Methods and a kit for use in the detection of a component in a sample on a solid support are disclosed which use a conjugate and polymer having metal particles of diameter in the nanometer range (that is between 0.1 and 500 nm). Methods and a kit for detection of a component in a sample on a solid support which have a conjugate and optionally a polymer bound to one or more supermagnetic particles are also disclosed. The methods and kits may be used for enhancing in vivo imaging and microscopy.