It is formed of nanoparticles made of a compound semiconductor containing an Ag component, an In component, and a Se component. The peak wavelength of the emission intensity is in the range of 700 to 1400 nm, and the full width at half maximum ΔH of the peak wavelength is 100 nm or less. An Ag compound and an In compound are dissolved in a modifier to prepare an Ag-In precursor solution, and Se powder is dissolved in a solvent to prepare an Se precursor solution. An Se-precursor solution is injected into the Ag-In precursor solution in a state where the Ag-In precursor solution is heated to, for example, 150 ° C. to prepare a mixed solution, and then the mixed solution is reacted at a reaction temperature of 200 ° C. or higher. Heat for about 30 to 120 minutes to produce a light emitter. The biological material labeling agent includes this illuminant. As a result, a light emitter that emits intense light in the near-infrared region, can detect a large amount of biological information, and is suitable for bioimaging, its manufacturing method, and a biological material labeling agent are realized.Ａｇ成分、Ｉｎ成分、及びＳｅ成分を含有した化合物半導体からなるナノ粒子で形成されている。発光強度のピーク波長が７００～１４００ｎｍの範囲にあり、かつピーク波長の半値幅ΔＨが、１００ｎｍ以下とされている。Ａｇ化合物とＩｎ化合物とを修飾剤に溶解させてＡｇ－Ｉｎ前駆体溶液を作製し、Ｓｅ粉末を溶媒に溶解させてＳｅ前駆体溶液を作製する。Ａｇ－Ｉｎ前駆体溶液を例えば１５０℃に加熱した状態でＳｅ前駆体溶液を前記Ａｇ－Ｉｎ前駆体溶液に注入し、混合溶液を作製し、その後、この混合溶液を２００℃以上の反応温度で３０～１２０分程度加熱し、発光体を製造する。生体物質標識剤はこの発光体を備えている。これにより近赤外領域で強く発光し、多くの生体情報の検出が可能でバイオイメージングに好適な発光体とその製造方法、生体物質標識剤を実現する。
