A method for sample analysis that employs a signal-amplifying nanosensor is provided. An Smart-phone Detection implementation of the present method may include a) obtaining a sample, b) applying the sample to a signal-amplifying nanosensor containing a capture agent that binds to an analyte of interest, under conditions suitable for binding of the analyte in a sample to the capture agent, c) washing the signal-amplifying nanosensor, and d) reading the signal-amplifying nanosensor, thereby obtaining a measurement of the amount of the analyte in the sample. In some embodiments, the analyte may be a biomarker, an environmental marker, or a foodstuff marker. Also provided herein are kits that find use in performing the present method.