the primary reasons for the difference in properties between nanoparticles and bulk materials are their increased surface area-to-volume ratio, quantum confinement effects, surface energy considerations, and unique mechanical, chemical, thermal, and magnetic properties. These differences make nanoparticles highly versatile in various applications, from medicine and electronics to energy and materials science.
NPs possess unique physical and chemical properties due to their high surface area and nanoscale size. They behave significantly different from the bulk of same material due to surface effect and quantum effect.
You can check some review articles for details :
1. Nanoparticles: Properties, applications and toxicities
2. Nanoparticle classification, physicochemical properties, characterization, and applications: a comprehensive review for biologists