Recent advances on next generation of polyzwitterion-based nano-vectors for targeted drug delivery

Poly (ethylene glycol) (PEG)-based nanomedicines are perplexed by the challenges of oxidation damage, immune responses after repeated injections, and limited excretion from the body. As an alternative to PEG, bioinspired zwitterions bearing an identical number of positive and negative ions, exhibit exceptional hydrophilicity, excellent biomimetic nature and chemical malleability, endowing zwitterionic nano-vectors with biocompatibility, non-fouling feature, extended blood circulation and multifunctionality. In this review, we innovatively classify zwitterionic nano-vectors into linear, hyperbranched, crosslinked, and hybrid nanoparticles according to different chemical architectures in rational design of zwitterionic nano-vectors for enhanced drug delivery with an emphasis on zwitterionic engineering innovations as alternatives of PEG-based nanomedicines. Through combination with other nanostratagies, the intelligent zwitterionic nano-vectors can orchestrate stealth and other biological functionalities together to improve the efficacy in the whole journey of drug delivery.

Switchable β-lactoglobulin (BLG) adsorption on protein resistant oligo (ethylene glycol) (OEG) self-assembled monolayers (SAMs)

HYPOTHESIS

Although protein adsorption at an interface is very common and important in biology and biotechnology, it is still not fully understood - mainly due to the intricate balance of forces that ultimately control it. In food processing (and medicine), controlling and manipulating protein adsorption, as well as avoiding protein adsorption (biofilm formation or membrane fouling) by the production of protein-resistant surfaces is of substantial interest. A major factor conferring resistance towards protein adsorption to a surface is the presence of tightly bound water molecules, as is the case in oligo ethylene glycol (OEG)-terminated self-assembled monolayers (SAMs). Due to strong attractive protein-protein and protein-surface interactions observed in systems containing trivalent salt ions, we hypothesize that these conditions may lead to a breakdown of protein resistance in OEG SAMs.

EXPERIMENTS

We studied the adsorption behavior of BLG in the presence of a lanthanum(III) chloride (LaCl₃) at concentrations of 0, 0.1, 0.8 and 5.0 mM on normally protein resistant triethylene glycol-termianted (EG3) SAMs on a gold surface. We used quartz-crystal microbalance with dissipation (QCM-D) and neutron reflectivity (NR) to characterize the morphology of the interfacial region of the SAM.

FINDINGS

We demonstrate that the protein resistance of the EG3 SAM breaks down beyond a threshold salt concentration c^∗ and mirrors the bulk behaviour of this system, showing reduced adsorption beyond a second critical salt concentration c^∗∗. These results demonstrate for the first time the controlled switching of the protein-resistant properties of this type of SAM by the addition of trivalent salt.

Modification of fluorous substrates with oligo(ethylene glycol) via "click" chemistry for long-term resistance of cell adhesion

In this work perfluorinated substrates fabricated from SiO2 glass slides are modified with oligo(ethylene glycol) (OEG) units for long-term resistance of cell adhesion purposes, based on fluorous interactions and click chemistry. Specifically, fluorous substrates, prepared by treatment of glass slides with 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane (FAS17), were coated with ethynyl-OEG-C8F17, followed by covalent attachment of an azido-OEG via copper-catalyzed azide-alkyne cycloaddition (CuAAC) "click" reaction. We demonstrate that the resultant surface avoid fibrinogen adsorption and resisted cell adhesion for over 14days. X-ray photoemission spectroscopy (XPS) analysis and contact angle goniometry measurements confirm the presence of the OEG molecules on the fluorous substrates. Bright field optical images show total absence of 3T3 fibroblast cells on the OEG modified fluorinated substrate for 1 and 5days, and a remarkably decrease of cell adhesion at 14days.