A paper-based point-of-care testing device for the colourimetric estimation of bilirubin in blood sample.

A paper-based colourimetric assay for the Point-of-Care Testing (PoCT) of bilirubin has been developed based on the formation of a green-coloured copper-bilirubin complex from a blue-coloured tetraamminecopper(II) sulphate complex. The reaction was studied and optimized by UV-Visible absorption spectroscopy and translated onto a paper strip. Hydrophobic circular well patterns on Whatman chromatography paper were created by wax printing. The tetraamminecopper(II) sulphate complex was drop cast and dried on the reagent zones in the wax-patterned paper. The images of reagent zones captured using a scanner were analyzed using ImageJ software. Bilirubin spiked blood serum was tested in the concentration range of 1.2 to 950 µM. The PAD exhibited sensitivities of 0.4197 a.u/µM and 0.1040 a.u/µM for concentration ranges of bilirubin 1.2 to 96 µM and 105 to 950 µM respectively and a low detection limit of 0.799 µM. The method is highly selective to bilirubin, even in the presence of other biomarkers in serum. A plasma separation membrane incorporated PAD was fabricated for the final testing and quantification of bilirubin from whole blood.

Development of a paper-based analytical device for the colourimetric detection of alanine transaminase and the application of deep learning for image analysis.

A paper-based colourimetric assay for the detection of alanine transaminase has been developed. In the presence of alanine transaminase, 2,4-dinitrophenyl hydrazine changes to pyruvate hydrazone leading to a colour change from pale yellow to dark yellow. Reaction conditions were optimized using absorption spectroscopic studies. Hydrophobic patterns on the Whatman chromatographic paper were created by wax printing, and the reagents were drop cast at the reagent zone. On the paper device, the intensity of the yellow colour increases with ALT concentration in the range of 20-140 U/L in human serum. For the quantification of ALT, coloured images were captured using a digital camera and were processed with Image J software. The machine learning approach was also explored for the ALT analysis by training with colour images of the paper device and testing using a cross-validation procedure. The results obtained with real clinical samples on the paper device showed good accuracy of less than 5% relative error with the clinical lab results. Furthermore, the paper device shows high selectivity to ALT in the presence of various interfering species in blood serum with a sensitivity of 0.261 a.u/(U/L), a detection limit of 4.12 U/L, and precise results with an RSD of less than 7%. For the testing of whole blood, a plasma separation membrane was integrated with the patterned paper.

A Novel N4-Like Bacteriophage Isolated from a Wastewater Source in South India with Activity against Several Multidrug-Resistant Clinical Pseudomonas aeruginosa Isolates.

Multidrug-resistant community-acquired infections caused by the opportunistic human pathogen Pseudomonas aeruginosa are increasingly reported in India and other locations globally. Since this organism is ubiquitous in the environment, samples such as sewage and wastewater are rich reservoirs of P. aeruginosa bacteriophages. In this study, we report the isolation and characterization of a novel P. aeruginosa N4-like lytic bacteriophage, vB_Pae_AM.P2 (AM.P2), from wastewater in Kerala, India. AM.P2 is a double-stranded DNA podovirus that efficiently lyses the model strain, PAO1, at a multiplicity of infection as low as 0.1 phage per bacterium and resistance frequency of 6.59 × 10-4 Synergy in bactericidal activity was observed between AM.P2 and subinhibitory concentrations of the antibiotic ciprofloxacin. Genome sequencing of AM.P2 revealed features similar to those of the N4-like P. aeruginosa phages LUZ7 and KPP21. As judged by two independent assay methods, spot tests and growth inhibition, AM.P2 successfully inhibited the growth of almost 30% of strains from a contemporary collection of multidrug-resistant P. aeruginosa clinical isolates from South India. Thus, AM.P2 may represent an intriguing candidate for inclusion in bacteriophage cocktails developed for various applications, including water decontamination and clinical bacteriophage therapy.IMPORTANCE In India, multidrug resistance determinants are much more abundant in community-associated bacterial pathogens due to the improper treatment of domestic and industrial effluents. In particular, a high bacterial load of the opportunistic pathogen P. aeruginosa in sewage and water bodies in India is well documented. The isolation and characterization of bacteriophages that could target emerging P. aeruginosa strains, representing possible epicenters for community-acquired infections, could serve as a useful alternative tool for various applications, such as phage therapy and environmental treatment. Continuing to supplement the repertoire of broad-spectrum bacteriophages is an essential tool in confronting this problem.

Correction to: Multicolor emitting N/S-doped carbon dots as a fluorescent probe for imaging pathogenic bacteria and human buccal epithelial cells.

The published version of this article, unfortunately, contains error. Figure 2 image was available in the multiple submissions during reviewing of the manuscript. But during the final submission, the author was asked to provide the word document of the manuscript with good resolution of the images.

Multicolor emitting N/S-doped carbon dots as a fluorescent probe for imaging pathogenic bacteria and human buccal epithelial cells.

Carbon dots co-doped with nitrogen and sulfur (NSCDs) were obtained from thiourea and TAE (Tris-acetate-ethylenediamine) buffer using microwave assisted hydrothermal synthesis. The synergistic presence of nitrogen and sulfur as a dopant results in teasing fluorescence properties and a fluorescence quantum yield of 57%. An HR-TEM study showed the NSCDs to be mono-dispersed and seemingly spherical with an average hydrodynamic diameter of 3.6 ± 0.88 nm. The NSCDs are nontoxic as proven by an MTT assay for cytotoxicity. The optical characterization was done by using UV-Vis absorption and fluorescence spectroscopy which revealed excitation wavelength-dependent multicolor emissions. The characterization of surface topology was done by using X-ray diffraction, FTIR, and X-ray photoelectron spectroscopy. The NSCDs were used to image various pathogenic bacteria (E. coli, Klebsiella, Pseudomonas & Staphylococcus) and human buccal epithelial cells by applying multicolor fluorometry. Graphical abstract Schematic presentation of microwave-assisted hydrothermal synthesis of nitrogen and sulfur doped carbon dots (NSCD) based on Thiourea and 50X Tris-acetate-ethylenediamine (TAE) buffer having multicolor fluorescence, used for tagging and imaging pathogenic bacteria and Human buccal epithelial cells using fluorescence microscope.

Tantalum oxide honeycomb architectures for the development of a non-enzymatic glucose sensor with wide detection range.

Tantalum oxide honeycomb nanostructures (THNS) were fabricated by electrochemical anodisation of tantalum in H2SO4-HF medium. XRD analysis showed that annealing of THNS at 400 °C improves the crystallinity. HRSEM and AFM results illustrated that nanopores with an average diameter of 30 nm were uniformly distributed and the pore size reduced to 24 nm and 18 nm during subsequent electrodeposition of Pt and CuO. Electrodeposited Pt and CuO exhibited face centered cubic (fcc) and monoclinic crystal structure respectively. Cyclic voltammetric studies revealed that, on the hybrid material electrooxidation of glucose occurs at a lower potential (0.45 V). The sensor exhibited linear response to glucose up to 31 mM, fast response time (<3 s) and a low detection limit of 1 µM (S/N=3). The sensor is free of interference from ascorbic acid, uric acid, dopamine and acetaminophen. Sensor was used to analyze glucose in blood serum samples.