The present invention provides particles comprising either a water-soluble polymer or a phospholipid, wherein at least one near infrared (NIR) fluorescent probe and optionally at least one active agent such as a targeting moiety, capable of selectively recognizing a particular cellular marker, are non-covalently bound to the outer surface of the particles. Pharmaceutical compositions comprising these particles may be used, inter alia, for detection and treatment of tumors in the gastrointestinal tract
