Syringe-Injectable, Self-Expandable, and Ultraconformable Magnetic Ultrathin Films

Abstract

Syringe-injectable biomaterials and medical devices are important as minimally invasive implants for diagnosis, therapy, and regenerative medicine. Free-standing polymeric nanosheets with a thickness less than 1 μm and a flexural rigidity less than 10 −2 nN m are a promising platform of syringe-injectable, implantable devices that provide conformable and long-term stable adhesion to the target biological tissues for in situ delivery of therapeutic materials. Here, we developed free-standing ultrathin films (<1 μm thick) based on polyurethane-based shape-memory polymer (SMP) and magnetic nanoparticles (MNP), termed MNP-SMP nanosheets. With the temperature-mediated shape-memory effect of SMP, we overcome the limitation in the manipulation of the conventional polymer nanosheets. In particular, we demonstrated the following four capabilities using the 710 nm thick MNP-SMP nanosheet with the glass transition temperature (T g ) of 25 °C:(1) syringe-injectability through the medical needles, (2) self-expandability after ejection, (3) conformability and removability on the biological surfaces, and (4) guidability in an external magnetic field. The MNP-SMP nanosheets were readily interfaced with an additional layer of poly(lactic-co-glycolic acid) (PLGA) to extend their functionality as a carrier of molecular and cellular drugs. The MNP-SMP nanosheets will contribute to the development of advanced syringe-injectable medical devices as a platform to deliver drugs, sensors, cells, and engineered tissues to the specific site or lesion in the body for minimally invasive diagnosis and therapy.

Ultra‐Deformable and Tissue‐Adhesive Liquid Metal Antennas with High Wireless Powering Efficiency

“…We previously demonstrated obtaining free‐standing polymeric/elastomeric ultrathin films by a spin‐coating‐assisted sacrificial layer method. [ 4,38 ] The same method was applied for the fabrication of free‐standing Ecoflex microsheets (Figure S1, Supporting Information). The mechanical conformability and adhesion strength of the thin film to the biological tissue surface depend on the flexural rigidity ( D ) of the film, which is given by the following equation (Equation ()): where E , t , and ν are Young's modulus, thickness, and Poisson's ratio of the film, respectively.…”

“…The DIW technique enabled the tailor‐made fabrication of microchannels on a wide range of thin‐film substrates without cleanroom facilities. Fabrication of microchannels on unique materials (such as functional polymer nanosheets [ 1,4,38 ] or bioadhesive hydrogels [ 51 ] ) is possible to enhance the range of applications in the field of implantable medical devices. Besides, the presented methods have made the fabrication of microfluidic electronics simple and rapid in terms of the integration of surface‐mounted components as well as the injection of liquid metals.…”

A Review of Shape Memory Polymers and Composites: Mechanisms, Materials, and Applications

“…In another study, Yamagishi et al. [ 175 ] investigated an ultrathin shape memory nanosheet that could be injected with a syringe and later unfold in 37 °C water. The nanosheet guided by a neodymium magnet in the water employed a bilayer structure, which involved a magnetic particle embedded in the polymer layer and poly(lactic‐ co ‐glycolic acid) layer.…”

Magneto‐/ electro‐responsive polymers toward manufacturing, characterization, and biomedical/ soft robotic applications

“…(d) The recovery stages of a 4D-printed occluder based on PLA/ F e 3 O 4 implemented in a male rat under a magnetic field [234] . (e) Syringe-injectable self-expandable magneto-responsive nanosheet that can be guided by an external magnetic field [233] .…”