alkaline phosphatase (ALP). ALP enzymatically converts the non-fluorescent 4-methylumbelliferyl phosphate (4-MUP) to soluble fluorescent methylumbelliferone that was measured using excitation at 355 nm and emission at 440 nm. The relative fluorescent response of methylumbelliferone is proportional to the concentration of anti-T. gondii IgG antibodies. The coefficients of variation are less than 4.73% for within-day assays and less than 6.34% for between-day assays. Results acquired by LIF immunosensor agree with those obtained by enzyme-linked immunosorbent assay method, suggesting that the designed sensor represents a promising tool for the quantitative determination of anti-T. gondii IgG antibodies of clinical samples.

Paper-based enzymatic platform coupled to screen printed graphene-modified electrode for the fast neonatal screening of phenylketonuria.

INTRODUCTION: The PKU is an inborn error of amino acid metabolism, in which phenylalanine (Phe) accumulated in the blood causing alterations at the central nervous system. We report a novel paper-based enzymatic platform coupled to screen printed graphene-modified electrode for the neonatal screening of phenylketonuria (PKU0. METHODS: The paper-based analytical device coupled to electrochemical detection (EPAD) is based on the use of paper microzones modified with phenylalanine dehydrogenase enzyme (PheDH). The modified PADs were placed on the surface of an electrode modified with electrochemically reduced graphene (ERGO). PheDH in the presence of NAD+ catalyzes the reversible deamination of Phe to form phenylpyruvate, ammonia, and NADH. The electrochemical oxidation of NADH was monitored by differential pulse amperometry (DPA) at 0.6 V. The method was linear in the concentration range from 1 to 600 µmol/L of Phe with a LOQ of 1 µmol/L and LOD of 0.2 µmol/L. Within day precision was 5.7% across 3 levels of control samples. Between-day precision was 8.3%. The comparison with the standard Phe enzyme assay kit showed good agreement. The time required for the overall assay was <5 min. The non-sophisticated equipment required, the short assay time and the appropriate LOQ and LOD achieved by our EPAD make it an attractive and easy to use alternative compared to existing methods applied to the screening of PKU in neonatal samples.

A simple, rapid and novel method based on salting-out assisted liquid-liquid extraction for ochratoxin A determination in beer samples prior to ultra-high-performance liquid chromatography coupled to tandem mass spectrometry.

A novel, simple, easy and cheap sample treatment strategy based on salting-out assisted liquid-liquid extraction for ochratoxin A (OTA) ultra-trace analysis in beer samples using ultra-high-performance liquid chromatography-tandem mass spectrometry determination was developed. The factors involved in the efficiency of pre-treatment were studied employing factorial design in the screening phase and the optimal conditions of the significant variables on the analytical response were evaluated using a central composite face-centred design. Consequently, the amount of salt ((NH4)2SO4), together with the volumes of sample, hydrophilic (acetone) and nonpolar (toluene) solvents, and times of vortexing and centrifugation were optimised. Under optimised conditions, the limits of detection and quantification were 0.02 µg l-1 and 0.08 µg l-1 respectively. OTA extraction recovery by SALLE was approximately 90% (0.2 µg l-1). Furthermore, the methodology was in agreement with EU Directive requirements and was successfully applied for analysis of beer samples.

Novel Electrochemical Paper-Based Immunocapture Assay for the Quantitative Determination of Ethinylestradiol in Water Samples.

