Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1994-11-22
1997-02-25
Seidleck, James J.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528170, 528176, 528183, 528184, 528186, 528192, 528194, 528195, 528208, 528220, 528224, 528228, 528229, 528310, 528322, 528328, 528332, 528345, C08G 7302
Patent
active
056060122
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to polyetheramidoamine hydrogels, to processes for the preparation thereof and to the use thereof as heparin adsorbing materials.
BACKGROUND OF THE INVENTION
In the biomedical field, the development of thromboresistant materials is hindered by the interaction of the blood itself with artificial surfaces. In normal situations, platelets or blood components do not adhere to the vasal lumen, whereas the contact with a synthetic material causes platelet deposition, often together with thrombotic phenomena. Accordingly, polymeric surfaces, which show the ability of inhibiting the formation of thrombus, are of great interest for the preparation of cardiovascular protheses and devices to be used in contact with blood.
Antithrombogenic surfaces can be divided into three main classes: properties for endothelial cells. Antithrombogenicity is due to the functional capacity of the cells themselves. inhibiting:
Surfaces belonging to the second class are particularly important from a technological point of view, and the present invention refers to this field.
Antithrombogenic materials must have one or more of the following requirements:
1. Low critical surface tension;
2. Negative surface charge;
3. Hydrated polymeric surface at the interface with blood;
4. Heparin binding capability, either by covalent or ionic bond, or heparin controlled release capability.
5. Capability of selectively adsorbing "passivant" blood proteins, such as albumin, or of interacting with blood elements (endothelial cells) without activating coagulation processes.
PRIOR ART
The surfaces capable of blocking thrombogenic process are mainly represented by the so called heparinized surfaces, namely those materials which interact with the heparin molecule such as to ensure its natural anticlotting activity. The antithrombotic effect can be obtained either by binding heparin stably to the material surface, thus acting mainly in the circulatory site where said material resides, for example a heart valve, or by means of a controlled release of heparin from the material itself, but without a complete release of heparin from the graft.
Hydrogels are three-dimensional lattices made of hydrophilic polymers or copolymers, which are capable of swelling in water or biological fluids. In the biomedical field, hydrogels are grouped into neutral, ionic or with interpenetrated lattices.
Hydrogels can absorb high percentages of water and show a low interfacial free energy in the aqueous systems, which renders them excellent materials to be used in contact with blood.
Polymers having a polyamidoamine structure (PAA) are well known as heparin complexing agents. (Ferruti e Al.; Polymer, 26, (1985), 133; Tanzi e Al.; Biomaterials, 5, (1984), 357). The formation of stable heparin complexes is due to the strong ionic interaction between the negative charges of heparin and the tertiary amino groups of the PAA chains, which are protonated at physiological pH, together with electrostatic interactions between the two types of macromolecules.
The application of the PAA in the haemocompatible field is difficult as none of the known PAA possesses suitable mechanical characteristics. Consequently, these polymers have been grafted or copolymerized with other polymeric structures, as to obtain suitable elastomeric materials having the desired properties (Barbucci e Al.; Biomaterials, 10, (1989) 299-308, Tanzi, Levi; J. of Biomed. Mater. Res. 23; (1989) 863).
Crosslinked PAA were described by Ferruti e Al. in Polymer, 26, (1985), 133, as heparin sequestering filters, but said structures are insufficiently hydrophilic and elastic.
DESCRIPTION OF THE INVENTION
It has now been found that hydrophilic crosslinked polyetheramidoamine polymers have surprisingly shown haemocompatible heparin-adsorbing properties, which have improved hydrophilic and elastic characteristics with respect to the crosslinked polyamidoamine of the above cited prior art.
Hydrogels of the invention are formed by polymeric polyetheramidoamine and/or polyamidoamine chains end
REFERENCES:
Chemical Abstracts, vol. 114, No. 14, 8 Apr. 1991, Abstract No. 123814y, Penczek, et al, "Preparation of cross-linked hydrogels", p. 51. col. 1.
Journal of Applied Polymer Science, vol. 28, 1983, pp. 3361-3368, Pesavento, et al, "Applied Macroinorganics. IV. Effects of the Crosslinking Agent on Protonation, and Metal Ions Complexing Abilities, of Ion Exchange Resins with Poly(amido-Amine) Structure" The month of publication is not available.
Biomaterials, vol. 5, Nov. 1984, pp. 357-361, Tanzi, et al., "Synthesis and characterisation of poly(amido-amines)s belonging to two different homologous series".
Chemical Abstracts, vol. 106, No. 26, 29 Jun. 1987, Abstract No. 214758j, Kopylova, et al, "Structure and properties of cross-linked hydrogels based on a poly(acylic acid)-polyethyeleneimine polyelectrolyte complex", p. 26, col. 2.
Palumbo Gianfranco
Tanzi Maria C.
Hampton-Hightower P.
Seidleck James J.
Societa Consortile Ricerche Angelini S.p.A.
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