title: Synthesis of highly pH-responsive glucose poly(orthoester).
abstract: pH-Responsive polymers have great potential in biomedical applications, including the selective delivery of preloaded drugs to tissues with low pH values. These polymers usually contain acid-labile linkages such as esters and acetals/ketals. However, these linkages are only mildly pH-responsive with relatively long half-lives (t1/2 ). Orthoester linkages are more acid-labile, but current methods suffer from synthetic challenges and are limited to the availability of monomers. To address these limitations, a sugar poly(orthoester) was synthesized as a highly pH-responsive polymer. The synthesis was achieved by using 2,3,4-tri-O-acetyl-α-D-glucopyranosyl bromide as a difunctional AB monomer and tetra-n-butylammonium iodide (TBAI) as an effective promoter. Under optimal conditions, polymers with molecular weights of 6.9 kDa were synthesized in a polycondensation manner. The synthesized glucose poly(orthoester), wherein all sugar units were connected through orthoester linkages, was highly pH-responsive with a half-life of 0.9, 0.6, and 0.2 hours at pH 6, 5, and 4, respectively.
authors.affiliation: Department of Chemistry, Science of Advanced Materials, Central Michigan University, Mount Pleasant, MI 48858 (USA).
authors.forename: Lingyao
authors.initials: L
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.forename: Ian
authors.initials: I
authors.lastname: Milligan
authors.forename: Liye
authors.initials: L
authors.lastname: Fu
authors.forename: Emily A
authors.initials: EA
authors.lastname: Franckowiak
authors.forename: Wenjun
authors.initials: W
authors.lastname: Du
mesh_terms: D004952:Esters / Q000138:chemical synthesis* / Q000737:chemistry; D005947:Glucose / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D058105:Polymerization; D011108:Polymers / Q000737:chemistry
chemical_list: D004952:Esters; D011108:Polymers; D005947:Glucose
keywords: carbohydrates; pH-responsive; poly(orthoester); polymerization; tetra-n-butylammonium iodide