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To ensure effective detection of bio-particles, it is crucial to understand the effects of collection method and archiving conditions on the survivability of bioaerosols, consequently, the survivability of the spore-forming Bacillus globigii (BG) and MG1655 Escherichia coli (E. coli), was determined after collection. The survivability was defined as the culturable fraction of the archived bacteria/culturable fraction of the as-collected bacteria. The bacteria were aerosolized for up to four days at room temperature (RT, 25 degrees C) and at 4 degrees C and collected in a 100 L/min wetted wall cyclone (WWC) and a 12.5 L/min SKC BioSampler. Aqueous solutions of 0.01% Tween-20 and 30% Ethylene Glycol (EG), with or without 0.5% ovalbumin (OA), were used as the collection fluids. Antifoam B (A-F), at a concentration of 0.2% (V:V) was added to the BG samples containing OA. In general, samples archived at 4 degrees C showed higher survivability than at RT. The survivability were more stable in EG than in Tween-20 especially for BG, very likely due to the surfactant effect of the Tween-20, which would remove the spore coat and initiate germination. In the WWC, adding OA significantly increased the survivability of BG in EG and in Tween-20, especially at RT. Similar effect of OA was found for E. coli samples stored in EG, suggesting that OA might be beneficial in maintaining the survivability. Adding A-F increased the survivability of BG in EG. In the SKC, neither the addition of OA nor A-F seems to have a beneficial effect on the survivability of the spores in EG samples. The best collection fluid for maintaining survivability in the WWC is EG+A-F for BG, and EG+OA for E. coli. However, in the SKC, EG is the best for BG collection and Tween-20 for E. coli. Viability transfer ratios, VTR, (cells surviving collection at time zero/viable cells aerosolized) were calculated for both devices. A performance ratio was calculated as the VTR of the WWC/VTR of the SKC. The geometric mean of the performance ratio is 1.51+/-0.83 for BG and 2.60+/-0.16 for E. coli, indicating that viability transfer ratio of the WWC is typically higher than that of the SKC.

Benzoyl peroxide (BP), used to bleach annatto in cheese whey, was encapsulated within the hydrophobic dispersed phase (phi) of nanoemulsions (NEs) to minimize its degradation and extend its efficacy to minimized usage levels. Three purified, saturated short-chain fatty acids of varying chain lengths: butyric (C4), hexanoic (C6) and octanoic (C8) acid, were chosen as the phi to completely dissolve various concentrations of BP. Stabilization was achieved with different concentrations and combinations of primary emulsifier (E), bovine serum albumin, and coemulsifier (CE), Tween 20. Different ultra-high pressures (UHP) were used to generate a stable NE. The best result was made by keeping these parameters: UHP 210 MPa/phi fraction 4x10-3/ BP 0.04% (w/v) constant, E (without CE) concentration of 0.04% (w/v) for both C4 and C6 or 0.6% (w/v) for C8. Annatto color reduction by 90% was achieved with C4-system using only half the typical concentration of BP used by the industry.

Fusarium graminearum is one of the most problematic phytopathogens in US agriculture. This fungus causes head blight, foot rot, and damping off on wheat and barley. The infection lowers the grain yield and causes contamination of the grain product with mycotoxins. Effective control measures are lacking, and new fungicides that kill F. graminearum but remain safe and economical to use are needed. Newly synthesized aminoglycosides (JL22, JL38, JL39, JL40, NEOF004, NEOF005), classic aminoglycosides (amikacin, gentamicin, kanamycin A, kanamycin B, neomycin, and ribostamycin), and a lipopeptide, syringomycin E (SRE), were studied to determine their antifungal potential to control F. graminearum. Aminoglycosides are protein synthesis inhibitors that mainly target bacteria, but a few were recently observed to kill fungi. They consist of an aminocyclitol ring bound with two or more amino sugars. Novel aminoglycosides were recently synthesized using novel glycodiversification synthetic schemes involving the replacement of the original amino sugars with unusual amino sugars. SRE is an antifungal lipodepsinonapeptide produced by Pseudomonas syringae pv. syringae. This bacterium is an opportunistic pathogen in a wide range of plant species and produces several fungicidal lipopeptides. SRE forms pores on fungal plasma membrane and causes ion fluxes. An enhancement of its antifungal activity is reported in the presence of rhamnolipid surfactants. The antifungal activities of various aminoglycosides, SRE, and a SRE-rhamnolipids mixture were determined against F. graminearum by measuring in vitro minimum inhibition concentrations (MICs) and in planta lesion area and chlorosis development using a leaf infection assay protocol. It was determined that using Tween® 20 at 0.2 % (v/v) concentration in the leaf infection assay promotes lesion development by F. graminearum with minimum phytotoxicity. In vitro, SRE, SYRA, and synthetic aminoglycoside JL38 showed the best antifungal activities. With the in planta assay, all three antifungal agents prevented infection by F. graminearum. However, inconsistent phytotoxicities were observed with SRE and SYRA that were influenced by the Tween® 20 surfactant included in the leaf infection assay. How Tween® 20 induces these phytotoxic inconsistencies is not known.

Thesis (Ph. D.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references.

