Paper-Based Biosensors for Analysis of Water

The presence of contaminants in water generates a great concern worldwide. As contaminants, we can refer different classes of chemicals, such as pharmaceuticals, personal care products, heavy metals, and also microorganisms, such as waterborne pathogens. Some of the chemical compounds have the potential to bioaccumulate in the aquatic biota. Hence, the development of simple and portable methods for the detection of contaminants in the aquatic environment can improve their monitoring and, consequently, the study of their environmental impact. In this context, the development of paper-based analytical tools and also of biosensor devices has been exploited for quantitative and semiquantitative analysis of several contaminants in different water matrices. The association of these two analytical strategies can provide the implementation of low-cost, portable, and easily handled methods for detecting chemical and biological contaminations in water. In this chapter, we provide a review of the developed paper-based analytical biosensors, highlighting the features of the paper-based (paper substrate and fabrication procedures) and biosensor devices (transducers and biorecognition elements). Moreover, the application of the referred paper-based biosensors for the detection of different water contaminants (pathogens, pharmaceuticals, and heavy metals) in environmental and wastewater samples is discussed

Fluorometric method based on molecular recognition solid-phase extraction for determination of riboflavin in milk and infant formula

Riboflavin (vitamin B2) is involved in several biological processes, particularly in energy production, and it is acquired from food ingestion, principally from supplemented food during the first years of life. Therefore, a simple, fast and cost-effective high-throughput method for determination of riboflavin in milk and infant formula is proposed, based on selective extraction using commercially available molecularly imprinted polymers targeted to riboflavin, followed by direct fluorometric determination. Several aspects were studied, namely microplate assay conditions, the composition of eluting solution and the stability of riboflavin in the eluate. Hence, elution using 1% (v/v) acetic acid in methanol or in acetonitrile is recommended, followed by immediate analysis or solvent evaporation, with reconstitution and analysis within 24 h. The proposed method provided a LOD of 0.03 mg L−1, with working range for undiluted samples between 0.125 and 2 mg L−1, and sample throughput of 24 h−1. It was successfully applied to certified reference material NIST-1846 and also to commercial milk and infant formula samples.info:eu-repo/semantics/publishedVersio

Spectrophotometric determination of Bromate in water using multisyringe flow injection analysis

A multisyringe flow injection system for the spectrophotometric determination of bromate in water is proposed, based on the oxidation of phenothiazine compounds by bromate in acidic medium. Several phenothiazines were tested, including chlorpromazine, trifluoperazine, and thioridazine. Higher sensitivity and lower LOD were attained for chlorpromazine. Interference from nitrite, hypochlorite, and chlorite was eliminated in-line, without any changes in the manifold. The automatic methodology using chlorpromazine allowed the determination of bromate between 25 and 750 lgL 1, with LOD of 6 lgL 1, good precision (RSD<1.6%, n¼10), and determination frequency of 35 h 1.info:eu-repo/semantics/submittedVersio

Sample introduction in multi-syringe flow injection systems: comparison between time-based and volume-based strategies

In multi-syringe flowinjection analysis (MSFIA), devices as selection, injection or commutation valves must be incorporated to the manifold to provide access to sample and standard solutions. Therefore, the definition of sample amount can be either volume or time-based. In the present work, four configurations for sample introduction (two for each approach) were tested in order to establish if the different strategies affect the analytical signal in MSFIA systems. The mean absorbance value from ten consecutive injections of a bromothymol blue solution obtained for the time-based strategy was lower than that provided by the volume-based approach as the exact volume delivered by each configuration was different from the “theoretical” volume. For time-based configurations, the exact volume delivered is 2–5% lower than the theoretical value while for volume-based configurations, the volume delivered was between 6 and 46% larger than the theoretical volume. Moreover, for time-based sampling, the order of steps in the analytical cycle was of utmost importance since any alteration in the flow direction affected the volume delivered in the subsequent step in the analytical cycle. The influence of the two sampling approaches was also evaluated in the MSFIA systems for the spectrophotometric determination of phenolic compounds and the potentiometric determination of chloride. There was no evidence that the use of either volume or time-based sampling would improve the analytical features of these determinations when real samples were tested.info:eu-repo/semantics/acceptedVersio

