Dynamic heat capacity changes of laser-irradiated type I collagen films.
OBJECTIVE
A common assumption made in the thermal response of biological materials due to laser irradiation is the constancy of the specific heat capacity at constant pressure, CP. In this investigation, CP of pure hydrated Type I collagen films is measured in time during laser irradiation.


METHODS
A Nd:YAG laser scanning calorimeter is developed and used to test the constant heat capacity assumption by monitoring transient, laser-induced thermal transitions in the collagen films.


RESULTS
Results of preliminary studies on the irreversible, laser induced thermal denaturation of collagen with heating rates of up to 110 K/sec show a broad CP transition that can attain large values (20 J/g K).


CONCLUSIONS
The magnitude of the CP change that occurs in response to laser irradiation shows that the assumption of a constant CP when modeling heat transport in tissues is not always valid.
Si
M S
MS
Beckman Laser Institute and Medical Clinic, University of California, Irvine 92715, USA.
Milner
T E
TE
Anvari
B
B
Nelson
J S
JS
D000465:Algorithms; D000538:Aluminum Silicates; D001672:Biocompatible Materials / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D003094:Collagen / Q000737:chemistry*; D006358:Hot Temperature; D007834:Lasers; D009354:Neodymium; D011312:Pressure; D011489:Protein Denaturation; D012815:Signal Processing, Computer-Assisted; D013055:Spectrophotometry, Infrared; D013814:Thermal Conductivity; D013816:Thermodynamics; D013997:Time Factors; D014867:Water; D015019:Yttrium
D000538:Aluminum Silicates; D001672:Biocompatible Materials; D014867:Water; D009354:Neodymium; D015019:Yttrium; D003094:Collagen