Designing cellulosic and nanocellulosic sensors for interface with a protease sequestrant wound-dressing prototype: implications of material selection for dressing and protease sensor design

Authors: Fontenot, Krystal; Edwards, Judson - Vince; HALDANE, DAVID - Innovatech-Engineering; PIRCHER, NICOLE - University Of Natural Resources & Applied Life Sciences - Austria; LIEBNER, FALK - University Of Natural Resources & Applied Life Sciences - Austria; Condon, Brian; QURESHI, HUZAIFAH - Virginia Commonwealth University; YAGER, DORNE - Virginia Commonwealth University

Submitted to: Journal of Biomaterials Applications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2017
Publication Date: 10/12/2017
Citation: Fontenot, K.R., Edwards, J.V., Haldane, D., Liebner, F., Pircher, N., Condon, B.D. 2017. Designing cellulosic and nanocellulosic sensors for interface with a protease sequestrant wound-dressing prototype: implications of material selection for dressing and protease sensor design. Journal of Biomaterials Applications. 32(5):622-637.

Interpretive Summary: We evaluated nanocellulosic materials as a transducer surface for the generation of a protease biosensor layer as an interface for a multilayered intelligent protease sequestrant wound dressings for chronic wounds. The proposed dressing not only detects but also sequester proteases via the use of cellulose print cloth (control) and nanocellulosic materials (nanocrystals, nanocellulose composites, and nanocellulosic aerogels). These materials were selected due to their (i) structural and biophysical similarities to commercially available dressings, i.e., gauze, films, and hydrogels, (ii) their favorable permeability, moisture retention, charge properties, and/or sensor functions, and (iii) their SSA, peptide loading, detection sensitivity, surface charge for sequestration purposes, and permeability as a function of a biosensor layer. These nanocellulosic materials combine compliant (structure, porosity, pore size, and hydrophilic properties) and nanocellulosic features (SSA, and surface charge) as a novel protease sequestrant biosensor layer. Conjugation of the nanocellulosic materials to a tripeptide or tetrapeptide substrates provided higher levels of peptide loading, detection sensitivity, surface charge, and protease sequestration compared to cellulosic PC. The detection and sequestration of proteases levels in simulated wound fluids indicate the onset of a non-healing wound and can signify the effectiveness of treatment. Therefore, interfacing the nanocellulosic biosensor with an intelligent dressing paradigm is adaptable for the detection of other biomarkers of clinical interest as well, via substitution of the biomolecule with the desired POC diagnostics or theranostic interest.

Technical Abstract: An intelligent dressing is a self-adjusting material with multifunctional properties and/or a biosensor-interface designed to treat specific pathological issues of wounds at a molecular or cellular level. The ability to detect and treat excessive protease levels in wounds, one indicator of chronic wound pathology, in a single dressing motif is a goal of intelligent material design. Different bio-sensing platforms for the detection of sensor proteases present in wound fluid include cellulosic paper, multiwall carbon nanotubes, and gold nanoparticles based on attaching peptide protease substrates to the transducer surface. Interfacing nanocellulosic-based biosensors with chronic wound dressings for protease point of care diagnostics is promising due to biocompatibility, functionality, high specific surface area, surface charge, and hydrophilic compatibility to the wound environment. We present here biosensors with a nanocellulosic transducer surface (nanocrystals, nanocellulose composites, and nanocellulosic aerogels) immobilized with a fluorescent elastase tripeptide or tetrapeptide biomolecule, which has selectivity and affinity for human neutrophil elastase present in chronic wound fluid. Material specific surface area correlated with a greater loading of the elastase peptide substrate, which in turn improves the bio-sensing sensitivity. Nitrogen adsorption and mercury intrusion studies revealed gas permeable systems with different porosities (28 – 98%) and pore sizes (2 – 50 nm, 210 µm) respectively, which influence water vapor transmission rates. A correlation between zeta potential values and the degree of protease sequestration imply that the greater the negative surface charge of the nanomaterials the greater the sequestration of positively charged neutrophil proteases. The biosensors gave detection sensitivities of 0.015 – 0.13 units/milliliter, which are at detectable HNE levels present in chronic wound fluid. Thus, the physical properties of the nano-based biosensors are suitable for interfacing with protease sequestrant prototype wound dressings. A discussion of the relevance of protease sensors and cellulose nanomaterials to current chronic wound dressing design and technology is included.