COMPOSITIONS COMPRISING POLYESTERS OF BIOLOGICAL ORIGIN AND BIOCOMPATIBLE INORGANIC COMPOUNDS, AND USES THEREOF IN THE COSMETIC FIELD

Abstract

A composition, comprising: at least one polyhydroxyalkanoate (PHA); and at least one calcium phosphate. The at least one calcium phosphate is in a form of aggregates having an average size greater than or equal to 0.1 micron (m) and less than or equal to 10 m.

Claims

1. A composition, comprising: at least one polyhydroxyalkanoate (PHA); and at least one calcium phosphate; wherein the at least one calcium phosphate is in a form of aggregates having an average size greater than or equal to 0.1 micron (m) and less than or equal to 10 m.

2. The composition of claim 1, wherein the at least one PHA is a polymer containing repeating units of formula:
OCHR.sub.1(CH.sub.2).sub.nCO(I), where R.sub.1 is selected from: H, C.sub.1-C.sub.12 alkyls, C.sub.4-C.sub.16 cycloalkyls, C.sub.2-C.sub.12 alkenyls, possibly substituted by at least one group selected from: halogen (F, cl, Br), CN, OH, COOH, OR, COOR (R=C.sub.1-C.sub.4 alkyl, benzyl), and where n is 0 or an integer greater than or equal to 1 and less than or equal to 6.

3. The composition of claim 1, wherein the at least one PHA has a weight average molecular weight (M.sub.w) greater than or equal to 5,000 daltons (Da) and less than or equal to 1,500,000 Da.

4. The composition of claim 1, wherein the at least one PHA is in a form of particles having an average size greater than or equal to 0.1 m and less than or equal to 100 m.

5. The composition of claim 1, wherein the at least one calcium phosphate is selected from: octacalcium phosphate, tricalcium phosphate, apatite, and hydroxyapatite.

6. The composition of claim 5, wherein the at least one calcium phosphate is apatite or hydroxyapatite.

7. The composition of claim 1, wherein the at least one calcium phosphate further comprises zinc ions which partially substitute calcium ions of the at least one calcium phosphate.

8. The composition of claim 1, wherein the at least one calcium phosphate further comprises carbonate ions which partially substitute phosphate ions of the at least one calcium phosphate.

9. The composition of claim 1, wherein the at least one calcium phosphate is a hydroxyapatite of formula:
Ca.sub.10xZn.sub.x(PO.sub.4).sub.6y(CO.sub.3).sub.y+z(OH).sub.2z where x is a number greater than or equal to 0.0055 and less than or equal to 0.6, where y is a number greater than or equal to 0.065 and less than or equal to 0.9, and where z is a number greater than or equal to 0 and less than or equal to 0.32.

10. The composition of claim 1, wherein the at least one PHA is present in an amount greater than or equal to 60% and less than or equal to 98% by weight with respect to a total weight of the composition.

11. The composition of claim 1, wherein the at least one calcium phosphate is present in an amount greater than or equal to 2% by weight and less than or equal to 40% by weight with respect to a total weight of the composition.

12. The composition of claim 1, further comprising: at least one bioactive substance.

13. The composition of claim 12, wherein the at least one bioactive substance is selected from: antioxidants, antibacterial substances, anti-inflammatories, and painkillers.

14. Use of the composition of claim 1 in a formulation for cosmetic use.

15. A process for preparing the composition of claim 1, the process comprising: providing a first aqueous suspension containing the at least one PHA in a form of particles in suspension; providing a second aqueous suspension containing the at least one calcium phosphate in a form of particles in suspension; and mixing the first aqueous suspension and the second aqueous suspension, so as to obtain an aggregation between PHA particles and calcium phosphate particles.

16. The process of claim 15, wherein the second aqueous suspension containing the at least one calcium phosphate is obtained by adding an aqueous solution of phosphoric acid (H.sub.3PO.sub.4) to an aqueous solution containing calcium ions (Ca.sup.2+), and mixing the solution thus obtained until the aqueous suspension containing the at least one calcium phosphate is obtained.

17. A process for preparing the composition of claim 1, the process comprising: providing a first aqueous solution comprising calcium ions with a concentration greater than or equal to 0.1 moles/liter and less than or equal to 10 moles/liter; adding to the first aqueous solution at least one first aqueous suspension of at least one PHA in a form of particles in suspension, so as to obtain a second suspension; adding to the second suspension a second aqueous solution containing phosphate ions at a concentration greater than or equal to 0.1 moles/liter and less than or equal to 10 moles/liter; and maintaining a suspension thus obtained under stirring at a temperature greater than or equal to 10 C. and less than or equal to 80 C., so as to obtain an aggregation between PHA particles and calcium phosphate particles.

18. The composition of claim 1, wherein the at least one calcium phosphate is in the form of aggregates having an average size greater than or equal to 0.2 m and less than or equal to 5 m.

19. The composition of claim 1, wherein the at least one calcium phosphate comprises one or more of octacalcium phosphate, tricalcium phosphate, apatite, or hydroxyapatite.

