Inverse thermogelling polyoxazoline copolymers

Abstract

Provided is a block copolymer comprising a polymer block (A) which comprises repeating units of formula (I) and a polymer block (B) which comprises repeating units of formula (II),

##STR00001##

wherein R.sup.1 is methyl or ethyl, and R.sup.2 represents a group CH.sub.2CH.sub.2-phenyl. The copolymer of the present invention allows a rapid thermoresponsive inverse gelation to be achieved, yielding a hydrogel with viscoelastic solid-like properties, as well as shear thinning, rapid structure recovery and good strain resistance properties. The hydrogel can be favorably used in 3D printing applications.

Claims

1. A block copolymer comprising: a polymer block (A) comprising repeating units of formula (I): ##STR00013## wherein R.sup.1 is methyl or ethyl, and a polymer block (B) comprising repeating units of formula (II): ##STR00014## wherein R.sup.2 represents a group CH.sub.2CH.sub.2-phenyl.

2. The block copolymer of claim 1, wherein the number of repeating units of formula (I) in each polymer block (A) is 5 or more and 100 or less, and wherein the number of repeating units of formula (I) is independently 5 or more and 100 or less for each polymer block (A) if more than one polymer block (A) is present.

3. The block copolymer of claim 1, wherein the number of repeating units of formula (II) in each polymer block (B) is 5 or more and 100 or less, and wherein the number of repeating units of formula (II) is independently 5 or more and 100 or less for each polymer block (B) if more than one polymer block (B) is present.

4. The block copolymer of claim 1, wherein the ratio of the total number of repeating units of formula (I) in the polymer block(s) (A) to the total number of repeating units of formula (II) in the polymer block(s) (B) is in the range of 20:1 to 1:1.

5. The block copolymer of claim 1, wherein the degree of polymerization of the block copolymer is in the range of 40 to 180.

6. The block copolymer of claim 1, wherein the block copolymer is a di- or triblock copolymer.

7. The block copolymer of claim 1, wherein the block copolymer comprises a triblock copolymer of two polymer blocks (A) and one polymer block (B) having the structure (A)-(B)-(A).

8. A hydrogel composition comprising the block copolymer of claim 1.

9. The hydrogel composition of claim 8, wherein the hydrogel composition comprises the block copolymer of claim 1 in combination with one or more further hydrogel forming polymers.

10. The hydrogel composition of claim 9, wherein the one or more further hydrogel forming polymers are selected from the group consisting of alginate, gelatin, silk protein, collagen, fibrin, and cellulose or its derivatives.

11. The hydrogel composition of claim 8 further comprising viable cells.

12. The block copolymer of claim 1, wherein the block polymer comprises at least a portion of a support material or a structural material in 3D printing, or as an internal sacrificial support material in 3D printing.

13. The hydrogel composition of claim 8, wherein the hydrogel composition comprises a bioink.

14. A method for the provision of a hydrogel scaffold with a predetermined geometry, comprising subjecting a composition comprising the block copolymer of claim 1 to 3D printing.

15. A method for the provision of an artificial tissue, comprising forming a hydrogel scaffold comprising viable cells from the hydrogel composition of claim 11.

Description

DESCRIPTION OF FIGURES

[0157] FIG. 1 shows GPC-Traces after every block and the purified ABA-triblock copolymer P1. [0158] M.sub.n(1.sup.st block): 1.8 kg/mol, .Math.(1.sup.st block): 1.05 [0159] M.sub.n(2.sup.nd block): 2.9 kg/mol, .Math.(2.sup.nd block): 1.08

[0160] FIG. 2 shows the .sup.1H-NMR of purified ABA-triblock copolymer Me-PMeOx.sub.37-b-PPhenOx.sub.17-b-PMeOx.sub.36-PipBoc (Mw: 9.4 kg/mol, PMeOx/PPhenOx: 4.3) in CD.sub.3CN.

[0161] FIG. 3 shows GPC-Traces after every block and the purified ABA-triblock copolymer P2. M.sub.n(1.sup.st block): 2.3 kg/mol, .Math.(1.sup.st block): 1.08 M.sub.n(2.sup.nd block): 3.3 kg/mol, .Math.(2.sup.nd block): 1.12

[0162] FIG. 4 shows the .sup.1H-NMR of purified ABA-triblock copolymer Me-PMeOx.sub.36-b-PPhenOx.sub.17-b-PMeOx.sub.36-EIP (Mw: 9.3 kg/mol, PMeOx/PPhenOx: 4.1) in CD.sub.3CN.

[0163] FIG. 5 shows that an increasing concentration of A-PPhenOx-A leads to hydrogel formation. A) Pictures of aqueous solutions at 5? C. and different polymer concentrations (10.fwdarw.15.fwdarw.20 wt. %). B) Pictures of aqueous solutions at 5? C. and 40? C. and a polymer concentration of 20 wt. %. C,D) Temperature dependent viscosity measurements (rolling ball system).

[0164] FIG. 6 shows the results for the rheological characterization for dispense plotting applications and cryoSEM analysis of A-PPhenOx-A hydrogel at 5? C. A) Amplitude sweep of 20 wt. % hydrogel at 5? C. and an angular frequency of 10 rad/s with storage moduli (G?), loss moduli (G=o) and loss factor (?) shown. B) Frequency sweep with fixed amplitude of 0.1%. C) Viscosity (?) and shear stress (?) in dependency of the applied shear rate for a 20 wt. % hydrogel. D) Viscosity (?) and shear rate (?) as a function of applied shear stress in steady shear stress experiment. E) ORO (oscillation-rotational-oscillation) recovery test of hydrogel. F) ROR (rotational-oscillation-rotational) 3 step recovery. G-I) Cryo-SEM images of 20 wt. % hydrogel at 1k?.fwdarw.2k?.fwdarw.10k?magnification.

[0165] FIG. 7 shows the results of direct ink-writing of a 20 wt. % hydrogel and a hybrid hydrogel (composition: 20 wt. % of the block copolymer in accordance with the invention and 1 wt. % alginate) at 8-10? C. (Nozzle 25 G, speed: 10 mm/s). A), E) Filament fusion test to visualize printing resolution. B), F) Filament collapse test by printing bridges of increasing distances. C), D), G), H) Printed 20 layer (5?5 mm cylindrical tube structures) constructs. A)-D) 20 wt. % hydrogel containing the described polymer. E)-H) 20 wt. % described polymer and 1 wt. % alginate. G), H) After crosslinking with CaCl.sub.2) and incubation at 37? C. in aqueous solution.

[0166] FIG. 8 summarizes the results of a bioprinting process and the analysis of cytocompatibility using NIH 3T3 cells. After dissolving the block copolymer in accordance with the invention, alginate and dispersing cells at 37? C. in cell culture medium, the bioink was processed at 8? C. The cell viability was analyzed using automatic cell counting in three fluorescence images (n=3) of 3 biological replicates (n=3) obtained with an epifluorescence microscope (Zeiss Observer, Germany).