Hydrophobic polysaccharide (PS) derivatives can self-assemble into spherical nanoparticles (NP) using facile dialysis or dropping-in procedures. These nanomaterials are of great interest for various applications, in particular in medicine and biotechnology, because they are easy to prepare and biocompatible. Moreover, it is possible to introduce desirable functions such as dyes, affinity ligands, and drugs by advanced polysaccharide chemistry. However, this can be a very laborious procedure depending on the number and type of functional substituents. In the present work, two facile approaches towards novel functional PS-NP are described. The overall aim of the project was to obtain bio-sensors in particular for immunoassay applications that carry dyes and reactive groups for an efficient coupling of antibodies.<br/>(I) Different hydrophobic dyes were physically entrapped within a cellulose acetate phthalate (CAPh) matrix by a co-self-assembling process. Depending on the preparation conditions and the chemical nature of the dye, spherical dye loaded PS-NP in the scale of 200-500 nm could be obtained. By electron microscopy and UV-vis spectroscopy, it was demonstrated that the dyes are well incorporated within the PS matrix and that spectroscopic properties are determined primarily by dye-dye interaction. The novel CAPh-NP feature reactive carboxyl groups that could be used for efficient coupling with antibodies. Thus, a lateral flow immunoassay for C-reactive protein (CRP) was constructed that was more sensitive than a reference test using nano-gold.<br/>(II) CAPh was chemically modified prior to the NP formation to quantitatively convert the carboxyl group into an activated <i>N</i>-hydroxy succinimide (NHS) ester. Four different reaction strategies were compared and the molecular structure of the products was characterized comprehensively. It was demonstrated that the NHS groups react quantitatively with amines and are not removed during the NP formation in aqueous media. Thus, it was possible to obtain activated PS-NP that could easily be functionalized with dyes and/or antibodies in one step.

Dye functionalized polysaccharide nanoparticles – From synthesis to bio-sensor applications in immunoassays

253rd National Meeting (2017)

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