Organic polymer particles containing poly(oxazoline) stabilizers and use of poly(oxazolines) for stabilizing organic polymer particles

Abstract

The invention relates to compositions containing water-soluble poly(oxazoline) and organic polymer particles chosen from the group of polyolefins, polyvinyl aromatics, polyvinyl esters, polyesters, polyamides, polyimides, polycarboxylic acids, polycarboxilic acid esters, polycarboxylic acid amides, polynitriles, polysulfonic acids, polyketones, polysulfones, polymeric polyols, polyurethanes, proteins, polymeric carbohydrates, nucleic acids or from a mixture of two or more of these polymers. The water-soluble poly(oxazolin) acts as a stabilizer for the polymer particles and can particularly advantageously be used as a stabilizer in the freeze-drying of aqueous polymer dispersions.

Claims

1. A composition comprising a water-soluble poly(oxazoline) compound and organic polymer particles, wherein the organic polymer particles comprise a polyester; a mean diameter D.sub.50 of the organic polymer particles is less than 10 μm; and the water-soluble poly(oxazoline) compound is not covalently bonded to the polymeric particles.

2. The composition according to claim 1, characterized in that the polyester is a polyhydroxyalkanoate.

3. The composition according to claim 2, characterized in that the polyhydroxyalkanoate is a lactic acid homo- or copolymer.

4. A composition comprising a water-soluble poly(oxazoline) compound and organic polymer particles, wherein a mean diameter D.sub.50 of the organic polymer particles is less than 10 μm; the organic particles being selected from the group of polyolefins, polyvinylaromatics, polyvinyl esters, polyesters, polyamides, polyimides, polycarboxylic acids, polycarboxylic acid esters, polycarboxylic acid amides, polynitriles, polysulfonic acids, polyketones, polysulfones, polymeric polyols, polyurethanes, proteins, polymeric carbohydrates, nucleic acids or a mixture of two or more of these polymers; the organic polymer particles contain one or more pharmaceutically active substances; and the water-soluble poly(oxazoline) compound is not covalently bonded to the organic polymeric particles.

5. The composition according to 1, wherein the organic polymer particles have diameters in the range of 50 to 999 nm.

6. The composition according to claim 1, wherein the organic polymer particles form a dispersed phase in a hydrophilic liquid.

7. The composition according to claim 4, wherein the organic polymer particles are in solid form and are coated by the poly(oxazoline).

8. The composition according to 4, wherein the organic polymer particles have diameters in the range of 50 to 999 nm.

9. The composition according to claim 4, wherein the organic polymer particles form a dispersed phase in a hydrophilic liquid.

10. The composition according to claim 4, wherein the organic polymer particles are in solid form and are coated by the poly(oxazoline).

11. The composition according to claim 4, wherein the organic polymer particles comprise a polyester.

12. The composition of claim 1, wherein at least 90 wt % of the water-soluble poly(oxazoline) compound has a recurring structural unit of formula I: —NR.sup.1—CR.sup.3H—CR.sup.4H— (I), wherein R.sup.1 is —CO—R.sup.2 with R.sup.2 being hydrogen or methyl or ethyl; and R.sup.3, R.sup.4 are independently hydrogen, methyl, ethyl, propyl, or butyl.

13. The composition of claim 12, wherein at least 95 wt % of the water-soluble poly(oxazoline) compound has the recurring structural unit of formula I.

14. The composition of claim 1, wherein the water-soluble poly(oxazoline) is a homopolymer.

15. The composition of claim 4, wherein at least 90 wt % of the water-soluble poly(oxazoline) compound has a recurring structural unit of formula I: —NR.sup.1—CR.sup.3H—CR.sup.4H— (I), wherein R.sup.1 is —CO—R.sup.2 with R.sup.2 being hydrogen or methyl or ethyl; and R.sup.3, R.sup.4 are independently hydrogen, methyl, ethyl, propyl, or butyl.

16. The composition of claim 15, wherein at least 95 wt % of the water-soluble poly(oxazoline) compound has the recurring structural unit of formula I.

