Fabrication of smartphone-based colorimetric device for detection of water leaks

South Africa is a water-scarce country due to the shortage of rainfall. This scarcity is further exacerbated by the loss of water through leakage from faulty pipes. This paper reports on the use of a simple microfluidic device in the early detection of water leakages. The microfluidic paper-based device (µPADs) were prepared by printing patterns of wax (100 μm width) on the paper surface and melting the wax into the paper to form hydrophobic barriers. Solutions of lower to higher pH were also prepared and were introduced to the chlorophenol red test strips and a range of colours from yellow (lower pH) to purple (higher pH) were obtained. The digital images obtained with the μPADs were analysed using the CIELab colour system. The optimized pH range was wider than the typical grayscale-based image analysis and was successful for a wide pH range of 2–12. The QR codes attached to the strips enable tracking to obtain the real-time location from which leakage was detected. The study conclusively shows that the combination of digital image analysis and a μPAD device is highly efficient for quantitative analysis, and thus useful for the detection of household water leaks.

Detection of Escherichia coli O157:H7 Using Automated Immunomagnetic Separation and Enzyme-Based Colorimetric Assay

The food industry requires rapid and simple detection methods for preventing harm from pathogenic bacteria. Until now, various technologies used to detect foodborne bacteria were time-consuming and laborious. Therefore, we have developed an automated immunomagnetic separation combined with a colorimetric assay for the rapid detection of E. coli O157:H7 in food samples. The colorimetric detection method using enzymatic reaction is fascinating because of its simplicity and rapidity and does not need sophisticated devices. Moreover, the proposed procedures for the detection of bacteria in food take less than 3 h including pre-enrichment, separation and detection steps. First, target-specific immunomagnetic beads were introduced to contaminated milk in a pre-enrichment step. Second, the pre-enriched sample solution containing target bacteria bound on immunomagnetic beads was injected into an automated pretreatment system. Subsequently, the immunomagnetic beads along with target bacteria were separated and concentrated into a recovery tube. Finally, released β-galactosidase from E. coli O157:H7 after lysis was reacted with chlorophenol red β-galactopyranoside (CPRG) used as a substrate and the colorimetric change of CPRG was determined by absorbance measuring or the naked eye. By the proposed approach in this study, we could detect 3 × 102 CFU/mL of E. coli O157:H7 from a milk sample within 3 h.

Efficient Biolistic Transformation of Immature Citrus Rootstocks Using Phosphomannose-isomerase Selection

This research utilized the E. coli manA gene encoding phosphomannose isomerase (PMI) selection on sucrose/mannose medium to increase transformation efficiencies after biolistic transformation of two immature citrus rootstock cultivars. Plasmid DNA, containing the manA gene and the enhanced green fluorescent protein (egfp) reporter gene, was bombarded into epicotyl explants of immature Carrizo citrange and Swingle citrumelo. GFP positive shoots were micro-grafted onto in vitro grown immature Carrizo rootstocks. Nineteen transgenic Carrizo shoots were obtained from ten paired shots, and eight Swingle shoots from five paired shots. The mean transformation efficiency of Carrizo was 1.9 transgenics/paired shot while the transformation efficiency of Swingle was comparable at 1.6 transgenics/paired shot. The transformants were analyzed by PCR for the presence of transgenes. Southern blot analysis of eight representative Carrizo transgenic events and four Swingle transgenic events showed that all transgenics had one to three copies of the manA gene. The PMI enzyme activity in the transgenic lines was confirmed using the chlorophenol red assay.

The Use of Artificial Neural Network to Optimize The pH Response Range of Chlorophenol Red

Artificial Neural Network (ANN) had been used in this study to extend the response range of the pH indicator. The input from absorbance values of the absorbance spectra of chlorophenol red at different pH was used to train the ANN. During the training process, the coefficient values of the ANN will be adjusted to obtain the desire output. In this research, back propagation algorithm had been used for optimizing the response range of the pH indicator chlorophenol red in solution. The result indicates that the use of ANN enable the pH response range to be extended from 4.8-6.8 to 1.0-10.0.

