Protein Resistance of PEG-Functionalized Dendronized Surfaces: Effect of PEG Molecular Weight and Dendron Generation

Abstract

Dendronized surfaces were prepared by chemisorption of poly(ethylene glycol) monothiol (HS-PEG 650 -OH) onto gold-coated silicon wafers followed by functionalization of the PEG terminal OH group with aliphatic polyester dendrons, generation 1-4, using divergent dendron growth. PEG monomethyl ether (PEG-OMe) chains of various molecular weight (MW) were covalently attached to the peripheral hydroxyl groups of the dendronized surfaces via EDC coupling and investigated for protein adsorption. Protein adsorption studies were carried out using fibrinogen (Fg) and lysozyme (Lys) as model proteins from phosphate buffered saline (PBS) (Fg, Lys) and plasma (Fg). In the first part of this study, the effect of functionalization of the peripheral hydroxyl groups with PEG-OMe oligomers (M n ) 350 Da) on protein adsorption was investigated. Results showed that adsorption of both Fg and Lys was reduced when dendronized surfaces were grafted with PEG-OMe oligomers. To investigate the effect of molecular weight on protein adsorption, PEG-OMe chains of greater length (750, 2000, and 5000 Da) were coupled to first generation dendronized surfaces (Au-G1(OH)). Results showed that protein adsorption decreased with increasing PEG-OMe MW up to 2000 Da. To further investigate the effect of dendron generation on protein resistance, dendronized surfaces of generation 1-4 were coupled with PEG 2000acid. Subsequent protein studies showed a decrease in Fg and Lys adsorption with increasing dendron generation.

Dendronization: A Useful Synthetic Strategy to Prepare Multifunctional Materials

“…These results showed that protein resistance was recovered when the dendronized surfaces were functionalized with PEG-OMe chains and both hydrogen bonding between the dendrons and the presence of hydrogen-bond donor groups were eliminated from the system. These results support their previous studies indicating that chain mobility and dynamics in water may be critical to protein repulsion [135].…”

“…This chain flexibility is impeded by introducing dendrons with multiple peripheral OH groups, which can lock the PEG chains via inter-and/or intramolecular H-bonding [134]. At the next very interesting step, the authors analyze the effect of PEG molecular weight and dendron generation [135]. PEG monomethyl ether (PEGOMe) chains of various molecular weights were covalently attached to the peripheral hydroxyl groups of the dendronized surfaces and investigated for protein adsorption.…”

Synthetic regimes due to packing constraints in dendritic molecules confirmed by labelling experiments

“…The dendrons can be attached to point-like cores, to linear polymer chains or to surfaces thus giving rise to three leading structural families of dendritic molecules: dendrimers [1][2][3][4][5] , dendronized polymers (DP) [6][7][8][9] and forests [10][11][12] . Their masses and spans depend on their generation g specifying the number of branching sites along a path between the attachment site and the terminus.…”

Cell adhesion and proliferation on hydrophilic dendritically modified surfaces

“…Prior to the coupling reaction, the terminal hydroxyl group of PEG-OMe was oxidized to a carboxyl end group using a TEMPO-mediated oxidation [30]. The PEG 2000 -acid derivative was subsequently coupled to the peripheral hydroxyl groups of G1-and G2-dendronized surfaces using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) coupling as described in our previous work [31].…”

“…The resulting hydroxyl-terminated dendrons were subsequently functionalized with PEG mono-methyl ether (PEGOMe) chains in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and a catalytic amount of 4-(dimethylamino)pyridine/p-toluene sulphonic acid (DPTS), as previously described (Scheme 1) [31]. All surfaces were characterized by contact angle measurements, atomic force microscopy (AFM) analysis, X-ray photoelectron spectroscopy (XPS), and timeof-flight secondary ion mass spectrometry (TOF-SIMS) analyses, as previously reported [29].…”