Progressive transpose from 3D to 4D printed materials for drug delivery and biomedical applications

Abstract

Four-dimensional (4D) printing is emerging as a cutting-edge area of research in the field of drug delivery and biomedical applications. Since its initial conception in 2013, 4D printing has drawn much interest. 4D printing is the next evolutionary step made possible by the advances made in biomedical research with three-dimensional (3D) printing. This technology integrates smart materials into additive manufacturing to create constructs that can change shape or functionality over time in response to specific external, non-mechanical stimuli, such as moisture, temperature, light, pH, and magnetic fields. 4D-printed structures can exhibit dynamic behaviours including flexibility, self-folding, self-healing, expansion, and controlled deformation. The advantages of 4D printing mainly include enhanced ability to print, improved productivity in manufacturing, enhanced quality, and the opportunity to create a more extensive variety of items. 4D printing has made use of a variety of raw materials, including shape-memory polymers (SMPs), shape-memory hydrogels (SMHs), shape-memory polymer composites (SMPCs), shape-memory ceramics (SMCrs), and liquid crystal elastomers (LCEs). In order to provide a better outlook for 4D printing applications in the future, this review attempts to highlight the most current uses of smart materials and 4D printing technology in drug delivery, tissue engineering, smart implants, etc. Artificial intravesicular implants for bladder problems, microneedles to repair tissue wounds, ulcer-treating hydrogel capsules, and delivery of anticancer drugs using theragrippers are current instances of advancements in the clinical field using 4D printing. Herein, a detailed overview and the main challenges with this technology are discussed, along with recommendations for further research to overcome current constraints.