We report a novel and innovative electrochemical paper-based immunocapture assay (EPIA) to address the need for ultrasensitive detection of emerging pollutants without regulatory status and whose effects on environment and human health are not completely yet understood. In particular, we present the application of this system toward highly sensitive detection of the emerging pollutant ethinyl estradiol (EE2). The EPIA approach is based on the use of paper microzones modified with silica nanoparticles (SNs) and anti-EE2 specific antibodies for capture and preconcentration of EE2 from river water samples. After the preconcentration procedure, the paper microzones are placed onto a screen-printed carbon electrode modified with electrochemically reduced graphene (RG). The bound EE2 is subsequently desorbed adding a diluted solution of sulfuric acid on the paper microzones. Finally, recovered EE2 is electrochemically detected by OSWV. The proposed novel methodology showed an appropriate LOD and linear range for the quantification of EE2 for water samples with different origins. The nonsophisticated equipment required, the adequate recovery values obtained (from 97% to 104%, with a RSD less than 4.9%), and the appropriate LOD and linear range value (0.1 ng L-1 and 0.5-120 ng L-1, respectively) achieved by our immunocapture sensor present significant analytical figures of merit, particularly when the routine quantification of EE2 is considered. In addition, our system was based on electrochemical paper-based technology, which allows obtainment of portable, easy-to-use, inexpensive, and disposable devices. The EPIA can also serve as a general-purpose immunoassay platform applicable to quantitation of other drugs and emerging pollutants in environmental samples.

Development of a nanostructured immunosensor for early and in situ detection of Xanthomonas arboricola in agricultural food production.

We report a microfluidic electrochemical immunosensor for Xanthomonas arboricola (XA) determination, based on the covalently immobilization of monoclonal anti-XA antibody (anti-XA) on a previously amino functionalized SBA-15 in situ synthesized in the central channel of a glass-poly(dimethylsiloxane) microfluidic immunosensor. The synthetized amino-SBA-15 was characterized by N2 adsorption-desorption isotherm, scanning electron microscopy and infrared spectroscopy. XA was detected by a direct sandwich immunoassay through an alkaline phosphatase (AP) enzyme-labeled anti-XA conjugate. Later, the substrate p-aminophenyl phosphate was converted to p-aminophenol by AP. The enzymatic product was detected at +100mV on a sputtered gold electrode. The measured current was directly proportional to the level of XA in walnut trees samples. The linear range was from 5 × 102 to 1 × 104CFUmL-1. The detection limit was 1.5 × 102CFUmL-1, and the within- and between-assay coefficients of variation were below 5%. Microfluidic immunosensor is a very promising tool for the early and in situ diagnosis of XA in walnuts avoiding serious economic losses.

Microfluidic immunosensor based on mesoporous silica platform and CMK-3/poly-acrylamide-co-methacrylate of dihydrolipoic acid modified gold electrode for cancer biomarker detection.

We report a hybrid glass-poly (dimethylsiloxane) microfluidic immunosensor for epidermal growth factor receptor (EGFR) determination, based on the covalent immobilization of anti-EGFR antibody (anti-EGFR) on amino-functionalized mesoporous silica (AMS) retained in the central channel of a microfluidic device. The synthetized AMS was characterized by N2 adsorption-desorption isotherm, scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and infrared spectroscopy. The cancer biomarker was quantified in human serum samples by a direct sandwich immunoassay measuring through a horseradish peroxidase-conjugated anti-EGFR. The enzymatic product was detected at -100 mV by amperometry on a sputtering gold electrode, modified with an ordered mesoporous carbon (CMK-3) in a matrix of poly-acrylamide-co-methacrylate of dihydrolipoic acid (poly(AC-co-MDHLA)) through in situ copolymerization. CMK-3/poly(AC-co-MDHLA)/gold was characterized by cyclic voltammetry, EDS and SEM. The measured current was directly proportional to the level of EGFR in human serum samples. The linear range was from 0.01 ng mL-1 to 50 ng mL-1. The detection limit was 3.03 pg mL-1, and the within- and between-assay coefficients of variation were below 5.20%. The microfluidic immunosensor is a very promising device for the diagnosis of several kinds of epithelial origin carcinomas.

Integrated bio-affinity nano-platform into a microfluidic immunosensor based on monoclonal bispecific trifunctional antibodies for the electrochemical determination of epithelial cancer biomarker.

