POS4-0772
In vivo patterning of hydrogels using low intensity focused ultrasound
Topic
S4. Colloids, Interfaces, and Molecular Assemblies for Functional Soft Materials
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Jeongin Eom (Seoul National University)
Co-Author(s)
Abstract
Injectable hydrogels enable minimally invasive delivery but difficult to make patterns after injection. In contrast, 3D printing allows precise patterning but requires surgical implantation. In this study, we present a platform that combines an injectable hydrogel with low-intensity focused ultrasound (LIFU) to achieve localized gelation and patterning without surgical intervention.
The injectable hydrogel consists of polyethylene glycol diacrylate (PEGDA)-based nanogels. To form a reversible network after injection, we utilize the jamming transition of colloidal particles. At high volume fractions (>64%), nanogel particles become densely packed and form a jammed state, exhibiting solid-like behavior in the absence of external stress. Under shear stress during injection, the material exhibits shear-thinning behavior, enabling syringe delivery. After injection, the jammed structure maintains the material at the target site until chemical crosslinking is induced.
Localized chemical gelation is triggered by LIFU. During nanogel synthesis, peracid groups are generated together with remaining acrylate groups. Upon ultrasound exposure, the peracid undergoes homolytic cleavage to generate radicals, which react with the remaining acrylates and induce interparticle crosslinking. As a result, bulk gel formation occurs only within the ultrasound-targeted region, enabling spatially controlled patterning.
Unlike high-intensity focused ultrasound (HIFU)-based approaches, this system operates while maintaining a temperature increase below 2°C above physiological temperature. By tuning nanogel and ultrasound parameters, the platform can be adapted to diverse tissue environments. This approach provides a basis for customized tissue fillers and localized delivery of cells, drugs, and other therapeutic cargos.
The injectable hydrogel consists of polyethylene glycol diacrylate (PEGDA)-based nanogels. To form a reversible network after injection, we utilize the jamming transition of colloidal particles. At high volume fractions (>64%), nanogel particles become densely packed and form a jammed state, exhibiting solid-like behavior in the absence of external stress. Under shear stress during injection, the material exhibits shear-thinning behavior, enabling syringe delivery. After injection, the jammed structure maintains the material at the target site until chemical crosslinking is induced.
Localized chemical gelation is triggered by LIFU. During nanogel synthesis, peracid groups are generated together with remaining acrylate groups. Upon ultrasound exposure, the peracid undergoes homolytic cleavage to generate radicals, which react with the remaining acrylates and induce interparticle crosslinking. As a result, bulk gel formation occurs only within the ultrasound-targeted region, enabling spatially controlled patterning.
Unlike high-intensity focused ultrasound (HIFU)-based approaches, this system operates while maintaining a temperature increase below 2°C above physiological temperature. By tuning nanogel and ultrasound parameters, the platform can be adapted to diverse tissue environments. This approach provides a basis for customized tissue fillers and localized delivery of cells, drugs, and other therapeutic cargos.
