WO2017063817A1

WO2017063817A1 - Method and kit for sanitising surfaces

Info

Publication number: WO2017063817A1
Application number: PCT/EP2016/072131
Authority: WO
Inventors: Srilaxmi Venkata Medepalli; Rohini Sukumaran NAIR; Sandip Bhanudas PATHAK; Lakshminarayana Rao
Original assignee: Unilever N.V.; Unilever Plc; Conopco, Inc., D/B/A Unilever
Priority date: 2015-10-13
Filing date: 2016-09-19
Publication date: 2017-04-20
Also published as: AR106317A1

Abstract

Disclosed is a method of treating a surface by applying to said surface either simultaneously or sequentially in any order: a) surfactant-free plasma activated water; and, b) a surfactant. Also disclosed is a dispenser, a kit and a packaged product through which the method can be practiced.

Description

METHOD AND KIT FOR SANITISING SURFACES Field of the invention The invention relates to a method and a kit for sanitizing animate as well as inanimate surfaces.

Background of the invention Various chemicals are often used to sanitize animate and inanimate surfaces. Non- limiting examples of such chemicals and compositions include bleach, phenyl, soaps and detergents, floor cleaners and toilet cleaning compositions. However some compositions are associated with one or more drawbacks or disadvantages. While phenyl, bleach and other corrosive chemicals are not meant for surfaces other than floor and toilets, they also emit and leave behind a strong odour. Some compositions are corrosive while some reportedly cause health and environmental concerns.

Researchers constantly aim for new compositions which are efficacious and yet have minimal side effects. Cleaning and disinfection are two important reasons for people to use surface hygiene compositions. Conventional methods need a high level of surfactants to remove dirt and organic matter. Santisation is achieved by use of chlorine compounds,

formaldehyde, glutaraldehyde, ortho-phthalaldehyde, hydrogen peroxide, iodophors, per-acetic acid, phenolics, and quaternary ammonium compounds.

Some publications disclose two-pack products in which a surface is contacted sequentially or simultaneously with two different types of compositions. The

compositions are often incompatible, therefore cannot be made available as a ready-to- use mix.

EP2060622 A1 (P&G, 2007) discloses a method for treating surfaces by an acidic component and an alkaline component. EP2436265 A1 (COOP Genossenschaft, 2010) discloses two separate compositions, one comprising hydrogen peroxide (in water) and one comprising surfactant (in water), which are mixed before or during use.

WO04024861 A1 (Reckitt Benckiser) discloses hard surface treating compositions in which hydrogen peroxide solution is to be mixed with cationic surfactant. WO9602624 A1 (Safe Specialty Products) discloses a cleaning kit and a cleaning composition and methods of using multi-component kit where one component has a surfactant and the other has an oxidising compound. The components are applied separately. US5914089 B1 (Suzuki, 1993) discloses a method of sterilization and disinfection by ozone in which there is an additional step of pre-washing with a surfactant. US8562907 B2 (Tristel PLC, 2013) discloses a hand sanitizer having first part in a first dispenser comprising a chlorite solution, and a second part in a second dispenser comprising an acid solution wherein the chlorite and the acid react to provide chlorine dioxide.

Development of activated water, in particular, plasma activated water, provided a new dimension to sanitation. This product needs only water, air and electricity and thereby is an inexpensive, sustainable and chemical-free alternative to the ones discussed earlier.

When cold plasma is generated in air, it instantaneously generates reactive oxygen and reactive nitrogen species. These species dissolve in the water in which they are generated. Due to the presence of such species as the water develops antimicrobial activity.

US2003/0035754 A1 (Sias et. al.) discloses an apparatus having a source of cleaning fluid, a mist generator having an input flow of the cleaning fluid and an output flow of a mist at ambient pressure. An activator is placed in the flow path to activate the mist as it flows through.