BACKGROUND: The epithelial cell adhesion molecule (EpCAM) is a biomarker that is highly overexpressed on the surface of epithelial carcinoma cells. In this study, silver nanoparticles covered with polyvinyl alcohol (AgNPs-PVA) were synthesized, characterized and used in a microfluidic immunosensor based on the use of anti-EpCAM recombinant antibodies as a trapping agent. METHODS: The concentration of trapped EpCAM is then electrochemically quantified by HRP-conjugated anti-EpCAM-antibody. HRP reacted with its enzymatic substrate in a redox process which resulted in the appearance of a current whose magnitude (at a working voltage as low as -0.10V) is directly proportional to the concentration of EpCAM. RESULTS: Under optimized conditions, the detection limits for the microfluidic immunosensor and a commercial ELISA were 0.8 and 13.9pg/L, respectively. The within-assay and between-assay coefficients of variation are below 6.5% for the proposed method. The immunosensor was validated by analyzing patient samples, and a good correlation with a commercial ELISA was obtained. CONCLUSIONS: The good analytical performance is attributed to the efficient immobilization of the anti-EpCAM recombinant antibodies on the AgNPs-PVA, and its high specificity for EpCAM. This microfluidic immunosensor is intended for use in diagnosis and prognosis of epithelial cancer, to monitor the disease, and to assess therapeutic efficacy.

Assessment of ochratoxin A occurrence in Argentine red wines using a novel sensitive quechers-solid phase extraction approach prior to ultra high performance liquid chromatography-tandem mass spectrometry methodology.

BACKGROUND: The assessment of ochratoxin A (OTA) in wine is relevant for food safety and its continuous control allows to reduce the risk of intake. Thus, a novel sensitive QuEChERS-SPE (Quick, Easy, Cheap, Effective, Rugged and Safe - Solid Phase Extraction) pretreatment prior to liquid chromatography coupled to tandem mass spectrometry was developed for the determination of OTA in red wine samples from different grape-growing regions in Argentine. RESULTS: A sensitive methodology was achieved and thus the limits of detection and quantification were 0.02 and 0.05 µg L-1 , respectively. Recoveries ranged from 89.0% to 105.3%. The method was applied to 136 red wine samples (Argentina's flagship varieties: Malbec and Cabernet Sauvignon) from ten grape-growing regions, during vintages 2013-2015. Although all of the samples investigated were contaminated with OTA (concentrations ranged from 0.02 to 0.98 µg L-1 ), the levels detected were lower than the maximum allowable concentration limit of 2.0 µg L-1 established by international regulations. CONCLUSION: The methodology proposed is suitable for reliable OTA analysis in red wines. Similarly, the values obtained from the samples analyzed were in accordance with the current regulations and, as a consequence, preventive actions to reduce this mycotoxin incidence can be undertaken. © 2016 Society of Chemical Industry.

A green alternative method for analysis of ivermectin and moxidectin in environmental water samples using automatized preconcentration previous MEEKC.

Antiparasitic drugs derived from macrocyclic lactones (MLs) are widely used in livestock activities around the world. An increasing concern for local authorities is the environmental pollution as a consequence of veterinary drugs widely used in rural areas. The purpose of environmental analysis is to monitor low levels of pollutant analytes in a large number of samples. Also, due to the lipophilic characteristic of these lactones, long-chain solvents are usually required for performing sample treatment before and during the analysis. Therefore, sensitive, specific, robust, and environmentally friendly analytical methods are still required. In this paper, a new automatized preconcentration methodology followed by microemulsion electrokinetic chromatography analysis was developed for the simultaneous separation and determination of the most used MLs, ivermectin (IVM) and moxidectin (MXD) in environmental water. XAD-4 resin was employed as an adsorbent for the preconcentration process and ethanol was used as the eluent. In contrast to traditional analysis for IVM and MXD, in this methodology nonpolluting solvents were involved during the whole process and therefore, it could be considered as a contribution to green analytical chemistry. Under optimal experimental conditions, LOD obtained for IVM and MXD were of 3 × 10-3 and 3.6 × 10-3 µg/L, respectively.

Enhanced electrochemical detection of quercetin by Natural Deep Eutectic Solvents.

