Utilizing 4D Printing to Design Smart Gastroretentive, Esophageal and Intravesical Drug Delivery Systems.

The breakthrough of 3D printing in biomedical research has paved the way for the next evolutionary step referred to as 4D printing. This new concept utilizes the time as the fourth dimension in addition to the x, y and z axes with the idea to change the configuration of a printed construct with time usually in response to an external stimulus. This can be attained through the incorporation of smart materials or through a preset smart design. The 4D printed constructs may be designed to exhibit expandability, flexibility, self-folding, self-repair or deformability. We focus in this review on 4D printed devices for gastroretentive, esophageal and intravesical delivery. We try to define the currently unmet needs and challenges for these application sites and report on published solution concepts involving 4D printing. In addition, we propose other promising application sites that may similarly benefit from 4D printing approaches such as tracheal and intrauterine drug delivery. This article is protected by copyright. All rights reserved.