I'm not using the special characters you listed, but look closely at the code below at how I am using FOR XML PATH to concatenate the values. Incorporate what you see there into your code and see if that helps.

declare @TestData table(id int);

with e1(n) as (select row_number() over (order by (select null)) from (values (1),(1),(1),(1),(1),(1),(1),(1),(1),(1))dt(n))

insert into @TestData

select n from e1;

select * from @TestData;

-- Concatenate the data:

select

stuff((select ',' + cast(id as varchar)

from @TestData

order by id

for xml path(''),TYPE).value('.','varchar(max)'),1,1,'');