Reactive nanoparticles with activated ester moieties from cellulose acetate phthalate derivatives

Reactive polysaccharide (PS) based nanoparticles (NP) with activated N-hydroxysuccinimide (NHS) ester moieties were prepared by a two-step approach: (i) homogeneous synthesis of activated cellulose ester derivatives followed by (ii) nano-self-assembling of these derivatives into spherical PS-NP. Four different conversions of cellulose acetate phthalate (CAP) into cellulose acetate (N-succinimidyl)phthalate (NHS-CAP) were studied. The carboxyl groups of CAP were converted into NHS-ester in good yield by using N,N'-disuccinimidyl carbonate as reagent. Spherical NP with diameters in the range of 200-400 nm were obtained by self-assembling NHS-CAP derivatives. The NHS moieties were stable in aqueous media and remained reactive. The reactive PS-NP were used for the immobilization of an amine- functionalized fluorescent dye. Under basic conditions, an amide bond was formed, which resulted in high binding efficiencies of up to 90%. On the contrary, only weak non-covalent interaction with the dye was observed for NP derived from CAP and cellulose acetate. The novel NHS-activated PS-NP have great potential for applications in drug delivery and bioimaging.