Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q15/00—Anti-perspirants or body deodorants
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/02—Cosmetics or similar toiletry preparations characterised by special physical form
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K8/00—Cosmetics or similar toiletry preparations
  • A61K8/18—Cosmetics or similar toiletry preparations characterised by the composition
  • A61K8/19—Cosmetics or similar toiletry preparations characterised by the composition containing inorganic ingredients
  • A61K8/26—Aluminium; Compounds thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61Q—SPECIFIC USE OF COSMETICS OR SIMILAR TOILETRY PREPARATIONS
  • A61Q17/00—Barrier preparations; Preparations brought into direct contact with the skin for affording protection against external influences, e.g. sunlight, X-rays or other harmful rays, corrosive materials, bacteria or insect stings
  • A61Q17/005—Antimicrobial preparations
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K2800/00—Properties of cosmetic compositions or active ingredients thereof or formulation aids used therein and process related aspects
  • A61K2800/40—Chemical, physico-chemical or functional or structural properties of particular ingredients
  • A61K2800/41—Particular ingredients further characterized by their size
  • A61K2800/413—Nanosized, i.e. having sizes below 100 nm

Definitions

• the present invention relates to a deodorant composition comprising a substance of the anionic clay type and silver nanoparticles, to a process for preparing a composition comprising a substance of the hydrotalcite type and silver nanoparticles, to a deodorant composition comprising a substance of the hydrotalcite type and silver nanoparticles and to the use of these compositions as a deodorant or antimicrobial agent.
• Hydrotalcites fall within the category of anionic clays, compounds which are widespread in nature but can also be synthesized in a laboratory and are constituted by a structure with superimposed and parallel charged layers, mutually bonded by weak electrostatic attractions.
• the size of the interlayer also known as basal space, depends on various factors, such as the degree of hydration of the clay and the size of the ion interposed between the layers.
• One of the main characteristics of clays is the ability to exchange interlayer ions: this is the reason for their extensive use in the industry as adsorbent materials, as supports for catalysts, ion exchangers.
• composition variables are:
• M(II) divalent ion M(II), which can also be of two different metals (Mg, Zn, Co, Ni, Mn, et cetera);
• M(III) trivalent ion M(III), in this case also of a metal or of two different metals (Al, Cr, Fe, V, Co, et cetera);
• n_ which can have variable dimensions, charge and properties (C0 3 2_ , S0 4 2_ , CI-, N0 3 ⁇ , halides, silicates, et cetera); - number m of water molecules;
• hydrotalcite In order to better understand the structure of hydrotalcite, it can be useful to start from brucite Mg(OH) 2 , in which the magnesium ions are bonded to 6 hydroxide ions with octahedral coordination.
• the various octahedra share an edge, forming layers which are mutually stacked and bonded by hydrogen bonds. If part of the magnesium ions is substituted with trivalent ions such as aluminum ions, the layers become positively charged and this charge excess must be balanced by anions, the most common of which is carbonate, which are intercalated between the hydroxide layers. Water molecules are also present in these interlayers and bond with the hydroxide layers and with the anions by means of hydrogen bonds.
• x In order to obtain a pure hydrotalcite substance, x must be comprised between 0.2 and 0.33 so that a hydroxide phase of the excess ion does not separate next to the hydrotalcite phase.
• M(III)(OH) 3 can form, whereas for lower values segregation of M(II)(OH) 2 can occur.
• hydrotalcites there are various methods for synthesizing hydrotalcites, including: precipitation at constant pH (coprecipitation); precipitation at variable pH; urea method; ion exchange; electrochemical methods; reconstruction of the structure (reference: Hydrotalcite-like compounds: Versatile layered hosts of molecular anions with biological activity - U. Costantino, V. Ambrogi, M. Nocchetti, L. Perioli, Microporous and Mesoporous Materials 107 (2008) 149-160).
• Silver in its metallic state is inert but can react, for example with substances that are present on the skin or with the fluid of a wound, and is ionized. Ionized silver is highly reactive, because it binds to the proteins of tissues and causes structural changes in the cellular and nuclear membrane of bacteria, leading to cell modification and death. Silver also bonds to bacterial DNA and/or RNA, leading to denaturation, and inhibits bacterial replication ⁇ "Silver nanoparticles as a new generation of antimicrobials", M. Rai, A. Yadav, A. Gade, Biotechnology Advances 27 (2009) 76-83).
• HS-SPME is a quick sampling method that ensures high sensitivity and good selectivity.
