A common mistake when learning French is to use the phrase "je suis intéressé(e) dans" to mean "I am interested in." This is a tricky one because students translate literally and it doesn't work in French for many reasons.

Use PAR (Not Dans)

We say "je suis intéressé(e) PAR blablabla".

For example: Je suis intéressé(e) par le cinéma. (I'm interested in cinema.)

But it gets more complicated than that. In French, you could also say "s'intéresser à."

For example: Je m'intésse au cinéma. (I'm interested in cinema.)

You Must Flip Your Sentence Around

Both these translations are fine grammatically. But it's unlikely a French person would use these constructions at all. We would flip our sentence around.

Le cinéma m'intéresse. (I'm interested in cinema.)

Etre Intéressé Means to Have Hidden Motives

Watch out that "être intéressé" followed by nothing can also be a way to describe someone who has hidden motives or bad intentions, like someone who does something that looks genuine but has hidden reasons.