Hi,

This is the simplest method of encapsulation technique. In the article alginate production is given. Did you produced sodium alginate and tried to make gel with CaCl2?. 

I have tried to make the gel, but what is the encapsulation technique? I have just dropped with a dropper sodium alginate into different concentrations of Calcium Chloride.

Which is the source of your alginate? If is a commercial blend, probably the glucuronic/mannuronic acids is not the adequate to form a gel with calcium chloride. The alginate structure allows the "egg box" attachment of Ca+2 ions between alginate chains, forming a gel. The balance of both acids define the gel strength.

Probably you must change the type or brand of your alginate. You can ask the supplier for a stronger alginate.

To clarify, the alginate is synthetically made using the procedure above. No other materials were added into the mixture just the ingredients listed.

I think I need a more structured way of cross-linking. I simply drop sodium alginate using a dropper into a concentration of calcium chloride. There is some bonding within 2-5% but not enough to gel.

Could be useful determinate the structure (glucuronic/mannuronic) in a further research.

Try this other technique, employing another calcium salt. The acidification rate could also affects, try weak organic acids or an acidulant (like glucono-lactone)

Hi Joshuh

I am also agreed with  Alfonso, you must first check the Alginate, if you got it from Merck or Sigma, give me the lot number, otherwise, if you got it commercially ask them to give you COA. I am working on alginate and have some problems like you, but certainly it depends on the G to M ratio and the kinds of Alginate. we have different kinds of Alginate.

Hope to success.

Hi all,

To clarify, I am making the Alginate. It is not from a supplier, rather made in my lab. 

I will look further into the article provided by Alfonso (Thank You!), and let you all know the results shortly after.

I wish a successful experiment

Take care

Two practical methods of forming calcium alginate gels were developed around 50 years ago to convert pulp from harvest-damaged fruit crops into structures resembling the original fruit. The calcium salt used was normally lactate rather than chloride, to avoid a bitter taste. These methods are described in detail in the book chapter by Wilma Sime, cited as reference 9 in the paper by Parthiban et al. The following simplified versions have been carried out successfully by around 200 undergraduate students in our teaching laboratories.

Prepare a 1.25 % solution of alginate by dispersing slowly in cold water and then heating, with continued stirring, until a clear solution is obtained.

Place approximately 10 ml of 3 % calcium lactate solution in a 50 ml beaker. Withdraw about 1 ml of alginate solution into a Pasteur pipette, put the tip of the pipette 1-2 cm above the surface of the solution, and slowly drip the alginate solution into the calcium lactate, to obtain spherical beads of calcium alginate gel. The beads can, of course, be made larger by dripping the alginate solution from a wider tube. [This procedure, known as the "Berry Mill" process, was used industrially to prepare re-formed blackcurrants].

Measure 80 ml of 1.25 % alginate solution into a 150 ml beaker. Weigh out (separately) 0.3 g of calcium sulphate, 0.3 g of trisodium citrate and 0.8 g of glucono-delta-lactone (GDL). Dissolve the trisodium citrate in 20 g of distilled water, add the GDL and stir until fully dissolved (approx. 10 seconds), add the calcium sulphate, stir for a further 15 seconds, then pour into the alginate solution. Stir for 10-15 seconds, then pour into a Petri dish (or other suitable container) and allow a continuous gel to form. [This "Internal Set" method was used to form larger structures such as apricot halves, and can also be used to prepare slabs of gel, or cylindrical samples for compression testing].

It might be worth trying either or both of these methods with your own alginate.

Since the procedure you used was effectively the Berry Mill process, I am surprised that you did not see gelation – unless you stirred the mixture, which would give a precipitate of calcium alginate, rather than gel beads. The only other possible reasons I can think of (apart from differences in the block composition of the alginates) are the use of chloride rather than lactate, or that the ratio of calcium to alginate was too high.

If you would like to discuss any of this in greater detail, I can be contacted by e-mail at: [email protected]

The crosslinking need to be in humid box, or the crosslinked polymer dry and crack. Did you do it in humid box and still fail?

Try cooling the cacl2 solution to 4°C before cross-linking it to sodium alginate

I think the concentrated sodium alliganate due to faille in gelation so the more dilute solution is prefer

The following discussions seemingly can be found of some interest, concerning to your query: https://www.researchgate.net/post/Does_change_in_pH_of_sodium_alginate_affect_final_encapsulated_cell_viability https://www.researchgate.net/post/How_can_I_make_alginate_disks_that_I_can_put_into_a_24-well_plate/1

About predicting the pH of CaCl2 aq. solutions ― cf. my posts at: https://www.researchgate.net/post/How-to-increase-pH-for-a-solution-without-making-a-chemical-reaction-with-CaCl2

Dear Joshuah Marian Gagan,

I think there is a problem with commercial Alginate. Try other Alginate rather than sodium Alginate. However, advantages with sodium is they yield humid automatically.

Ashish

Hi everyone. I have another question. Crosslinking of alginate can be made by using divalent cations such as Cu, Ba, Mg, etc. But, what is the main reason for using CaCl2 generally? What makes it advantageous?