• Sweat is rich in molecules of acid nature (anions) which are often malodorous.
• anions anions
• uric acid and lactic acid other substances form in situ which are generally responsible for the acrid and pungent odor of sweat and are produced by bacteria and enzymes such as protease and lipase.
• Sweat is mainly constituted by lipids, proteins, nitrogenous derivatives and glucides and is therefore an excellent medium for bacterial metabolism.
• Absorbents such as zinc magnesium and calcium oxide, are already used in deodorants in powder form due to their function of absorbents of excess humidity and of malodorous volatile substances that are formed by the enzymatic degradation of sweat, contrasting its evaporation, without however blocking the physiological mechanism of perspiration and the growth of the bacterial flora.
• antiperspirants based on aluminum is correlated with the onset of irritations, inflammations and even breast tumors.
• the aim of the present invention is to provide a composition for cosmetic use that is capable of contrasting effectively the forming of unpleasant odors caused by the degradation of sweat with high absorbent power, excellent tolerability and high effectiveness in a wide range of conditions of use and in low doses.
• Another object of the present invention is to provide active ingredients for use as skin deodorants.
• Another object of the present invention is to provide a composition comprising a substance of the hydrotalcite type and silver nanoparticles which can be used in various fields of application, including use as antimicrobial agent and as deodorant active ingredient.
• Another object of the present invention is to provide a process that can be applied easily on an industrial scale, with the appropriate modifications that are known to the person skilled in the art, for the production of said composition comprising a substance of the hydrotalcite type and silver nanoparticles.
• M(II) is a divalent ion, which can be of one or two different metals selected from Mg, Zn, Ni, Co and Fe;
• - M(III) is a trivalent ion, which can be of one or two different metals selected from Al, Cr, Fe and Mn;
• - x is a number that indicates the stoichiometric ratio between divalent and trivalent metal ions and is comprised between 0.2 and 0.33;
• n_ is at least one anion intercalated in the structure, wherein n is the number of negative charges, selected from C0 3 2_ , S0 4 2_ , Cl ⁇ , N0 3 ⁇ , C10 4 ⁇ , F ⁇ , Cl ⁇ , Br- and silicates; - S is a water molecule;
• step iii. leaving the suspension obtained in step iii. under agitation at a temperature comprised between 20 and 35°C for a time comprised between 0.5 and 5 hours.
• compositions that can be obtained by said process, by a deodorant composition comprising said composition and by its use as an active ingredient with an action as a skin deodorant or as a antimicrobial agent.
• nanoparticle references a particle with dimensions comprised between 2 and 200 nanometers.
• the terms "deodorant” and “antiperspirant” reference a substance that is capable of preventing or removing unpleasant odors produced at the skin level, particularly by the bacterial degradation of sweat.
• the present invention relates to a deodorant composition
• a deodorant composition comprising:
• composition according to the invention in which at least one anionic clay is a substance of the hydrotalcite type having the general formula (I)
• M(II) is a divalent ion, which can be of one or two different metals selected from Mg, Zn, Ni, Co and Fe;
• - M(III) is a trivalent ion, which can be of one or two different metals selected from Al, Cr, Fe and Mn;
• - x is a number that indicates the stoichiometric ratio between divalent and trivalent metal ions and is comprised between 0.2 and 0.33;
• n_ is at least one anion intercalated in the structure, wherein n is the number of negative charges, selected from CO3 2- , S0 4 2_ , Cl ⁇ , NO3-, C10 4 ⁇ , F ⁇ , Cl ⁇ , Br ⁇ and silicates;
• composition according to the invention comprising at least one anionic clay is capable, even in extremely low quantities, of inhibiting the proliferation of the bacteria that are responsible for the degradation of sweat with generation of the substances that are responsible for unpleasant odors.
• synthetic hydrotalcites because they have the same properties as natural ones and have the advantage of being free from impurities and of having a known and clearly defined composition. Moreover, their degree of crystallinity can be controlled during preparation. The aspect of purity is an extremely important aspect in the prospect of using these materials in cosmetic formulations which must be hypoallergenic. Generally, HT crystals have dimensions of a few microns (microfine powders) and this is highly advantageous, since these materials are easy to incorporate in any type of formulation and never cause problems in terms of spreadability or abrasion for formulations to be applied to the skin.
• HTs give semisolid preparations good rheological characteristics and allow formulations to adhere very well to the skin, thus having a protective, anti-inflammatory and also deodorant effect.
