Effect of different gamma-irradiation doses on cytotoxicity and material properties of porous polyether-urethane polymer.

Biomaterials respond to sterilization methods differently. Steam sterilization might decrease the performance of thermoplastic polyether-urethane (TPU); however, the effect of different gamma-radiation doses on this polymer is contradictory in present literature. The purpose of this study was to investigate the differences between irradiative doses in comparison with steam sterilization on a porous TPU scaffold produced by a new processing method. No significant differences in the surface chemical structure were found with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) analysis when comparing with the sterilization methods. The molecular weight (M(w)) had a net increase from 11.5 +/- 0.039 to 13.2 +/- 0.072 kDa by gamma-sterilization from 10 to 60 kGy. The samples that were irradiated (>60 kGy) had also an increase in polydispersity index (PDI; 1.45 +/- 0.007) in comparison with the nonsterile ones (1.31 +/- 0.017), which indicate branching. Liquid chromatography/mass spectroscopy (LC/MS) analysis showed that there was a correlation between the concentration of the breakdown product, methyl dianiline, and cytotoxicity. The concentration of this compound was found to be four times higher in steam-sterilized sample (1.3 +/- 0.01 ppb) compared with that of the polymer sample gamma-sterilized at 10 kGy (0.3 +/- 0.01 ppb). The cytotoxicity of TPU was found to decrease with higher radiation doses, and was significantly higher for the steam-sterilized samples. It is recommended that TPU produced with the described foaming method should be sterilized by gamma-irradiation at 25 kGy or higher doses.

[1]  N. Lamba.  Polyurethanes in Biomedical Applications , 1997 .

[2]  Hideharu Shintani,et al.  Formation and elution of toxic compounds from sterilized medical products: Toxic compound formation from irradiated products , 1996 .

[3]  C. Das,et al.  Effect of processability on the thermal stability of the blends based on polyurethane (Part III) , 2000 .

[4]  R. Kusy,et al.  Structural degradation of polyurethane-based elastomeric modules , 1995 .

[5]  R L Reis,et al.  Cytocompatibility and response of osteoblastic-like cells to starch-based polymers: effect of several additives and processing conditions. , 2001, Biomaterials.

[6]  A. Kettrup,et al.  Thermal degradation of thermoplastic polyurethane elastomers (TPU) based on MDI , 2002 .

[7]  R. Gurny,et al.  Gamma Sterilization of a Semi-Solid Poly(ortho ester) Designed for Controlled Drug Delivery—Validation and Radiation Effects , 1994, Pharmaceutical Research.

[8]  H Shintani,et al.  The relative safety of gamma-ray, autoclave, and ethylene oxide gas sterilization of thermosetting polyurethane. , 1995, Biomedical instrumentation & technology.

[9]  A. Goossens,et al.  Occupational allergic contact dermatitis caused by isocyanates , 2002, Contact dermatitis.

[10]  R. Bailey,et al.  Hydrolytic stability of toluene diisocyanate and polymeric methylenediphenyl diisocyanate based polyureas under environmental conditions. , 2004, Environmental Science and Technology.

[11]  H. Shintani.  Formation and Elution of Toxic Compounds from Sterilized Medical Products: Methylenedianiline Formation in Polyurethane , 1995, Journal of biomaterials applications.

[12]  D. Han,et al.  Sulfonated poly(ethylene oxide)-grafted polyurethane copolymer for biomedical applications. , 1998, Journal of biomaterials science. Polymer edition.

[13]  G. Leng,et al.  Concentration-dependence of biomarkers of exposure of methylenediphenyl-diisocyanate following acute inhalation exposure of rats. , 2003, Toxicology.

[14]  C. P. Smith,et al.  Determination of extractable methylene dianiline in thermoplastic polyurethanes by HPLC. , 1984, Journal of biomedical materials research.

[15]  A. Behjat,et al.  RADIATION CROSSLINKING OF LDPE AND HDPE WITH 5 AND 10 MEV ELECTRON BEAMS , 2001 .

[16]  E. Turi,et al.  Thermal characterization of polymeric materials , 1981 .

[17]  D. Hatchett,et al.  FTIR analysis of thermally processed PU foam , 2005 .

