A Visual Hydrogen Sensor Prototype for Monitoring Magnesium Implant Biodegradation

Abstract

Alternative metals such as magnesium (Mg) and its alloys have been recently developed for clinical applications such as temporary implants for bone and tissue repair due to their desirable mechanical properties and ability to biodegrade harmlessly in vivo by releasing Mg 2+ , OH − , and H 2 as biodegradation products. The current methods for monitoring in vivo Mg-alloy biodegradation are either invasive and/or costly, complex, or require large equipment and specially trained personnel, thus making real-time and point-of-care monitoring of Mg-alloy implants problematic. Therefore, innovative methods are critically needed. The objective of this research was to develop a novel, thin, and wearable visual H 2 sensor prototype for noninvasive monitoring of in vivo Mg-implant biodegradation in medical research and clinical settings with a fast response time. In this work, we successfully demonstrate such a prototype composed of resazurin and catalytic bimetallic gold-palladium nanoparticles (Au-Pd NPs) incorporated into a thin agarose/alginate hydrogel matrix that rapidly changes color from blue to pink upon exposure to various levels of H 2 at a constant flow rate. The irreversible redox reactions occurring in the sensor involve H 2 , in the presence of Au-Pd NPs, converting resazurin to resorufin. To quantify the sensor color changes, ImageJ software was used to analyze photographs of the sensor taken with a smartphone during H 2 exposure. The sensor concentration range was from pure H 2 down to limits of detection of 6 and 8 μM H 2 (defined via two methods). This range is adequate for the intended application of noninvasively monitoring in vivo Mg-alloy implant biodegradation in animals for medical research and patients in clinical settings.

Supraparticles for Bare‐Eye H2 Indication and Monitoring: Design, Working Principle, and Molecular Mobility

“…[43][44][45] Hence, a H 2 indicator based on resazurin/ resorufin may allow for real-time monitoring and irreversible indication of H 2 exposure via a two-step color change reaction. Note that the use of redox-dye/catalyst combinations as visual H 2 indicators is restricted to the liquid phase [43] or hydrogels, [46] as it requires a three-phase system. This is due to the transport of H 2 as reactive H 2 species from the catalytically active metal surface to the indicator dye molecules or vice versa.…”

In Vivo Study of Local and Systemic Responses to Clinical Use of Mg–1Ca Bioresorbable Orthopedic Implants

“…Finally, some concerns have been raised through the years that pneumarthrosis can be induced as a result of hydrogen production during the corrosion process [ 32 , 33 , 34 , 35 , 36 , 37 , 38 ]. As such, the synovial membrane can be furthermore damaged as a secondary effect to hydrogen accumulation [ 32 , 33 , 34 ].…”

Wearable Electrochemical Sensors Based on Nanomaterials for Healthcare Applications

“…Keerthi G. Nair group [235] produced a hydrogen sensor-Platinum nanocatellite-functionalized carbon nanofibers (CNFs@NiÀ Pt) using less platinum bimetallic nickel. Michael E. Smith [236] devel- ops a novel wearable vision H 2 sensor for non-invasive monitoring of biodegradation of magnesium implants in vivo in medical research and clinical Settings. The development of a real-time NO 2 sensor is also of interest [237].…”