Green Chemistry

Protease-activated receptor 2 (PAR2) is a G-protein-coupled receptor critical in regulating inflammation, pain, and physiological functions such as wound healing and epithelial barrier integrity. Chronic PAR2 activation contributes to numerous inflammatory and immune diseases, including inflammatory bowel disease (IBD), asthma, and arthritis, and plays a role in tumor progression by promoting proliferation, angiogenesis, and metastasis.

Chitin, a polysaccharide abundantly sourced from squid pens and crustacean shells, is a versatile biopolymer with diverse applications. α-chitin is predominant in crustacean shells, exhibiting a hierarchical nanofibrillar organization interspersed with proteins and calcium carbonate. Recent attention has focused on chitin nanocrystals (CNCs), produced via acid hydrolysis, which exhibit exceptional mechanical, thermal, and optical properties owing to their high aspect ratio, large surface area, and distinctive crystalline structure.

Chitin, the most abundant aminopolysaccharide, can be found in the exoskeleton of crustacean shells, a major waste product of the fishing industry. The water-soluble derivative of chitin, chitosan, acquired through a process of deacetylation affords derivatization and processability of this natural biopolymer. Traditionally, deacetylation processes utilizing harsh chemical conditions and high energy inputs limiting scalability and sustainable practices. Furthermore, these methods result in depolymerization, presenting low molecular weight fragments.

Unsymmetrical ethers are generally synthesized via the Williamson ether method, but the unwanted formation of symmetrical ethers plus the basic and harsh conditions of the route pose a synthetic challenge. Other methods employed in the synthesis of unsymmetrical ether require the use of toxic mineral acids, and requires high catalyst loading which limits their large-scale application. Dehydration of alcohols in the presence of base-metal catalyst has, however, recently offered the greenest approach to synthesize unsymmetrical ethers, leaving water as by-product.