There are no PHP interpreters that I know of for Android or IOS (or WebOS or BlackBerryOS).
If you want to run a web site as an app on a mobile device or tablet as a native application, all functionality needs to be in Javascript and wrapped with a library like PhoneGap or Titanium. Android and IOS web apps are both able to use local storage databases where data can be kept until a network connection is made. Any server-side logic would require a call out to your web server and an active internet connection on the device.
