Confined growth of CdSe quantum dots in colloidal mesoporous silica for multifunctional nanostructures

Abstract

We report a new and convenient strategy for incorporating fluorescent semiconductor nanocrystals into silica hosts for the synthesis of multifunctional nanostructures. Mesoscale porosity was first created in conventional Stöber silica spheres by chemical etching under the protection of polymeric ligands. Uniform and highly luminescent CdSe nanocrystals were then directly grown in the porous silica network by reacting the silica spheres in a growth solution at high temperature. The confinement of silica network led to slower nanocrystal growth and subsequently smaller CdSe dots with blue shifted fluorescence compared with those without confinement. The loading number of CdSe nanocrystals can be easily tuned by changing the degree of porosity of the silica. The advantages of this strategy include simplicity as no special surface treatment processes are needed, general applicability to silica hosts of various shapes and sizes, high flexibility in tuning the dimensions of both the active nanocrystals and host particles, and ample opportunities for incorporating multiple functionalities. With the demonstration of a porous Fe3O4@SiO2/CdSe composite structure with combined magnetic and optical properties, we believe this strategy may provide a platform for the fabrication of a large variety of multifunctional composite nanostructures.

Versatile design and synthesis of nano-barcodes

“…[59][60][61][62][63] QDs have been explored to prepare barcodes for bio-detection, cell labelling, imaging, anti-counterfeiting and other applications by putting them in/on nanospheres, nanoclusters, nanosheets, nanorods, nanotubes, nanowires and nanodisks. 33,[64][65][66][67][68][69][70][71][72][73][74][75][76][77][78][79] 2.1.1.3 Fluorescent carbon dot encoded nano-barcodes. Fluorescent carbon dots (CDs) are small carbon nanoparticles of size less than 10 nm.…”

“…Using this process, CdSe QD precursors are embedded and grown directly under high temperature conditions inside porous silica nanospheres to prepare the barcode element. 64 The swelling method is advantageous due to its applicability to a wide range of organic and inorganic dyes and nanoparticles to prepare nano-as well as micro-barcodes. 36,175,176 The successful embedding using this approach, however, requires a match between the pore size of the nanospheres and the size of the encoding element.…”

Antibacterial activity of chlorogenic acid-loaded SiO2 nanoparticles caused by accumulation of reactive oxygen species

“…The pH value of the solution was adjusted to 10 using 1 M NaOH. A fresh NaHSe solution was rapidly injected into the above solution under a nitrogen stream, and stirred vigorously for 30 min, and the mixture was refluxed at 60 °C for 2 h, thereby obtaining bright yellow CdSe quantum dots [28,29].…”

Surface modification toward luminescent and stable silica-coated quantum dots color filter

“…, enhance the chemical stability of the QDs [26,27], and promote surface conjugation with the ligand [15]. Moreover, it was reported that a silica shell can prolong the shelf life of QD devices: after long-term operation for 100 h at a driving current of 60 mA, a silica QD-LED retained 88% of its initial QY, while a pristine QD-LED only retained 65% of its initial value [28].…”