Au Nanocomposite Based Chemiresistive Ammonia Sensor for Health Monitoring

We have developed a fast and highly sensitive chemiresistive sensor based on the nanocomposite of polysaccharide (guar gum) and gold nanoparticles for the room temperature detection of ammonia in the range of 0.1 parts-per-quadrillion (ppq) to 75 000 parts-per-million (ppm). Sensor response, selectivity, and stability studies reveal excellent sensing of the nanocomposite. The room temperature operation under ambient conditions and the wide range sensing indicates that the composites can be explored for environmental as well as biomedical applications. We have for the first time quantified the ammonia level released from the urine and blood serum of human beings using the resisitive sensor. The urine ammonia level was found to be ∼24 000 ppm and is higher for patients with renal problems. This demonstrated the utility of the sensor for health monitoring

Zone of diameters of LF, 21LF, 38LF and 45LF against <i>Candida albicans</i>.

<p>Zone of diameters of LF, 21LF, 38LF and 45LF against <i>Candida albicans</i>.</p

The entire sequence of bovine native LF.

<p>Arrows [blue (21LF), green (38LF), red (45LF)] indicate the origin sites of the three fragments respectively. The amino acid sequence of the first fifteen residues of 21LF, 38LF and 45LF is indicated against their names towards the left,</p

LC₉₀ values of LF, 21LF, 38LF and 45LF against <i>Candida albicans</i>.

<p>All the data were expressed as mean values ± standard deviations; <i>P</i><0.05, student's <i>t-</i> test.</p

Zone of diameters of LF, 21LF, 38LF and 45LF against bacterial species.

<p>Zone of diameters of LF, 21LF, 38LF and 45LF against bacterial species.</p

LC₅₀ values of LF, 21LF, 38LF and 45LF against bacterial species.

<p>All the data were expressed as mean values ± standard deviations; <i>P</i><0.05, student's <i>t-</i> test.</p><p>*Highest concentration tested.</p

Comparative study of iron-desaturation of LF and its three tryptic fragments.

<p>The iron desaturation was plotted against decrease in pH for iron saturated bovine lactoferrin (black), 21LF (orange), 38LF (green) and 45LF (red) and their corresponding apo form of bovine lactoferrin (blue), 21LF (brown), 38LF (pink), 45LF (cyan) under identical conditions.</p

Superimposition of the backbone chains of iron-saturated LFs from various species.

<p>The figure shows that the overall chain folds in a similar fashion in all the species.</p

Antifungal activity of LF and its three tryptic fragments.

<p>The antifungal activity of (A) LF (•), (B) 21LF (♦), (C) 38LF (▾) and (D) 45LF (▪) is plotted against <i>C. albicans</i> ATCC 90028. All the data were expressed as mean values ± standard deviations; <i>P</i><0.05, student's <i>t-</i> test</p

Sequence comparison of the cleavage sites of LF from various species.

<p>The different species are human (HLF), bovine (CLF), buffalo (BLF), equine (ELF) and caprine LF (GLF). The identity in the sequences is shown in blue. The places where trypsin cleaves the molecules are indicated by an arrow.</p