• Anionic clays, particularly HTs are eudermics, excellent dermatological protectors and are used for this purpose directly as powders or introduced in emulsions and pastes. They can protect the skin against external agents or even against agents produced by the skin and excreted in liquids (epidermal debris). As a consequence of this adsorbent effect, they adhere strongly to the skin, forming a film that is capable of offering mechanical protection against chemical and/or physical external agents. Furthermore, due to the mechanism of adsorption of skin secretions, they also have a refreshing and antiseptic action.
• HTs containing inorganic ions between their lamellae
• they have excellent hydrating and remineralizing properties and can also be used in case of dry skin.
• semisolid formulations such as gels, creams, pastes, cream-gels and suspensions, in addition to having their function as active ingredients, they are excellent rheological agents capable of modifying favorably the flow characteristics of preparations, positively affecting preservation, ductility and spreadability, which are essential for good usability.
• Formulations containing HTs are characterized by higher viscosity at rest, a favorable characteristic during preservation, whereas as a consequence of an increase in temperature or of mechanical stresses (massage) they tend slightly to fluidify, facilitating application.
• HTs due to the specific ion exchange mechanism and to their nanoporous structure, ensure the absorption and removal of waste, of skin exudates and of sweat, storing them within their lamellar structure.
• Bacterial proteases allow the forming of ammonia, amines and sulfurated derivatives (sulfurated hydrogen and mercaptans), while bacterial lipases degrade triglycerides, forming short-chain fatty acids, such as valeric acid, caprylic acid, caproic/capronic acid, capric acid, enanthic acid, pelargonic acid, butyric acid and propionic acid.
• HTs are a weak base and in contact with sweat can facilitate the ionization of the carboxylic group of these fatty acids, which can be exchanged more easily with the counterions that are present between the lamellae of HT.
• HTs HT-containing microorganisms
• the particular structure of HTs allows to absorb microorganisms, thus interacting with the supported particles.
• the use of HTs, even if they contain metals including aluminum, offers assurances in terms of lack of toxicity.
• Silver nanoparticles can be deposited on the structure of the HT or can be within the structure of the HT itself. Preferably, the nanoparticles are deposited on the structure of the HT.
• the effectiveness of the composition is affected directly by the cosmetic form of the product that comprises it and specifically of the active ingredient that is used and its concentration.
• composition according to the present invention can be formulated in various forms, including the form of a water-alcohol solution, of an atomizable aqueous emulsion, of an aerosol spray, of a stick, of a spray formulation without propellant gas ("no gas" deodorant).
• the composition of the present invention is in the form of a water-alcohol solution or atomizable aqueous emulsion.
• the content of substance of the hydrotalcite type having the general formula (I) and of silver nanoparticles is comprised between 1 and 30% by weight on the total weight of the composition.
• the content of silver nanoparticles is comprised between 0.05 and 5% by weight on the weight of the substance of the hydrotalcite type of formula (I). More preferably, the content is between 0.1 and 1% by weight on the weight of the substance of the hydrotalcite type of formula (I).
• the silver nanoparticles have dimensions comprised between 2 and 200 nm.
• the silver nanoparticles have a size of 25 nm.
• compositions of the invention comprising hydrotalcites based on zinc/aluminum and magnesium/aluminum are easy to prepare by means of known and reliable methods (reference: "Hydrotalcite- like compounds: Versatile layered hosts of molecular anions with biological activity", U. Costantino, V. Ambrogi, M. Nocchetti, L. Perioli, Microporous and Mesoporous Materials 107 (2008) 149-160 and "Preparation and catalytic properties of cationic and anionic clays", Angelo Vaccari, Catalysis Today 1998, 41, 53-71) with minimal modifications which are within the grasp of the person skilled in the art and demonstrate an excellent deodorant and antibacterial action.
• M(II) is Mg or Zn
• M(III) is Al
• a n" is C0 3 2" or the Zn/Al ratio is 2: 1.
• Examples of preferred formulas are Zn 0,68 Alo, 32 (OH) 2 (C0 3 )o ,32 x 0,42H 2 O or Mg 0,68 Alo, 32 (OH) 2 (C0 3 )o ,32 x 0,42H 2 O.
• composition according to the invention comprises one or more excipients that are suitable for cosmetic use, in particular for the treatment of the skin in areas subjected to intense sweating.
• the effectiveness of the composition is linked to the cosmetic form of the product that comprises it and the targeted choice of excipients can give desirable properties, for example a long duration of action.
