As the title says, is there any MEF equivalent for .NET Framework 3.5?

I'm doing something that requires code to be in .NET Framework 3.5, and I'd like to have a plugin framework that loads DLLs that were made using later versions of .NET or even made in other programming languages. Is there a way to make a .NET 3.5 program/library load DLLs from a specific folder and instantiate them and interact with them?

EDIT: Just an FYI. The .NET 3.5 thing I am working with uses a special mscorlib dll that has some features removed, such as System.IO, and I can't replace said dll or else the thing will break.