New trends in analytical chemistry encourage the development of smart techniques and methods aligned with Green Chemistry. In this sense, Natural Deep Eutectic Solvents represents an excellent opportunity as a new generation of green solvents. In this work a new application for them has been proposed and demonstrated. These solvents were synthesized by combinations of inexpensive and natural components like, Glucose, Fructose, Citric acid and Lactic acid. The different natural solvents were easily prepared and added to buffer solution in different concentrations, allowing the enhancement of electrochemical detection of an important representative antioxidant like quercetin (QR) with improved signal up to 380%. QR is a ubiquitous flavonoid widespread in plants and food of plant origin. The proposed method using phosphate buffer with a eutectic mixture of Citric acid, Glucose and water in combination with carbon screen printed electrodes exhibited a good analytical performance. Detection and quantification limits were of 7.97 and 26.3 nM respectively; and repeatability with %RSDs of 1.41 and 7.49 for peak potential and intensity respectively. In addition, it has proved to be faster, greener and cheaper than other sensors and chromatographic methods available with the additional advantage of being completely portable. Furthermore, the obtained results demonstrated that the proposed method is able for the determination of QR in complex food samples.

Development of nitrocellulose membrane filters impregnated with different biosynthesized silver nanoparticles applied to water purification.

Bactericidal water filters were developed. For this purpose, nitrocellulose membrane filters were impregnated with different biosynthesized silver nanoparticles. Silver nanoparticles (AgNPs) from Aspergillus niger (AgNPs-Asp), Cryptococcus laurentii (AgNPs-Cry) and Rhodotorula glutinis (AgNPs-Rho) were used for impregnating nitrocellulose filters. The bactericidal properties of these nanoparticles against Escherichia coli, Enterococcus faecalis and Pseudomona aeruginosa were successfully demonstrated. The higher antimicrobial effect was observed for AgNPs-Rho. This fact would be related not only to the smallest particles, but also to polysaccharides groups that surrounding these particles. Moreover, in this study, complete inhibition of bacterial growth was observed on nitrocellulose membrane filters impregnated with 1 mg L(-1) of biosynthesized AgNPs. This concentration was able to reduce the bacteria colony count by over 5 orders of magnitude, doing suitable for a water purification device.

Study of antitumor activity in breast cell lines using silver nanoparticles produced by yeast.

In the present article, we describe a study of antitumor activity in breast cell lines using silver nanoparticles (Ag NPs) synthesized by a microbiological method. These Ag NPs were tested for their antitumor activity against MCF7 and T47D cancer cells and MCF10-A normal breast cell line. We analyzed cell viability, apoptosis induction, and endocytosis activity of those cell lines and we observed that the effects of the biosynthesized Ag NPs were directly related with the endocytosis activity. Moreover, Ag NPs had higher inhibition efficacy in tumor lines than in normal lines of breast cells, which is due to the higher endocytic activity of tumor cells compared to normal cells. In this way, we demonstrate that biosynthesized Ag NPs can be an alternative for the treatment of tumors.

Copper nanoparticles applied to the preconcentration and electrochemical determination of ß-adrenergic agonist: an efficient tool for the control of meat production.

A novel method for preconcentration and electrochemical detection of zinterol in bovine urine samples was developed. In order to improve the limit of detection, the surface of a screen-printed carbon electrode was modified with electrodeposited metal copper nanoparticles. The experimental electrodeposition optimization was performed using a central composite design (CCD), involving the variables: precursor concentration, potential and time applied. Copper nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, cyclic voltammetry, and energy dispersive X-ray spectroscopy. Mesoporous shuttle-like copper oxide nanoparticles were used for the preconcentration step to avoid interferences with many compounds present in the sample matrix. The optimal working conditions for the preconcentration approach were found by means of both two-level fractional factorial and CCD designs. The obtained enhancement factor for a sample volume of 30 mL was 35 fold. The calibration curve showed linearity between 0.5 and 45 ng mL(-1) and the limit of detection was 0.16 ng mL(-1). The intra and inter assay coefficients of variability were below 4% and 5%; respectively.