A primary emulsion with whey protein isolate (WPI) and hexanoic acid was prepared, and chitosan (Ch) (0.01%, 0.02%, and 0.03%) was added to evaluate its impact on particle size distribution of the emulsion. NaCl (0, 20, 40, and 80 mM) was added to increase ionic interactions to stabilize the multilayer emulsion. Lecithin (0.5%, 1%, 2%, 3 %, w/v) was mixed with the primary emulsion in order to form a multilayer, and casein hydrolysate (CH) was used to stabilize the tertiary emulsion system without the use of NaCl for 28 d at 4 °C. Stable O/W nanoemulsions were generated for use as nano-vesicular vehicles (NVV) to carry Curcumin (CU). Two important variables, (1) addition of casein hydrolysate (CH) (1:50, w/w WPI) and, (2) use of high pressure (140 and 210 MPa), were studied for their effect on the stabilization of monodispersed NVV and persistence of antioxidant activity of the CU as cargo in the NVV throughout storage. Addition of CH reduced nano-particle size and increased emulsion stability with UHPH pressure. The nanoparticle distribution was not changed by the addition of CU. Addition of casein hydrolysate reduced particle size as well as enhanced the positive functional properties of the NVV. Similar trends were observed in zeta-potential, surface energy, contact angle and antioxidant efficacy of the NVV, both with and without CU when UHPH was applied. The effect of Ultraviolet (UV) radiation (254 nm) on the stability of O/W nanoemulsion systems was investigated. A nano vesicular vehicle (NVV) was generated using ultra-high pressure homogenization (UHPH) that was stabilized using whey protein isolate (WPI) (1%, w/v), Tween 20 (20% w/w WPI) and casein hydrolysate (CH) (1:50 of WPI, w/w). Coarse emulsions were prepared by blending for three min. The coarse emulsion was exposed to UV radiation (0-60 min), followed by a single-pass of UHPH at 140 and 210 MPa. The UHPH treated NVV-CU had greater (P<0.05) short and long term antioxidant properties. After 28 d of storage, the CU-NVV treated at 210 MPa retained 7.0 and 1.4% greater AA and AP, respectively, when compared to the unpressurized CU-NVV.

I. Combined cloud point extraction and Tween 20-stabilized gold nanoparticles for colorimetric assay of silver nanoparticles in environmental water This study investigated a simple, sensitive and selective method for the colorimetric assay of silver nanoparticles (AgNPs) using Triton X-114-based cloud point extraction (CPE) as a preconcentration step and Tween 20-stabilized gold nanoparticles (Tween-AuNPs) as a colorimetric probe. After heating beyond the cloud point temperature of Triton X-114, a solution containing Triton X-114 micelles and AgNPs separated into a surfactant-rich phase (small volume) and a dilute aqueous phase. AgNPs partitioned into a Triton X-114-rich phase through a hydrophobic interaction between Triton X-114 micelles and AgNPs. After phase separation, the concentrated AgNPs oxidized to form Ag+ upon adding H2O2. The generated Ag+ triggered the aggregation of Tween 20-AuNPs in a high-ionic-strength solution because the reduction of Ag+ on the AuNP surface enabled Tween 20 (stabilizer) to be removed from the NP surface. The efficiency of Triton X-114-based CPE of the AgNPs was found to be iv insensitive to their size and coating type. Under optimal extraction and detection conditions, the selectivity of this method for AgNPs was considerably higher than for other nanomaterials. The minimum detectable concentrations for 7, 22, and 54 nm AgNPs were measured to be 0.1, 420, and 600 ng/mL, respectively. This method was successfully applied to the analysis of 7 nm AgNPs in drinking water, tap water and seawater. Keyword: silver nanoparticles, gold nanoparticles, cloud point extraction, Tween-20, colorimetric assay II. Functionalized silver nanoparticles as an extracting and preconcentrating agent for detection of mercury ions In this research we provided highly sensitive and selective for fluorescence assay of combined polythymine oligonucleotide (PolyT) with silver nanoparticles (AgNPs) as an extracting agent to detect mercury ion in environmental water. According to previous researches, PolyT will form a hairpin structure in the presence of Hg2+, this structure provide several 3-D grooves that the fluorescent dye can inlay with it. SYBR Green I (SG) is a staining dye for DNA, when binding with single strand DNA, it shows low fluorescence. On the contrast, SG inlay with grooves of hairpin structure, it shows v 11-fold of fluorescence signal. Hence, we used SG as a fluorescence probe for Hg2+. We modified thiol group at the 5¡¦ of PolyT DNA, because of forming silver sulfur bond, PolyT will able to modified on the surface of AgNPs. PolyT33SH-AgNPs are the extracting and concentrating agent in Hg2+ solution, by the centrifugation, we collected the PolyT33SH-AgNPs. For the purpose of releasing PolyT from AgNPs¡¦ surface, we adding H2O2 to oxidize the AgNPs into Ag+. By mixing buffer and SG into previous solution, mercury ion could be detected. In this study, we successfully detecting Hg2+ in the aqueous solution contained drinking water and tap water. The detection limit in drinking water is 20 pM, which is below Environmental Protection Agency limit for Hg2+ in drinkable water (10 nM), the linear range is from 50-600 pM. On the other hand, the detection limit in tap water is 50 pM, linear range is from 100-700 pM. Keyword: silver nanoparticles, mercury ion, PolyT, SYBR Green I, thymine