The invention comprises a method for treating a pathogen, comprising the steps of: reacting, in a solution, poly(2-alkyl-2-oxazoline) with a strong acid to form a polyalkylenimine and a carboxylic acid, the polyalkylenimine comprising protonated sites; increasing relative concentration of the polyalkylenimine through removal of at least 95% of the carboxylic acid from the solution; adjusting pH of the solution to greater than 2.5; producing a film on a substrate from the solution; contacting first bacteria with the film; and reducing activity of the first bacteria contacting the film by: greater than 9% and less than 99.99995% in less than one minute; greater than 99.999% in less than four days; and greater than 99.99995% in less than seven days.

A method for reducing interaction of a single virus member with a host, comprising the steps of: forming a film from a solution comprising an at least partially protonated/deacylated poly(2-alkyl-2-oxazoline) and an at least partially protonated polyalkylenimine, the film comprising a total cationic charge in a range of 0.001 to 10.0 coulombs per square inch; inhibiting interaction of the single virus member, on the film, with the host through the steps of electrostatically pulling together first and second anionic sites of the virus with first and second respective multiple cationic sites of the polyalkylenimine and the poly(2-alkyl-2-oxazoline); and inactivating at least fifty percent of a set of the virus according to tests and procedures of ISO 21702 on a non-porous surface.

A method for reducing interaction of a single virus member with a host, comprising the steps of: forming a film from a solution comprising an at least partially protonated/deacylated poly(2-alkyl-2-oxazoline) and an at least partially protonated polyalkylenimine, the film comprising a total cationic charge in a range of 0.001 to 10.0 coulombs per square inch; inhibiting interaction of the single virus member, on the film, with the host through the steps of electrostatically pulling together first and second anionic sites of the virus with first and second respective multiple cationic sites of the polyalkylenimine and the poly(2-alkyl-2-oxazoline); and inactivating at least fifty percent of a set of the virus according to tests and procedures of ISO 21702 on a non-porous surface.

A method for forming an antimicrobial film, comprising the steps of: providing in a solution a polyalkylenimine, first free chloride anions, and chloride counterions associated with protonated sites of the polyalkylenimine; removing at least seventy percent of the first free chloride anions, through evaporation; exchanging hydroxide anions for residual free chloride anions in the solution; increasing a number of the protonated sites through addition of a carboxylic acid to the solution; preparing a formulation from the solution comprising greater than ten percent ethanol; forming the film from the formulation; and inactivating greater than ninety percent of a bacteria with the film after a durability rubbing treatment, the antibacterial effectiveness resultant from a combination of the polyalkylenimine and the carboxylic acid, in a mass range of 0.1 to 10 and 0.001 to 0.1 mg per square inch, respectively.

A method for forming an antimicrobial film, comprising the steps of: providing in a solution a polyalkylenimine, first free chloride anions, and chloride counterions associated with protonated sites of the polyalkylenimine; removing at least seventy percent of the first free chloride anions, through evaporation; exchanging hydroxide anions for residual free chloride anions in the solution; increasing a number of the protonated sites through addition of a carboxylic acid to the solution; preparing a formulation from the solution comprising greater than ten percent ethanol; forming the film from the formulation; and inactivating greater than ninety percent of a bacteria with the film after a durability rubbing treatment, the antibacterial effectiveness resultant from a combination of the polyalkylenimine and the carboxylic acid, in a mass range of 0.1 to 10 and 0.001 to 0.1 mg per square inch, respectively.

An apparatus for coating a substrate, comprising: an antimicrobial film, comprising: a partially protonated polyethylenimine in a range of 0.1 to 5 mg per square inch; a polydiallyldimethylammonium salt; chloride counterions; first conjugate base counterions of a first organic acid, the first conjugate base counterions comprising a first mass of 0.001 to 0.1 mg per square inch; second conjugate base counterions of a second organic acid, the second conjugate base counterions comprising a second mass of 0.05 to 1 mg per square inch; and a total cationic charge of the antimicrobial film in a range of 200 to 3000 C/m.sup.2, the total cationic charge countered by anions in the antimicrobial film, the antimicrobial film comprising an antimicrobial efficacy of greater than ninety percent according to PAS 2424:1024.

An apparatus for coating a substrate, comprising: an antimicrobial film, comprising: a partially protonated polyethylenimine in a range of 0.1 to 5 mg per square inch; a polydiallyldimethylammonium salt; chloride counterions; first conjugate base counterions of a first organic acid, the first conjugate base counterions comprising a first mass of 0.001 to 0.1 mg per square inch; second conjugate base counterions of a second organic acid, the second conjugate base counterions comprising a second mass of 0.05 to 1 mg per square inch; and a total cationic charge of the antimicrobial film in a range of 200 to 3000 C/m.sup.2, the total cationic charge countered by anions in the antimicrobial film, the antimicrobial film comprising an antimicrobial efficacy of greater than ninety percent according to PAS 2424:1024.

A method for treating pathogens on a substrate, comprising the steps of: providing a solid polyethylenimine in a basic pH form comprising protonated and unprotonated nitrogens, a ratio of the protonated nitrogens-to-the unprotonated nitrogens less than 5:95; solubilizing the solid polyethylenimine in a strong acid to form a solution of a polyethylenimine, the polyethylenimine comprising protonated nitrogen sites and counterions to the protonated nitrogen sites; removing at least ten percent of the strong acid from the solution; forming a formulation from the solution, the formulation further comprising at least one of ethanol and isopropyl alcohol; spraying the formulation onto the substrate to form a film, the film reducing activity of the first bacteria contacting the film by: greater than 9% and less than 99.99995% in less than three minutes; and greater than 99.99995% in less than seven days.

A method for treating pathogens on a substrate, comprising the steps of: providing a solid polyethylenimine in a basic pH form comprising protonated and unprotonated nitrogens, a ratio of the protonated nitrogens-to-the unprotonated nitrogens less than 5:95; solubilizing the solid polyethylenimine in a strong acid to form a solution of a polyethylenimine, the polyethylenimine comprising protonated nitrogen sites and counterions to the protonated nitrogen sites; removing at least ten percent of the strong acid from the solution; forming a formulation from the solution, the formulation further comprising at least one of ethanol and isopropyl alcohol; spraying the formulation onto the substrate to form a film, the film reducing activity of the first bacteria contacting the film by: greater than 9% and less than 99.99995% in less than three minutes; and greater than 99.99995% in less than seven days.

A method for treating a pathogen, comprising the steps of: (1) providing a polyethylenimine in a solution, the polyethylenimine comprising a total cationic charge of protonated secondary amines of the polyethylenimine, the solution comprising anionic counterions associated with the protonated secondary amines; (2) tuning a protonated site of the polyethylenimine, in a formulation of the solution containing ions, to an activity coefficient () in a range of 0.93 to 0.999; (3) forming from the formulation an antibacterial film, the antibacterial film comprising a mean thickness of less than 5 m and the total cationic charge of the protonated secondary amines in a range of 0.1 to 1.8 C/in.sup.2; and (4) inactivating greater than 99% of first bacteria within less than five minutes of contact with the antibacterial film.