A hyaluronic acid–methotrexate conjugate for targeted therapy of rheumatoid arthritis

In an effort to improve the therapeutic efficacy of methotrexate (MTX), we prepared the hyaluronic acid–MTX conjugate for targeted therapy of rheumatoid arthritis (RA). Owing to the pH-sensitive nature of the conjugate, MTX was rapidly released under the mildly acidic conditions, similar to the environment of inflamed synovial tissue in RA.