Characterization of Gold Nanorods Conjugated with Synthetic Glycopolymers Using an Analytical Approach Based on spICP-SFMS and EAF4-MALS.

A new comprehensive analytical approach based on single-particle inductively coupled plasma-sector field mass spectrometry (spICP-SFMS) and electrical asymmetric-flow field-flow-fractionation combined with multi-angle light scattering detection (EAF4-MALS) has been examined for the characterization of galactosamine-terminated poly(N-hydroxyethyl acrylamide)-coated gold nanorods (GNRs) in two different degrees of polymerization (DP) by tuning the feed ratio (short: DP 35; long: DP 60). spICP-SFMS provided information on the particle number concentration, size and size distribution of the GNRs, and was found to be useful as an orthogonal method for fast characterization of GNRs. Glycoconjugated GNRs were separated and characterized via EAF4-MALS in terms of their size and charge and compared to the bare GNRs. In contrast to spICP-SFMS, EAF4-MALS was also able of providing an estimate of the thickness of the glycopolymer coating on the GNRs surface.

Glycosylated star polypeptides from NCA polymerization: selective binding as a function of degree of branching and glycosylation.

Star-shaped polypeptides were synthesized via N-carboxyanhydride (NCA) polymerization initiated from various generations of PPI dendrimers. Molecular weight, arm length, and arm density were readily controlled to afford a series of star-shaped poly(glutamic acid) derivatives. Glycosylation of star-shaped poly(glutamic acid) resulted in the formation of a diverse range of glycopolypeptide architectures with tuneable degree of sugar conjugation. The secondary structure of the branched glycopolypeptides was studied as a function of the degree glycosylation. The bioactivity of the described glycopoly-peptides toward the lectin ConA was investigated and was shown to be architecture dependent.

Hydrophobic spacers enhance the helicity and lectin binding of synthetic, pH-responsive glycopolypeptides.

The influence of different hydrophobic spacers on the structural and lectin binding properties of well-defined glycopolypeptides decorated with galactose moieties was investigated. All glycopolypeptides were prepared from a poly(α,l-glutamic acid) (PGA) precursor via a polymer-analogous aqueous amide coupling reaction. Thereby, two alkyl spacers of different length (C6 and C11) as well as an aromatic spacer were introduced between the backbone and the galactose moieties, as confirmed by (1)H NMR spectroscopy. The secondary structure was investigated as a function of the sugar density and the pH by circular dichroism (CD) spectroscopy. It was found that the helicity in acidic medium and thus the typical coil-to-helix transition is strongly enhanced by the hydrophobic spacers. Preliminary lectin binding tests via turbidimetric assay revealed that the spacers also significantly enhance the interaction of the glycopolypeptides with the lectin RCA120.