Thermal degradation and stability of sodium hyaluronate in solid state.
The kinetics and mechanism of depolymerisation of solid sodium hyaluronate at elevated temperatures and various pH have been investigated. Depolymerisation was found to be governed by random chain scission. The activation energy at neutral pH was found to be 127 kJ/mol. The solid polymer was most stable at neutral pH. Results suggest the depolymerisation mechanism in solid- and solution state to be the same. Correlation of log intrinsic viscosity to log weight-average molecular weight was investigated to ensure high quality data for polymer size. Based on more than sixty hyaluronate samples spanning from 0.4 to 2.3 MDa, it was concluded that a second order polynomial regression gives a better fit than the linear regression offered by classical Mark-Houwink-Kuhn-Sakurada description. This finding was supported by literature data and could be expanded to other simple, well behaving linear polymers, such as polystyrene and polyethylene.
Novozymes, Krogshoejvej 36, 2880 Bagsvaerd, Denmark. Electronic address: mbcp@novozymes.com.
Mikael Bjerg
MB
Caspersen
Novozymes, Krogshoejvej 36, 2880 Bagsvaerd, Denmark. Electronic address: jorr@novozymes.com.
Johannes P
JP
Roubroeks
Novozymes Biopharma, 35 Taihuai Road TEDA, 300457 Tianjin, China. Electronic address: qulu@novozymes.com.
Liu
L
Qun
Novozymes Biopharma, 35 Taihuai Road TEDA, 300457 Tianjin, China. Electronic address: shnx@novozymes.com.
Huang
H
Shan
Novozymes, Hallas Alle, 4400 Kalundborg, Denmark. Electronic address: jfog@novozymes.com.
Jytte
J
Fogh
Novozymes Biopharma, 35 Taihuai Road TEDA, 300457 Tianjin, China. Electronic address: zrd@novozymes.com.
Zhao
Z
Ruidong
Novozymes, Krogshoejvej 36, 2880 Bagsvaerd, Denmark. Electronic address: kitosan30@hotmail.com.
Kristoffer
K
Tømmeraas
D004355:Drug Stability; D006820:Hyaluronic Acid / Q000737:chemistry*; D007700:Kinetics; D008970:Molecular Weight; D058105:Polymerization; D013696:Temperature; D014783:Viscosity
D006820:Hyaluronic Acid
Activation energy; Depolymerisation; Hyaluronan; Mark–Houwink–Kuhn–Sakurada; Thermal degradation