• at least one excipient is selected from a hydrophobic polymer, a fragrance, an antimicrobial agent, an enzyme deviator, a viscosity agent, a rheological agent and essential oils.
• hydrophobic polymer particularly hydrophobically modified acrylates
• fragrances particularly geraniol, citronellol et cetera
• Antiperspirant astringents with these substances, one works at the level of secretions. By reducing the extent, stagnant moisture is reduced and the quantity of material that can be metabolized by the microbial flora is also reduced;
• Antimicrobial agents with these, one works at the level of bacteria, the colonies of which are reduced, so as to reduce the potential of intervention on glandular secretions;
• Bacteriostatic agents with this means, excessive microbial proliferation is prevented and the forming of odorous catabolites is reduced accordingly; 4. Enzyme deviators: these substances block the hydrolytic activity of bacteria, reducing the forming of odorous volatile fractions;
• Absorbent agents these are substances that intercept odorous bodies by means of a chemical-physical capture process. These agents retain within their structure the odorous molecules that originate from the degradation of secretions.
• Triclosan, triclocarban, chlorhexidine, oxyglycerol etc. are among the most widely used antimicrobial agents.
• these antiseptic substances are used at a concentration that is sufficient to ensure a bacteriostatic action.
• the component that is most widely used is in any case triclosan.
• mixtures have been devised which are constituted by 50% aromatic bodies having an antimicrobial action and a harmonious fragranced composition for the remaining part.
• Enzyme deviators are compounds that act on the bacterial enzymes that are responsible for the degradation of glandular products. Triethyl citrate is the main representative of this category of compounds.
• Absorbents are substances that act as chelating agents of short-chain fatty acids, reducing their vapor pressure and therefore making them nonvolatile and consequently non-odorous.
• the substance most used so far is zinc ricinoleate. Every formulation seeks a good compromise between good tolerability and effectiveness in a very significant percentage of users.
• the composition according to the invention comprises at least one additional active ingredient selected among an antimicrobial agent, an enzyme deviator, an absorbent agent, a rheological agent, an essential oil and a propellant.
• an antimicrobial agent an enzyme deviator, an absorbent agent, a rheological agent, an essential oil and a propellant.
• the antimicrobial agent is triclosan and the enzyme deviator is triethyl citrate.
• the present invention relates to use as active ingredient with skin deodorant action of a composition
• a composition comprising:
• At least one anionic clay is a substance of the hydrotalcite type comprising silver nanoparticles and having the general formula (I)
• M(II) is a divalent ion, which can be of one or two different metals selected from Mg, Zn, Ni, Co and Fe;
• - M(III) is a trivalent ion, which can be of one or two different metals selected from Al, Cr, Fe and Mn;
• - x is a number that indicates the stoichiometric ratio between divalent and trivalent metal ions and is comprised between 0.2 and 0.33;
• n_ is at least one anion intercalated in the structure, wherein n is the number of negative charges, selected from C0 3 2_ , S0 4 2_ , Cl ⁇ , N0 3 ⁇ , C10 4 ⁇ F ⁇ CI " , Br " and silicates;
• the concentration of silver nanoparticles is comprised between 0.1 and 1% by weight on the total weight of the substance of the hydrotalcite type having formula (I) and of the silver nanoparticles.
• the silver nanoparticles have dimensions comprised between 2 and 200 nm.
• the silver nanoparticles have dimensions equal to 25 nm.
• M(II) is Mg or Zn
• M(III) is Al
• a n ⁇ is C0 3 2_ .
• the active ingredient is ⁇ 0.6 8 ⁇ 1 ⁇ . 32 ( ⁇ ) 2 ( 0 3 ) ⁇ .32 x 0.42H 2 O or Mgo.6 8 Alo .32 (OH) 2 (C0 3 )o .32 x 0.42H 2 O.
• the present invention relates to a process for the preparation of a composition
• a composition comprising:
• M(II) is a divalent ion, which can be of one or two different metals selected from Mg, Zn, Ni, Co and Fe;
• - M(III) is a trivalent ion, which can be of one or two different metals selected from Al, Cr, Fe and Mn;
• - x is a number that indicates the stoichiometric ratio between divalent and trivalent metal ions and is comprised between 0.2 and 0.33;
• n_ is at least one anion intercalated in the structure, wherein n is the number of negative charges, selected from C0 3 2_ , SCV-, CI-, N0 3 ⁇ ,
• step iii adding under agitation at a temperature comprised between 20 and 35°C the calcined substance obtained in step i. to the suspension obtained in step ii.;
• step iii. leaving the suspension obtained in step iii. under agitation at a temperature comprised between 20 and 35°C for a time comprised between 0.5 and 5 hours.