US 20130272929 A1 (Pelfrey, et.al.) discloses a sanitization station having a fluid source and one or more plasma generators for generating non-thermal plasma. A set of nozzles is there to spray a mist or stream of activated fluid to sterilize an object. Another sanitization station includes a chamber for holding a fluid and a plasma generator in fluid communication with the chamber for generating plasma. A circulating source moves the fluid in the chamber past plasma generated by the plasma generator to activate the fluid and one or more spray nozzles coat the surface of an object with fluid that is activated by plasma. However, there are some publications, which disclose the activation of water, which contains added chemicals such as salts or surface-active agents.

US2007243597 AA (Forum Bioscience Holdings Ltd) discloses plasma-activation of water with a chlorine content of no more than 8 ppm. The activated water kills micro- organisms such as bacteria and viruses as is useful for cleaning medical apparatus or for disinfecting other devices.

US20140100277 A1 (Gray, et.al.) discloses activation of water containing acetic acid. The activation results in generation of per-acid species, which act against microbes.

WO2007/048806 A1 (ASEPTIX TECHNOLOGIES BV) discloses the addition of a lower alcohol to the water which is subjected to plasma-activation. The addition of alcohol reduces the time required to generate the active species in water. Addition of hydrogen peroxide is disclosed in US6706243 B1 (Intecon Systems, 2004).

Yet another method has been disclosed in WO2014/145570 A1 (EP Technologies LLC). This patent application discloses a method in which a surface is first contacted with a fluid, which may contain an additive e.g., alcohol, followed by plasma-treating the surface itself.

We have determined that that when an animate or inanimate surface contaminated with bacteria is contacted with surfactant-free activated water and a surfactant, especially cationic surfactant, either sequentially or simultaneously, such that these two agents come in contact with each other only upon the target surface; there is significant reduction in the viable bacterial count of the surface. The bacterial count measured as the log-reduction and brought about by these two agents acting in tandem, is more than the arithmetic sum of log-reduction brought about by them individually. Especially good results have been observed against at least some common pathogenic Gram- positive and Gram-negative bacteria.

Summary of the invention

Disclosed in accordance with a first aspect is a method of treating a surface by applying to said surface either simultaneously or sequentially in any order:

(a) surfactant-free plasma activated water; and,

(b) a surfactant.

In accordance with a second aspect is disclosed a dispenser comprising:

(a) a first chamber spatially separated from a second chamber; and,

(b) a first means for dispensing surfactant-free water through said first chamber and a second means for dispensing surfactant through said second chamber either simultaneously or sequentially in any order, characterized in that the first chamber comprises an activator for activating said surfactant-free water by plasma activation.

Disclosed in accordance with a third aspect is a kit comprising:

(a) a first container for dispensing surfactant-free water through a first dispensing means; and,

(b) a second container for dispensing a surfactant through said a second dispensing means where said containers are not attached to each other,

characterized in that said kit comprises means for activating said surfactant-free water by plasma activation; which is either integral with said first container or is separate therefrom.

Also disclosed is a packaged product comprising a dispenser, said dispenser comprising

(a) a first chamber spatially separated from a second chamber containing surfactant- free water and a surfactant respectively, and

(b) means for dispensing contents of each chamber either simultaneously or

sequentially in any order, characterized in that the surfactant-free water is plasma activated water or is activatable by means of plasma activation, which is either integral with said first chamber or separate therefrom. Detailed description of the invention

Plasmas, or ionized gases, have one or more free electrons that are not bound to an atom or molecule. Plasma may be generated using a variety of gases including air, as well as water, under application of electric field. Plasmas provide high concentrations of energetic and chemically active species. They can operate far from thermodynamic equilibrium where the temperature of free electrons in the plasma is significantly higher than neutral atoms, ions and molecules. Such plasmas have high concentrations of active species and yet remain at substantially the room temperature. The energy from the free electrons may be transferred to additional plasma components initiating additional ionization, excitation and/or dissociation processes. Any fluid that is contacted with plasma becomes "activated" and is referred to as plasma activated fluid. When the fluid is water, the resultant product is plasma activated water. The plasmas may contain superoxide anions. Other radical species may include OH- and NO- in aqueous phase or the presence of air or gas.

