Concatenate Expression Help Needed

We have an sync integration between Salesforce and Netsuite and need to combine a number of 2 fields and 3 items of text to place a script in a Netsuite field on the invoice.

"Sample Text 1" [inserted field 1] "Sample Text 2" [inserted field 2] "Sample Text 3".

There are a few additional challenges as the text we need to import actually contains quotations marks which may be confusing matters further somewhat.

Here is exactly the input we want to achieve:

[{"Is Person":false,"ItemSubtype":"Sale","Transaction Line":4,"Statistical Value - Base Currency":0.0,"Rate":100000.0,"Print Item Name/Number":false,"Print Items":false,"Amount":100000.0,"Quantity":1.0,"ItemType":"OthCharge","Item Internal identifier":"153","Item Reference Name":"Assets Under Management - Deposit DPP","Account Internal identifier":"741","Account Reference Name":"741""}]

Any help really appreciated.