This book highlights the latest clinical research and advancements in 3D (bio)printing and 4D printing using stimulus-responsive hydrogels as well as the concept of self-healing and its amalgamation with 3D printed injectable cell-laden tissue constructs. It also explores the use of metal-free "click" chemistry and enzymes such as horseradish peroxidase, hematin, tyrosinase, and transglutaminase to obtain chemically crosslinked hydrogels and the in vitro and in vivo responses. Lastly, the book briefly examines the future of drug delivery and the potentials offered by microrobotics and self-powered devices based on triboelectric nanogenerators. This book caters to biomedical researchers and clinical practitioners working in tissue reconstruction and drug/therapeutic delivery.