This dissertation is the cumulative work towards the development of bioactive hydrogel nanoparticles by way of DNA incorporation. First, a collection of orthogonal DNA sequences is fabricated and binding coefficients quantified via surface plasmon resonance imaging (SPRI). Then, using a sample sequence from the collection, the DNA is polymerized into the backbone of hydrogel nanoparticles (HNPs) to be characterized by single-nanoparticle SPRI microscopy as surface adsorption measurements to gold thin-films. The SPRI responses, Δ%RNP, from several hundred nanoparticle adsorption events are used to generate frequency distribution histograms that characterize the nanoparticle size, composition, and bioactivity through complementary DNA hybridization and enzymatic-induced hydrolysis. These analyses reveal a dependence on the base sequence to aid in the incorporation of DNA into the HNPs. Lastly, DNA incorporation is further elaborated upon by the formation of nanocomposite HNPs, wherein the magnetic nanoparticle ferrite is present during DNA-HNP formation, alluding to a preferential covalent incorporation of DNA over that of ferrite nanoparticles as characterized by SPRI microscopy.