20. The composition of claim 12, wherein the at least one bioactive substance comprises one or more antioxidants, antibacterial substances, anti-inflammatories, or painkillers.

Description

EXAMPLE 1

[0069] An aqueous suspension of hydroxyapatite (HA) was prepared as follows.

[0070] An aqueous solution of 25.0 g of Ca(OH).sub.2 and 0.2 g of CaCO.sub.3 was prepared by mixing said products in 250 ml of demineralized water, kept under stirring for 1 hour at 45 C. A solution of 6.3 g of phosphoric acid (H.sub.3PO.sub.4) in 250 ml of demineralized water was added dropwise to this solution. The mixture thus obtained was kept under stirring for 24 hours at 25 C. The suspension of HA thus obtained was used as such as described hereunder.

[0071] The HA thus obtained was characterized by its crystallinity degree (CD), defined as above and measured in accordance with the method described in Landi, E., Tampieri, A., Celotti, G., Sprio, S., Densification behaviour and mechanisms of synthetic hydroxyapatites, J. Eur. Ceram. Soc., 2000, 20, 2377-2387. The CD value obtained was equal to 71.0%.

[0072] A solution was prepared, consisting of 1 g of procyanidin dissolved in 7.5 g of demineralized water. The solution was added to the HA suspension prepared as described above (containing 10 g of HA). The dimensions of the single HA crystals ranged from 0.05 to 0.4 microns. These were in turn spontaneously aggregated in clusters having an average size of 1 micron.

[0073] The suspension was kept under stirring for about 60 minutes.

[0074] 5 g of PHA, in the form of particles obtained from the fermentation broth without being dried, having an average size of around 10 m, were suspended in 10 g of demineralized water, with vigorous stirring for 30 minutes (concentration of PHA: 10% by weight).

[0075] The suspension of HA containing procyanidin was mixed with the suspension of PHA, the whole mixture was kept under stirring for 120 minutes.

[0076] The composition according to the present invention was separated from the suspension thus obtained, by filtration.

[0077] The starting materials and the composition thus obtained were characterized as follows.

[0078] FT-IR Spectra

[0079] FIG. 1 shows the FT-IR spectra of HA as such (spectrum A), of HA+procyanidin (spectrum B), of composition HA+PHA+procyanidin (spectrum C), of procyanidin as such (spectrum D), of PHA as such (spectrum E). In spectrum A relating to HA alone, the presence can be observed of the band typical of phosphate group at 1100-1030 cm.sup.1. After the combination with procyanidin (spectrum B), a remarkable reduction in the intensity of this band can be noted, and the accentuation of the bands at 2800-3000 cm.sup.1, characteristic of the groups present in procyanidin and visible in spectrum D.

[0080] After the combination with PHA (spectrum C), there is also the appearance of some bands typical of PHA, first of all that at 1800 cm.sup.1, clearly visible in the spectrum of PHA alone (spectrum E).

[0081] SEM Images

[0082] Some SEM (scanning electron microscope) images were taken of PHA particles as such (FIG. 2) and PHA particles after being bound with the HA particles containing procyanidin (FIG. 3). A different aggregation state of the PHA particles can be observed, before and after the combination with HA.

[0083] EDX Analysis

[0084] The composition of the surface of the particles of PHA as such (FIG. 4) and of the particles of PHA after being bound to the HA particles containing procyanidin (FIG. 5), was analyzed by means of elemental analysis with an EDX probe (Energy Dispersive X-ray Analysis).

[0085] FIG. 4 shows how the EDX analysis carried out on the surface of the PHA particles reveals the presence of Au (gold), which is present as it is added by the instrument used for carrying out the analysis, sodium (probably present in the liquid in which the PHA is suspended), but above all carbon and oxygen.

[0086] In FIG. 5, on the other hand, it can be noted that elemental analysis reveals the presence of calcium and phosphorous, elements characteristic of hydroxyapatite, and in the same ratio in which the latter was synthesized. This means that a thin layer of HA was deposited on the micrometric granules of PHA, which interacts with the HA.

EXAMPLE 2

[0087] A solution was prepared, consisting of 21 g of coenzyme Q10 dissolved in 7 g of demineralized water. The solution was added to a suspension in water of 10 g of hydroxyapatite (HA) obtained as described in Example 1.

[0088] The dimensions of the single crystals of HA ranged from 0.05 to 0.4 microns. These were in turn spontaneously aggregated in clusters having an average size of 1 micron.

[0089] The suspension was kept under stirring for about 60 min.

[0090] 10 g of a suspension of PHA, obtained directly from the fermentation process for the production of PHA itself, previously subjected to purification, were mixed with the suspension of HA containing coenzyme Q10. The whole mixture was kept under stirring for 180 minutes.

[0091] The composition according to the present invention was separated from the suspension thus obtained, by filtration.

[0092] The starting materials and the composition thus obtained were characterized as follows.

[0093] FT-IR Spectra

[0094] FIG. 6 shows the FT-IR spectra of HA as such (spectrum A), of coenzyme Q10 as such (spectrum B), of composition HA+PHA+coenzyme Q10 (spectrum C), of PHA as such (spectrum D).

