Directly determining the molecular weight of chitosan with atomic force microscopy

Abstract

Molecular weight will not only affect cytotoxicity, viscosity and other basic properties of molecules in physical and chemical fields, but also influence its efficiency of drug delivery in nanomaterial fields. It is of great importance to measure the molecular weight of a substance. In this study, we proposed a new method to directly determine the molecular weights of polymers with linear and repeated molecular structures. An empirical molecular weight formula of Chitosan with different molecular weights were chosen to value our new proposed method. Our results imply that the molecular weight of chitosan obtained with the new method is reasonable. Moreover, the distributions of molecular weight and molecular lengths can also be acquired at the same time with this novel method.

Characterisation of chitosan molecular weight distribution by multi-detection asymmetric flow-field flow fractionation (AF4) and SEC

“…The main techniques used to determine the molecular weight of chitosan are similar to those used for any polymer, namely viscometry, light scattering, high performance size exclusion chromatography (GPC or SEC), osmometry, and sedimentation equilibrium by centrifugation [18]. More recently, a method using atomic force microscopy has also been reported [19]. All of these techniques require the complete dissolution of the polymer chains by the solvent (normally an acidic aqueous solution with sufficient ionic strength provided by a suitable salt).…”

Effect of Chitosan on the Activity of Water-Soluble and Hydrophobic Porphyrin Photosensitizers Solubilized by Amphiphilic Polymers

“…Thereby, when PVP is added to the DMG-CT 100 system, a significant (4-5 times) increase in the effective constant k eff of the photo-oxidation rate of tryptophan is observed (Figure 4a), which is apparently associated with the partial binding of porphyrin molecules, that were previously localized in the aggregated state near the amino groups of chitosan, with polyvinylpyrrolidone macromolecules. From the literature it follows that the supramolecular structure of chitosan in solutions, which possibly determines the functional activity of the polysaccharide, depends on its molecular weight and the degree of deacetylation [27,28]. Since the values of the degree of deacetylation for CT 20 and CT 100 are close, it is obvious that the conformation of chitosan under the conditions of our experiments is determined by its molecular weight.…”

Liposomal-Based Formulations: A Path from Basic Research to Temozolomide Delivery Inside Glioblastoma Tissue

“…Chitosan, produced by the deacetylation of chitin, is a linear cationic polysaccharide composed of D-glucosamine and N-acetyl-D-glucosamine units linked through a β (1 → 4) linkage (Figure 4) [56,57]. Its degree of deacetylation, which reflects the glucosamine residues, ranges from 30 to 95%, while its average molecular mass is within the range of 126-1000 kDa; both properties are essential for the quality of the final material [57][58][59][60]. For liposomal formulations, the cationic chitosan is adsorbed on the negatively charged surface of liposomes through electrostatic interactions, forming a positive layer around it, a stable chitosan-based network entrapping the liposomes [61][62][63].…”