Injectability of Thermosensitive, Low-Concentrated Chitosan Colloids as Flow Phenomenon through the Capillary under High Shear Rate Conditions

Abstract

Low-concentrated colloidal chitosan systems undergoing a thermally induced sol–gel phase transition are willingly studied due to their potential use as minimally invasive injectable scaffolds. Nevertheless, instrumental injectability tests to determine their clinical utility are rarely performed. The aim of this work was to analyze the flow phenomenon of thermosensitive chitosan systems with the addition of disodium β-glycerophosphate through hypodermic needles. Injectability tests were performed using a texture analyzer and hypodermic needles in the sizes 14G–25G. The rheological properties were determined by the flow curve, three-interval thixotropy test (3ITT), and Cox–Merz rule. It was found that reducing the needle diameter and increasing its length and the crosshead speed increased the injection forces. It was claimed that under the considered flow conditions, there was no need to take into account the viscoelastic properties of the medium, and the model used to predict the injection force, based solely on the shear-thinning nature of the experimental material, showed very good agreement with the experimental data in the shear rate range of 200–55,000 s−1. It was observed that the increase in the shear rate value led to macroscopic structural changes of the chitosan sol caused by the disentangling and ordering of the polysaccharide chains along the shear field.

Doxycycline hyclate-loaded in situ forming gels composed from bleached shellac, Ethocel, and Eudragit RS for periodontal pocket delivery

“…Comparison between the polymers at 15% w/w concentration revealed that the energy required for injecting the DH-loaded ERS solution was lower than that for injecting DH-loaded BS and EC, respectively ( P < 0.05). The linear relationship between the expulsion force and the viscosity of the solution should be obtained ( Ryl and Owczarz, 2020 ). Although ERS ISG systems showed higher viscosity, their expulsive work was apparently lower than that of BS ISG systems.…”

Influence of Injection Application on the Sol–Gel Phase Transition Conditions of Polysaccharide-Based Hydrogels

“…Based on the obtained flow curves presented in Figure 1b, it has been shown tha 10% colloidal HPC suspension exhibits non-Newtonian behavior. The determined de of shear thinning is lower (n = 0.7) than in the case of chitosan systems (n = 0.44) [28] worth noting that after exceeding the value of the shear rate equal to 3160 s −1 , the va of the shear stress decrease, which is inconsistent with the measurement theory. It suggest that permanent structural changes occur in the tested system, and it is impos to unequivocally assess the properties above the indicated shear rate.…”

“…This means that compared to chit Based on the obtained flow curves presented in Figure 1b, it has been shown that the 10% colloidal HPC suspension exhibits non-Newtonian behavior. The determined degree of shear thinning is lower (n = 0.7) than in the case of chitosan systems (n = 0.44) [28]. It is worth noting that after exceeding the value of the shear rate equal to 3160 s −1 , the values of the shear stress decrease, which is inconsistent with the measurement theory.…”

“…The injection application, although minimally invasive for the patient, involves the flow of the polymer sol through the capillary under high shear rates conditions [28,29]. Rył and Owczarz [28] showed that during the flow of Newtonian liquid injected at a typical manual injection rate of 1 mm/s [30,31], the observed shear rate ranges from approx. 200 to over 43,000 s −1 (depending on the needle diameter) or even 55,000 s −1 taking into account the strongly shear-thinned nature of polymer systems.…”

Rheological Properties of Chitosan – Lactic Acid Lyotropic Liquid Crystal Systems

“…Данную модель исключили из рассмотрения, поскольку для исследуемых ЛЖК систем характерно определенное предельное напряжение сдвига. В работе [24] описаны реологические свойства золя хитозана при скоростях сдвига 100-18000 с -1 . Экспериментальные данные ап-проксимировались степенным законом Оствальдаде Вааля.…”