expression, suru verb (special)
Almost always used in the negative form 意に介さない, meaning 'not mind', 'not care', or 'not be bothered by'. Formal and somewhat literary.
彼は周囲の批判をまったく意に介さなかった。
He didn't mind the criticism from those around him at all.
彼女は自分の失敗を少しも意に介していないようだった。
She didn't seem to care about her mistake in the slightest.