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Method for determination of gelation time by low field nuclear magnetic resonance technology

A low-field nuclear magnetic resonance and gelation time technology, applied in the direction of analysis using nuclear magnetic resonance, can solve the problems of being susceptible to subjective influence and inapplicability, and achieve the effect of simple and quick judgment, good repeatability and stability

Active Publication Date: 2015-07-08
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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  • Method for determination of gelation time by low field nuclear magnetic resonance technology
  • Method for determination of gelation time by low field nuclear magnetic resonance technology
  • Method for determination of gelation time by low field nuclear magnetic resonance technology

Examples

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Embodiment

[0024] Example: Determination of the gelation time of chitosan-disodium glycerophosphate (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 magnetic pole diameter is greater than 160mm, and the magnet temperature is controlled at 31.99-32.00℃.

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

[0028] (2) The sample is in the heating process T 2 Determination of the spectrum: Take 2ml of CS-GP solution in a NMR tube with a diameter of 10mm on the bottom surface, and set the instrum...

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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 specifically relates to a method for measuring the gelation time of a temperature-sensitive hydrogel by applying a low-field nuclear magnetic resonance relaxation technique. Background technique [0002] Temperature-sensitive hydrogels have the characteristics of being able to undergo solution-gel conversion under environmental temperature stimulation. This environmental responsiveness makes them have good application prospects in the fields of biomedicine and biotechnology, and they are especially suitable as injectables. In situ hydrogel drug delivery vehicle. The gelation temperature and gelation time of temperature-sensitive hydrogels are key factors that determine whether it can be a suitable temperature-sensitive hydrogel. Therefore, the characterization of the gelation characteristics of temperature-sensitive hydrogels is very important for its application. [0003] The temperature...

Claims

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Application Information

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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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