Nanoparticles are often associated with their small size and numerous applications. However, the synthesis process is equally important as it determines the size and properties of the nanoparticles. While traditional nanoparticle synthesis methods require the use of hazardous chemicals and high-energy consumption, green synthesis offers a sustainable, cost-effective, and environmentally friendly alternative. This approach utilizes natural resources and biologically active compounds that can act as reducing, stabilizing, or capping agents in the one-step synthesis of nanoparticles. Green synthesis offers numerous advantages, including the development of processes with minimal environmental impact and improved safety for nanoparticle synthesis. Overall, the synthesis of nanoparticles using green chemistry is a promising approach for sustainable and efficient production. This chapter provides a general overview of nanoparticles, their applications, and green synthesis, and highlights the various biological resources used in these processes and the factors affecting their synthesis.

The advent of 3D printing technologies has led to a new era in tissue regeneration, offering unparalleled precision and versatility in fabricating scaffolds for various biomedical applications. Robocasting and stereolithography stand out among these technologies for their distinct advantages in engineering complex tissue structures. Robocasting, an extrusion-based 3D printing technique, has shown significant promise in cartilage tissue engineering. Its ability to precisely deposit biomaterials layer-by-layer allows the creation of porous scaffolds with encapsulated cells and bioactive molecules that improve mechanical properties and biological functionality. These scaffolds support the proliferation and differentiation of chondrocytes or mesenchymal stem cells, facilitating the regeneration of damaged cartilage. Stereolithography, a light-based 3D printing technique, offers remarkable resolution and accuracy with highly detailed structures that closely resemble the complex architecture of tissues. This makes it particularly suitable for new treatments for injuries and diseases of cartilage and ocular tissue regeneration. Integrating robocasting and stereolithography presents a synergistic approach to replicating cartilage and ocular tissues' complex physical and biological environments, offering innovative regenerative therapies. This review highlights the recent advancements and potential of robocasting and stereolithography in regenerative medicine, focusing on their applications in cartilage and ocular tissue regeneration. Graphical Abstract