Detecting and Monitoring Hydrogels with Medical Imaging

Abstract

Hydrogels, water-swollen polymer networks, are being applied to numerous biomedical applications, such as drug delivery and tissue engineering, due to their potential tunable rheologic properties, injectability into tissues, and encapsulation and release of therapeutics. Despite their promise, it is challenging to assess their properties in vivo and crucial information such as hydrogel retention at the site of administration and in situ degradation kinetics are often lacking. To address this, technologies to evaluate and track hydrogels in vivo with various imaging techniques have been developed in recent years, including hydrogels functionalized with contrast generating material that can be imaged with methods such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), optical imaging, and nuclear imaging systems. In this review, we will discuss emerging approaches to label hydrogels for imaging, review the advantages and limitations of these imaging techniques, and highlight examples where such techniques have been implemented in biomedical applications.

Editorial: Special Issue on Advanced Biomedical Hydrogels

“…To advance hydrogels further, a thorough understanding of their retention and detail of their properties (e.g., degradation kinetics) after implantation or injection is needed. Regarding the visualization techniques of hydrogels in vivo , Cormode and colleagues provide a comprehensive review on how hydrogels can be engineered with intrinsically imageable properties through physical embedding or chemical modification with contrast agents and chemical moieties . Further, Tibbitt and colleagues provide a comprehensive summary of the interface between hydrogels and surfaces and how this junction can be controlled for adhesion .…”

“…Regarding the visualization techniques of hydrogels in vivo, Cormode and colleagues provide a comprehensive review on how hydrogels can be engineered with intrinsically imageable properties through physical embedding or chemical modification with contrast agents and chemical moieties. 20 Further, Tibbitt and colleagues provide a comprehensive summary of the interface between hydrogels and surfaces and how this junction can be controlled for adhesion. 21 Advances in imaging and adhesion of hydrogels have broad implications in their medical use.…”

Bioinspired Hydrogels as Platforms for Life-Science Applications: Challenges and Opportunities

“…Since their design, the properties of hydrogels can be tuned to mimic the mechanical, biochemical, and functional characteristics of the soft tissues. The biomimetic materials are applied for controlled drug delivery [4,6,41,58,59,108,122,126,127,178,179], in regenerative medicine (tissue engineering, modulating tissue environment to promote the tissue repair) [3,4,176,180], biosensors and actuators [4,9,[11][12][13]86,176,[180][181][182], bioprinting [4,[10][11][12], 3D cell culture [4,42,46,79,177], imaging for medical diagnostics and therapy [183][184][185], personal healthcare and hygienic products [16,165], etc. A variety of hydrogels responsive to different external stimuli were reported: temperature [4,9,22,35,53,78,…”

Emerging scaffold- and cellular-based strategies for brain tissue regeneration and imaging

“…PET-CT and SPECT are nuclear imaging techniques that combine the use of ionising radiation and radiotracers to label numerous cell types (including neural and stem cells) or biomaterials to obtain functional tissue information [213]. For example, biomaterials such as polytopic alginate can be cross-linked with several radiotracers for the in vivo visualisation of the hydrogel through SPECT or PET imaging [214]. More recently, genetically labelled cells using a reporter gene have been shown to withstand repetitive imaging.…”