17. The composition of claim 4, wherein the water-soluble poly(oxazoline) is a homopolymer.

18. The composition of claim 4, further comprising an auxiliary agent and/or an additive.

Description

(1) The following examples illustrate the invention without limiting it.

EXAMPLE 1

Preparation of poly(2-oxazoline)s (PD.SUB.x.)

(2) The synthesis of poly(2-oxazoline)s has already been described in the literature (see, for example, Wiesbrock, F. et al., Macromolecular Rapid Communications 2004, 25, 1895-1899). The procedure is therefore exemplified for poly(2-ethyl-2-oxazoline) having a degree of polymerization (DP) of 61 (P(EtOx).sub.61).

(3) In a microwave reaction vessel 2-ethyl-2-oxazoline (6.06 mL, 60.0 mmol), methyl tosylate (0.15 mL, 0.1 mmol) and acetonitrile (8.79 mL) were mixed under inert conditions. The reaction vessel was then heated to 140° C. in a synthesis microwave for 14 minutes. Subsequently, the reaction was terminated by the addition of 0.5 mL of deionized water and stirred overnight at room temperature. The resulting solution was purified by diluting with dichloromethane and then precipitated in excess ice-cold diethyl ether. The precipitated polymer was then filtered off and dissolved in dichloromethane. The solvent was then removed on a rotary evaporator and the polymer was dried under high vacuum until completely free of solvent. The final product was a crystalline, white solid.

(4) .sup.1H-NMR (CDCl.sub.3, 300 MHz): δ=4.34 (0.1H, s, backbone-OH), 3.44 (4.0H, s, backbone), 3.02 (0.3H, s, CH.sub.3-backbone), 2.4 (1.7H, m, CH.sub.2 (EtOx)), 1.11 (2.5H, s, CH.sub.3 (EtOx)) ppm.

(5) SEC (eluent: DMAc.sup.1), 0.21% LiCl, PS.sup.2) standard): M.sub.n=11,200 g mol.sup.−1, M.sub.w=12,200 g mol.sup.−1, D=1.09.

(6) FIG. 1 shows the .sup.1H NMR (300 MHz, CDCl.sub.3) plot of P(EtOx).sub.61.

(7) FIG. 2 shows the size exclusion chromatogram (DMAc.sup.1), 0.21% LiCl, PS.sup.2)calibration) of P(EtOx).sub.61. .sup.1) DMAc=dimethylacetamide .sup.2) PS=polystyrene

EXAMPLE 2

Freeze-Drying Experiments

(8) PLGA.sup.3) nanoparticles were prepared by nanoprecipitation (see Example 3) and characterized by dynamic light scattering in terms of size (particle diameter, z-average) and size distribution (PDI). Following this characterization, a certain amount of cryoprotectant was added to the nanoparticle suspension at various concentrations. The suspensions were frozen in a −80° C. freezer and then freeze-dried (24 h, −56° C., 0.01 mbar). About 2 mg of the resulting powder was resuspended in 1 mL ultrapure water and then characterized again with dynamic light scattering for particle diameter (z-average) and PDI. The ratios were determined by dividing the values taken after lyophilization by those determined immediately after preparation.

(9) TABLE-US-00001 TABLE 1 Results of the PLGA lyophilization experiments.sup.3) Nanoparticles with different concentrations of P(EtOx).sub.61 as cryoprotectant. Concentration Cryoprotectant [%] 0 0.05 0.10 0.50 1.00 2.50 5.00 Size after 88.9 ± 0.8 preparation [nm] Size after 2131.2 + 1090.4 171.2 ± 12.7 130.5 ± 19.1 123.5 ± 24.3 133.4 ± 28.6 129.8 ± 20.1 138.5 ± 31.6 lyophilization [nm] Size ratio 23.9 1.9 1.5 1.4 1.5 1.5 1.6 PDI after 0.095 ± 0.007 preparation PDI after 0.669 ± 0.131 0.387 ± 0.050 0272 ± 0.046 0.190 ± 0.065 0.217 ± 0.049 0.230 ± 0.064 0.240 ± 0.064 lyophilization PDI ratio 7.0 4.1 2.9 2 2.3 2.4 2.5 Zeta potential after −29.6 ± 0.2 preparation [mV] Zeta potential after −29.7 ± 4.4 −29.2 ± 2.5 −30.9 ± 9.4 −21.1 ± 6.7 −19.7 ± 12.1 −23.1 ± 10.7 −23.9 ± 7.9 lyophilization [mV] Zeta potential ratio 1.0 1.0 1.0 0.7 0.7 0.8 0.8

