A detection system for an enclosed container includes many nanosensors for detecting materials harmful to human beings within an enclosed container and transmitting a corresponding resonance frequency. The nanosensors are carried on or within walls of the container, e.g., embedded in a coating. At least one detection device detects a condition of the nanosensors and outputs a signal responsive thereto, which can be received by a monitoring system external to the container. Containers which have harmful materials within them can be inspected or stopped before entering the country.