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

Abstract

Interfacing nanocellulosic-based biosensors with chronic wound dressings for protease point of care diagnostics combines functional material properties of high specific surface area, appropriate surface charge, and hydrophilicity with biocompatibility to the wound environment. Combining a protease sensor with a dressing is consistent with the concept of an intelligent dressing, which has been a goal of wound-dressing design for more than a quarter century. 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. The specific surface area of the materials correlates with a greater loading of the elastase peptide substrate. 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/ml, which are at detectable human neutrophil elastase levels present in chronic wound fluid. Thus, the physical and interactive biochemical 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.

Ultrasensitive Physical, Bio, and Chemical Sensors Derived from 1‐, 2‐, and 3‐D Nanocellulosic Materials

“…Biosensors are a class of devices that detect, transmit, and record information on physiological or biochemical changes, which are ideal tools for point‐of‐care diagnostics since they are portable, cost effective, and easy to use 19h,34,41. They generally consist of an immobilized biocomponent and a transducer surface.…”

“…The global market for this kind of product is estimated to be hundreds of billions USD 44. Chronic wound fluid contains cytokines, chemokines, growth factors, electrolytes, and proteolytic enzymes 34. Among various systems for wound monitoring, protease biomarkers have attracted significant attention.…”

“…Fluorescence is widely used for sensing because of its versatility and high sensitivity toward external stimuli 46. Fontenot et al34 designed a biosensor with CNC and fluorescent elastase tripeptide or tetrapeptide for the detection of HNE in chronic wound fluid. The high specific surface area of CNC allows it to load large amounts of elastase peptide, which is beneficial for sensor sensitivity since the sensitivity correlates with the specific surface area of the transducer surface.…”

Preparation and Characterization of Bacterial Cellulose-Carbon Dot Hybrid Nanopaper for Potential Sensing Applications

“…Diagnostic or theranostic devices in human medicine typically rely on sensitive biosensors and event-triggered controlled release of active compounds. This is also the case for intelligent wound dressings capable of assessing critical protease concentrations in chronic wounds, for example [4,5]. Beyond the core features allowing for reporting critical levels of a target analyte and triggering a controlled response, respective wound dressings or biosensors interacting with living tissue are required to be biocompatible, free of potentially harmful trace compounds and should have excellent moistening capabilities.…”

“…The latter can be linked to the substrate by a specific peptide which is designed to interact with the respective target analyte, such as human neutrophile elastase. As a result, the fluorophore is cleaved off indirectly reporting an elastase concentration dependent optical response [5,9,10]. Alternatively, photoluminescent nanoparticles covalently immobilized on the transducer's surface can be used whose optical response is either triggered or quenched depending on the type and concentration of the analyte.…”