EXAMPLE 3a

Production of Nanoparticle Suspensions by Nanoprecipitation

(10) 5 mg PLGA.sup.3) was dissolved in 2.5 mL acetone and then added by syringe pump at a defined rate with constant stirring into a vessel with 4.5 mL of an aqueous P(EtOx).sub.61 solution. The organic solvent was then evaporated overnight with constant stirring and the nanoparticles were characterized in terms of their particle diameter and PDI.

(11) TABLE-US-00002 TABLE 2 Results of the production of PLGA.sup.3) nanoparticles by nanoprecipitation with different concentrations of P(EtOx).sub.n as surfactant. Concentration of surfactant [mg mL.sup.−1] 0 0.3 0.5 1 Size [nm] 98.0 ± 9.9  118.0 ± 0.7  122.2 ± 5.9  116.6 ± 5.2  PDI 0.103 ± 0.020 0.093 ± 0.007 0.153 ± 0.043 0.086 ± 0.017 .sup.3)PLGA = lactic acid-glycolic acid copolymer

EXAMPLE 3b

Preparation of Nanoparticle Suspensions by Nanoemulsion

(12) A defined amount of P(EtOx).sub.61 was dissolved in 1 mL ultrapure water. 10 mg PLGA.sup.3) was dissolved in 0.5 mL of ethyl acetate, carefully pipetted onto the surfactant solution and then treated with the ultrasonic finger (power: 40 W, cycle: 100%, amplitude: 100%, time: 10 sec). Subsequently, the particle suspension was diluted by a factor of 10 with ultrapure water and stirred overnight at room temperature to evaporate the organic solvent and the nanoparticles were characterized in terms of their particle diameter and the PDI.

(13) TABLE-US-00003 TABLE 3 Results of the preparation of PLGA.sup.3) nanoparticles using nanoemulsion with different concentrations of P(EtOx).sub.61 as surfactant. Concentration of surfactant [%] 0 0.3 0.5 1 Size [nm] 231.5 ± 15.3  448.9 ± 21.2  460.5 ± 48.5  217.4 ± 6.1  PDI 0.353 ± 0.010 0.383 ± 0.039 0.463 ± 0.061 0.164 ± 0.015

EXAMPLE 4a

Influence of the DP of Poly(2-Oxazoline) on the Size of the Polymer Nanoparticles after Preparation by Nanoprecipitation

(14) 5 mg PLGA.sup.3) was dissolved in 2.5 mL acetone and then added by syringe pump at a defined rate with constant stirring into a vessel with 4.5 mL of an aqueous P(EtOx).sub.n or P(MeOx).sub.n solution. The organic solvent was then evaporated overnight with constant stirring and the nanoparticles were characterized for their particle diameter and PDI by dynamic light scattering. A portion of the suspension was frozen in the −80° C. freezer and then lyophilized overnight. Approximately 2 mg of the resulting powder was then resuspended in 1 mL ultrapure water and recharacterized. The ratio of the values was calculated by dividing the corresponding readings after lyophilization by those after preparation.

(15) TABLE-US-00004 TABLE 4 Results of the preparation of PLGA.sup.3) nanoparticles by nanoprecipitation with P(EtOx).sub.n as surfactant in a concentration of 1% (w/v). DP P(EtOx).sub.n 25 61 107 184 Size after preparation [nm] 157.5 ± 7.2  118.0 ± 0.7  164.4 ± 11.5  172.5 ± 10.8  Size after lyophilization [nm] 272.1 ± 167.8 134.5 ± 4.7  167.1 ± 15.7  173.4 ± 13.8  Size ratio 1.7 1.4 1.02 1.0 PDI after preparation 0.071 ± 0.009 0.093 ± 0.007 0.076 ± 0.007 0.074 ± 0.010 PDI after lyophilization 0.261 ± 0.054 0.147 ± 0.052 0.114 ± 0.007 0.112 ± 0.002 PDI ratio 3.7 1.6 1.5 1.5 .sup.3)PLGA = lactic acid-glycolic acid copolymer

