COMPOSITIONS AND METHODS TO DETECT MICROORGNAISMS

1 . A composition, comprising:

amine-modified silica nanoparticles,

an indicator compound, and

a liquid medium comprising water and no greater than 30 wt-% organic solvent, if present, based on the total weight of liquid medium.

2 . The composition of claim 1 , further comprising a plurality of cells or enzymes.

3 . The composition of claim 2 , wherein the cells comprise prokaryotic and eukaryotic cells including bacteria, archaea, fungi, protists and mammalian cells.

4 . The composition of claim 2 , wherein the cells comprise spore-forming bacteria.

5 . The composition of claim 1 , wherein the indicator compound is selected from the group consisting of a chromogenic enzyme substrate, a fluorogenic enzyme substrate, a pH indicator, a redox indicator, a chemiluminescent enzyme substrate, a dye, and a combination of any two or more of the foregoing indicator compounds.

6 . The composition of claim 1 , wherein the enzyme is selected from the list of consisting of α-glucosidase, α-galactosidase, lipase, esterase, acid phosphatase, alkaline phosphatase, proteases, aminopeptidase, chymotrypsin, β-glucosidase, β-galactosidase, α-glucoronidase, β-glucoronidase, phosphohydrolase, plasmin, thrombin, trypsin, calpain, α-mannosidase, β-mannosidase, a-L-fucosidase, leucine aminopeptidase, a-L-arabinofuranoside, cysteine aminopeptidase, valine aminopeptidase, β-xylosidase, α-L-iduronidase, glucanase, cellobioside, cellulase, α-arabinosidase, glycanase, sulfatase, butyrate, glycosidase, arabinoside, and a combination of any two or more of the foregoing enzymes.

7 . The composition of claim 1 , wherein the amine-modified silica nanoparticles are tertiary amine-modified silica nanoparticles having tertiary amine groups attached to the surface through covalent bonds.

8 . A method, comprising:

providing the composition of claim 1 ; and

contacting a plurality of cells or enzymes with the composition.

9 . The method of claim 8 , further comprising analyzing the liquid medium to detect a biological activity of the cells or enzymes.

10 . The method of claim 9 , wherein analyzing the liquid medium to detect a biological activity of the cells comprises detecting an enzyme activity of bacteria, archaea, fungi, protists or mammalian cells.

11 . The method of claim 9 , wherein the cells comprise spore-forming bacteria and the enzyme is derived from the spores or from germination and/or outgrowth of a spore.

12 . The method of claim 9 , wherein detecting an enzyme activity comprises detecting an enzyme activity selected from the list of consisting of α-glucosidase, α-galactosidase, lipase, esterase, acid phosphatase, alkaline phosphatase, proteases, aminopeptidase, chymotrypsin, β-glucosidase, β-galactosidase, α-glucoronidase, β-glucoronidase, phosphohydrolase, plasmin, thrombin, trypsin, calpain, α-mannosidase, β-mannosidase, a-L-fucosidase, leucine aminopeptidase, a-L-arabinofuranoside, cysteine aminopeptidase, valine aminopeptidase, β-xylosidase, α-L-iduronidase, glucanase, cellobioside, cellulase, α-arabinosidase, glycanase, sulfatase, butyrate, glycosidase, arabinoside, and a combination of any two or more of the foregoing enzymes.

13 . The method of claim 8 , wherein analyzing the liquid medium to detect a biological activity of the cells or enzymes comprises analyzing the liquid medium at a pH between 5 and 9.

14 . The method of claim 8 , wherein the composition can comprise a reagent selected from the group consisting of an effective amount of a nutrient that facilitates germination growth or proliferation of the cells, an indicator compound facilitates detection of cell metabolic activity and a combination of any two or more of the foregoing reagents.

15 . An article, comprising:

a film; and

a dried coating adhered to the film, the coating comprising

tertiary amine-modified silica nanoparticles; and

a plurality of cells or enzymes.