Can I create on twitter a broadcast personalized for one my specific followers?

No

gagara Yes, you can can just put the ”” symbol and his/her username on twitter. Well yes if you don’t follow them on twitter, if you are set to private, then it would be that person and not that other person. Yes, this does excludes Direct Messages. My account is set to private check me out: http://www.twitter.com/panicpack121.

didn’t get this last one, you mean @ symbol? wouldn’t that show to all other followers of mine/his?

@gagara yes, you do put that symbol. No, depends if you follow all of them or not, if you he or she are private. Do you get what I’m saying? Yes or no?

Nope. Twitter doesn’t have anything built-in that hides public @replies. You can use certain third party services, like vimeo for instance, that support sign in: to do this sort of thing first you record your message on the third party site and specifically share it only with that person on that service (usually you’ll need their email), then grab the url for your message and tweet the url @ that user on twitter or using any twitter client.