Unity3d 2D mode lighting?

I have TOP DOWN 2D game.

When i shoot bullet from a 2d sprite barrel, i want to see a light flash on the background sprite at least, nothing fancy.

How would i go about achieving this, I'm really not sure.

I know i can make a point light source in 3D to achieve that effect but in 2D i have no clue.

UPDATE:

I tried creating a diffuse particle sprite material but the effect sucks balls. I have to make the light HUGE to get any effect on the background sprite and even when i do its in big chunks.

I'm trying to create the lighting on small tiny sections like a muzzle flash on a 2D gun barrel. Is there a technique for doing this?

UPDATE 2: Wait isn't lighting calculated from like the vertices of the sprite or something like that? Is there any way to make the background sprite contain more "pieces" so lighting looks more natural on it? thanks. or is there a better way to do this.