Study of thermal phase transitions in iota carrageenan gels via fluorescence technique

Abstract

The effect of carrageenan concentration on thermal phase transitions of the iota carrageenan gels was investigated by using fluorescence technique. During heating and cooling processes, scattered light, I sc , and fluorescence intensity, I p , were monitored against temperature to investigate phase transitions. Transition temperatures from the derivative of the transition paths were determined. Two regions were observed during the heating and cooling processes. At the first step of the heating, dimers were converted into double helix by undergoing dimer to double helix (d-h) transition. At the higher tem-perature region, double helix to coil (h-c) transition took place. During the cooling process, these transitions are arranged in the order of coil to double helix (c-h) and double helix to dimer (h-d). A hysteresis was observed between (h-d) and (d-h) transitions. The critical gel fraction exponents, b, were found to be independent of the system by indicating that they all fall into the same universality class.

Kinetics of Food Biopolymer Film Dehydration: Experimental Studies and Mathematical Modeling

“…A laser beam was shone on the sample, and the reflected beam was detected using a silicon photodiode, throughout the drying process, to collect data on the film thickness, which was used to create moisture loss versus time curves. The intensity of fluorescence given off by polymers as they dry has also been monitored, , where, as more water is released from a polymer, an increase in intensity of the pyranine-based fluorescence is seen. Results obtained using this method are supported by gravimetric and volumetric data, and type II diffusion models, in which Fick’s laws cannot describe the entire process, fit the data well.…”

Porous PLGA microspheres tailored for dual delivery of biomolecules via layer‐by‐layer assembly

“…Microspheres (5 mg) were mixed with 150 µL of the preheated carrageenan solution using a sterile pipette and transferred into sterilized silicon rings (Silastic®, Dow Corning, USA; 6.3 mm inner diameter with 1.5 mm thickness, 4 mm height) placed within a sterile six well tissue culture plate (BioOne Greiner, Germany). The samples were allowed to gel at 4°C overnight prior to implantation . All preparations were performed in sterile conditions in a Class II biosafety cabinet.…”

“…The samples were allowed to gel at 4 C overnight prior to implantation. 36 All preparations were performed in sterile conditions in a Class II biosafety cabinet.…”

Sorption and Desorption of PVA-Pyrene Chains in and out of Agarose Gel

“…There are many studies on determination of pore sizes [3,23,24], diffusion coefficients and diffusion models for transportation of macromolecules such as micelles, proteins, and other agents [17,22,[25][26][27]. Recently, steadystate fluorescence (SSF) technique was employed in our laboratory for studying thermal phase transitions of agarose [14], and carrageenan gels [28,29], and also for studying small molecule diffusion into carrageenan [30], and polyacrylamide gels [31].…”