(16) TABLE-US-00005 TABLE 5 Results of the production of PLGA.sup.3) nanoparticles by nanoprecipitation with P(MeOx).sub.n as surfactant in a concentration of 1% (w/v). DP P(MeOx).sub.n 25 57 100 211 Size after preparation [nm] 169.8 ± 9.7  195.8 ± 6.0  172.9 ± 18.8  181.8 ± 5.9  Size after lyophilization [nm] 299.4 ± 114.1 223.0 ± 36.6  181.6 ± 27.0  173.4 ± 15.9  Size ratio 1.8 1.1 1.1 1.0 PDI after preparation 0.059 ± 0.006 0.069 ± 0.009 0.069 ± 0.015 0.124 ± 0.092 PDI after lyophilization 0.343 ± 0.069 0.125 ± 0.065 0.137 ± 0.023 0.108 ± 0.026 PDI ratio 5.8 1.8 2.0 0.9 .sup.3) PLGA=lactic acid-glycolic acid copolymer

EXAMPLE 4b

Influence of the DP of Poly(2-Oxazoline) on the Particle Size of the Polymer Nanoparticles after Preparation by Means of Nanoemulsion

(17) A defined amount of P(EtOx).sub.n or P(MeOx).sub.n was dissolved in 1 mL ultrapure water. 10 mg PLGA.sup.3) was dissolved in 0.5 mL of ethyl acetate, carefully pipetted onto the surfactant solution and then treated with the ultrasonic finger (power: 40 W, cycle: 100%, amplitude: 100%, time: 10 seconds). Subsequently, the particle suspension was diluted by a factor of 10 with ultrapure water and stirred overnight at room temperature to evaporate the organic solvent and the nanoparticles were characterized in terms of their particle diameter and the PDI. A portion of the suspension was frozen in the −80° C. freezer and then lyophilized overnight. Approximately 2 mg of the particles was then resuspended in 1 mL ultrapure water and recharacterized. The ratio of the values was calculated by dividing the corresponding readings after lyophilization by those after preparation.

(18) TABLE-US-00006 TABLE 6 Results of the preparation of PLGA.sup.3) nanoparticles using nanoemulsion with P(EtOx).sub.n as surfactant in a concentration of 1% (w/v). DP P(EtOx)n 25 61 107 184 Size after preparation [nm] 808.1 ± 362.7 217.4 ± 6.1  230.2 ± 18.5  194.2 ± 10.3  Size after lyophilization [nm] nd 204.4 ± 4.3  213.1 ± 12.8  179.2 ± 13.1  Size ratio nd 0.9 0.9 0.9 PDI after preparation 0.754 ± 0.426 0.164 ± 0.015 0.146 ± 0.047 0.086 ± 0.011 PDI after lyophilization nd 0.100 ± 0.017 0.113 ± 0.010 0.102 ± 0.008 PDI ratio nd 0.6 0.8 1.2 nd: not determined.

(19) TABLE-US-00007 TABLE 7 Results of the preparation of PLGA.sup.3) nanoparticles using nanoemulsion with P(MeOx).sub.n as surfactant in a concentration of 1% (w/v). DP P(MeOx).sub.n 25 57 100 211 Size after preparation [nm] 803.7 ± 231.8 159.7 ± 4.0  273.2 ± 20.7  200.5 ± 5.3  Size after lyophilization [nm] nd 164.4 ± 6.7  269.9 ± 32.5  191.8 ± 7.2  Size ratio nd 1.0 1.0 1.0 PDI after preparation 0.289 0.086 ± 0.003 0.165 ± 0.007 0.080 ± 0.004 PDI after lyophilization nd 0.108 ± 0.019 0.185 ± 0.083 0.100 ± 0.013 PDI ratio nd 1.3 1.1 1.3 .sup.3)PLGA = lactic acid-glycolic acid copolymer nd: not determined.

