Change Image Upload title

I am trying to upload image by saving it with the post title but currently it saves like this sample post of laravel.jpg but i want it to save like this sample-post-of-laravel.jpg

here is my code below

if($request->featured_image)
        {
            $exploded = explode(',', $request->featured_image);
            $decoded = base64_decode($exploded[1]);
            $fileName = $request->title.'.'.'jpg';
            $request->merge(['featured_image' => $fileName]);
            Storage::disk('public')->put($fileName, $decoded);
        }