Genotoxicity studies of tetrahydro-naphthalenebenzimidazole/ thiazolidinedione as retinoid derivatives / Tetrahidro-naftalen-benzimidazol/tiyazolidindion retinoid türevlerinin genotoksisitesi

Objective: Mutagenicity is an undesirable side effect of clinically prescribed drugs, thus raises the question of their potential carcinogenicity. Taking into account that nitro compounds are known for their genotoxicity, it will be considerable interest to assess the genotoxic activities of the benzimidazole/thiazolidinedione retinoid derivatives. For this reason, the present study reports the genotoxicity of previously synthesized benzimidazole/ thiazolidinedione-retinoid derivatives (Ates-Alagoz and Buyukbingol, 2001; Ates-Alagoz et. al., 2009) by the umu-microplate test system.Methods: In this study, since this derivates involve nitro groups, makes advantageous the use of the umu-test, using NM2009 and NM1011 strains especially designed for detecting the mutagenicity of nitro compounds. Two bacterial strains Salmonella typhimurium NM1011 and S. typhimurium NM2009, expressing high levels of nitroreductase (NR) and O-acetyltransferase (O-AT) respectively, were used in the tests. Chlorophenol red-β-D-galactopyranoside (CPRG), O-nitrophenyl- β-D-galactopyranoside (ONPG) were used as substrate in the enzyme assays along with a well-known genotoxic nitro compound, 4-nitroquinoline 1-oxide (4NQO), as the positive control in the test.Results: Benzimidazole/ thiazolidinedione-retinoids that contain NOConclusion: None of the derivatives showed genotoxic effects, a very important data, making them a potential drug candidate.

Efficient use of the PMI/mannose selection system in Agrobacterium-mediated transformation of tobacco (Nicotiana tabacum)

A safe and environment friendly selectable marker system using phosphomannose isomerase (pmi) gene was employed for Agrobacterium tumefaciens mediated transformation of tobacco (Nicotinia tabacum L.). Sensitivity of tobacco leaf explants to mannose as selective agent was determined before genetic transformation. Twenty mg/L mannose was chosen for selection to suppress the emergence of untransformed shoots from the explants. Leaf explants from 4-week old seedlings of tobacco cv. Gewone Groene were transformed using Agrobacterium harbouring plasmid pCAMBIA3300-PMI carrying the pmi gene. Regenerating transformed shoots were selected on Murashige & Skoog basal medium supplemented with 1.0 mg/L 6-benzylaminopurine, 0.1 mg/L indole-3-butyric acid, and 20 g/L mannose as carbon source. The mannose-resistant shoots were rooted on a plant growth regulator-free Murashige & Skoog basal medium and the potted transgenic plants were acclimatized successfully in the greenhouse, with a survival rate of 100%. Selection efficiency and transformation efficiency based on PCR analysis of individual putative transformants were achieved as high as 94.56% and 21.75%, respectively, with a lower rate of untransformed plant escapes. Southern blot analysis of selected putative transformed plants confirmed the transgene integration into the tobacco genome. The following reverse transcription PCR analysis showed transcriptional activity of the pmi transgene in all T0 transgenic plants analysed with differences in the level of pmi transcripts, and chlorophenol red assay confirmed the activity of PMI in transgenic plants. The PMI/mannose-based transformation system presented here is efficient and reproducible, and can be used for the mass production of transgenic tobacco plants to produce novel products with industrial and medicinal values.

Determination of Chlorine Dioxide and Chlorite in Water Supply Systems by Verified Methods

This work is dedicated to the development and optimization of appropriate analytical methods for the determination of chlorine dioxide and chlorite in drinking water in order to obtain accurate and correct results in the quality control of drinking water. The work deals with the development and optimization of a method for the determination of chlorine dioxide using chlorophenol red. Furthermore, a new spectrophotometric method for the determination of chlorite via bromometry using methyl orange was developed, optimized and validated. An electrochemical method for the determination of chlorite by flow coulometry was also developed, optimized and validated.