Emerging Nano Bioinks in Bioprinting: Functional Materials, Engineering Strategies, and Biomedical Applications.

Nano bioinks have recently emerged as a promising class of biomaterials for advanced bioprinting applications, offering new opportunities in regenerative medicine, controlled drug delivery, and biosensing technologies. These materials are typically developed by integrating nanostructures such as nanoparticles, nanosheets, and nanofibers into polymeric or hydrogel matrices to enhance mechanical strength, bioactivity, and printing performance. Various fabrication approaches such as direct blending, in-situ polymerization, and surface functionalization are used to incorporate nanomaterials into bioink formulations. Subsequent crosslinking strategies are employed to improve print fidelity and structural stability while maintaining cell viability and biological functionality during the bioprinting process. Despite significant progress in recent years, several challenges continue to hinder the clinical translation of nano bioinks. Achieving consistent batch-to-batch reproducibility, ensuring long-term biocompatibility, and optimizing rheological properties for reliable printing remain critical issues. In addition, regulatory pathways and ethical considerations related to the biomedical use of nano-enabled bioinks are still insufficiently addressed in the literature. This review provides a comprehensive overview of recent advances in the design and fabrication of nano bioinks, highlighting key synthesis strategies, functional nanomaterials used in bioink formulations, and their emerging applications in tissue engineering, drug delivery, and biosensing. Furthermore, the review discusses the major technical, regulatory, and translational challenges that need to be addressed to facilitate the safe and effective implementation of nano bioinks in future biomedical applications.