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A method for determining gelation time using low-field nuclear magnetic resonance technology

A technology of low-field nuclear magnetic resonance and gelation time, which is applied in the analysis of nuclear magnetic resonance, etc., can solve the problems of being easily affected by the subjective, not applicable, etc., and achieve the effect of simple and fast judgment, good repeatability and stability

Active Publication Date: 2017-08-29
INST OF PROCESS ENG CHINESE ACAD OF SCI
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Problems solved by technology

However, these methods have some disadvantages, such as the results of the inverted test tube method are easily affected by the subjective, the DSC method is not suitable for gels with weak thermal effects in the gelation process, and the rheological method is determined by the fact that the viscosity modulus and elastic modulus are equal. While the resulting gel point may be frequency dependent, some errors will occur

Method used

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  • A method for determining gelation time using low-field nuclear magnetic resonance technology
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  • A method for determining gelation time using low-field nuclear magnetic resonance technology

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Embodiment

[0024] Example: Determination of gelation time of chitosan-glycerophosphate disodium (CS-GP) thermosensitive hydrogel

[0025] Experimental material: CS-GP system with GP concentration of 7%-11%.

[0026] Experimental instrument: NMI20-Analyst, the magnetic field strength is greater than 0.05T, the resonance frequency is 2MHz-3MHz, the diameter of the magnetic pole is greater than 160mm, and the temperature of the magnet is controlled at 31.99-32.00℃.

[0027] (1) Sample preparation: under the conditions of ice bath and stirring, slowly add 50% GP dropwise to the 2% chitosan solution dissolved in 0.1M hydrochloric acid to prepare a chitosan concentration of 1.6%. The CS-GP temperature-sensitive system with GP concentration of 7%-11% is stored at 4°C for future use after measuring the pH value.

[0028] (2) During the heating process of the sample T 2 Determination of spectrum: Take 2ml of CS-GP solution in a nuclear magnetic tube with a bottom diameter of 10mm, set the instr...

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Abstract

The invention discloses a method for determination of gelation time by a low field nuclear magnetic resonance technology. The method comprises the steps of: employing a Carr-Purcell-Meiboom-Gill (CPMG) sequence to determine a nuclear magnetic resonance decay curve of hydrogel heated for different time at a specific temperature, and conducting fitting by a multi-exponent equation to obtain a T2 distribution curve; calculating the weighted average values of gel internal water corresponded T2 distribution peaks at each time point, and drawing a curve of the T2 value changing along with time; and using a bilinear regression model to fit the T2-t curve, determining the solution-gel transition point of the system, and acquiring the gelation time. The invention provides a new method for simple, rapid and nondestructive determination of gelation time.

Description

technical field [0001] The invention belongs to the technical field of polymer materials, and in particular relates to a method for measuring the gelation time of a temperature-sensitive hydrogel by using a low-field nuclear magnetic resonance relaxation technique. Background technique [0002] Temperature-sensitive hydrogels have the characteristics of being able to undergo solution-gel transitions under the stimulation of ambient temperature. This environmental responsiveness makes them have good application prospects in biomedicine, biotechnology and other fields, especially suitable as injectable In situ hydrogel drug release carrier. The gelation temperature and gelation time of thermosensitive hydrogels are the key factors to determine whether they can be suitable thermosensitive hydrogels, so the characterization of the gelation properties of thermosensitive hydrogels is very important for their applications. [0003] The temperature-sensitive hydrogel system has a l...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N24/08
Inventor 李秀男李亚琼陈超赵大伟苏志国
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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