[18]  H J Lee,et al.  Surface photograft polymerization on segmented polyurethane using the iniferter technique. , 1999, Journal of biomedical materials research.

[19]  H. Shintani.  Solid-phase extraction of a carcinogen, 4,4'-methylenedianiline, in serum. , 1991, Journal of analytical toxicology.

[20]  B. Ratner,et al.  Variations between Biomer lots. 2: The effect of differences between lots on in vitro enzymatic and oxidative degradation of a commercial polyurethane. , 1993, Journal of biomedical materials research.

[21]  R. Ian Freshney,et al.  Culture of Animal Cells: A Manual of Basic Technique and Specialized Applications , 2010 .

[22]  R L Reis,et al.  A new approach based on injection moulding to produce biodegradable starch-based polymeric scaffolds: morphology, mechanical and degradation behaviour. , 2001, Biomaterials.

[23]  A. F. Johnson,et al.  Effect of processing route and acetone pre-treatment on the biostability of pellethane materials used in medical device applications. , 2005, Biomaterials.

[24]  H. Shintani,et al.  Formation of 4,4'-methylenedianiline in polyurethane potting materials by either gamma-ray or autoclave sterilization. , 1991, Journal of biomedical materials research.

[25]  L. Låstbom,et al.  Effects of thermal degradation products from polyurethane foams based on toluene diisocyanate and diphenylmethane diisocyanate on isolated, perfused lung of guinea pig. , 2003, Scandinavian journal of work, environment & health.

[26]  Y. Grohens,et al.  Electron irradiation of polyurethane using UV spectroscopy, GPC and swelling analyses , 2002 .

[27]  H. Shintani,et al.  Analysis of a carcinogen, 4,4'-methylenedianiline, from thermosetting polyurethane during sterilization. , 1989, Journal of analytical toxicology.

[28]  A. H. Samuel,et al.  Sterilisation of implantable devices. , 1994, Clinical materials.

[29]  P. Aljama,et al.  Sterilization procedures and biocompatibility. , 2002, Contributions to nephrology.

[30]  D J Mooney,et al.  Open pore biodegradable matrices formed with gas foaming. , 1998, Journal of biomedical materials research.

[31]  S. Gogolewski,et al.  The effect of gamma radiation on molecular stability and mechanical properties of biodegradable polyurethanes for medical applications , 2003 .

[32]  S. D. Bruck,et al.  Radiation sterilization of polymeric implant materials. , 1988, Journal of biomedical materials research.

[33]  James M. Anderson,et al.  Polyurethane Elastomer Biostability , 1995, Journal of biomaterials applications.

[34]  Muthu Jayabalan,et al.  Studies on the effect of crosslinker on the stability of castor-oil-based aliphatic polyurethane potting compound , 1997 .

[35]  K. Kanemitsu,et al.  Residual formaldehyde on plastic materials and medical equipment following low-temperature steam and formaldehyde sterilization. , 2005, The Journal of hospital infection.

[36]  R. Maxwell,et al.  NMR analysis of γ-radiation induced degradation of halthane-88 polyurethane elastomers , 2003 .

[37]  L. Bjursten,et al.  Tissue response to commercial silicone and polyurethane elastomers after different sterilization procedures. , 1996, Biomaterials.

[38]  P. Sharrock,et al.  Influence of sterilization on injectable bone biomaterials. , 1999, Bone.

[39]  E. Wintermantel,et al.  Water as foaming agent for open cell polyurethane structures , 2004, Journal of materials science. Materials in medicine.

[40]  Chuh‐Yung Chen,et al.  Study on the morphology and permeation property of amine group-contained polyurethanes , 1998 .

[41]  B. Gabryel,et al.  Piracetam and vinpocetine exert cytoprotective activity and prevent apoptosis of astrocytes in vitro in hypoxia and reoxygenation. , 2002, Neurotoxicology.

[42]  E. Kastenbauer,et al.  Distribution and viability of cultured human chondrocytes in a three-dimensional matrix as assessed by confocal laser scan microscopy , 1997, In Vitro Cellular & Developmental Biology - Animal.

[43]  J. Santerre,et al.  Isolation of methylene dianiline and aqueous-soluble biodegradation products from polycarbonate-polyurethanes. , 2003, Biomaterials.