Aldehyde (Ald/CHO)PEG

Aldehyde (Ald/CHO)PEG is a compound that is a combination of polyethylene glycol (PEG) and an aldehyde group. Polyethylene glycol is a polymer with repeating glycol units, while aldehyde is a structural group containing a carbon-oxygen double bond and a hydrogen atom.

What is Aldehyde PEG?

Aldeyde PEG is an amine-reactive PEG derivative that can be used to modify biomolecules through available amine groups. The reaction between the aldehyde group and the ε-amine of the lysine residue and the N-terminal α-amine produces the intermediate Schiff base. Further reduction with hydride will form stable C-N bonds. PEG aldehydes react with amine groups at pH values from 5.5 to 9.5. Higher pH values will result in multiple polyethylene glycolization of the terminal groups and lysine groups. Aldehyde PEG is a commonly used PEG reagent for N-terminal polyethylene glycolization of proteins or peptides.

Fig. 1. Synthesis of PEG modified aldehyde (Polymers for Advanced Technologies. 2015, 26(12): 1456-1460).

Examples of Aldehyde PEG

Aldehyde-PEG-Maleimide

Aldehyde-PEG-Maleimide is one of the reagents for thiol (-SH) and N-terminal amine-based polyethylene glycolization. The maleimide group reacts rapidly and specifically with the thihydrogen (thiol) group at pH 6.5-7.5, while the aldehyde group reacts with the N-terminal α-amine to yield the intermediate. Polyethylene glycolated maleimides and aldehydes are water soluble and all reactions can be carried out in aqueous buffers.

Aldehyde-PEG-NHS

In the structure of Aldehyde-PEG-NHS, NHS stands for N-hydroxysuccinimide. NHS is a commonly used activating reagent that reacts with amine groups to form stable amide bonds. CHO-PEG-NHS is widely used in biochemistry and biomedicine to prepare bioconjugates with specific functionalities.

Aldehyde-PEG-Thiol

Aldehyde-PEG-Thiol is a linker for bioconjugation containing an aldehyde group and a terminal thiol group linked by a linear PEG chain. Conjugates can be prepared for biomarkers and bioimaging.

PEG Aldehyde Synthesis

The following is a procedure for the preparation of PEG Aldehyde:

Selection of PEG

Selection of the desired molecular weight and length of the PEG depends on the requirements of the final application. Common PEGmolecular weights range from 200 to 20,000 Da.

Selection of Appropriate Aldolization Reagents

Aldolization reagents include acetylaluminum oxide (Ac₂O/Al₂O₃), acetic anhydride (Ac₂O) and N-bromosuccinimide (NBS).

Aldehyde Reaction

PEG is reacted with an aldolization reagent in a suitable solvent. Typically, the reaction is carried out under an inert atmosphere (e.g., nitrogen) to prevent oxidation of the aldehyde group. The reaction temperature and reaction time depend on the selected reagent and reaction conditions.

Purification and Removal of By-products

The product after synthesis may contain unreacted reagents and by-products. Common purification methods include solvent extraction, gel permeation chromatography, and gel electrophoresis. Removal of by-products can be accomplished by appropriate washing steps.

Applications of Aldehyde PEG

Crosslinking Agent

Aldehyde-PEG can be used as a cross-linking agent for biomaterials and hydrogels. Aldehyde-PEG can undergo a condensation reaction with compounds containing amino functional groups to form a stable cross-linked network. This crosslinked network can be used to prepare highly biocompatible materials, microspheres, hydrogels and tissue engineering scaffolds.

Preparation of Bioconjugates

By reacting with nucleophilic compounds, Aldehyde-PEG can form stable chemical bonds with them to prepare bioconjugates with specific functions.

Surface Modifiers

Aldehyde-PEG can be used as a surface modifier, reacting with amino or sulfhydryl compounds on the surface of the material to achieve covalent binding.

BOC Sciences plays a vital role in providing high-quality aldehyde (Ald/CHO) PEG to support cutting-edge research and development in the biotechnology and pharmaceutical industries, if you are interested in our PEG modification and functionalization, please get in touch with us.

Reference

1. Mauri, E. et al. Simple and efficient strategy to synthesize peg‐aldehyde derivatives for hydrazone orthogonal chemistry. Polymers for Advanced Technologies. 2015, 26(12): 1456-1460.