Biological sterilization indicator
Spore carriers suitable for use in biological indicators are described. The spore carriers include a substrate such as polymeric film or non-woven web with a hydrophilic nanostructured layer bonded to it. Spores are bonded to the nanostructured layer. Nanostructured layers including nanoparticles, such as acid-sintered silica nanoparticles are described. Biological indicators including such spore carriers are also described.
1. A biological sterilization indicator comprising:
a housing defining a reservoir, the housing comprising a cap that includes one or more apertures to provide fluid communication between the reservoir and ambience;
a frangible container within the housing; and
a spore carrier comprising a substrate, a hydrophilic nanostructured layer bonded to a surface of the substrate and spores bonded to the nanostructured layer, wherein the nanostructured layer comprises silica nanoparticles.
2. The biological sterilization indicator of claim 1 , wherein the nanostructured layer has a receding contact angle of no greater than 50 degrees as measured by the Contact Angle Method.
3. The biological sterilization indicator of claim 1 , wherein the nanostructured layer has a receding contact angle of no greater than 20 degrees as measured by the Contact Angle Method.
4. The biological sterilization indicator of claim 1 , wherein the frangible container contains liquid.
5. The biological sterilization indicator of claim 4 , wherein the liquid comprises nutrient medium.
6. The biological sterilization indicator of claim 1 , wherein the silica nanoparticles are acid sintered.
7. The biological sterilization indicator of claim 1 , wherein the nanoparticles have an average diameter of no greater than 20 nm.
8. The biological sterilization indicator of claim 1 , wherein the nanostructured layer has an RMS roughness of at least 10 nm.
9. The biological sterilization indicator of claim 8 , the nanostructured layer has an RMS roughness of no greater than 500 nm.
10. The biological sterilization indicator of claim 1 , wherein the nanostructured layer further comprises microparticles.
11. The biological sterilization indicator of claim 1 , wherein the nanostructured layer further comprises a binder.
12. The biological sterilization indicator of claim 11 , wherein the binder comprises a tetraalkoxysilane.
13. The biological sterilization indicator of claim 1 , wherein the substrate is a polymeric substrate.
14. The biological sterilization indicator of claim 13 , wherein the polymeric substrate comprises polyester.
15. The biological sterilization indicator of claim 13 , wherein the polymeric substrate comprises polypropylene.
16. The biological sterilization indicator of claim 1 , wherein the substrate is a woven or non-woven web.
17. The biological sterilization indicator of claim 1 , wherein the substrate is a film.
18. The biological sterilization indicator of claim 1 , wherein the spores comprise at least one of Geobacillus stearothermophilus and Bacillus atrophaeus.
19. The biological sterilization indicator of claim 1 , wherein the spore carrier further comprises one or more wells.
20. The biological sterilization indicator of claim 1 , wherein the nanostructured layer comprises silica nanoparticles deposited out of an aqueous coating composition having a pH of less than 3.