Plasma activated water produced by dissolving reactive oxygen and reactive nitrogen species in water is known to provide chemical free disinfection. Room temperature plasma generated in air produces many chemical species in small quantities namely, N₂0, 0₃, C0₂, HNOs, ONOOH, N0₃ ^", N0₂ ^" and H₂0₂, which gives antimicrobial properties to water and no side effects. As these species are short lived and are present at very low concentrations, usually there are no side effects.

Non -thermal plasma (popularly known as cold plasma) based ozone generators which use electrical discharges to produce ozone are used most widely. All cold plasma based ozone generators use electrical discharges to produce high number density of electrons. This high number density of electrons dissociates the oxygen present in the feed air/oxygen stream to produce ozone. It is believed that the disinfecting effect of electrochemically activated water is a function of concentration of the active species in the water. As their concentration increases, so does the redox potential and the disinfectant activity. As a result, it is generally considered that the higher the content of the active species in the

electrochemically activated water, the greater its disinfectant activity. It is hypothesized that long-lived secondary products, such as peroxides, nitrites and nitrates, are responsible for the extended biological effects of plasma-activated water (PAW) after plasma treatment. On the other hand, some surface-active agents are also known to have antibacterial effect, at least against some of the common pathogenic bacteria. Some are even known to have bactericidal and not merely bacteriostatic activity.

Bacterial contamination of surfaces is a worldwide concern. It is now addressed through several means such as use of antibacterial products like soaps, detergents, cleaning wipes and hand sanitisers. However, prolonged use of such products, though unavoidable at times, is not recommended even by health practitioners. Therefore there is need for milder yet efficacious products. We have determined that that when an animate or inanimate surface contaminated with bacteria is contacted sequentially or simultaneously with surfactant-free activated water and a surfactant, such that these two agents come in contact with each other only upon the target surface; there is a significant reduction in the viable bacterial count of the contaminated surface.

The bacterial count, measured in log-reduction, brought about by these two agents when acting in tandem, is more than the arithmetic sum of log-reduction brought about by them individually. Especially encouraging results are seen in the case of some common pathogenic Gram-positive and Gram-negative bacteria.

Accordingly, in a first aspect is disclosed a method of treating a surface by applying to said surface either simultaneously or sequentially in any order:

(a) surfactant-free plasma activated water; and, (b) a surfactant.

It is preferred that the surfactant-free plasma activated water and the surfactant are made to contact the desired surface simultaneously. In other words, the time lag between the two is less than 10 seconds, preferably less than 5 seconds. It is preferred that the two are not intermixed beforehand.

It is preferred that the surfactant is a cationic surfactant. Further preferably the cationic surfactant is cetyl trimethyl halide or benzalkonium halide. The surfactant may also be chosen from those described in well-known textbooks. These include "Surface Active Agents" Vol.1 , by Schwartz & Perry, Interscience 1949, Vol. 2 by Schwartz, Perry & Berch, Interscience 1958; and/or the current edition of "McCutcheon's Emulsifiers and Detergents" published by Manufacturing Confectioners Company or "Tenside- Taschenbuch", H. Stache, 2nd Edn., Carl Hauser Verlag, 1981 ; "Handbook of Industrial Surfactants" (4th Edn.) by Michael Ash and Irene Ash; Synapse Information

Resources, 2008.

Preferred cationic surfactants include benzalkonium chloride (BKC) and cetyltrimethyl ammonium chloride (CTAC) and cetyltrimethyl ammonium bromide (CTAB).