• the present invention relates to a composition that can be obtained by such process.
• the silver nanoparticles have dimensions comprised between 2 and 200 nm.
• the present invention relates to a deodorant composition
• a deodorant composition comprising the composition that can be obtained by this process.
• the present invention relates to the use of the composition as an active ingredient with an action as skin deodorant and/or as antimicrobial agent.
• example 1 related to a common Zn/Al 2: 1 hydrotalcite by co-precipitation
• example 2 related to a common Mg/Al 2: 1 hydrotalcite
• example 3 related to the preparation of the nanoparticles from sugars and to the reconstruction of calcined HT with the nanoparticles.
• a synthesis is performed in which the total concentration of the metals is 1.5 M and the ratio between the moles of the salts of Zn and Al is 2: 1.
• a 0.25M solution of Na 2 C0 3 is prepared and 300 mL of this solution are placed in a 2L beaker.
• a 1M NaOH solution is prepared.
• the beaker is placed on a heating plate with magnetic agitation.
• the pH-meter is immersed in the solution.
• the beaker is then covered with parafilm and is left to age at 21°C for 24 hours.
• the precipitate is then placed to dry for 24 h in a stove at 110°C.
• a 0.25M solution of Na 2 C0 3 is prepared and 300 mL of this solution are placed in a 2L beaker.
• a 1M NaOH solution is prepared.
• the beaker is placed on a heating plate with magnetic agitation.
• the pH-meter is immersed in this solution.
• the beaker is then covered with parafilm and is left to age at 21°C for 24 hours.
• Filtration is then performed with a Biichner filter, making sure to wash well the precipitate with at least 2 L of water in order to eliminate the nitrates: long times (approximately 6 hours) are needed and increase as the layer of precipitate on the filter increases. Indeed, in case of large quantities it is convenient to use at least 2 Biichner filters. Attention must be paid continuously to ensure that the precipitate remains at all times wetted with a thin layer of liquid, in order to avoid the forming of cracks and therefore of preferential paths that would lead to incomplete washes.
• the precipitate is then placed to dry for 24 h in a stove at 110°C.
• glucose 0.4 g are weighed in a 25 mL beaker and are dissolved with 7.8 mL of H 2 0 UPP; then 200 ⁇ of 0.01 M AgN0 3 are added and the system is placed to heat in a water bath at 100-150°C, under agitation for approximately 2 hours.
• the system is then allowed to cool to 20-25 °C in an adapted sample holder wrapped with silver-coated paper (clear yellow solution).
• the preparation of nanoparticles is rather delicate: it is important that the glassware is perfectly clean and that the solutions used are fresh. If the solutions are stored in a refrigerator, allow them to stabilize at ambient temperature.
• dissolving 0.4 g of glucose in 7.8 mL of UPP H 2 it is possible to prepare 50 mL of a solution at the same glucose concentration by weighing 2.564 g and dissolving them in a 50 mL flat- bottom flask, bringing to volume with UPP H 2 0 and then draw from there the 7.8 mL cited above (in this manner the preparation times are speeded up experimentally).
• the AAS technique (atomic absorption spectroscopy) has been used to determine the content of Zn, Mg respectively in ZnAl and MgAl hydrotalcites.
• the samples In order to perform analyses with the first line, the samples must therefore be prepared so as to remain in the range 0.01-2 ppm (mg/L or ⁇ g/mL).
• HN0 3 /H 2 0 13.6 100 (10 mL HN0 3 68% + 40 mL distilled H 2 0) is used as diluent to make the solutions and dissolve the samples.
• the flows used for the flame are:
• the HT concentrations are obtained by dividing the weighing by the volume.
• the Zn concentrations are derived from the analyses.
• the Zn mass % is calculated by multiplying by 100 the value of the ratio between Zn Cone and HT Cone.
• Mg is similar to that of Zn; it is only necessary to observe the analysis specifications and prepare the 4 standards and the samples to be analyzed in the concentration range for the wavelength that is chosen.
• the results obtained for Mg are listed hereafter in the table and are expressed clearly and concisely.
• the analyzed samples are:
• the AgN0 3 weighing to be performed is calculated as follows:
• the actual weighing was exactly 0.0004 g, which correspond to a % w/w of Ag of 0.05%.
