Submitted to: Sensors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2016
Publication Date: 10/26/2016
Citation: Edwards, J.V., Fontenot, K.R., Prevost, N.T., Pircher, N., Liebner, F., Condon, B.D. 2016. Preparation, characterization, and activity of a peptide-cellulosic aerogel protease sensor from cotton. Sensors. 16(11):1-19.

Interpretive Summary: A natural source of greige cotton fibers was employed to generate nanocellulose aerogel sensors for the detection of human neutrophil elastase that is not only a marker for chronic wounds but is also a marker for inflammatory diseases. Nanocellulosic aerogels were prepared by employing calcium thiocyanate octahydrate/lithium chloride as a dissolution vehicle with subsequent gel casting, coagulation, solvent exchange, and drying gave a homogeneous material. The aerogels were found to contain small amounts of pectin as well. The nanocellulose aerogel sensors were esterified and covalently attached to a fluorogenic elastase peptide substrate to generate the biosensor. Characterization and the bioactivity of the peptide nanocellulosic aerogels support the aerogel as a good surface for generating sensors and are able to detect human neutrophil elastase levels found in chronic wounds.

Technical Abstract: Nanocellulosic aerogels (NA) provide a lightweight biocompatible material with structural properties of both high porosity and specific surface area for biosensor design. We report here the preparation, characterization, and activity of a peptide-nanocellulose aerogel (PA) made from unprocessed cotton and designed with protease detection activity. Low-density cellulosic aerogels were prepared from highly cleaned greige cotton by employing calcium thiocyanate octahydrate/lithium chloride as a dissolution vehicle. Subsequent gel casting, coagulation, solvent exchange, and drying gave a homogeneous material. The principle morphology of the cotton-based aerogel is consistent with a fibrous cellulose II network. The aerogel was 99% porous with an average pore size of 11 nm, and a specific surface area of 163 m2g-1. A fluorescent tripeptide-cellulose analog (Alanine-Proline-Alanine-4-Amino-7-methyl-coumarin) (Ala-Pro-Ala-AMC) was tethered to NA by way of a of the succinimidyl-Glycine-cellulose ester of NA. The degree of substitution (D.S.) of the peptide analog attached to the anhydroglucose units of PA was 0.015. The detection sensitivity of PA for human neutrophil elastase (HNE), a diagnostic biomarker for inflammatory diseases, was found to be 0.125 U/mL, the physical properties of the aerogel are suitable for interfacing with a protease sequestrant wound dressing.