Sulfonate (tosyl, mesyl, tresyl) PEG

Sulfonate PEG, also known as sulfonated polyethylene glycol, is a type of polymer containing sulfonate functional groups. The addition of sulfonic acid groups (-SO₃H) to the PEG polymer chain is known as sulfonation. PEG gains additional features as a result of this alteration, including better stability, greater ion exchange capacity, and increased water solubility. Sulfonate PEGs are frequently employed in systems for medication delivery where they can act as carriers for beneficial compounds. The interaction of the sulfonic acid groups with molecules that have opposing charges can help with medication encapsulation and controlled release.

Synthesis of Sulfonate PEG

Sulfonate groups are commonly added to the PEG backbone to create sulfonate PEGs. A number of techniques, such as direct sulfonation, sulfonation of PEG esters, or sulfonation of PEG ethers, can be used to accomplish this. When PEG reacts with a sulfonating substance like chlorosulfonic acid or sulfonyl chloride, the hydroxyl group is replaced by a sulfonate group, a process known as direct sulfonation. PEG esters or ethers are first synthesized, and then they are subjected to a further sulfonation process employing the proper reagents. To produce the required sulfonate PEG derivative with certain features, the sulfonating agent and reaction conditions can be customized.

Properties of Sulfonate PEG

Sulfonate PEG is a polymer that is well-suited for biomedical applications because of its distinctive qualities. First off, it still has PEG's great water solubility, making it simple to create aqueous solutions and compatible with biological systems. The sulfonate PEG has ionic characteristics due to the presence of sulfonic acid groups, which boosts hydrophilicity and increases water absorption capacity. For medication delivery systems, which need high water content for effective drug release, this feature is very helpful.

Fig. 1. Preparation of PS-PEG-bound sulfonic acid (RSC Adv. 2015, 5: 49006).

Sulfonate PEG is also excellently biocompatible, making it appropriate for usage in a variety of biological settings. Targeted medication delivery or tissue engineering applications can benefit from the electrostatic interactions that the sulfonic acid groups on the PEG backbone have with biomolecules like proteins and cells. Sulfonate PEGs' potential uses are further increased by the controllable hydrophilicity and charge density of their interactions with biological components.

Applications of Sulfonate PEG

Drug Delivery Systems

Sulfonate PEG-based polymers have been extensively studied for drug delivery applications. The hydrophilic and ionic properties of sulfonate PEG facilitate the encapsulation and controlled release of hydrophobic drugs. In addition, the presence of sulfonic acid groups can modify the surface of drug carriers, thereby enabling targeted delivery of drugs to specific tissues or cells. Sulfonate PEG-based drug delivery systems show promise in treating a variety of diseases, including cancer, inflammation, and infection.

Tissue Engineering

Sulfonate PEG hydrogels have been explored as scaffolds for tissue engineering. The hydrophilic nature of sulfonate PEG promotes cell adhesion and proliferation, while the ionic properties allow the incorporation of bioactive molecules such as growth factors into the hydrogel matrix. Sulfonate PEG hydrogels can mimic the natural extracellular matrix and provide a suitable environment for tissue regeneration and repair.

Bioconjugation

Biomolecules (such proteins or peptides) can be conjugated with sulfonate PEG to increase their stability and biological activity. In order to create stable covalent connections, the sulfonic acid groups on the PEG main chain can interact with functional groups found on biomolecules. Using this bioconjugation technique, protein therapies, antibody-drug conjugates, and imaging agents for diagnostic purposes have all been created.

Biosensors

Sulfonate PEG is a desirable substance for biosensor applications due to its special characteristics. Sulfonate PEG's hydrophilicity and charge density can help biomolecules like enzymes or antibodies immobilize on the sensor surface. This makes it possible to detect and measure certain analytes, such glucose or antigens, with great sensitivity and selectivity.

Reference

1. Patel, H.D. et al. Sulfonated polyethylene glycol (PEG-OSO3H) as a polymer supported biodegradable and recyclable catalyst in green organic synthesis: recent advances. RSC Adv. 2015, 5: 49006