Characterization of amorphous solids with weak glass transitions using high ramp rate differential scanning calorimetry.
Measurement of the glass transition temperature (T(g)) of proteins and other high molecular weight polymers in the amorphous state is often difficult, since the transition is extremely weak, that is, the DeltaC(p) at the glass transition temperature is small. For example, little is known about the solid-state properties of hydroxyethyl starch (HES), which is beginning to become more commonly evaluated as a bulking agent in pharmaceutical products. For weak thermal events, such as the change in heat capacity at the T(g) of a pure protein or large synthetic polymer, increased heating rate should produce greater sensitivity in terms of heat flow. Recent innovations in rapid scanning technology for differential scanning calorimetry (DSC) allow measurements on materials where the thermal events are difficult to detect by conventional DSC. In the current study, measurements of the T(g) of proteins in the solid state, amorphous pharmaceutical excipients which have small DeltaC(p) at the glass transition temperature, and bacterial spores, have all been made using high ramp rate DSC, providing information on materials that was inaccessible using conventional DSC methods.
Katayama
Derrick S
DS
Department of Pharmaceutical Sciences, Center for Pharmaceutical Biotechnology, University of Colorado Health Sciences Center, Denver, Colorado, USA.
Carpenter
John F
JF
Manning
Mark Cornell
MC
Randolph
Theodore W
TW
Setlow
Peter
P
Menard
Kevin P
KP
D002152:Calorimetry, Differential Scanning / Q000379:methods*; D005612:Freeze Drying; D006895:Hydroxyethyl Starch Derivatives / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D013171:Spores, Bacterial / Q000502:physiology
D006895:Hydroxyethyl Starch Derivatives; D011506:Proteins