EXAMPLE 5

Nanoparticles from Different Shell Polymers

(20) 100 mg P(EtOx).sub.n or P(MeOx).sub.n was dissolved in 1 mL ultrapure water. 10 mg of shell polymer was dissolved in 0.5 mL of ethyl acetate, carefully pipetted onto the surfactant solution and then treated with the ultrasonic finger (power: 40 W, cycle: 100%, amplitude: 100%, time: 10 seconds). Subsequently, the particle suspension was diluted by a factor of 10 with ultrapure water and stirred overnight at room temperature to evaporate the organic solvent and the nanoparticles were characterized in terms of their particle diameter and the PDI. The nanoparticles were purified differently as described in the Table. Thereafter, all resulting particle suspensions were frozen in the −80° C. freezer and then lyophilized overnight. Approximately 2 mg of the powder was then resuspended in 1 mL ultrapure water and recharacterized. The ratio of the values was calculated by dividing the corresponding readings after lyophilization by those after preparation.

(21) TABLE-US-00008 TABLE 8 Properties of nanoparticles from different shell polymers using P(EtOx).sub.61 or P(MeOx).sub.57 as surfactant after preparation by nanoemulsion. Coating polymer Zeta Potential Surfactant Size [d, nm] PDI [mV] PLGA.sup.3) P(EtOx).sub.61 214.9 ± 1.5 0.147 ± 0.030 −33.0 ± 0.9  P(MeOx).sub.57 155.8 ± 0.9 0.087 ± 0.023 −37.9 ± 0.5  None n.a. n.a. n.a. Eudragit ® RS 100.sup.4) P(EtOx).sub.61 214.0 ± 0.7 0.063 ± 0.018 35.7 ± 0.4 P(MeOx).sub.57 244.3 ± 2.5 0.081 ± 0.012 42.1 ± 1.7 None 101.6 ± 0.5 0.246 ± 0.020 58.6 ± 0.4 P(MMAg.sub.7-co-MAEMA.sub.32).sup.b) P(EtOx).sub.61 155.2 ± 2.8 0.165 ± 0.012 32.3 ± 0.1 P(MeOx).sub.57 162.9 ± 1.3 0.138 ± 0.028 33.6 ± 1.4 None 176.2 ± 2.4 0.191 ± 0.012 49.1 ± 0.4 n.a.: not available (not available because the nanoparticles were too strongly aggregated).

(22) TABLE-US-00009 TABLE 9 Properties of the nanoparticles from different shell polymers using P(EtOx).sub.6i or P(MeOx).sub.57 as surfactant after purification and lyophilization. P(MeOx).sub.57 is a poly(2−methyl−2−Oxazoline) with a degree of polymerization (DP) of 57. P(MMA.sub.97-co-MAEMA32).sup.5) Surfactant P(EtOx).sub.61 P(MeOx).sub.57 None Purification method Size [d, nm] PDI Size [d, nm] PDI Size [d, nm] PDI After preparation 155.2 ± 2.8 0.165 ± 0.012 162.9 ± 1.3 0.138 + 0.028 176.2 ± 2.4 0.191 ± 0.012 Lyophilization 172.2 ± 2.7 0.215 ± 0.021 157.5 ± 1.9 0.109 + 0.026 n.a. n.a. without purification Centrifugation and 229.2 ± 14.9 0.330 ± 0.019 294.7 ± 67.1 0.375 ± 0.033 325.8 ± 88.1 0.362 ± 0.034 resuspension in 1 mL ultrapure water Centrifugation and 175.4 ± 2.3 0.258 ± 0.035 179.7 ± 3.8 0.128 ± 0.083 253.4 ± 4.1* 0.278 ± 0.042* resuspension in 1 mL 0.5% POx solution Syringe filtration n.a. n.a. 211.6 ± 3.1 0.269 ± 0.032 n.a. n.a. Eudragit ® RS100.sup.44) Surfactant P(EtOx).sub.61 P(MeOx).sub.57 None Purification method Size [d, nm] PDI Size [d, nm] PDI Size [d, nm] PDI After preparation 214.0 ± 0.7 0.063 ± 0.018 244.3 ± 2.5 0.081 ± 0.012 101.6 ± 0.5 0.246 ± 0.020 Lyophilization 217.2 ± 2.2 0.080 ± 0.024 247.3 ± 4.3 0.086 ± 0.038 n.a. n.a. without purification Centrifugation and 239.3 ± 1.7 0.105 ± 0.037 315.9 ± 8.3 0.220 + 0.044 n.a. n.a. resuspension in 1 mL ultrapure water Centrifugation and 223.3 ± 1.5 0.069 ± 0.026 252.0 ± 3.4 0.105 ± 0.039 n.a. n.a. resuspension in 1 mL 0.5% POx solution Syringe filtration 220.4 ± 4.4 0.062 ± 0.042 257.5 ± 3.7 0.068 ± 0.033 n.a. n.a. n.a.: Not available (not available because the nanoparticles were too strongly aggregated).

