| Liver failure is a disease that can affect the liver function leading to liver injury with a high mortality rate.For example,mortality rate of acute liver failure can reach 87.8%.Treatment of liver failure via blood purification can remove toxins from patients,improve the patient's liver function,and further provide a safe transition period for patients to enter the liver transplantation.At present,the dialysis-combined adsorption system can avoid the contact between the adsorption materials and blood and can competitively adsorb protein-bound toxins.Molecular Adsorbents Recycling System(Molecular Adsorbent Recycling System,MARS)is a widely used as an effective blood dialysis system,but in this system,human serum albumin(Human serum albumin,HSA)as an adsorbent has high cost and limited source,which limit its applications.In this paper,bilirubin as the most common hydrophobic toxin in patients with liver failure was employed as a model toxin,and we prepared a kind of low-cost water-soluble polymer instead of HSA to clear bilirubin during dialysis.Because the hydrophobic cavity of ?-cyclodextrin(?-CD)can adsorb hydrophobic toxin,such as bilirubin,different water-soluble ?-cyclodextrin polymers(polyCD1,polyCD2 and polyCD3)were prepared via crosslinking of ?-CD to epichlorohydrin with increasing reaction time.After crosslinking,water solubility of the polyCDs increased nearly 10 times than ?-CD.Along with the elongation of reaction time,crosslinking degree was increased,but molar ratio of ?-CD and effective ?-CD in the polyCDs decreased.The molar ratio of effective ?-CD was 63.0%?57.2%?53.4%.As a result,the molecular weight of polyCD1,polyCD2 and polyCD3 increased and could reach the maximum 279~780 kD.Adsorption capacity results of polyCDs on bilirubin showed that the polyCD1 could most effectively adsorb free bilirubin ~71 mg/g at 37 oC,and could reach the adsorption equilibrium within 30 min.PolyCD1(40 ml,1 % m/v)were used to adsorb bilirubin in serum(30 ml,0.3 mg/ml)for 4 hours in a dialysis-combined adsorption system,and the removal rate was 10.3%,which the adsorption capacity reached 2.3 mg/g.To improve the adsorption capacity of polyCD1 on bilirubin in serum and the yield of prduction,polyCD1 modified polyethyleneimine(PEI)(PEI-polyCD1)was prepared via the chemical reaction between the amino groups of PEI and the remaining epoxy groups of polyCD1.After optimization of addition of PEI,we found that the modification of PEI played a promoting role in the adsorption capacity of polyCD1 on bilirubin.With the increasing amount of PEI,the amount of adsorbed bilirubin increased first and then decreases.When the ratio of epoxy group and amino group was 1:20,the removal rate was 17.1%.In this paper,the experimental results showed that the polyCDs had a certain adsorption effect on bilirubin in dialysis-combined adsorption experiments,and after modification of PEI,the adsorption effect was obviously improved.The cost was lower than HSA,and has the potential to replace HSA for clinical treatment. |
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