title: An implantable compound-releasing capsule triggered on demand by ultrasound.
abstract: Implantable devices have a large potential to improve human health, but they are often made of biofouling materials that necessitate special coatings, rely on electrical connections for external communication, and require a continuous power source. This paper demonstrates an alternative platform, which we call iTAG (implantable thermally actuated gel), where an implanted capsule can be wirelessly controlled by ultrasound to trigger the release of compounds. We constructed a millimeter-sized capsule containing a co-polymer gel (NiPAAm-co-AAm) that contracts above body temperature (i.e. at 45 °C) to release compounds through an opening. This gel-containing capsule is biocompatible and free of toxic electronic or battery components. An ultrasound hardware, with a focused ultrasound (FUS) transducer and a co-axial A-mode imaging transducer, was used to image the capsule (to monitor in real time its position, temperature, and effectiveness of dose delivery), as well as to trigger a rapid local rise in temperature, contraction of gel, and release of compounds in vitro and in vivo. The combination of this gel-based capsule and compact ultrasound hardware can serve as a platform for triggering local release of compounds, including potentially in deep tissue, to achieve tailored personalized therapy.
authors.affiliation: Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, United States.
authors.forename: Olga
authors.initials: O
authors.lastname: Ordeig
authors.affiliation: Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, United States.
authors.forename: Sau Yin
authors.initials: SY
authors.lastname: Chin
authors.affiliation: Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, United States.
authors.forename: Sohyun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Bioengineering, George Mason University, 4400 University Drive, Fairfax, VA 22032, United States.|F. L. Lizzi Center for Biomedical Engineering, Riverside Research, New York, NY 10038, United States.
authors.forename: Parag V
authors.initials: PV
authors.lastname: Chitnis
authors.affiliation: Department of Biomedical Engineering, Columbia University, 351 Engineering Terrace, 1210 Amsterdam Avenue, New York, NY 10027, United States.
authors.forename: Samuel K
authors.initials: SK
authors.lastname: Sia
mesh_terms: D020341:Absorbable Implants; D000818:Animals; D002214:Capsules / Q000737:chemistry; D016503:Drug Delivery Systems; D005782:Gels / Q000737:chemistry; D006801:Humans; D051379:Mice; D013696:Temperature; D000069453:Ultrasonic Waves
chemical_list: D002214:Capsules; D005782:Gels