(23) TABLE-US-00010 TABLE 10 Ratios of the properties of the nanoparticles from different shell polymers using P(EtOx).sub.61 or P(MeOx).sub.57 as surfactant after purification and lyophilization. P(MeOx).sub.57 is a poly(2-methyl-2-Oxazoline) with a degree of polymerization (DP) of 57. Surfactant P(EtOx).sub.61 P(MeOx).sub.57 None Purification method Size ratio PDI ratio Size ratio PDI ratio Size ratio PDI ratio P(MMA.sub.97-co-MAEMA32).sup.5) Lyophilization 1.11 1.30 0.97 0.79 n.a. n.a. without purification Centrifugation and 1.48 2.00 1.01 1.06 1.85 1.90 resuspension in 1 mL ultrapure water Centrifugation and 1.13 1.56 1.10 0.93 1.44* 1.46* resuspension in 1 mL 0.5% POx solution Syringe filtration n.a. n.a. 1.30 1.95 n.a. n.a. Eudragit ® RS100.sup.4) Lyophilization 1.01 1.27 1.01 1.06 n.a. n.a. without purification Centrifugation and 1.12 1.67 1.29 2.71 n.a. n.a. resuspension in 1 mL ultrapure water Centrifugation and 1.04 1.10 1.03 1.30 n.a. n.a. resuspension in 1 mL 0.5% POx solution Syringe filtration 1.03 0.98 1.05 0.84 n.a. n.a. .sup.3)PLGA = lactic acid-glycolic acid copolymer .sup.4)Eudragit ® RS 100 = methyl methacrylate (2-(N,N,N-trimethylammonium))methacrylate-ethyl acrylate copolymer .sup.5)P(MMAg.sub.7-co-MAEMA.sub.32) = 2-(N-methylaminoethyl)methacrylate-methyl acrylate copolymer n.a.: Not available (not available because the nanoparticles were too strongly aggregated).

EXAMPLE 6

Influence of the Purification on the Size of the Nanoparticles

(24) 5 mg PLGA.sup.3) was dissolved in 2.5 mL acetone and then added by syringe pump at a defined rate with constant stirring into a vessel with 4.5 mL of an aqueous P(EtOx).sub.61 solution. The organic solvent was then evaporated overnight with constant stirring and the nanoparticles were characterized in terms of their particle diameter and PDI. The nanoparticles were purified differently as described in the Table. Thereafter, all resulting particle suspensions were frozen in the −80° C. freezer and then lyophilized overnight. Approximately 2 mg of the powder was then resuspended in 1 mL ultrapure water and recharacterized. The ratio of the values was calculated by dividing the corresponding readings after lyophilization by those after preparation.

(25) TABLE-US-00011 TABLE 11 Properties of PLGA.sup.3) nanoparticles using P(EtOx).sub.6i or P(MeOx).sub.57 as surfactant after purification and lyophilization. Surfactant Purification method P(EtOx).sub.61 P(MeOx).sub.57 before lyophilization Size [d, nm] PDI Size [d, nm] PDI After preparation 157.7 ± 1.3 0.102 ± 0.017 201.7 ± 4.2 0.062 ± 0.029 Lyophilization without  1262 ± 1182 0.714 ± 0.201 213.5 ± 3.1 0.067 ± 0.010 purification Centrifugation and   898 ± 1062 0.549 ± 0.305 206.7 ± 3.1 0.111 ± 0.034 resuspension in 1 mL ultrapure water Syringe filtration and 165.1 ± 1.0 0.172 ± 0.044 189.6 ± 1.2 0.068 ± 0.018 addition of 1 ml. 0.5% POx solution Syringe filtration   1075 ± 111.6 0.948 ± 0.100 190.6 ± 1.5 0.101 ± 0.019

