Abstract: Multi-layered semiconductor nanoparticles having a very narrow grain-size distribution and exhibiting a spectrum having a narrow wavelength-width peak are prepared by a manufacturing method combining a monodisperse semiconductor nanoparticle manufacturing method and a multi-layer semiconductor nanoparticle preparation method. The nature of a solution of monodisperse semiconductor nanoparticles that is stabilized by a surface stabilizer is transformed between hydrophilic and lipophilic by substituting the surface stabilizer. The stabilized semiconductor nanoparticles are then shifted between an aqueous layer and an organic layer. The semiconductor nanoparticles are coated with multiple layers in the organic layer, and the organic layer is drawn off to recover the semiconductor nanoparticles therefrom.

Abstract: A technique is provided that easily detects biopolymers such as a DNA or a protein by utilizing semiconductor nanoparticles having different excitation wavelengths and fluorescence due to differences in particle size. By binding the semiconductor nanoparticles with avidin (or biotin), detection of biopolymers labeled with biotin (or avidin) is enabled.

Abstract: Detects the presence of binding between a sample biopolymer and a probe biopolymer and the amount of binding, without modifying the sample biopolymer in any way. The present invention provides a reagent for biopolymer detection comprising semiconductor nanoparticles on which a functional group having a positive or negative charge is exposed, and a method for biopolymer detection which detects the presence of binding between a sample biopolymer and a probe biopolymer and the amount of binding by electrostatically binding a semiconductor nanoparticle on which a functional group having a positive or negative charge is exposed to a negative or positive charge of the sample biopolymer.

Abstract: A compact and low-cost fluorescence reading apparatus capable of detecting multiple wavelengths is provided. The apparatus employs a semiconductor nanoparticle (201) as a fluorescent substance so as to enable a plurality of kinds of fluorescent substances to be simultaneously excited by a single excitation light source (220). Alternatively, the plurality of kinds of fluorescent substances are simultaneously excited by the application of a voltage.