Sodium Alginate Beads have many applications but are usually found in biomedical devices.
They are biocompatible and low cost, and can therefore be used for drug delivery and biomedical implants.
One of the great abilities of sodium alginate beads is their encapsulation ability, which means that things like enzymes and drugs can be added into the beads, and will stay in there, while other things like substrates can pass through.


This article will show you how to make Sodium Alginate Beads with your choice of infusion of a drug or enzyme.
I will be adding the enzyme Urease to my Sodium Alginate Beads that will then interact with Urea and make Ammonia.
I will be extracting Urease from soybeans and then adding it to Sodium Alginate Beads.
To validate that the Sodium Alginate Beads work I will test them using Urea in a well plate.
This will mimic a dialysis machine as it will be able to take in liquid that contains Urea and then turn out a liquid on the other side where the Urea was turned into ammonia, without containing Urease, as it will stay in the beads.
And I won’t cover it here, but taking it further you could make Zirconium Phosphate beads, which would capture the ammonia, so the only thing left in the blood would be some carbon dioxide, which can be breathed out.

Background Info (Theory):

Sodium Alginate and Calcium Chloride ions interact together to form small gel beads, which are great for adding extra things.
Urease is an enzyme that catalyzes the hydrolysis of Urea and turns it into ammonia and carbon dioxide.
So when the Urea substrate binds to the active site of Urease, it can be indicated by using a simple pH indicator, as ammonia is a weak base.

The Procedure:

Step 1 (Urease Extraction):

The first thing you need before making the beads is your infusion, and for me it was Urease.
For Urease, you need to put 2g of soybean meal and around 20mL of acetone in a tube, but be careful with it, as it is a dangerous chemical.
Put your tube in a 35 C water bath for 30 minutes until the liquid in the tube is yellowish and mixed.

Step 2 (Bead Creation):

For making the beads, you need to take 0.2g of Sodium Alginate and 9mL of water and mix it in a tube until is a weird sticky texture.
And if you want to add anything add it to the Sodium Alginate-Water solution too, for me I added 3mL of Urease.
Then let the Sodium Alginate tube set for about an hour, and make a new tube with 0.8g of Calcium Chloride and 40mL of water in a tube and shake to mix very thoroughly.
After one hour, take a pipette with a big radius tip or cut the tip off a disposable pipette so it makes a 6mm diameter.
Then use the pipette to drop Sodium Alginate drops into your Calcium Chloride solution which will form the beads.

The small sparkly things are the beads

Step 3 (Bead Validation):

For validation take a couple of non-infused beads and some infused beads and put them in a well plate.

The first 3 wells will be different kinds of controls so that you can be sure that no cross-contamination happens.
The first well should just have plain beads, water, and indicator.
The second well should have plain beads, urea, and indicator.
The third well should have Urease beads, water, and indicator.
The fourth well will be the tester, which has Urease beads, urea, and indicator.
After a couple of minutes and a light shake/move around of the well plate you should see a color change in the pH indicator.

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