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Title: Method for the Destruction of Endotoxin in Synthetic Spider Silk Proteins

Abstract

Although synthetic spider silk has impressive potential as a biomaterial, endotoxin contamination of the spider silk proteins is a concern, regardless of the production method. The purpose of this research was to establish a standardized method to either remove or destroy the endotoxins present in synthetic spider silk proteins, such that the endotoxin level was consistently equal to or less than 0.25 EU/mL, the FDA limit for similar implant materials. Although dry heat is generally the preferred method for endotoxin destruction, heating the silk proteins to the necessary temperatures led to compromised mechanical properties in the resultant materials. In light of this, other endotoxin destruction methods were investigated, including caustic rinses and autoclaving. It was found that autoclaving synthetic spider silk protein dopes three times in a row consistently decreased the endotoxin level 10–20 fold, achieving levels at or below the desired level of 0.25 EU/mL. Products made from triple autoclaved silk dopes maintained mechanical properties comparable to products from untreated dopes while still maintaining low endotoxin levels. Triple autoclaving is an effective and scalable method for preparing synthetic spider silk proteins with endotoxin levels sufficiently low for use as biomaterials without compromising the mechanical properties of the materials.

Authors:
 [1];  [1];  [1];  [1]; ORCiD logo [1];  [1]
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  1. Utah State Univ., Logan, UT (United States)
Publication Date:
Research Org.:
Utah State Univ., Logan, UT (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1500013
Grant/Contract Number:  
EE0006857
Resource Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Decker, Richard E., Harris, Thomas I., Memmott, Dylan R., Peterson, Christopher J., Lewis, Randolph V., and Jones, Justin A. Method for the Destruction of Endotoxin in Synthetic Spider Silk Proteins. United States: N. p., 2018. Web. doi:10.1038/s41598-018-29719-6.
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Decker, Richard E., Harris, Thomas I., Memmott, Dylan R., Peterson, Christopher J., Lewis, Randolph V., & Jones, Justin A. Method for the Destruction of Endotoxin in Synthetic Spider Silk Proteins. United States. doi:10.1038/s41598-018-29719-6.
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Decker, Richard E., Harris, Thomas I., Memmott, Dylan R., Peterson, Christopher J., Lewis, Randolph V., and Jones, Justin A. Wed . "Method for the Destruction of Endotoxin in Synthetic Spider Silk Proteins". United States. doi:10.1038/s41598-018-29719-6. https://www.osti.gov/servlets/purl/1500013.
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@article{osti_1500013,
title = {Method for the Destruction of Endotoxin in Synthetic Spider Silk Proteins},
author = {Decker, Richard E. and Harris, Thomas I. and Memmott, Dylan R. and Peterson, Christopher J. and Lewis, Randolph V. and Jones, Justin A.},
abstractNote = {Although synthetic spider silk has impressive potential as a biomaterial, endotoxin contamination of the spider silk proteins is a concern, regardless of the production method. The purpose of this research was to establish a standardized method to either remove or destroy the endotoxins present in synthetic spider silk proteins, such that the endotoxin level was consistently equal to or less than 0.25 EU/mL, the FDA limit for similar implant materials. Although dry heat is generally the preferred method for endotoxin destruction, heating the silk proteins to the necessary temperatures led to compromised mechanical properties in the resultant materials. In light of this, other endotoxin destruction methods were investigated, including caustic rinses and autoclaving. It was found that autoclaving synthetic spider silk protein dopes three times in a row consistently decreased the endotoxin level 10–20 fold, achieving levels at or below the desired level of 0.25 EU/mL. Products made from triple autoclaved silk dopes maintained mechanical properties comparable to products from untreated dopes while still maintaining low endotoxin levels. Triple autoclaving is an effective and scalable method for preparing synthetic spider silk proteins with endotoxin levels sufficiently low for use as biomaterials without compromising the mechanical properties of the materials.},
doi = {10.1038/s41598-018-29719-6},
journal = {Scientific Reports},
number = 1,
volume = 8,
place = {United States},
year = {2018},
month = {8}
}
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Journal Article:
Free Publicly Available Full Text
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DOI:  10.1038/s41598-018-29719-6
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Figures / Tables:

Table 1 Table 1: Combined average endotoxin levels of all goat-derived spider silk proteins and films before and after treatments. Individual sample group averages are shown in Supplementary Table S1. The R2 of the endotoxin analysis kit standard curve was ≥0.989 for all experiments. Silk samples below 0.25 EU/mL are in bold.more » Standard deviations were calculated using STDEV.P in Microsoft Excel.« less
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