Unable to update mongodb document with special characters

I have a string as follows:
Maggi®is awesome.

As can be seen, there is the registered symbol in the string.

This is input through the input tag of HTML. I take the string as it is and then try to update a record's attribute with that string - this record / document is then updated in MongoDb too..

However, I get back an error saying "Invalid JSON: Unexpected end of input".

I suspect I have to handle the special character in some way - what do I need to do to store the string as it is in MongoDB and then be able to retrieve the same (with the symbol) without getting the above error? Is there something I need to do on the client side when getting the value from the input tag or something that I can do from the server side or both?

I am using NodeJS along with MongoDB (and using AngularJS) but I don't think it has got anything to do with the above.