An Investigation of the Sol-Gel Transition of Chitosan Lactate and Chitosan Chloride Solutions via Rheological and NMR Studies

Abstract

In recent years, intensive research has been carried out on the use of hydrogels obtained from natural polymers, mainly chitosan. These products are increasingly replacing solutions based on synthetic materials in medicine. This publication presents the results of studies on the sol-gel transition of chitosan solutions as the base material for the preparation of thermosensitive hydrogels for potential applications in tissue engineering. The measurements were carried out for systems consisting of chitosan lactate and chitosan chloride solutions using β-glycerol phosphate disodium salt pentahydrate and uridine 5′-monophosphate disodium salt as the cross-linking agents. The sol-gel transition point of the solutions was determined based on the rheological measurements in the cone-plate configuration of the rotational rheometer and experiments performed using the method of nuclear magnetic resonance. The obtained results showed a significant influence of the cross-linking agent on the course of the sol-gel transition of chitosan salt solutions, and the systems that consisted of chitosan lactate seemed to be especially interesting for biomedical applications.

Nanoarchitectonics and Biological Properties of Nanocomposite Thermosensitive Chitosan Hydrogels Obtained with the Use of Uridine 5′-Monophosphate Disodium Salt

“…From the course of the curves of G ′ = f ( T ) and G ″ = f ( T ) for the CH/LA/UMP and CH/HCL/UMP systems containing 0.028 mg GO ·mL −1 chit. salt , four regions are indicated, similar to the unmodified systems discussed in our publications [ 24 , 25 ], that characterize the processes that occur in the samples during the measurement: Region 1— G ′ moduli dominate over G ″ moduli, and the systems exhibit typical gel behavior: flexible networks are formed; Region 2 (the sol area)—the viscous properties prevail over the elastic ones; Region 3—further increasing the temperature leads to the initiation of the sol–gel transition process ( G ′ > G ″); Region 4—the gelation process occurs more slowly. …”

“…From the course of the curves of G ′ = f (T) and G ′′ = f (T) for the CH/LA/UMP and CH/HCL/UMP systems containing 0.028 mg GO •mL −1 chit. salt , four regions are indicated, similar to the unmodified systems discussed in our publications [24,25], that characterize the processes that occur in the samples during the measurement: In turn, for the CH/LA/UMP and CH/HCL/UMP systems containing 0.1 mg GO • mL −1 chit. salt , over the whole temperature range, the elastic properties (G ′ moduli) prevail over the viscous ones (G ′′ moduli).…”

Recent Development of Functional Chitosan-Based Hydrogels for Pharmaceutical and Biomedical Applications

“…Chitosan-based hydrogels can be obtained by various crosslinking approaches with different advantages and disadvantages. Although the physical crosslinking is relatively simple, mild, and avoids the use of organic solvents and high temperatures, the physically crosslinked hydrogels possess weak mechanical properties (compressive modulus of less than 10 Pa) [ 143 ]. The recent studies attempt to combine the two crosslinking techniques, resulting in dual-network hydrogels with improved mechanical properties, promising to be a reliable route to high performance materials.…”

Synthesis, Characterization, Properties, and Biomedical Application of Chitosan-Based Hydrogels

“…The test is necessary for the research and development of thermosensitive CBHs. When stimulated by temperature changes, thermosensitive CBHs transform from the solution state to the gelation state [48].…”