Nanotechnology enables the design and application of nanostructures to improve drug delivery by modulating release, enhancing solubility, and increasing bioavailability of poorly soluble APIs, while reducing side effects. This Special Issue includes original research articles and reviews on innovative nanocarriers, such as liposomes, metal and carbon nanoparticles, nanocrystals, and polymeric systems, utilizing sustainable and environmentally friendly synthesis methods. Special emphasis is placed on formulation strategies for encapsulating biological macromolecules, advancing the development of efficient, eco-friendly delivery platforms.