Polymeric nanoparticles with a hydrophobic core and a hydrophilic shell are formed from: 1) N-
isopropyl acrylamide (NIPAAM), at a 
molar ratio of about 50% to about 90%, and preferably 60% for specific delivery routes such as oral or parenteral; either water-soluble vinyl derivatives like vinylpyrolidone (VP) or 
vinyl acetate (VA), or 
water insoluble vinyl derivatives like 
methyl methacrylate (MMA) or 
styrene (ST), at a 
molar ratio of about 10% to about 30%; and 
acrylic acid (AA), at a 
molar ratio of about 10% to about 30%. The formed nanoparticles may be optionally surface functionalized using reactive groups present in AA, including 
PEGylation, or conjugation of moieties such as chemotherapeutics, contrasting agents, antibodies, radionucleides, ligands, and sugars, for diagnostic, therapeutic, and imaging purposes. The 
polymeric nanoparticles are preferably dispersed in aqueous solutions. The 
polymeric nanoparticles incorporate one or more types of medicines or bioactive agents in the hydrophobic core; on occasion, the 
medicine or bioactive agent may be conjugated to the 
nanoparticle surface via reactive functional groups. The 
polymeric nanoparticles are capable of delivering the said medicines or bioactive agents through oral, parenteral, or topical routes. The polymeric nanoparticles allow poorly 
water soluble medicines or bioactive agents, or those with poor oral 
bioavailability, to be formulated in an 
aqueous solution, and enable their convenient delivery into the 
systemic circulation.