Highly Stable Passive Wireless Sensor for Protease Activity Based on Fatty Acid-Coupled Gelatin Composite Films.

Palraj Kalimuthu,Javier Sotres,Tautgirdas Ruzgas,Juan F Gonzalez-Martinez

doi:10.1021/acs.analchem.0c02153

Abstract

Proteases are often used as biomarkers of many pathologies as well as of microbial contamination and infection. Therefore, extensive efforts are devoted to the development of protease sensors. Some applications would benefit from wireless monitoring of proteolytic activity at minimal cost, e.g., sensors embedded in care products like wound dressings and diapers to track wound and urinary infections. Passive (batteryless) and chipless transponders stand out among wireless sensing technologies when low cost is a requirement. Here, we developed and extensively characterized a composite material that is biodegradable but still highly stable in aqueous media, whose proteolytic degradation could be used in these wireless transponders as a transduction mechanism of proteolytic activity. This composite material consisted of a cross-linked gelatin network with incorporated caprylic acid. The digestion of the composite when exposed to proteases results in a change of its resistivity, a quantity that can be wirelessly monitored by coupling the composite to an inductor–capacitor resonator, i.e., an antenna. We experimentally proved this wireless sensor concept by monitoring the presence of a variety of proteases in aqueous media. Moreover, we also showed that detection time follows a relationship with protease concentration, which enables quantification possibilities for practical applications.

Highlights

Proteases are often used as biomarkers of many pathologies as well as of microbial contamination and infection
The characteristic frequency would depend, e.g., on the volume of water surrounding the antenna, a parameter difficult to standardize if sampling is to be avoided. These drawbacks can be overcome with a design where the sensor section of the transponder, that is susceptible to analyteinduced impedance changes, is connected but well differentiated from the antenna section, which is kept outside the investigated aqueous medium.[30]
We developed a crosslinked gelatin−caprylic acid composite characterized by a high stability, surface adherence, and resistivity in aqueous media

Summary

Introduction

Proteases are often used as biomarkers of many pathologies as well as of microbial contamination and infection. The digestion of the composite when exposed to proteases results in a change of its resistivity, a quantity that can be wirelessly monitored by coupling the composite to an inductor−capacitor resonator, i.e., an antenna We experimentally proved this wireless sensor concept by monitoring the presence of a variety of proteases in aqueous media. A different possibility is to make use of passive wireless technologies i.e., those that do not require an energy source These can be classified according to the incorporation of an integrated circuit (chip) in the transponder/sensor. The characteristic frequency would depend, e.g., on the volume of water surrounding the antenna, a parameter difficult to standardize if sampling is to be avoided These drawbacks can be overcome with a design where the sensor section of the transponder, that is susceptible to analyteinduced impedance changes, is connected but well differentiated from the antenna section, which is kept outside the investigated aqueous medium.[30]

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Conclusion