Nano-patterned hydrogel reduced inflammatory effects in subcutaneous tissue

We present a nano-patterned poly-acrylamide (PAAm) hydrogel that can reduce inflammatory effects after subcutaneous implantation. Although hydrogel is considered as an excellent biomaterial for implants due to its biocompatibility, hydrogel still induces inflammation after implantation. To enhance biocompatibility for subcutaneous implantable sensors, we modified hydrogel surface with nano-patterns using simple molding process. To test the anti-inflammatory effect, we implanted the samples to rat's back. Since macrophages play an important role in the immune response and development of encapsulation after inflammation reaction, we counted macrophages neighboring the implanted nano-patterned hydrogels after 3 and 7 days and measured thickness of encapsulation after 21 days from implantation. We found that the sample with the line-and-space pattern of 600 nm in space successfully suppressed the inflammation reaction. Therefore, nano-patterned hydrogel is promising for long-term subcutaneous implantable sensors.