Influence of pH on cellular growth of Pichia pastoris KM71H by fed-batch process

Pichia pastoris is a methylotrophic yeast that can be genetically engineered to express proteins for industrial use. One of the most important advantages of protein expression in P. pastoris is its capability of growing on minimal medium and efficiently secreting heterologous proteins with low secretion levels of endogenous proteins. Operational variables such as pH, temperature, stirring rate, among others, usually affect the microorganism’s growth during the fermentation processes. Therefore, the present work aimed to evaluate the influence of pH on cellular growth of P. pastoris KM71H by fed‐batch process. The fermentation run was carried out in a 1.6 L (total volume) bioreactor, being performed in two phases: In the first stage (24 h), the yeast was batchcultured in BMGH medium; while in the second stage (72 h), it was cultivated by feed‐batch operation with a feeding medium containing 50% glycerol and 12ml/l of trace metal solution. During the overall process, which lasted after 96 h, the aeration and temperature conditions were fixed at 10 ml\L.h, 1.5 vvm and 30°C, respectively. Different pH values were evaluated: 5.0, 5.5 and 6.0. Cellular growth was determined by measuring the fermentation broth UVspectrophotometric absorbance at 600 nm, which was correlated to a calibration curve (dry weight ´ optical density). Glycerol consumption was detected by HPLC analysis. P. pastoris KM71H successfully grew in all the evaluated pH values; but the highest biomass production was observed at pH 5.0 (98.79 g/L). Although P. pastoris is reported as being a microorganism able to grow over a wide pH range (from 3 to 7); it was not observed high cell density of P. pastoris KM71H strain when cultivated at pHs 5.5 and 6.0. High cellular growth is especially important for proteins secretion, as the concentration of product in the medium is roughly proportional to the concentration of cells in culture. Finally, these results reveal the possibility of obtaining high cell density of P. pastoris KM71H by fed‐bach cultivation at pH 5.0, which can be a suitable condition for the yeast application in heterologous proteins production.Conselho Nacional de Desenvolvimento Científico e Tecnológico Brazil (CNPq)Improving Skills Across Continents (ISAC ) - Erasmus Mundus External Cooperation Window (ERASMUS

IKZF1 Deletions with COBL Breakpoints Are Not Driven by RAG-Mediated Recombination Events in Acute Lymphoblastic Leukemia

IKZF1 deletion (ΔIKZF1) is an important predictor of relapse in both childhood and adult B-cell precursor acute lymphoblastic leukemia (B-ALL). Previously, we revealed that COBL is a hotspot for breakpoints in leukemia and could promote IKZF1 deletions. Through an international collaboration, we provide a detailed genetic and clinical picture of B-ALL with COBL rearrangements (COBL-r). Patients with B-ALL and IKZF1 deletion (n = 133) were included. IKZF1 ∆1-8 were associated with large alterations within chromosome 7: monosomy 7 (18%), isochromosome 7q (10%), 7p loss (19%), and interstitial deletions (53%). The latter included COBL-r, which were found in 12% of the IKZF1 ∆1-8 cohort. Patients with COBL-r are mostly classified as intermediate cytogenetic risk and frequently harbor ETV6, PAX5, CDKN2A/B deletions. Overall, 56% of breakpoints were located within COBL intron 5. Cryptic recombination signal sequence motifs were broadly distributed within the sequence of COBL, and no enrichment for the breakpoint cluster region was found. In summary, a diverse spectrum of alterations characterizes ΔIKZF1 and they also include deletion breakpoints within COBL. We confirmed that COBL is a hotspot associated with ΔIKZF1, but these rearrangements are not driven by RAG-mediated recombination