Dissertation > Excellent graduate degree dissertation topics show

Basic and Experimental Research of Low Molecular Weight Hyaluronic Acid by Ultrasonic-chemical Method

Author: LiTengFei
Tutor: WangBoChu
School: Chongqing University
Course: Biopharmaceutical engineering
Keywords: Low molecular weight hyaluronic acid Ultrasound - Chemical Combine degradation Kinetic model
CLC: TQ464.7
Type: Master's thesis
Year: 2011
Downloads: 96
Quote: 0
Read: Download Dissertation

Abstract

Low molecular weight hyaluronic acid and hyaluronic acid oligosaccharides with its unique sound penetrating, excellent biological compatibility, ease of assembly, and other characteristics of the human body has angiogenic, immunomodulatory effects, has become the drug carrier and materials research hotspot. Degradation of hyaluronic acid polymer existing methods are chemical, physical and enzymatic hydrolysis. Enzymatic narrow molecular weight distribution can be obtained, the low molecular weight hyaluronic acid, but because hyaluronidase is expensive and can not be recycled, is not conducive to large-scale industrial production; the chemical and physical preparation of hyaluronic acid high molecular weight, and a molecular weight distribution is wide, can not be prepared for clinical products. In this paper, a low molecular weight hyaluronic acid research, based on analysis of relative molecular viscosity method, focusing on the impact of chemical degradation and physical degradation method of key factors, prediction and evaluation of constructed ultrasound and chemical degradation of hyaluronic acid kinetics model, and the establishment of multiple ultrasound - Chemical Combine degradation method, while establishing a low molecular weight hyaluronic acid liquid chromatography method for low molecular weight hyaluronic acid development and application of foundation. ① In order to study the degradation of chemical degradation and physical key factor experiment was established by determination of viscosity changes in viscosity average molecular weight was measured to evaluate the chemical and physical degradation of hyaluronic acid method. First, the temperature and the pH value was found for the impact of chemical degradation of hyaluronic acid evident in higher than 25 ℃ under the conditions of hyaluronic acid rapidly degraded within 8 hours, while the low-temperature reaction is relatively slow, but the reaction is carried out more fully. Only when the temperature of 4 ℃, 24h after the final degradation relative molecular weight less than 100kDa. Second, the pH is greater than 9 for the chemical degradation of hyaluronic acid significantly affected, will be significantly accelerated strongly alkaline reaction. Again, in the different levels of hyaluronic acid degrades oxidant conditions found oxidant for the degradation is very significant. 4h the reaction when compared with the oxidant usage 8mL use 1mL components, molecular weight difference of 2.60 times; at 24h when a difference of 3.48 times. In the ultrasonic degradation, the experiments found that the temperature for the ultrasonic degradation of hyaluronic acid has little effect, the degradation curve approximation, and the final molecular weight is basically the same. Finally, the hyaluronic acid degrades at different frequencies found in the range 300kHz to 1.7MHz, the degradation of the reaction rate is accelerated with increasing ultrasonic frequency, the ultimate molecular weight decreases with increasing frequency. Experiments show that the chemical degradation of the oxidant and the pH key factor, and when the pH is greater than 9, the chemical degradation of the oxidant content of the key factors; For sonication, the key factors affecting ultrasonic frequency. ② In order to predict and evaluate ultrasound and chemical degradation of hyaluronic acid, studies to establish the Rice-Herzfeld theory dynamics model, and the model is validated. In the chemical and ultrasonic degradation, the experimental content of free radicals were found in the reaction, which are the most important role, it is assumed that thermal effect is ignored, and that free radical reactions of transient response, no side reaction occurs under the conditions established by the radicals dominated The chain reaction model. By differentiation of the reaction rate is derived, that in the known molecular weight and conditions of time, limit the activation rate of the molecular weight of a radical corresponding relationship. In order to characterize the reaction rate, the experimental detection of salicylic acid decomposition by HPLC, using the external standard method to calculate 2,3-DHBA content and then get free radicals, and calculates the activation reaction rate. The theoretical and experimental values ??for comparison and found both within 20% deviation proved dynamic model can predict the reaction rate and the molecular weight limit, you can predict and evaluate chemical and ultrasonic degradation of hyaluronic acid reactions. ③ For the preparation of low molecular weight and narrow molecular weight distribution of hyaluronic acid, study the establishment of multiple ultrasound - chemical degradation of hyaluronic acid combined approach. Experiments to establish the use of different frequencies simultaneously ultrasonic shock sub multiple ultrasonic degradation of hyaluronic acid degradation method and compared the single-source and multi-source ultrasound ultrasound relative molecular weight. The results show rapid degradation of macromolecules multiple ultrasound can eventually molecular weight 10kDa level, combined with the high and low that multiple degradation is more effective. Optimizing ultrasonic method and the chemical conditions found 4 ℃, pH range of 9.0-10.0, dual source ultrasound (1.7MHz and 800kHz), degradation of eight hours to obtain low molecular weight hyaluronic acid than 10kDa 24 hours relative molecular weight of hyaluronic acid below 5kDa, reach levels of hyaluronic acid oligosaccharides. Infrared spectra illustrate the structure of hyaluronic acid did not change. Using molecular dynamics model to evaluate the limits and reaction rate, the experimental values ??with the theoretical limit of the molecular weight deviation was 6.4%, indicating that the reaction is more complete. ④ In order to analyze the molecular weight distribution of the low molecular weight hyaluronic acid, study established HPLC method for detection of low molecular weight hyaluronic acid. Liquid phase conditions selected as: Column SHISEIDO CAPCELL PAK NH ₂: 5μm, 4.6 × 250mm; UV, 210nm absorption; A phase 0.1N NaH ₂ PO ₄, B-phase H ₂ O; 1mL/min flow; gradient: B%: 100 (0) → 0 (60min); injection volume, 20μL. Using gel permeation chromatography and liquid chromatography spectra, the results show that the use of liquid chromatography separation can effectively analyze and low molecular weight hyaluronic acid, its methods of economic, high sensitivity. By liquid and gel spectra spectrum analysis, further evidence of the ultrasound - chemical degradation method can quickly and efficiently obtain low molecular weight hyaluronic acid and hyaluronic acid oligosaccharides.

Related Dissertations

CLC: > Industrial Technology > Chemical Industry > Pharmaceutical chemical industry > Drug production of biological products > Amino acids,peptides,proteins
© 2012 www.DissertationTopic.Net Mobile