Ultrasmall Near-Infrared Ag₂Se Quantum Dots with Tunable Fluorescence for in Vivo Imaging

Abstract

A strategy is presented that involes coupling Na(2)SeO(3) reduction with the binding of silver ions and alanine in a quasi-biosystem to obtain ultrasmall, near-infrared Ag(2)Se quantum dots (QDs) with tunable fluorescence at 90 °C in aqueous solution. This strategy avoids high temperatures, high pressures, and organic solvents so that water-dispersible sub-3 nm Ag(2)Se QDs can be directly obtained. The photoluminescence of the Ag(2)Se QDs was size-dependent over a wavelength range from 700 to 820 nm, corresponding to sizes from 1.5 ± 0.4 to 2.4 ± 0.5 nm, with good monodispersity. The Ag(2)Se QDs are less cytotoxic than other nanomaterials used for similar applications. Furthermore, the NIR fluorescence of the Ag(2)Se QDs could penetrate through the abdominal cavity of a living nude mouse and could be detected on its back side, demonstrating the potential applications of these less toxic NIR Ag(2)Se QDs in bioimaging.

Pressure tuning the lattice and optical response of silver sulfide

“…By varying the thickness [16][17][18][19][20] , its activation gap can be effectively tuned. 16 By changing the particle size, its optical band-gap could also be engineered.…”

“…16 By changing the particle size, its optical band-gap could also be engineered. [17][18][19] Compared with the above methods, pressure is a powerful tool in modifying the way atoms arrange and thus to tune materials electronic structure and physical properties. In this work, we aim at solving following tasks: 1) explore possible structural transition at higher pressure, 2) clarify the structural connections among the different phases, 3) and determine how pressure tunes the optical response which relates to the band-gap's and optical conductivity's evolution.…”

Nanoparticle biosynthesis using unicellular and subcellular supports

“…25 The biomimetic process for the reduction of SeO3 2 − led to GSSeH formation, and this precursor subsequently reacted with silver metal ions to form the Ag 2 Se QDs. In addition, the authors used the amino acid alanine (Ala) to form the Ag + -Ala complex, which is an important stabilizer for preparation of monodispersed Ag 2 Se QDs in aqueous phase.…”

“…Furthermore, quasi-biosynthesized Ag 2 Se QDs are good candidates for use as low-toxicity fluorescent tags for in vivo imaging diagnosis. 25 Overall, these cases provide selected examples of biomedical applications of biosynthesized nanomaterials. However, more comprehensive studies using biosynthesized nanoparticles as nanomedicine still remain to be explored.…”

Near-infrared quantum dots for HER2 localization and imaging of cancer cells

“…Light in the NIR range does not undergo this absorption and scattering effect, allowing deeper penetration and visibility. [16][17][18][19][20] Multiple QDs of different colors can be excited by a single wavelength of light, a concept of multiplexed imaging that is a certain advantage in biological imaging where multiple targets can be detected at a single point in time. Also, their small size and free surface reactive groups allow conjugation to various biomolecules for targeted localization, making them potential candidates for various applications, like cancer localization, detection of micrometastasis, image-guided drug delivery, and image-guided cancer surgery.…”