Engineering approaches to transdermal drug delivery: a tribute to contributions of prof. Robert Langer

Transdermal drug delivery continues to provide an advantageous route of drug administration over injections. While the number of drugs delivered by passive transdermal patches has increased over the years, no macromolecule is currently delivered by the transdermal route. Substantial research efforts have been dedicated by a large number of researchers representing varied disciplines including biology, chemistry, pharmaceutics and engineering to understand, model and overcome the skin's barrier properties. This article focuses on engineering contributions to the field of transdermal drug delivery. The article pays tribute to Prof. Robert Langer, who pioneered the engineering approach towards transdermal drug delivery. Over a period spanning nearly 25 years since his first publication in the field of transdermal drug delivery, Bob Langer has deeply impacted the field by quantitative analysis and innovative engineering. At the same time, he has inspired several generations of engineers by collaborations and mentorship. His scientific insights, innovative technologies, translational efforts and dedicated mentorship have transformed the field.