What is unique about nanomedicine? The significance of the mesoscale

Unlike drugs and medical devices, for which long standing and continuously improving quality assurance/quality control infrastructures exist, many nano-based products lack well-defined standards that are useful to manufacturers and regulators. Inherent variabilities in nanoparticle sizes and shapes, their large surface-to-volume ratios, and their mesoscale interactions with subcellular structures, suggest new complexities and challenges that must be met before widespread application of nanomedicines can be expected.