The Influence of Bloom Index, Endotoxin Levels and Polyethylene Glycol Succinimidyl Glutarate Crosslinking on the Physicochemical and Biological Properties of Gelatin Biomaterials.

Zhuning Wu,Anne Maria Mullen,Dimitios I Zeugolis,Stefanie H Korntner,Jos Olijve

doi:10.3390/biom11071003

Abstract

In the medical device sector, bloom index and residual endotoxins should be controlled, as they are crucial regulators of the device’s physicochemical and biological properties. It is also imperative to identify a suitable crosslinking method to increase mechanical integrity, without jeopardising cellular functions of gelatin-based devices. Herein, gelatin preparations with variable bloom index and endotoxin levels were used to fabricate non-crosslinked and polyethylene glycol succinimidyl glutarate crosslinked gelatin scaffolds, the physicochemical and biological properties of which were subsequently assessed. Gelatin preparations with low bloom index resulted in hydrogels with significantly (p < 0.05) lower compression stress, elastic modulus and resistance to enzymatic degradation, and significantly higher (p < 0.05) free amine content than gelatin preparations with high bloom index. Gelatin preparations with high endotoxin levels resulted in films that induced significantly (p < 0.05) higher macrophage clusters than gelatin preparations with low endotoxin level. Our data suggest that the bloom index modulates the physicochemical properties, and the endotoxin content regulates the biological response of gelatin biomaterials. Although polyethylene glycol succinimidyl glutarate crosslinking significantly (p < 0.05) increased compression stress, elastic modulus and resistance to enzymatic degradation, and significantly (p < 0.05) decreased free amine content, at the concentration used, it did not provide sufficient structural integrity to support cell culture. Therefore, the quest for the optimal gelatin crosslinker continues.

Highlights

Bloom index, a unit that and medical device sectors development, bloom index, a unit measures the extent of hydrolysis, is anisimportant parameter that should be assessed as it that measures the extent of hydrolysis, an important parameter that should be assessed affects the gelling capacity, gel strength and celland response of gelatin
One as notgelatin forgetisthat as gelvia collagen hydrolysis, exogenous crosslinks should becrosslinks introduced to enhance mechanical atin is produced via collagen hydrolysis, exogenous should be introduced to strength,mechanical but without compromising cellular functions ofcellular gelatinfunctions biomaterials
We assessed the and biological properties of gelatinand we correlated them to their bloom index, amounts of endotoxins present in original based biomaterials and we correlated them to their bloom index, amounts of the endotoxins raw materials and polyethylene glycol succinimidyl glutarate crosslinking

Summary

Introduction

Gelatin is attracting growing attention in the fields of tissue engineering and drug delivery due to its low antigenicity, high cell affinity, relatively easy processability and high availability at low cost [1,2,3,4]. Gelatin is a mixture of peptides produced by partially acid (gelatin type A, isoelectric point of ~8) or alkaline Subject to the stage of the extraction, gelatin preparations are classified as low (initial stage of extraction/incomplete hydrolysis) or high (late stage of extraction/complete hydrolysis) bloom index (ranging from 50 to 300) [7]. High bloom numbers are associated with high molecular weight gelatin preparations, increased dynamic moduli and increased gelation and melting temperatures [8]. The bloom index and Biomolecules 2021, 11, 1003.

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