(26) TABLE-US-00012 TABLE 12 Ratios of properties of PLGA.sup.3)-nanoparticles using P(EtOx).sub.6i or P(MeOx).sub.57 as a surfactant after purification and lyophilization. Additives P(EtOx).sub.61 P(MeOx).sub.57 Purification method Size ratio PDI ratio Size ratio PDI ratio Lyophilization without 8.00 7.00 1.06 1.08 purification Centrifugation and 5.69 5.38 1.02 1.79 resuspension in 1 mL ultrapure water Syringe filtration and 1.05 1.69 0.94 1.10 addition of 1 mL 0.5% PO.sub.x solution Syringe filtration 6.82 9.29 0.94 1.63 .sup.3)PLGA = lactic acid-glycolic acid copolymer n.a.: not available (not available because the nanoparticles were too strongly aggregated).

EXAMPLE 7

Encapsulation of Nile Red

(27) From 10 mg of PLGA.sup.3) and 0.1 mg of Nile Red from a 1 mg mL.sup.−1 stock solution in acetone, nanoparticles were prepared by nano-precipitation or nanoemulsion as in Example 3. As the surfactant concentration (if present in the aqueous solution), a final concentration of 1% for the nanoemulsion and 0.3% for the nano-precipitation was sought.

(28) The nanoparticles were purified differently as described in the Table. Thereafter, all resulting particle suspensions were frozen in the −80° C. freezer and then lyophilized overnight. Approximately 2 mg of the powder was then resuspended in 1 mL ultrapure water and recharacterized. The ratio of the values was calculated by dividing the corresponding readings after lyophilization by those after preparation. A part of the resulting nanoparticles was dissolved in DMF.sup.6) and the encapsulation efficiency of the active ingredient was determined by means of UV/VIS spectroscopy via its absorption.

(29) TABLE-US-00013 TABLE 13 Properties of PLGA.sup.3)- Nile Red nanoparticles using P(EtOx).sub.61 or P(MeOx).sub.57 as a surfactant after preparation by nanoemulsion and nanoprecipitation. Active substance Surfactant Preparation method Size [d, nm] PDI Nile Red P(EtOx).sub.61 Nanoprecipitation 160.8 ± 1.5 0.053 ± 0.028 Nile Red P(EtOx).sub.61 Nanoemulsion 190.7 ± 1.9 0.124 ± 0.013 Nile Red P(MeOx).sub.57 Nanoprecipitation 151.2 ± 0.8 0.065 ± 0.021 Nile Red P(MeOx).sub.57 Nanoemulsion 180.0 ± 0.8 0.099 ± 0.014 Nile Red None Nanoprecipitation 145.2 ± 2.5 0.075 ± 0.018 Nile Red None Nanoemulsion n.a. n.a. n.a. = not available (not available).

(30) TABLE-US-00014 TABLE 14 Properties of PLGA.sup.3)- Nile Red nanoparticles using P(EtOx).sub.61 or P (MeOx).sub.57 as surfactant after purification and lyophilization, Additive P(EtOx).sub.6i P(MeOx).sub.57 None Purification method Size [d, nm] PDI Size [d, nm] PDI Size [d, nm] PDI After preparation 160.8 ± 1.5 0.053 ± 0.028 169.0 ± 2.5 0.069 ± 0.021 145.2 ± 2.5 0.075 ± 0.018 Lyophilization 168.0 ± 1.6 0.087 ± 0.031 n.a. n.a. n.a. n.a. without purification Centrifugation and 184.3 ± 1.6 0.145 ± 0.028 187.4 ± 3.2 0.123 ± 0.052 n.r. n.r. resuspension in 1 mL 0.5% POx solution Syringe filtration 167.7 ± 3.2 0.148 ± 0.045 233.1 ± 8.4 0.314 ± 0.022 180.5 ± 1.6 0.169 ± 0.020 and addition of 1 mL 0.5% POx solution Syringe filtration 161.7 ± 3.4 0.157 ± 0.011 n.a. n.a. n.a. n.a. n.a.: not available (not available because the nanoparticles were too strongly aggregated), n.r.: not resuspendable.

