NodeJS application layout and variable passing

Hi guys I'm having a small problem with an application layout. I'm setting my controllers up like this.

ApplicationController = function(_app) {
    this.app = _app;
    console.log(this.app); //this works
};

ApplicationController.prototype.index = function(req, res, next) {
    console.log(this.app); //this is undefined
    res.json("hello");
};

module.exports = function(app) {
    return new ApplicationController(app);
};

And in my routes file I'm doing this.

module.exports = function(app) {

    //require controllers
    var Application = require('./controllers/ApplicationController')(app);       


    //define routes
    app.get('/', Application.index);
    app.get('/blah', Application.blah);

    return app;
};

The app variable I'm passing is not showing up in the other instance methods. Is there a reason for this that I'm missing? Thanks for any help.

In the past I've set my controllers up like this.

module.exports = function(app) {

    var controller = {

            //app is defined
            res.render('index', {
                title: "Index"
            });
        }
    };

    return controller;
};

But I like this other pattern more and I'm more curious then anything why it won't work.