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In this article, Mn 2+ -doped CdS quantum dots (QDs) were synthesized using acetyl acetonate as a stabilizing agent in aqueous media. The as-prepared QDs exhibited reversible photoluminescence (PL) via partial oxidation of the emitting Mn species and subsequent reduction of the oxidized form. Treatment of the QDs with K 2 S 2 O 8 as oxidizing agents led to decrease in PL emission intensity due to Mn 2+ ( 4 T 1 – 6 A 1 ), and subsequent addition of NaBH 4 into K 2 S 2 O 8 -treated QDs resulted in PL recovery. The PL changes of the QDs were almost fully reversible after undergoing repeated oxidizing–reducing cycles, indicating their potential applications as versatile PL probes and labels for biological assays, imaging of cells and tissues in vivo , especially for the detection of redox reactions.

Luminescent silver nanocrystals (L-AgNCs) were synthesized using an amphiphilic polymer template, consisting of dodecylamine (DDA) grafted poly(acrylic acid) (PAA). Upon UV-light irradiation at 365 nm for different time intervals, AgNCs were gradually achieved and exhibited distinct luminescence. After undergoing 1.5 h irradiation, the maximum emission peak of L-AgNCs was located at 612 nm. In addition, the resulting L-AgNCs possessed pH-triggered phase transfer from water to chloroform. When adjusting pH of buffer solutions contained L-AgNCs from 5.0 toward 4.0, the hydrophilic AgNCs gradually became hydrophobic, together with a significant transfer from H 2 O phase to chloroform phase. This design could be further developed toward a smart luminescence imaging reagent, or therapeutic nanoparticles with controllable solubility by a small pH change.