In situ bioprinting: Control strategies, bioinks, applications, challenges, and future perspectives

In situ bioprinting is an emerging technology that directly deposits bioinks on demand within clinical environments to generate targeted tissue structures. It integrates the printing and implantation processes, allowing the printed constructs to interact directly with the host biological microenvironment. This technology reduces the risk of contamination during transplantation and improves operational precision, thus demonstrating broad application prospects in fields such as tissue repair and biomedical sensor fabrication. This article discusses the following aspects: (i) from the perspective of control strategies, it summarizes the developmental trend of in situ bioprinting from open-loop control toward closed-loop control, and outlines key procedures including geometric reconstruction, conformal slicing, infill trajectory planning, and parameter mapping in in situ bioprinting; (ii) with reference to body-surface and open-exposure scenarios, minimally invasive intervention scenarios, remote energy-driven scenarios, and biosensing scenarios, this review discusses the demands faced by in situ bioprinting in different application settings, the design logic of bioinks, and representative research progress; (iii) the printable characteristics and application boundaries of natural polymers, synthetic polymers, and 4D smart materials in in situ bioprinting are summarized. Finally, the challenges faced by this technology and its potential directions for improvement in the future are also discussed.