Check out this paper. 

http://www.sciencedirect.com/science/article/pii/S0144861707005528

Thanks Zoe but I am unable to access this paper. Can you or anyone from the followers give me the pdf of this paper?

You can prepare without surfactant also... First you dissolve chitosan in 2% acetic acid , concentration 1mg/ml completely. Precipitate the chitosan nanoparticles with TPP (1mg/ml). Add TPP drop wise to chitosan solution until  precipitation. Centrifuge and separate.

thanks for the help ma'am. But are you sure that these are nanoparticles and not micro??

You can standardise the size of the particles by considering certain factors like concentration of polymer, TPP droplet size, stirring speed, interval between the two drops etc.....

sounds great. Ma'am can you tell me the paper in which you found these factors or are these based on your personal observations?

this article will hep you

thank you all but after much attempts i am unable to get CS/TPP NPs at given concentration in calvo et al. paper.

However I managed to get precipitate at this formulation:

Chitosan Solution : 1 mL in 9 mL DI water (.1% w/v)

TPP solution : .05g in 5mL [c=10mg/ml]

On adding 2.6mL of TPP in 10mL of prepared CS solution I am getting precipitate which is light bluish color. 

Temp is 27 degrees and pH is between 6 and 7.

This is highly repeatable method. If anyone could do it and see the resultant solution and let me know whether this method is giving nanoparticles or not, it will be very helpful.

Thanks

There is  very complex answer behind. What kind of chitosan are you using? What about the DDA? There is something special with the MW? normally the gelation follows a stoichiometric ratio, and the number of charged amino groups (depending of the pH) will define the amount of TPP you need. Of course, with very hydrophobic chitosan you can include PVA or PEG at 1% to enhance the stability. If the product is nano or macro, you will easily see based on the "transparency" of the solution.  

the chitosan being used here is LMW. DDA is upto 95%. Viscosity is way lesser than that of MMW or HMW chitosan. 

We've worked on this preparation using several molecular weights of chitosan and TPP alone. Results showed particle size at 10 micrometers. Please be careful about results in the literature atwhich they assumes nanoparticles with measurement using scanning electron microscopy (SEM), but aggregates are clear in SEM.

I believe that surfactant addition is necessary to prevent aggregation.

yes I got the same answer from few other scientists as well. thanks a lot Rana Obaidat. Before closing this discussion, can you please put light on what type of surfactants can be used here to get particle size below 50nm.

hello, I prepared Chitosan NPs(600 nm)  by dropping quickly TPP(0.2% w/v) into chitosan solution (0.25 % w/v). The NPs size was determined by zetasizer malvern instruments.

Hassan Hajjali

We worked with chitosan concentration (1-5)%, and TPP conc (0.2-10)%. We didnot use below 1% chitosan conc., and this is important variable to determine the size. We used also zetasizer in addition to SEM

Did you check presence of aggregation in the prepared 600 nm particles??

I second with Rana sir on this. Please share detailed results of your experiment with us sir Hassan Hajjali.

Enclosed an article which may help your research 

Article FORMULATION AND CHARACTERIZATION OF EPIGALLOCATECHIN GALLATE...

Dear Rajat, I would suggest you to use Tween-80 as a surfactant to avoid aggregation (up to 0.5%) as  well as lowering down the concentration of your TPP stock from 10 mg/ml to 1 mg/ml. Secondly you have to test the stirring speed between 400-1200 rpm. Third while you measure the size of your colloidal preparation, make sure that you dilute your sample through serial dilutions and make dilution in the same  composition of dilution solution (except TPP) as that of your solutions in which you initially dissolved your chitosan, so that you do not break the colloidal system and nano particles are in the similar dilution environment as they were in the original colloidal suspension to avoid further aggregation of particles. Before you measure your particle size in different serial dilutions, sonicate your diluted samples in water bath sonicator for 1-2 minutes so as to further disperse the particles. I do not know which instrument you are using for the size estimation, but if it is Malvern nanoS or ZS, you may go to their website and register for various live as well as recorded webinars by their experts on various aspects of particle characterization. They are very helpful. Additionally you may have to confirm the size of your particles via electron microscopy especially FESEM as small or ultra small nano particles are tricky to observe under TEM or SEM. Good luck with your research.

Thanks for the input sir, will try n let u know what happened.

sir can't we prepare these nano particles without using tpp.or is there any alternative for it?

I have another question: Is it possible to produce high chitosan nanoparticles concentrations? 

I am currently using ionic gelation to produce chitosan nanoparticles with TPP. But since high concentrations lead to larger nanoparticles, i was able to get the nanoparticles only starting with a maximum of 4 g/L chitosan solution. I need to produce large-scale quantities, so it would be better to do it at higher concentrations. Is there any way I can do this? Thanks!

High or low MW?

Why you use the surfactants in preparation nanochitosan?

I prepared chitosan nanoparticles by ionic gelation method but after centrifuging a thick pellet was obtained which was not dispersed. Any suggestion please

dear colleague : may be this paper help you

@komal Jain Yeah you can use vanillin as cross-linker instead of TPP