Judgment about the Endpoint of Primary Drying for Freeze-dried Pig Aorta

Lihao Huang Leren Tao

doi:10.19026/ajfst.10.2288

Abstract

How to process and preserve these biological material has always been a concerning problem. Vascular studying and evaluating the feasibility of preparing the vessel scaffold by freeze-drying technology is expected to provide high-qualified and reliable vascular graft for the clinical treatment of the related diseases. Judgment of the end of primary drying has always been a key point on the process of freeze-dried pig aorta, because it can directly affect the final quality of the dried sample if improper judgment has been used. In this study, different methods have been adopted to determine the endpoint of primary drying and then various methods of observation on the status of the aorta are used for contrast, including Micro-CT scanning, percentage of dehydration and calculation of the rehydrated rate and so on. From the results, differences are obvious. These experiments point out how to judge the endpoint of the pig aorta’s primary drying when they are freeze-dried by small laboratory equipments in which heat leakage and other external factors cannot be ignored.

Highlights

IntroductionVacuum freeze-drying technology can well keep the compositions and structures of the heat-sensitive material because of its lower temperature in the whole process, in addition, dehydrated samples can be stored (Dong et al, 2011; Xiao et al, 2010), so it has universally applied in biological (Jong-Pil et al, 1997; Todor et al, 1996; Zheng and Wang, 1997; Gao et al, 2011), medical (Ding and Zhao, 2011) and food (Gooding and Macdougall, 1961; Yu et al, 2011; Lu et al, 2010; Wu et al, 2010; Chen et al, 2010) fields is a universal application
Through comparative analysis of repeated weighing, scanning and mechanical properties experiments for the freeze-dried pig aorta, it puts forward the optimized method which can reduces the pleat and collapse on vessel for estimating the end point of primary drying under the existing instruments and experimental conditions, in order to get pig aortas of better quality for application of transplant
The established premise of the theory that sample temperature is equal to the shelf temperature as the end point is, under the condition of the minimal pressure of the chamber, convective heat transfer indoors and radiation heat transfer outdoors can be ignored, that is, the sample gets the heat totally dependent on the shelf to provide the heat only through heat transfer, but in actual operation, the radiation heat transfer outdoors are so high that it cannot be ignored, which leads to the final sample temperature exceeding the shelf temperature

Summary

Introduction

Vacuum freeze-drying technology can well keep the compositions and structures of the heat-sensitive material because of its lower temperature in the whole process, in addition, dehydrated samples can be stored (Dong et al, 2011; Xiao et al, 2010), so it has universally applied in biological (Jong-Pil et al, 1997; Todor et al, 1996; Zheng and Wang, 1997; Gao et al, 2011), medical (Ding and Zhao, 2011) and food (Gooding and Macdougall, 1961; Yu et al, 2011; Lu et al, 2010; Wu et al, 2010; Chen et al, 2010) fields is a universal application. Once the control of the primary drying or the end point of the primary drying is operated of judged improperly, it will cause the collapse and structure change of the sample, primary drying process is very important to the impact of sample qualities after freeze-drying (Tang et al, 2006; Roos, 1987). Through comparative analysis of repeated weighing, scanning and mechanical properties experiments for the freeze-dried pig aorta, it puts forward the optimized method which can reduces the pleat and collapse on vessel for estimating the end point of primary drying under the existing instruments and experimental conditions, in order to get pig aortas of better quality for application of transplant. Vascular studying and evaluating the feasibility of preparing the vessel scaffold by freeze-drying technology is expected to provide high-qualified and reliable vascular graft for the clinical treatment of the related diseases

Results

Discussion

Conclusion