Determination of the optical properties of PNIPAAm gels used in biological applications

Abstract

Poly(N-isopropylacrylamide) that is PNIPAAm is a temperature sensitive smart material which displays a lower critical solution temperature (LCST) at 33-35oC. At the lower critical solution temperature, the gel changes from hydrophilic to hydrophobic which has significant consequences in cell culturing. The first known measurements of the optical properties that is absorption (µa) and reduced scattering (µ's) coefficients, as a function of temperature, of a series of crosslinked PNIPAAm gels, using an integrating sphere setup, is presented at a wavelength of 632.8 nm. These properties showed a direct correlation between the scattering coefficient and the crosslinker density for the gels. The absorption properties correlated well with the known absorption characteristics of these gels.