Issue with using external DLL build against .NET 4.0

Hello, So I'm having trouble with importing a dll build against .NEt 4.0. I'm wondering is it even possible to use something like that in unity? I'm trying to use this -> http://cudafy.codeplex.com/. That needs framework 4.0, when I try to add this dlls into Plugins folder I'm getting internal compiler exception that says: Internal compiler error. See the console log for more information. output was: Unhandled Exception: System.TypeLoadException: Could not load type 'System.Runtime.Versioning.TargetFrameworkAttribute' from assembly 'Cudafy.NET'. Any idea if that dlls are usable within Unity3d? Thank you