An interleukin-6 ZnO/SiO(2)/Si surface acoustic wave biosensor.

A novel high sensitivity ZnO/SiO(2)/Si Love mode surface acoustic wave (SAW) biosensor for the detection of interleukin-6 (IL-6), is reported. The biosensors operating at 747.7 MHz and 1.586 GHz were functionalized by immobilizing the monoclonal IL-6 antibody onto the ZnO biosensor surface both through direct surface adsorption and through covalent binding on gluteraldehyde. The morphology of the IL-6 antibody-protein complex was studied using scanning electron microscopy (SEM), and the mass of the IL-6 protein immobilized on the surface was measured from the frequency shift of the SAW resonator biosensor. The biosensor was shown to have extended linearity, which was observed to improve with higher sensor frequency and for IL-6 immobilization through the monoclonal antibody. Preliminary results of biosensor measurements of low levels of IL-6 in normal human serum are reported. The biosensor can be fully integrated with CMOS Si chips and developed as a portable real time detection system for the interleukin family of proteins in human serum.

Morphological and binding properties of interleukin-6 on thin ZnO films grown on (100) silicon substrates for biosensor applications.

To develop effective protein immobilization technology with minimal amounts of protein for high sensitivity surface acoustic wave biosensors, we determined the binding properties, and morphological characteristics of human interleukin-6 (IL-6), a pro-inflammatory cytokine, on the surface of ZnO, and SiO(2) films grown onto (100) Si substrates, for the first time. Interleukin-6 was immobilized in the range of 0.276-10 pg/ml on the surface of ZnO and SiO(2), and visualized at each stage, while protein-protein interactions were measured with the antigen/antibody immunoassay of solid-phase ELISA, which we modified for these types of substrates. A relative mass value was determined in each case. ELISA detected upward of 1 and 6 ng/ml of protein applied on ZnO and SiO(2), respectively. It is concluded that the more reactive ZnO surface is a new and more effective template for protein immobilization.

Effect of dissolution profile and (-)-alpha-bisabolol on the gastrotoxicity of acetylsalicylic acid.

The effect of particle size and (-)-alpha-bisabolol on the gastric toxicity produced by acetylsalicylic acid (AAS) was studied in rats. AAS crystals of size 0.5-0.4, 0.2-0.05 mm and AAS pellets were administered orally (dose 200 mg/kg) to rats. The effect of particle size on gastric toxicity was not significant (P < 0.05). Small AAS crystals (0.2-0.05 mm) were granulated with ethanol to produce pellets (0.5-0.4 mm). The resultant pellets were less ulcerogenic than AAS crystals (P < 0.05). The pelletization process improves the wetting process of AAS crystals and for this reason produces a faster dissolution profile of AAS. When (-)-alpha-bisabolol, a natural essential oil obtained from camomile oil, was administered orally (dose 0.8-80 mg/kg) with AAS (dose 200 mg/kg), a significant (P < 0.05) protective effect was found. Some possible mechanisms of protection are suggested for (-)-alpha-bisabolol.

Muscle cell growth in protein deficient rats following administration of sheep red blood cells.

In order to observe the effects of sheep red blood cells (SRBC) administration on the muscle cell growth in malnourished states, adult male Wistar rats (135 +/- 10 g 10 animals per group) subjected during 30 days to 1% and 10% protein diets, were injected (i.v.) either 15.5 x 10(8) sheep red blood cells or 0.5 ml saline/100 g b.w. after 20 days of experiment. On the 10th day after injection the animals were sacrificed and the gastrocnemius muscle was removed, weighed and homogenized. The supernatant fluids were used to evaluate muscle protein, DNA and RNA rates and acid DNase activity. All parameters were depleted in malnourished rats, indicating a muscle cellular atrophy as well as a decrease in muscle protein synthesis per DNA-unit. Muscle hyperplasia and hypertrophy were found in antigenically stimulated rats fed 10% protein against non-stimulated control. In contrast, muscle growth in protein-deficient rats SRBC-treated was unmodified when compared to non-stimulated malnourished muscle, although RNA functionality seems to be enhanced (RNA/DNA). These data suggest that a redistribution of essential nutrients occurred for muscle growth adaptation rather than for defensive mechanism.