Surface plasmon resonance of Au/Ag metals for the photoluminescence enhancement of lanthanide ion Ln3+ doped upconversion nanoparticles in bioimaging

Deep tissue penetration, chemical inertness and biocompatibility give UCNPs a competitive edge over traditional fluorescent materials like organic dyes or quantum dots. However, the low quantum efficiency of UNCPs becomes an obstacle. Among extensive methods and strategies currently used to prominently solve this concerned issue, surface plasmon resonance (SPR) of noble metals is of great use due to the agreement between the SPR peak of metals and absorption band of UCNPs. A key challenge of this match is that the structures and sizes of noble metals have significant influences on the peak of SPR formants, where achieving an explicit elucidation of relationships between the physical properties of noble metals and their SPR formants is of great importance. This review aims to clarify the mechanism of the SPR effect of noble metals on the optical performance of UCNPs. Furthermore, novel research studies in which Au, Ag or Au/Ag composites in various structures and sizes are combined with UCNPs through different synthetic methods are summarized. We provide an overview of improved photoluminescence for bioimaging exhibited by different composite nanoparticles with respect to UCNPs acting as both cores and shells, taking Au@UCNPs, Ag@UCNPs and Au/Ag@UCNPs into account. Finally, there are remaining shortcomings and latent opportunities which deserve further research. This review will provide directions for the bioimaging applications of UCNPs through the introduction of the SPR effect of noble metals.

Large enhanced photocatalytic activity of g-C3N4 by fabrication of a nanocomposite with introducing upconversion nanocrystal and Ag nanoparticles

A novel heterostructured nanocomposite UCNPs@SiO2@Ag/g-C3N4 was developed for the first time to substantially boost the solar-light driven photocatalytic activity of g-C3N4. Its photocatalytic properties and photocatalytic mechanism were investigated. The as-synthesized photocatalyst with excellent improvement in the solar absorption and separation efficiency of photoinduced electron-hole pairs exhibited optimum solar-induced photocatalytic activity in dye degradation and hydrogen production. The experimental results showed that the rates of degradation of Rhodamine B (RhB) and hydrogen evolution were about 10 and 12 times higher than that of pristine g-C3N4, respectively. The excellent photocatalytic activity was attributed to the synergetic effect of upconversion nanoparticles (UCNPs) and Ag nanoparticles (NPs) on the modification of the photocatalytic properties of g-C3N4, resulting in a broad light response range for g-C3N4 as well as the fast separation and slow recombination of photoinduced electron-hole pairs. This study provides new insight into the fabrication of g-C3N4-based nanocomposite photocatalysts with high catalytic efficiency through the artful assembly of UCNPs, Ag NPs and g-C3N4 into a hetero-composite nanostructure. The prominent improvement in photocatalytic activity enables the potential application of g-C3N4 in the photocatalytic degradation of organic pollutants and hydrogen production utilizing solar energy.

NIR/blue light emission optimization of NaY1−(x+y)YbxF4:Tmy upconversion nanoparticles via Yb3+/Tm3+ dopant balancing

A data driven approach provides better understanding of the role of dopant balancing in the upconversion process and presents an effective strategy to enhance the optical properties of upconversion nanoparticles.

Assembly of 1D coaxial nanoribbons into 2D multicolor luminescence array membrane endowed with tunable anisotropic electrical conductivity and magnetism via electrospinning

A flexible 2D color-tunable coaxial nanoribbon array membrane with anisotropic electrical conductivity and magnetism is successfully fabricated via one-pot electrospinning.

Drug delivery function of carboxymethyl-β-cyclodextrin modified upconversion nanoparticles for adamantine phthalocyanine and their NIR-triggered cancer treatment

In this manuscript COOH-β-CD was used to connect UCNPs and Ad-ZnPc. The system has a strong NIR light triggered PDT activity toward cancer cells.

Preparation of a novel nanocomposite NaLuF4:Gd,Yb,Tm@SiO2@Ag@TiO2 with high photocatalytic activity driven by simulated solar light

A novel nanocomposite photocatalyst NaLuF₄:Gd,Yb,Tm@SiO₂@Ag@TiO₂ was developed for the first time.

Huge enhancement of upconversion luminescence by broadband dye sensitization of core/shell nanocrystals

The UCL intensity of dye-sensitized UCNCs excited at 820 nm is 800-folds higher than that of pure UCNCs excited at 980 nm.

Greatly enhanced photocatalytic activity of semiconductor CeO2 by integrating with upconversion nanocrystals and graphene

A novel nanocomposite photocatalyst of NaLuF₄:Gd,Yb,Tm@SiO₂@CeO₂:Tm/GN has been developed. The designed structure takes advantage of a synergetic effect from UCNCs, GN, and Tm-doping, which improves the photocatalytic activity of CeO₂ significantly.

Improving photocatalytic activity by combining upconversion nanocrystals and Mo-doping: a case study on β-NaLuF4:Gd,Yb,Tm@SiO2@TiO2:Mo

A novel double-shell-structured β-NaLuF₄:Gd,Yb,Tm@SiO₂@TiO₂:Mo nanocomposite photocatalyst has been developed for the first time.