[0095] In spectrum A (relating to HA alone), the presence can be observed of the band typical of phosphate group at 1100-1030 cm.sup.1. After the combination between HA, Q10 and PHA (spectrum C), a significant reduction in the intensity of this band can be noted, and the accentuation of the bands at 2800-3000 cm.sup.1, characteristic of the groups present in Q10 and visible in spectrum B relating to Q10 alone. In spectrum C, there is also the appearance of some bands typical of PHA, first of all that at 1800 cm.sup.1, clearly visible in the spectrum of PHA alone (Spectrum D).

EXAMPLE 3

[0096] Example 2 was repeated using, instead of the solution of coenzyme Q10, a solution consisting of potassium ascorbate (0.20 g) dissolved in 5 ml of demineralized water.

[0097] FT-IR Spectra

[0098] FIG. 7 shows the FT-IR spectra of HA as such (spectrum A), of ascorbate+HA (spectrum B), of composition HA+PHA+ascorbate (spectrum C), of ascorbate as such (spectrum D), of PHA as such (spectrum E).

[0099] In spectrum A, the presence can be observed of the band typical of phosphate group at 1100-1030 cm.sup.1. After the combination with ascorbate (spectrum B), a significant reduction in the intensity of this band can be noted, and the accentuation of the bands at 2800-3000 cm.sup.1, characteristic of the groups present in the ascorbate and visible in spectrum D. Again in spectrum B, a broadening of the absorption band at 3200 cm.sup.1 can also be observed, due to the overtone of absorption bands typical of ascorbate with those of HA.

[0100] After the combination with PHA (spectrum C), in addition to the above-mentioned overtone at 3200 cm.sup.1, the appearance of some bands typical of PHA is noted, first of all that at 1800 cm.sup.1, clearly visible in the spectrum of PHA alone (spectrum E).

EXAMPLE 4

[0101] 100 ml of a solution containing calcium ions with a concentration equal to 3.60 g/l were introduced into a reaction flask in an environment thermostat-regulated at 25 C.

[0102] 10 g of a suspension of PHA, obtained directly from the fermentation process for the production of PHA itself, previously subjected to purification, were mixed with the above-mentioned solution of calcium ions. The whole mixture was kept under stirring for 60 minutes.

[0103] 20 ml of an aqueous solution containing phosphate ions were prepared separately, at a concentration equal to 17.85 g/l. This solution was added dropwise (dripping rate equal to 0.3 ml/min), to the suspension of PHA containing calcium ions as indicated above, under vigorous stirring. The suspension was then subjected to maturation, keeping it under stirring at 25 C. for about 24 hours.

[0104] Finally, a solution of lactoferrin, obtained by dissolving 200 mg of lactoferrin in 10 ml of demineralized water (concentration: 20 mg/ml), was added to the suspension. The whole mixture was kept under stirring for a time equal to about 360 minutes.

[0105] The composition according to the present invention was separated from the suspension thus obtained, by filtration. The starting materials and the composition thus obtained were characterized as follows.

[0106] Ft-IR Spectra.

[0107] FIG. 8 shows the FT-IR spectra of HA as such (spectrum A), of composition HA+PHA+lactoferrin (spectrum B), of lactoferrin as such (spectrum C), of PHA as such (spectrum D).

[0108] In spectrum A, the presence can be observed of the band typical of phosphate group at 1100-1030 cm.sup.1. After the combination with lactoferrin (spectrum B), a significant reduction in the intensity of this band can be noted, and the accentuation of the bands at 2800-3000 cm.sup.1, characteristic of the groups present in lactoferrin as such (spectrum C). Due to the interaction with PHA, in addition to the above-mentioned overtone at 3200 cm.sup.1, the appearance can also be noted of some bands typical of PHA, first of all that at 1800 cm.sup.1, clearly visible in the spectrum of PHA alone (Spectrum D).

EXAMPLE 5

[0109] Following the same procedure described in Example 4, two compositions of lactoferrin, hydroxyapatite and PHA were prepared, using solutions of lactoferrin with concentrations equal to 60 mg/ml and 80 mg/ml, and the same aqueous suspensions of HA and PHA used in Example (weight ratio between lactoferrin and mixture of HA+PHA equal to 1:1). The antibacterial effectiveness of these compositions was assessed, by means of bacterial count on Petri plates with respect to the growth of Streptococcus mutans ATCC 35668. The results are reported in Table 1, which also shows for comparative purposes the percentage reduction values of bacterial growth for a mixture of HA and PHA (weight ratio 1:1), obtained from the same products used in Example 4, and for lactoferrin alone (aqueous solution with a concentration of 60 mg/ml and 80 mg/ml).

TABLE-US-00001 TABLE 1 Reduction bacterial growth (%) HA + PHA (1:1) 8 Lactoferrin (60 mg/ml) 30 Lactoferrin (80 mg/ml) 35 Lactoferrin (60 mg/ml) + 41.8 HA + PHA Lactoferrin (80 mg/ml) + 62.2 HA + PHA

[0110] From the results obtained, the improved antibacterial effect deriving from the use of the compositions according to the present invention with respect to the use of the separate components (synergic effect), is evident.