(31) TABLE-US-00015 TABLE 15 Relationships of the properties of PLGA.sup.3)- Nile Red nanoparticles using P(EtOx).sub.61 or P(MeOx).sub.57 as surfactant after purification and lyophilization. P(EtOx).sub.61 P(MeOx).sub.57 None Additive Size PDI EE Size PDI EE Size PDI EE Purification method ratio ratio [μg mg.sup.1] ratio ratio [μg mg.sup.1] ratio ratio [μg mg.sup.1] Lyophilization 1.04 1.64 0.52 n.a. n.a. n.a. 28.21 12.23 1.53 without purification Centrifugation 1.14 2.74 0.28 1.15 1.71 0.32 n.a. n.a. n.a. and resuspension in 1 mL 0.5% POx solution Syringe 1.04 2.79 0.21 n.a. n.a. n.a. 1.24 2.25 0.28 filtration and addition of 1 mL 0.5% POx solution Syringe 1.01 2.96 0.51 n.a. n.a. n.a. n.a. n.a. n.a. filtration .sup.3) PLGA = lactic acid-glycolic acid copolymer .sup.6) DMF = dimethylformamide EE: Encapsulation efficiency.

EXAMPLE 8

Encapsulation of PKC 412.SUP.7)

(32) 10 mg PLGA.sup.3) was dissolved in 1 mL acetone. 0.3 mg PKC 412.sup.7) was dissolved in 30 μL DMSO.sup.8) and added to the PLGA.sup.3) solution. Then, the polymer-active substance solution was added by syringe pump at a defined rate with constant stirring into a vessel with 10 mL of an aqueous solution, optionally containing a surfactant. The organic solvent was then evaporated overnight with constant stirring and the nanoparticles were characterized in terms of their particle diameter and PDI. Thereafter, all resulting particle suspensions were frozen in the −80° C. freezer and then lyophilized overnight. Approximately 2 mg of the particles was then resuspended in 1 mL ultrapure water or a 0.5% solution of the corresponding poly(2-oxazoline) and recharacterized.

(33) The ratio of the values was calculated by dividing the corresponding readings after lyophilization by those after preparation. A part of the resulting nanoparticles was dissolved in DMSO.sup.8) and the encapsulation efficiency of the active ingredient was determined by means of UV/VIS spectroscopy via its absorption.

(34) TABLE-US-00016 TABLE 16 Properties of PLGA-PKC 412.sup.3,7) nanoparticles using P(EtOx).sub.61 or P(MeOx).sub.57 as surfactant after purification and lyophilization. After preparation After lyophilization Ratio Surfactant Size [d, nm] PDI Size [d, nm] PDI Size PDI EE [μg mg'] P(EtOx).sub.6i 168.6 ± 2.4 0.061 ± 0.019 178.9 ± 2.0 0.058 ± 0.025 1.06 0.95 0 P(MeOx).sub.57 184.6 ± 1.1 0.063 ± 0.034 190.4 ± 2.4 0.086 ± 0.022 1.03 1.36 0.92 ± 0.08 None 156.1 ± 0.9 0.077 ± 0.024 7272 ± 2494 0.740 ± 0.383 n.a. n.a. 0.98 ± 0.31 .sup.3) PLGA = lactic acid-glycolic acid copolymer .sup.7) PKC 412 = [9S-(9α,10β,11β,13α)]-N-(2,3,10,11,12,13-hexahydro-10-methoxy-9-methyl-1-oxo-9,13-epoxy-1H,9H-diindolo[1,2,3-gh:3′,2′,1′Im]pyrrolo[3,4-y7[1,7]benzodiazonin-11-yl)-N-methylbenzamide .sup.8) DMSO = dimethyl sulfoxide n.a.: not available (not available because the nanoparticles were too strongly aggregated). EE: Encapsulation efficiency.