Synthesis and characterization of polymer-(multi)-peptide conjugates for control of specific cell aggregation

Abstract

A new synthetic approach has been applied to obtain novel di-, tetra-, and (multi)-peptide containing polymer conjugates in quantitative yields with a high degree of conjugation. Bis-(N-hydroxysuccinimidyl) esters of PEG (Mw = 200, 600, 1400, 2000, and 3400) were synthesized and studied in a condensation reaction with synthetic peptides: glycine-glycine-tyrosine-arginine (GGYR), a model peptide, and glycine-arginine-glycine-aspartic acid-tyrosine (GRGDY), a sequence known to promote cell adhesion and aggregation. Tetra-substituted derivatives of PEG-based conjugates were synthesized by coupling L-aspartic acid and L-aspartyl-L-phenylalanine through a condensation procedure in organic media. Poly(acrylic acid) and co-polymers (Mw = 2000 and 5000) were studied as a model of multifunctional linear polymers in the reaction with L-tryptophan and GGYR. Alternative polymer-(multi)-peptide conjugates were successfully synthesized using Starburst dendrimer PAMAM (G = 3), 'short' and 'long'-chain PEG-based active esters and GRGDY. The structure of the intermediate precursors and peptide-conjugates was confirmed by spectral (UV-Vis, FTIR, H-NMR) and chromatographic (RP-HPLC and SEC) methods. By varying the properties of the interconnecting polymer--such as hydrophobicity, molecular weight, and functionality--a set of polymer-GRGDY conjugates was synthesized.

Nanosystems for simultaneous imaging and drug delivery to T cells

“…In addition, this modifi cation provides for enhanced solubility, biocompatibility, lower immunogenicity, and desirable pharmacokinetics, while the main biological functions such as receptor recognition are maintained. [79][80][81] Our work has examined the utility of dendrimers in delivering doxorubicin, a widely used antiproliferative agent, to proliferating T cells and antigen-specifi c T cells. We found that the small size of the dendrimers, which allows for their effi cient internalization, coupled with their ability to deliver a large number of doxorubicin molecules to specifi c T cells, led to an effi cient system for inhibiting the specifi c proliferation of both polyclonal and antigen-specifi c T cells.…”

Aggregation Enhances Catecholamine Secretion in Cultured Cells

“…The factor was synthesized from poly(ethylene glycol) and GRGDY, a cell-binding peptide 29,33 ; its activity in cell aggregation has been described earlier. 34,35 The addition of either serum or aggregation factor (PEG-RGD) enhanced aggregation significantly (Table 1).…”

“…29 Cells were also aggregated in a NASA-designed rotating wall vessel (the high-aspect ratio vessel or HARV) by culturing within the vessel for 2 weeks as previously described. 30 Aggregates were analyzed prior to encapsulation by computer-aided image analysis (see refs.…”

PEGylation of Melittin: Structural Characterization and Hemostatic Effects

“…In contrast, the multiplearm conjugates were increased under these conditions in DMSO. The conjugation was confirmed by NMR spectra of the ethylene oxide resonance for PEG at 3.7 ppm [41] and the aromatic tryptophan residue of MLT at 6.9-8 ppm [43]. The quantitative analysis (Table 1) indicates that an average of 0.4-1.5 out of four arms of PEG had been functionalized with MLT.…”

“…Proton resonance assignments of each amino acid in MLT and the ether unit in PEG were based on literature reports [39,40]. The ratio between tryptophan protons (6.9-8.0 ppm) and ethylene oxide protons (3.5-3.8 ppm) was calculated to estimate the number of MLT per PEG molecule [39,41,42]. The weight percentage of PMLT in the conjugate was then calculated based on the ratio and the molecular weights of MLT and PEG.…”