The cationic surfactant is a quaternary ammonium compound. The quaternary ammonium compounds have general formula R-i R2R3R₄N⁺X^", wherein Ri is a C12-C18 alkyl group, an aryl group or an aryl- alkyl group, R2 is selected from an aryl group or an aryl-alkyl group having 1 to 5 carbon atoms or a C1-C3 alkyl group, R3 and R₄ are independently selected from C1-C3 alkyl groups and X^" is an inorganic anion. The inorganic anion may also be chosen from phosphate, sulphite, sulphate, bisulphate or hydroxyl ions.

It is preferred that the water is activated by cold plasma. The term cold plasma is well known to persons ordinarily skilled in the art. In accordance with a preferred aspect of the method, the surfactant is in the form of a dilute aqueous solution or a composition comprising said surfactant. The composition may be any suitable composition. It preferably is an aqueous composition. It is preferred that the concentration of said surfactant in said aqueous solution or said composition is from 0.001 wt% to 10 wt%. It is further preferred that the surfactant-free water and said surfactant are applied at a ratio of from 1 :0.5 to 1 :20 parts by weight. More preferably the ratio is 1 :0.5 to 1 :5 parts by weight. The ratio will depend largely on factors, such as the type and nature of the surface, the number of microbes present or believed to be present on it, the time that is available for sanitisation, concentration of the cationic surfactant and the time for which the water has been activated and/or the strength of electrical parameters, such as voltage/current applied to it.

The surfactant-free plasma activated water:

In the method of the invention, the plasma-activated water is preferably generated in a stand-alone vessel of suitable shape and size.

A device for activating water generally includes a vessel that has an inlet and two outlets and a plasma activator at a suitable position inside the container. Plasmas are conductive assemblies of charged particles, and neutrals that exhibit collective effects. A typical plasma generator consists of a cold type plasma power supply and plasma electrodes. The vessel can be any suitable size and shape, as long as water being treated is subjected to energy from the plasma under conditions that produce the desired characteristics in the treated water. It is preferred that the vessel is substantially cylindrical, with a circular cross-section, other suitable vessels may have a polygonal, oval or other horizontal cross section. Small units are contemplated, for example, where the volume is only about 200 ml or less. On the other hand large units are contemplated that have an internal volume of at least 10 ml. It is preferred that the container is made of stainless steel to reduce corrosion effects, although any sufficiently strong and resistant material could be used, including for example titanium, tantalum, stainless steel coated with titanium, molybdenum, platinum, iridium, and so forth.

The surfactant-free water can be contacted with the plasma activator in any suitable manner. This can be advantageously accomplished by flowing water past a plasma activator but can also be accomplished in a batch mode. For example, a plasma activator can be placed inside the first chamber of the dispenser/packaged product or the first container of the kit and removed when the water is sufficiently treated.

Alternatively, water can be treated in a batch mode, ex situ from where it can be eventually used. Such a step may be used for the method of the invention.

The water for plasma activation can have substantially any practical purity such as 95% H2O and 99.99% H2O. Water from any suitable source may be used. Tap water can be used and so can treated water such as reverse osmosis water. The water may also be hard. Distilled water is less suitable because it contains little or no dissolved salts. The water is surfactant-free. In other words, the water contains not greater than 0.5 wt% surfactant.

The means for activating water comprises a high voltage plasma power supply and plasma electrodes. The high voltage plasma power supply can be a single phase or multiphase power supply capable of producing an open circuit voltage of more than 0.1 kV or higher and a closed circuit current of up to 30 mA. The secondary output voltage from the power supply can have a high frequency output between 1 kHz to 100 kHz. The plasma electrodes may either be metallic strip electrodes or braided metallic wires separated by a dielectric sheet.

Suitable modifications can be made to the container/chamber in which plasma is produced. For example, the electrodes can be either fabricated a stripes or discs or can be coiled braided wires and embedded in the lid. The electrodes should be positioned suitably to allow the generated actives to interact with the water. Other base and modulation frequencies can be utilized, so long as the resulting plasma provides energy of sufficient frequency and power to achieve desired effects on water passing through or placed inside the container/chamber. The container/chamber can be scaled up or down to suit the needs of the intended application and scale.

