Hydroxyapatite-binding Silver/Titanium Dioxide as a Potential Control Compound Against Mosquito Vectors, Aedes aegypti (Diptera: Culicidae) and Anopheles dirus (Diptera: Culicidae).

Controlling mosquitoes is vital for counteracting the rising number of mosquito-borne illnesses. Vector control requires the implementation of various measures; however, current methods lack complete effectiveness, and new control agents or substances are urgently needed. Therefore, this study developed a nonwoven fabric sheet coated with hydroxyapatite-binding silver/titanium dioxide compound (hydroxyapatite-binding silver/titanium dioxide sheet [HATS])and evaluated its effectiveness on all stages of laboratory Aedes aegypti (Linnaeus); Diptera: Culicidae and Anopheles dirus (Peyton & Harrison); Diptera: Culicidae. We reared larvae with HATS and control sheets and assessed their mortality, emergence, and hatching rates. The submersion rates of engorged female mosquitoes in submerged HATS and control sheets were also compared. The HATS strongly affected mosquito development, resulting in high mortality rates (mean ± SE) of 99.66 ± 0.58% (L1-L2) and 91.11 ± 9.20% (L3-L4) for Ae. aegypti and 100% of both stages for An. dirus. In contrast, mosquitoes raised in the control sheet showed relatively high survival rates of 92.33 ± 3.21% (L1-L2) and 95.67 ± 0.58% (L3-L4) for Ae. aegypti and 86.07 ± 3.53% (L1-L2) and 92.01 ± 8.67% (L3-L4) for An. dirus. Submersion of engorged females was found in the HATS oviposition cup, leading to a decreased number of eggs and a low hatching rate compared to that of the control. Overall, HATS may be a useful new control method for Ae. aegypti and An. dirus.

Studies on safety and efficacy of particles containing a mixture of hydroxyapatite-argentum-titanium oxide (HAT) and sheets coated with HAT particles to be used in masks to improve nasal allergy: II. Cellular, in vivo, and clinical studies.

PURPOSE: We report the manufacture of particles containing a mixture of hydroxyapatite-argentum-titanium oxide (HAT), followed by attachment to nonwoven polyester fabrics to produce HAT-coated sheets (HATS) for use in masks. The purpose of the present study was to perform cellular, in vivo, and clinical studies to further examine the safety of HATS for use in masks to improve nasal allergy. METHODS: Reverse mutation tests for HAT were performed using five bacterial strains. A cellular toxicity test was performed using a Chinese hamster cell line incubated with the HATS extracts. Skin reactions after intradermal administration were examined in rabbits. Skin sensitization tests in guinea pigs were performed using the HATS extracts. HAT was administered to the nasal cavity and conjunctival sac of the rabbits. An oral administration study was performed in rats. Finally, a human skin patch test was performed using the HATS. RESULTS: Reverse mutation tests showed negative results. The cellular toxicity test showed that the HATS extract had moderate cytotoxicity. The intradermal skin reaction and skin sensitization tests were all negative. The administration of HAT to the nasal cavity and intraocular administration showed negative results. No toxicity was observed after oral administration of HAT powder up to a dose of 2000 mg/kg. Finally, the skin patch test result was negative. CONCLUSION: Although HAT showed moderate cytotoxicity, in vivo results indicated that HAT is safe because it does not come in direct contact with cells in normal usage, and HATS is safe when used in masks.

Applicability assessment of ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ to the eradication of Legionella in rainwater storage tanks for household use.

Water environments appear to be the habitats of Legionella species. Legionellosis is considered as a preventable illness because bacterial reservoirs can be controlled and removed. Roof-harvested rainwater has attracted significant attention not only as a groundwater recharge but also as a potential alternative source of nonpotable water. We successfully developed ceramic microbeads coated with hydroxyapatite-binding silver/titanium dioxide ceramic composite earthplus™ using the thermal spraying method. The ceramic microbeads were demonstrated to have bactericidal activities against not only Legionella but also coliform and heterotrophic bacteria. Immersing the ceramic microbeads in household rainwater storage tanks was demonstrated to yield the favorable eradication of Legionella organisms. Not only rapid-acting but also long-lasting bactericidal activities of the ceramic microbead were exhibited against Legionella pneumophila. However, time-dependent attenuation of the bactericidal activities against Legionella were also noted in the sustainability appraisal experiment. Therefore, the problems to be overcome surely remain in constantly managing the Legionella-pollution by means of immersing the ceramic microbeads. The results of our investigation apparently indicate that the earthplus™-coated ceramic microbeads would become the favorable tool for Legionella measures in household rainwater storage tanks, which may become the natural reservoir for Legionella species. Our investigation would justify further research and data collection to obtain more reliable procedures to microbiologically regulate the Legionella in rainwater storage tanks.

Bactericidal activities of woven cotton and nonwoven polypropylene fabrics coated with hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus".

BACKGROUND: Bacteria from the hospital environment, including linens and curtains, are often responsible for hospital-associated infections. The aim of the present study was to evaluate the bactericidal effects of fabrics coated with the hydroxyapatite-binding silver/titanium dioxide ceramic nanocomposite "Earth-plus". METHODS: Bactericidal activities of woven and nonwoven fabrics coated with Earth-plus were investigated by the time-kill curve method using nine bacterial strains, including three Staphylococcus aureus, three Escherichia coli, and three Pseudomonas aeruginosa strains. RESULTS: The numbers of viable S. aureus and E. coli cells on both fabrics coated with Earth-plus decreased to below 2 log(10) colony-forming units/mL in six hours and reached the detection limit in 18 hours. Viable cell counts of P. aeruginosa on both fabrics coated with Earth-plus could not be detected after 3-6 hours. Viable cells on woven fabrics showed a more rapid decline than those on nonwoven fabrics. Bacterial cell counts of the nine strains on fabrics without Earth-plus failed to decrease even after 18 hours. CONCLUSION: Woven cotton and nonwoven polypropylene fabrics were shown to have excellent antibacterial potential. The woven fabric was more bactericidal than the nonwoven fabric.