Effect of Tris and Bicine buffer on the in vitro properties of uricase liposomes

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Uricase is an important enzyme in the pathway of purine metabolism in organisms. It can catalyze oxygen and uric acid to avoid gout and hyperuricemia caused by excessive accumulation of uric acid in the blood. Uricase liposomes (ULPs) overcome the shortcomings of other uricase preparations by encapsulating drugs in a lipid bilayer, with good stability, high safety, and certain targeting and sustained release effects. But in the preparation process, its performance will be affected by the buffer system. Tris-HCl and Bicine are the two most commonly used buffers. This article will summarize their effects on the in vitro properties of ULPs. First, let's take a look at the advantages of Tris-HCl and Bicine.

Tris-HCl buffer is a buffer system commonly used in biochemical experiments and is widely used as a solvent for nucleic acids and proteins. It has the advantage of little interference with biochemical processes; Bicine buffer belongs to the Good's buffer system, and has the It does not interfere with the process of biochemical reactions, and is resistant to chemical and enzymatic hydrolysis. Therefore, both are often used in biochemical experiments such as cells and proteins.

Preparation method of uricase liposome

The reverse evaporation method is a very suitable method for preparing liposomes for encapsulating water-soluble macromolecular substances. The liposome obtained by the preparation method has high encapsulation efficiency, uniform particles, good stability and simple preparation method. Weigh a certain proportion of lecithin and cholesterol in a round-bottomed flask, add a certain amount of chloroform to fully dissolve, remove the chloroform under reduced pressure on a rotary evaporator to form a uniform film. After adding ether to re-disperse, add a Tris-HCl buffer containing 2 mg of uricase at pH=8.5. Ultrasound in an ice bath, after forming a uniform opalescent dispersion system, decompress and rotate to steam until the gel collapses to form a uniform opalescent liquid. Tris-HCI buffer was added and filtered through 0.22μm filter membrane to prepare ULPs samples. ULPs samples with Bicine as buffer were prepared in the same way.

Comparison of the in vitro properties of two buffers for preparing uricase liposomes

Encapsulation efficiency: The gel column method was used to measure the entrapment efficiency of uricase liposomes. It was found that the entrapment efficiency of liposomes prepared with Bicine buffer was higher than that of samples prepared with Tris-HCl buffer;

Activity: The activity of uricase liposomes was measured in Boric acid-Borax buffer with a uric acid concentration of 75gmol/L, and it was found that the uricase activity prepared by Bicine buffer was higher than that prepared by Tris-HCl buffer;

Stability: Store the uricase liposomes in a dark and sealed manner at 4°C, take out the uricase activity in the sample at a specified time, and find that the uricase liposomes prepared with Bicine buffer have better storage stability. To

To sum up, in the process of preparing uricase liposomes, Bicine buffer is better than Tris-HCl buffer, which can improve the encapsulation efficiency of ULPs and the activity and stability of uricase in vitro. Clinical administration will also bring better therapeutic effects.