The water may also contain promoting species, other than surfactants, that are not themselves sources of activatable species such as hydroxyl ions, but instead modify the decontamination profile in a beneficial manner. Examples include

ethylenediaminetetraacetate (EDTA), which binds metal ions and allows the activated species to destroy the cell walls more readily; an alcohol such as isopropyl alcohol, which improves wetting of the mist to the cells; enzymes, which speed up or intensity the redox reaction in which the activated species attacks the cell walls; fatty acids, which act as an ancillary anti-microbial and may combine with free radicals to create residual anti-microbial activity; and acids such as citric acid, lactic acid, or oxalic acid, which speed up or intensity the redox reaction and may act as ancillary anti-microbial species to pH-sensitive organisms, salts like sodium chloride, acids like lactic acid or citric acid. Mixtures of the various activatable species and the various promoting species may be used as well.

In order to facilitate the industrial applicability of this invention, the invention also has other aspects which are a dispenser, a kit and a packaged product.

The kit may additionally comprise a set of printed instructions for use. The instructions could also be provided in electronic form.

The invention is useful to sanitise surfaces to thereby reduce the bacterial as well as viral count thereon.

The invention will be explained in details with the help of non-limiting examples.

Examples

Example 1 : Synergy of activated water and surfactant against pathogenic bacteria Plasma activated water (PAW) was produced using cold plasma technology.

Antimicrobial activity of the PAW was tested on E-coli and S.aureus. The details are explained below. Preparation of PAW:

PAW was produced using a cold plasma setup. The setup to produce PAW consisted of a closed vessel with a lid to hold surfactant-free reverse osmosis water. A single phase plasma power supply was used which had output characteristics of 4kV, 30 mA and high frequency output (25 kHz). Cold plasma electrodes were fitted inside the lid of the vessel. The electrodes were metallic strip electrodes separated by a dielectric sheet

About 20 ml of surfactant-free water was added to the container and it was closed by the lid containing the plasma electrodes. The electrodes were switched on for fixed time periods, 60 seconds, 120 seconds, 180 seconds and 600 seconds. At the end, the lid containing the plasma electrodes was replaced by a regular lid and the contents were shaken to allow the gaseous plasma-activated species inside the water to mix therewith. This water was used further for various experiments.

To study the synergy between PAW and surfactant, 1 ml of a bacterial culture suspension E-coli (Refer Table 1 ) or S.aureus (Refer Table 1 ) was mixed with 1 ml of an interfering substance (3% sterile bovine serum albumin (BSA) and this was added to:

(a) a first test vial A containing 8 ml plasma activated water in one case,

(b) a second test vial B containing a 0.01 % solution of a cationic surfactant (8 ml) in another case.

(c) a third test vial C containing identical amounts of the plasma-activated water and the cationic surfactant solution which were added simultaneously to the culture containing the BSA.

At the end of contact time of one minute and five minutes, 1 ml of reaction mixture from each test vial was transferred to 9 ml of sterile neutralizing broth to arrest the reaction. Further serial dilutions were prepared and plated using sterile TSA and plates were incubated at 37 ^° C for 24 to 48 hours. At the end of the incubation period, the number of surviving bacteria was enumerated and log reduction was calculated by using standard mathematical method.

Observations on the viable count of E-coli:

Table 1 shows the synergistic effect of the surfactant-free plasma activated water and the surfactant on the viable count (log reduction) of E-coli. The log reduction observed for individual cases i.e., PAW alone, 0.01 % BKC (benzalkonium chloride) alone and the mixture of the two are also shown in table 1.

Table 1

As can be seen from table 1 , for both one and five minutes incubation time, neither the activated water alone nor the surfactant was able to provide the extent of log-reduction which the two provided in combination. The synergistic effect against E.coli is clearly evident, more so at incubation time of five minutes.

