Quantitative Luminescence Photography of a Swellable Hydrogel Dressing with a Traffic‐Light Response to Oxygen

Abstract

Sensor-integrated wound dressings are emerging tools applicable to a wide variety of medical applications from emergency triage to at-home monitoring. Uncomfortable, unnecessary wound dressing changes may be avoided by providing quantitative insight into tissue characteristics related to wound healing such as tissue oxygenation, pH, and exudate/transudate volume. Here, a simple cost-effective methodology for quantifying oxygen and pH in a swellable hydrogel dressing using a single photograph is presented. The red and green luminescence of a novel dendritic polyamine Pt-porphyrin and fluorescein conjugate quantitatively responds to oxygen and pH, respectively, and enables robust sensing. The porphyrin conjugate, when combined with a four-arm star polyethylene glycol (PEG) amine polymer, rapidly crosslinks at room temperature with an N-hydroxysuccinimide (NHS)-PEG crosslinker to form a color-changing hydrogel dressing with tunable swelling capabilities applicable to a variety of wound environments. An inexpensive digital single-lens reflex (DSLR) camera modified with bandpass filters captures the hydrogel luminescence using simple macroscopic photography, and conversion to HSB colorspace allows for intensity-independent image analysis of the hydrogels' dual modality response. The hydrogel formulation exhibits a robust and validated visible red-orange-green "traffic light" spectrum in response to oxygen changes, regardless of swelling state, pH, or autofluorescence from skin, thereby enabling the clinician friendly naked-eye feedback.

Organic–Inorganic Porphyrinoid Frameworks for Biomolecule Sensing

“…The porphyrin–fluorescein conjugate displayed a red dominant (Pt-porphyrin) emission at low oxygen level and a green dominant (fluorescein) emission in room air, resulting in red-to-green traffic-light response. Reprinted with permission from ref . Copyright 2022 Wiley-VCH GmbH.…”

“…Results from an in vivo tourniquet porcine model showed that the device is sensitive toward the oxygen partial pressure range of 0–80 mmHg and exhibited a reproducible response to changes in intramuscular oxygen. The same group further developed a swellable hydrogel dressing which displayed traffic-light response to oxygen . Hydrogels are characterized by their analogy to extracellular matrix owing to their soft and porous skeleton together with their huge water holding capacity and biocompatibility.…”

“…The same group further developed a swellable hydrogel dressing which displayed traffic-light response to oxygen. 61 Hydrogels are characterized by their analogy to extracellular matrix owing to their soft and porous skeleton together with their huge water holding capacity and biocompatibility. The fluorescein functionalized porphyrin dendrimer in combination with four-arm PEG was crosslinked with N-hydroxysuccinimide−PEG cross-linker to generate a color-changing hydrogel dressing with tunable swelling capabilities as represented in Figure 5B.…”

Progress in Hydrogels for Skin Wound Repair

“…Synthetic polymers mainly include polyethylene glycol (PEG), polydopamine (PDA), polyacrylamide (PAM), polyvinyl alcohol (PVA), etc. [57][58][59][60] Due to the controllable molecular weight and physical and chemical properties, synthetic polymer hydrogels have unique advantages in skin tissue engineering. Compared with natural polymers, synthetic polymers exhibit higher mechanical strength and controllable biodegradation rate.…”

Editors’ Choice—Luminescent Oxygen Sensors: Valuable Tools for Spatiotemporal Exploration of Metabolism in In Vitro Systems

“…This sensing mechanism has gained traction in a variety of fields and has proven to be applicable for both in vitro studies of cell metabolism and in vivo applications for physiological monitoring with implantable or wearable transcutaneous devices. While transcutaneous devices for physiological O 2 monitoring have made significant progress in recent years, [11][12][13][14][15] this perspective will mainly focus on the in vitro use of luminescent sensors that are quenched by O 2 with the main goal of guiding the reader towards a logical sensor choice for their desired application. As such, we are not attempting to review the entire field of O 2 sensing for metabolic evaluation, but rather to provide the reader with examples of what is possible to help guide their research and facilitate innovation in this domain.…”