Abstract
C-6 oxidized chitosan is of great interest in obtaining a new moisture retention polymer like hyaluronic acid. The direct C-6 specific oxidation of chitosan mediated by the TEMPO/NaClO/NaBr system has proven to be difficult because of the high crystalline and high C-2 amino group content. In this work, the pre-modification of chitosan by N-succinylation was investigated and followed by the TEMPO-mediated C-6 specific oxidation under homogeneous conditions. The desired 6-oxidized N-succinyl chitosan product was obtained within 15 min with a yield of about 92%. The structure of these chitosan derivatives was confirmed by FTIR and NMR spectroscopy. Moreover, it was observed that the selective oxidation led to a great improvement in water solubility and moisture retention ability. These results present a wide range of possibilities for expanding the utilization of chitosan resources.
Highlights
In the past two decades, hyaluronic acid (HA), composed of d-glucuronic acid and N-acetyl-dglucosamine, has played a critical role in cosmetics and clinical medicine because of its unique physical and chemical properties [1]
Despite the significant progress that has been achieved on the microbial production of HA, the continuous rise in the cost of raw materials weakens the commercial competitiveness of microbial HA production [2,3,4,5]
The moisture absorption and retention properties of N-succinylchitosan chitosan (NSCS) determined by gravimetric methods and Differential Scanning Calorimeter (DSC) were close to that of commercial HA
Summary
In the past two decades, hyaluronic acid (HA), composed of d-glucuronic acid and N-acetyl-dglucosamine, has played a critical role in cosmetics and clinical medicine because of its unique physical and chemical properties [1]. Chitosan (CS), a linear polysaccharide composed of randomly distributed β-(1→4)-d-glucosamine and N-acetyl-d-glucosamine, is obtained from the deacetylation of chitin, which is the second most abundant natural polysaccharide next to cellulose [6]. Because of the abundant reserves, excellent biocompatibility, and d-glucosamine as one constituent of the main chain similar to HA, CS appears to be a suitable choice for preparing a new kind of moisture retention polymer similar to hyaluronic acid. There are numerous reactive amino and hydroxyl functional groups in CS which make it easier to be modified to improve its water-solubility and extend its utilization, such as carboxylation, acylation, alkylation, and so on, where C-6 oxidized chitosan has attracted much attention [7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
