Effectiveness of Sensors Contact Metallization (Ti, Au, and Ru) and Biofunctionalization for Escherichia coli Detection

In designing a bacteria biosensor, various issues must be addressed: the specificity of bacteria recognition, the immobilization of biomolecules that act as the bacteria receptor, and the selectivity of sensor surface. The aim of this paper was to examine how the biofunctionalized surface of Ti, Au, and Ru metals reacts in contact with strains of Escherichia coli (E. coli). The focus on metal surfaces results from their future use as electrodes in high frequency biosensors, e.g., resonant circuits or transmission-line sections. First, the surfaces of different metals were chemically functionalized with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde or with 3-glycidylooxypropyltrimethoxysilane (GPTMS) followed by N-(5-amino-1-carboxypentyl) iminodiacetic acid (AB-NTA) and NiCl2. Secondly, the lipopolysaccharide binding protein (LBP), polyclonal anti-Escherichia coli antibody and bacteriophage protein gp37 were tested as bacteria receptors. The selectivity and specificity have been confirmed by the Enzyme-Linked Immunosorbent Assay (ELISA) and visualized by scanning electron microscopy at low landing energies. We noticed that LBP, polyclonal antibody, and gp37 were successfully immobilized on all studied metals and recognized the E. coli bacteria selectively. However, for the antibody, the highest reactivity was observed when Ti surface was modified, whereas the bacteria binding was comparable between LBP and gp37 on the functionalized Ru surfaces, independent from modification. Thus, all surfaces were biocompatible within the scope of biosensor functionality, with titanium functionalization showing the best performance.

Repeat region of Brugia malayi sheath protein (Shp-1) carries Dominant B epitopes recognized in filarial endemic population

Transmission of lymphatic filariasis is mediated through microfilariae (L1 stage of the parasite) which is encased in an eggshell called sheath. The sheath protein Shp-1 stabilizes the structure due to the unique repeat region with Met-Pro-Pro-Gln-Gly sequences. Microfilarial proteins could be used as transmission blocking vaccines. Since the repeat region of Shp-1 was predicted to carry putative B epitopes, this region was used to analyze its reactivity with clinical samples towards construction of peptide vaccine. In silico analysis of Shp-1 showed the presence of B epitopes in the region 49–107. The polypeptide epitopic region Shp-149–107 was cloned and expressed in Escherichia coli. Antibody reactivity of the Shp-149–107 construct was evaluated in filarial endemic population by ELISA. Putatively immune endemic normals (EN) showed significantly high reactivity (P < 0.05) when compared to all the other categories. Antibody reactivity of Shp-1 repeat region was similar to that of whole protein proving that this region carries B epitopes responsible for its humoral response in humans. Thus this can be employed for inducing anti-microfilarial immunity in the infected population that may lead to reduction in transmission intensity and also it could be used along with other epitopes from different stages of the parasite in order to manage the disease effectively.

Detection to E. Coli O157 by Surface Plasmon Resonance Immunosensor

This work describes an approach for the development of two bacteria biosensors based on surface plasmon resonance (SPR) technique. The first biosensor was based on functionalized gold substrate and the second one on immobilized silver nanoparticles. For the first biosensor, the gold substrate was functionalized with acid–thiol using the self-assembled monolayer technique, while the second one was functionalized with silver nanoparticles immobilized on modified gold substrate. A polyclonal anti-Escherichia coli antibody was immobilized for specific (E. coli) bacteria detection. Detection limit with a good reproducibility of 104 and 103 cfu•mL−1 of E. coli bacteria has been obtained for the first biosensor and for the second one respectively.

Prognostic indicators of post partum viability of kids born to Escherichia coli-vaccinated or unvaccinated does : research communication

This study was undertaken to determine some blood and other physiological parameters with potential for use as prognostic indicators of viability of newborn goat kids. Of the 143 kids born during the on-farmstudy, 97 were crosses of Galla × Small East African (SEA) and 46 were pure SEA. The SEA × Galla kids were 46 single males, with a mean body weight at birth of 2.77 ± 0.22 kg , 43 females with a mean body weight at birth of 2.36 ± 0.76 kg and 5 and 3 sets of female and male twins (mean body weight at birth of 1.8 ± 0.19 kg and 2.05 ± 0.07 kg for the female and male kids, respectively). The SEA kids comprised 36 single male and female kids (mean body weight at birth of 2.48 ± 0.04 kg and 10 sets of twins (both male and female) (mean body weight at birth of 1.50 ± 0.04 kg ). Pre-suckling sera obtained on-station from kids born of does vaccinated against Escherichia coli (n = 8) and unvaccinated does (n = 7) had a total protein content of < 40.0 g/l and no detectable levels of IgG and A or E. coli antibodies. Sera obtained 12 hours post partum from kids that survived in both groups contained about 19-22 g of Ig g/ , 50-80 g total protein/ , blood glucose of >5 mmol/l and had an E. coli antibody titre of between 1/160 and 1/640. On the other hand, kids that died within 48 hours of birth (parturient deaths) and had been classified in categories 3 and 4 righting reaction had low (< 40 g//l ) total protein, low white blood cell count (4000/m/l ) and low blood glucose concentration (< 4.9 mmol//l ). It is concluded that kids with delayed righting reaction (> 45 minutes), low rectal temperature (< 36 °C), low birth weights (< 1.5 kg for singles and < 1.0 kg for twins), low white blood cells (< 4000/ m/l ), low (< 2 mmol/l ) blood glucose levels, low total protein (< 40.0 g//l ), low (< 1:160) E. coli antibody titre and IgG ( < 3350 mg//l ) in sera obtained 12 hours after birth have a poor prognosis for survival.