As can be seen from table 1 (row 3), for both one and five minutes incubation time, neither the activated water alone nor the surfactant was able to provide the extent of log-reduction which the two provided in combination. The synergistic effect against S.aureus is also clearly evident.

The data in Table 2 indicates the observations when the Example 1 was repeated to determine the effect against E coli using fabrics as the inanimate substrate. Table 2

The data in Table 3 indicates how the synergistic activity of plasma activated and surfactant lead to lower and lower number of viable bacteria left on the cloth, as determined by the residual log value of the colony forming units (cfu).

Example 2: Antiviral effect Plasma activated water (PAW) was produced using cold plasma technology as described earlier in the case of Example 1 . Antiviral activity of the PAW was tested on Herpes Simplex Virus (HSV), an enveloped virus. The details are explained below.

0.1 ml of a suspension of the virus was mixed with 0.1 ml of interfering substance (3g/L sterile BSA) and this was added to:

(a) a first test vial A containing 8 ml plasma activated water in one case,

(b) a second test vial B containing a solution of a cationic surfactant (8 ml. 0.001 %) in another case.

At the end of 5 minutes contact time, 0.1 ml of reaction mixture was transferred to MicroSpin® S 400 HR columns and centrifuged at 735 g for two minutes at 4 °C. After centrifugation, 0.1 mL of filtrate was added to ice-cold maintenance medium (DMEM + 2% FCS) and then serially diluted in the maintenance medium. Further serial dilutions were prepared and each dilution was transferred on to 6 to 8 wells of Microtitre plate containing confluent (>90%) Vero cell monolayer and the plates were incubated at 37 ^° C for 72 to 96 hours. At the end of incubation period, cytopathic effects produced were noted down and log reduction was calculated.

Table 3

The data in Table 3 demonstrates synergistic interaction between the activated water and the surfactant in terms of log reduction in the viable count of HSV. As can be seen from Table 3, at incubation time of five minutes, neither PAW nor the surfactant could provide even 1 -log reduction. On the other hand, in combination they brought about more reduction than their arithmetic sum.

Claims

1 . A method of treating a surface by applying to said surface either simultaneously or sequentially in any order:

a) surfactant-free plasma activated water; and,

b) a surfactant.

2. A method as claimed in claim 1 wherein said surfactant is a cationic surfactant.

3. A method as claimed in claim 2 wherein said cationic surfactant is cetyl trimethyl halide or benzalkonium halide.

4. A method as claimed in any one of claims 1 to 3 wherein said water is activated by cold plasma.

5. A method as claimed in any one of claims 1 to 4 wherein said surfactant is in the form of a dilute aqueous solution or a composition comprising said surfactant.

A method as claimed in claim 5 wherein the concentration of said surfactant said aqueous solution or said composition is from 0.001 wt% to 10 wt%.

7. A method as claimed in any one of claims 1 to 6 wherein said surfactant-free water and said surfactant are applied at a ratio of from 1 :0.5 to 1 :20 parts by weight.

8. A dispenser comprising:

a) a first chamber spatially separated from a second chamber; and, b) a first means for dispensing surfactant-free water through said first chamber and a second means for dispensing surfactant through said second chamber either simultaneously or sequentially in any order, characterized in that the first chamber comprises an activator for activating said surfactant-free water by plasma activation.

9. A kit comprising:

a) a first container for dispensing surfactant-free water through a first

dispensing means; and,

b) a second container for dispensing a surfactant through said a second dispensing means where said containers are not attached to each other, characterized in that said kit comprises means for activating said surfactant-free water by plasma activation; which is either integral with said first container or is separate therefrom.

10. A packaged product comprising a dispenser, said dispenser comprising

a) a first chamber spatially separated from a second chamber containing surfactant-free water and a surfactant respectively, and

b) means for dispensing contents of each chamber either simultaneously or sequentially in any order,

characterized in that the surfactant-free water is plasma activated water or is activatable by means of plasma activation, which is either integral with said first chamber or separate therefrom.