A nano particle vector comprised of poly lactic-co-glycolic acid and monophosphoryl lipid A and recombinant Mycobacterium avium subsp paratuberculosis peptides stimulate a pro-immune profile in bovine macrophages.

AIMS: We evaluated the potential of a nanoparticle (NP) delivery system to improve methods of delivery of candidate peptide-based vaccines for Paratuberculosis in cattle. METHODS AND RESULTS: Peptides derived from Mycobacterium avium subsp. paratuberculosis (Map), and the pro-inflammatory monophosphoryl lipid A (MPLA) were incorporated in polymeric NPs based on poly (d,l-lactide-co-glycolide) (PLGA). The PLGA/MPLA NPs carriers were incubated with macrophages to examine their effects on survival and function. PLGA/MPLA NPs, with and without Map antigens, are efficiently phagocytized by macrophages with no evidence of toxicity. PLGA/MPLA NP formulations did not alter the level of expression of MHC I or II molecules. Expression of TNFα and IL12p40 was increased in Map-loaded NPs. T-cell proliferation studies using a model peptide from Anaplasma marginale demonstrated that a CD4 T-cell recall response could be elicited with macrophages pulsed with the peptide encapsulated in the PLGA/MPLA NP. CONCLUSIONS: These findings indicate PLGA/MPLA NPs can be used as a vehicle for delivery and testing of candidate peptide-based vaccines. SIGNIFICANCE AND IMPACT OF THE STUDY: These results will assist on more in depth studies on PLGA NP delivery systems that may lead to the development of a peptide-based vaccine for cattle.

Microstructure evolution and photoluminescence in nanocrystalline Mg(x)Zn(1 - x)O thin films.

The effects of Mg concentration and annealing temperature on the characteristics of nanocrystalline Mg(x)Zn(1 - x)O thin films (where x = 0-0.4) were studied using electron microscopy and photoluminescence. The films were prepared by a sol-gel method. The solid solubility limit of MgO in ZnO for the sol-gel-derived Mg(x)Zn(1 - x)O films in the present study was determined to be ∼ 20 at.%. Microstructural characterization of the films showed that the wurtzite crystallites decrease in size with increase in Mg concentration up to the solubility limit. Increasing Mg concentration beyond the solubility limit resulted in a decrease in crystallinity of the films. The bandgap energy was found to increase with Mg concentration whereas the linewidth first increased and then decreased when the Mg concentration was increased beyond the solubility limit. Photoluminescence properties have been correlated to the microstructure of the films. A growth mechanism for Mg(x)Zn(1 - x)O nanocrystalline films under the present processing conditions has also been proposed.

Transport properties of hybrid nanoparticle-nanowire systems and their application to gas sensing.

Experimental data and theoretical modelling of the I-V characteristics of a gas sensor constructed from a mat of Au nanoparticle-coated GaN nanowires are presented. The principal mechanism for the response of the gas sensor to methane is explained in terms of the formation of a depletion layer within the nanowires due to the presence of the gold nanoparticles. The depth of the depletion layer is modulated by the potential induced by the physisorption of gas molecules onto the Au nanoparticles. A statistical model of the temperature-dependent I-V characteristics of bare and Au nanoparticle-decorated mats of GaN nanowires based on Poisson's equation has been used to determine the depth of the depletion layers of the nanowires. The room-temperature carrier concentration for the GaN nanowires was determined to be approximately 2.2 × 10(17) cm(-3). The induced potential due to methane physisorption onto the Au nanoparticles that decorate the GaN nanowires was determined to be approximately -37 mV.

Identification and characterization of a gene that controls colony morphology and auto-aggregation in Escherichia coli K12.

Many Escherichia coli K12 strains undergo switching between two forms which differ in a number of surface properties including colony morphology and the ability to auto-aggregate. This paper describes the identification of a gene which appears to play a part in controlling this switching phenomenon. This gene has been designated mor and is located at 89 minutes on the E. coli chromosome map between the argECBH operon and the trmA gene. By manipulation of this gene it is possible to overcome the switching of surface properties and fix a strain in one form or the other. The mor gene has been cloned and its DNA sequence determined. The putative protein sequence shows a high level of homology with four regulatory genes, the ilvY, cysB and lysR genes from E. coli and the metR gene from Salmonella typhimurium. It has also been shown that the mor gene is autoregulated at the transcriptional level.