• ZnA1216P is added until 0.5 g is reached, then the system is ground well and placed in a pelletizer for approximately 10 minutes.
• the AgN0 3 weighing to be performed is calculated as follows:
• the actual weighing was 0.0010 g, which correspond to a % w/w of Ag of 0.125%.
• ZnA1216P is added until 0.5 g is reached, then the system is ground well and placed in a pelletizer for approximately 10 minutes.
• the actual weighing was exactly 0.004 g, which correspond to a % w/w of Ag of 0.5%.
• ZnA1216P is added until 0.5 g is reached, then the system is ground well and placed in a pelletizer for approximately 10 minutes.
• the AgN0 3 weighing to be performed is calculated as follows:
• the actual weighing was 0.009 g, which correspond to a % w/w of Ag of 1.125%.
• ZnA1216P is added until 0.5 g is reached, then the system is ground well and placed in a pelletizer for approximately 10 minutes.
• a PX-10 crystal is used for analysis in order to have as much transmission as possible.
• the ZnAlAgl, ZnAlAg3 samples have IR spectra that are practically identical and the MgAlAgl, MgAlAg3 samples also have practically identical IR spectra. For this reason, only the following IR spectra are given in Figures 3-6: ZnA1212P; ZnAlAgl ; MgA121 ; MgAlAgl .
• the widened peak that is present at approximately 3420 cm “1 is due to the stretching of the hydroxyl groups (v 0.H ), both of the layers of the hydrotalcite and of the interlamellar water molecules.
• the low- intensity peak that is present at 1637-1648 cm “1 is assigned to the bending vibrations of highly absorbed water molecules.
• the peak at 1356 cm “1 is assigned to the asymmetric stretching of the carbonate anions (v 3 ) and the shoulder around 1500 cm-1 is attributed to the splitting of the vibration v 3 of the carbonate.
• the interlamellar carbonate ions of the HT can also be observed at v 2
• FIG. 7 plots the UV spectrum of the silver nanoparticles obtained with 3 different methods (1 glucose, 3 sodium citrate, 2 fructose for comparison).
• Figures 8-10 are SEM images of the most representative samples. In particular:
• Figure 10 -ZnAlAg3 20000 QBSD.
• FIG 11 lists the results of the antibacterial tests performed in the following manner.
• a liquid culture medium heated to 120°C for 20 min, constituted by a triptone concentration equal to 10 g/L (chemically hydrolyzed casein) is prepared.
• Adapted sterile flasks are used with a lateral attached portion which allows to read the transmittance with a turbidimeter.
• the flasks are placed under agitation at 37°C.
• Bacterial growth is evaluated by measuring transmittance every hour, making sure to perform the analysis well (same position of the lateral attached part).
• the transmittance values are all converted into absorbance values.
• the following values are all related to transmittance % measurements.
• MgAlAg3 hydrotalcite has a bacteriostatic effect (bacterial growth is stopped for 8 hours and then resumes).
• the test is not significant, since a smaller amount than the others has been drawn and evidently it was not sufficient to provide a bacteriostatic or antimicrobial power. It is believed that by repeating the test with a larger amount (higher concentration) an effect similar to that of MgAlAg3 would be obtained. It is important to specify this because hydrotalcites assuredly will be used in larger quantities in order to ensure the adsorbent effect.
• the materials obtained have excellent antibacterial properties.
• Figures 12-17 show the exemplifying chromatographs related to the adsorption tests on the part of substances of the hydrotalcite type which comprise silver nanoparticles of a mixture of fatty acids (mixture 16) intended to simulate the components of the odor produced by the bacterial decomposition of sweat.
• Figure 12 relates to the control
• Figure 13 relates to
• MIXTURE 16 is always used:
• Analysis is performed by introducing the fiber in the GC with a holder height of 3.6 cm.
• ZnAlAg3 hydrotalcite i.e., ZnAl hydrotalcite with deposited nanoparticles pre- synthesized from glucose.
• Control is the reference required to understand how much each sample adsorbs. The smaller the normalized areas for the analytes and therefore the smaller the signals that reach the detector, the more that sample absorbs that analyte. All samples adsorb.
• Zinc ricinoleate (Zn RIC) is the main constituent of non— antiperspirant deodorants and therefore acts as a commercial reference.
• Zn IC As regards the Zn IC, it has a lower adsorbent effect than ZnAl hydrotalcite samples, comparable with that of MgAl hydrotalcite samples, albeit clearly lower as regards 2-ethylhexanoic, octanoic and heptanoic acids.

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