Modified polylactic acid degradable stent and preparation method thereof

A technology of polylactic acid and polylactic acid copolymer, which is applied in the field of medical devices, can solve problems such as uneven wall thickness of pipes, decrease in radial support force, and rapid decrease in radial support force, so as to reduce mechanical relaxation behavior and increase diameter. The effect of supporting force and enhancing the stability of the structure

Active Publication Date: 2014-04-09
上海发微医用材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] At present, the degradable stents made of polylactic acid or polylactic acid copolymers or blends have the following shortcomings: (1) The mechanical strength is not enough, that is, the radial compression resistance is poor, and the retraction phenomenon (recoiling) occurs during the rhythmic contraction and expansion of blood vessels. ), (2) thermoplastic polymer materials generally have mechanical relaxation, which leads to a decrease in the radial support force of the stent product during storage, a short shelf life of the product, and unstable product quality. (3) the radial support force during the degradation process The drop is too fast, resulting in premature retraction of the stent, and (4) the high molecular weight polylactic acid or polylactic acid copolymer has a high melt viscosity, and it must be above 200°C to be injected and extruded to form a tube
On the one hand, the high melt viscosity leads to uneven wall thickness of the extruded pipe, and the quality of the stent cannot be well controlled; on the other hand, the degradation of polylactic acid is very obvious during the high-temperature extrusion process, and the intrinsic viscosity may even decrease by 50%. Degradation of lactic acid, making it difficult to control the quality of stent products

Method used

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  • Modified polylactic acid degradable stent and preparation method thereof
  • Modified polylactic acid degradable stent and preparation method thereof
  • Modified polylactic acid degradable stent and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0053] Example 1: Synthesis of 3-arm star crosslinkers

[0054] Before polymerization, the 3-liter glass reactor was vacuum-dried at 60°C for 1 hour, and 2000g L-lactide (L-lactide), 100g glycolide (glycolide) and 14g 1,2,6-hexyl The triol was added into the reactor and dried under vacuum at 60°C for 1 hour. Then add 2g of stannous octoate, increase the temperature to 140°C, and keep it at 140°C for 3 hours to obtain a star-shaped polylactic acid prepolymer with a number average molecular weight of 20,000 (see Reaction Formula 1 with three hydroxyl groups (n =3) degradable polymer).

[0055] Reaction 1: Formation of a star PLA prepolymer with 3 arms

[0056]

[0057] Among them, x=3-300, y=1-100.

[0058] For clarity, the above structure simplifies to:

[0059]

[0060] That is, a degradable polymer with three hydroxyl groups (n=3).

[0061] Using a similar method, prepolymers of polylactic acid or polylactic acid copolymers of different compositions can be synthesi...

Embodiment 2

[0066] Example 2: Synthesis of 2-arm linear crosslinkers

[0067] Before polymerization, the 3-liter glass reactor was vacuum-dried at 60°C for 1 hour. Under nitrogen protection, 2000g of L-lactide and 50g of Poly(THF) were added to the reactor, and vacuum-dried at 60°C for 1 hour. Then add 2g of stannous octoate, increase the temperature and react at 140°C for 3 hours to obtain a linear polylactic acid prepolymer with a number average molecular weight of 20,000. The molecular weight of the linear polylactic acid prepolymer is controlled by the relative content of the initiator and the monomer, and the number average molecular weight is controlled between 5,000 and 50,000. When the molecular weight of the star-shaped polylactic acid copolymer prepolymer meets the requirements of the experimental design, directly add isocyanoethyl methacrylate and 300ppm free radical inhibitor p-hydroxyanisole to form a cross-linkable linear polymer (See Equation 3).

[0068] Reaction 3: Synt...

Embodiment 3

[0071] Example 3: Synthesis of a 4-arm star crosslinker

[0072] Before polymerization, vacuum-dry the 3-liter glass reactor at 60°C for 1 hour, add 2000g of L-lactide, 100g of caprolactone (ε-caprolactone), and 60g (0.44mol) of pentaerythritol into the reactor. Vacuum dry at 60°C for 1 hour. Then add 2g of stannous octoate, increase the temperature to 125°C and keep it at 140°C for 3 hours to obtain a polylactic acid prepolymer with a number average molecular weight of 18,000 (see Reaction Formula 4 with four hydroxyl groups (n=4) degradable polymers).

[0073] The molecular weight of the prepolymer is controlled by the relative content of initiator and monomer, and the number average molecular weight is controlled between 5,000 and 50,000. When the molecular weight of the star-shaped polylactic acid prepolymer meets the requirements of the experimental design, directly add 72g (0.47mol) methacrylic anhydride and 0.6g free radical inhibitor (p-hydroxyanisole) to form a cros...

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Abstract

The invention relates to the field of medical devices, and more specifically discloses a biodegradable stent based on a modified polylactic acid or a polylactic acid copolymer, and a preparation method thereof. According to the present invention, a linear polylactic acid or polylactic acid copolymer with a high molecular weight is blended with a biodegradable cross-linking agent, injection extrusion, injection molding or other processing methods are adopted to prepare a pipe material, the pipe material is subjected to a cross-linking polymerization reaction to form a semi-interpenetrating polymer network, and finally laser cutting is adopted to obtain the stent. The stent has characteristics of sufficient mechanical strength, sufficient structural stability, and improved processability.

Description

technical field [0001] The invention relates to the field of medical instruments. More specifically, the present invention relates to a modified polylactic acid degradable scaffold and a preparation method thereof. Background technique [0002] At present, the stents used in the treatment of postoperative vascular restenosis usually include metal stents, drug-coated metal stents and biodegradable stents. Although metal stent-related technologies have made continuous progress and solved the elastic recoil of blood vessels after PTCA, they still have limitations and cannot solve the problems of intimal hyperplasia caused by intimal injury and metal foreign bodies. Drug-coated metal stents inhibit intimal hyperplasia to a certain extent and reduce the occurrence rate of restenosis. However, the stimulation of metal foreign bodies is inevitable, and long-term antiplatelet therapy drugs are required. After 3-4 years after drug-eluting metal stents are implanted in the cardiova...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/91C08G63/08C08L67/04C08J3/24A61L31/06A61L31/14
CPCC08G63/08C08G63/912
Inventor 姜洪焱罗七一
Owner 上海发微医用材料有限公司
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