The influence of precursor chemistry on thermal decomposition and particle growth in a rapid microwave-assisted strategy was investigated, demonstrating the selective synthesis of small and ultrasmall luminescent lanthanide-doped NaGdF4 nanoparticles.

Plant-derived phytoglycogen nanoparticles (PhG NPs) have the advantages of size uniformity, dispersibility in water, excellent lubrication properties, and lack of cytotoxicity; however, their chemical functionalization may lead to loss of NP structural integrity. Here, we report a straightforward approach to the generation of PhG NP conjugates with biologically active molecules. Hydrogen bonding of bovine serum albumin with electroneutral PhG NPs endows them with additional ligand binding affinity and enables the electrostatically governed attachment of methotrexate (MTX), a therapeutic agent commonly used in the treatment of cancer and arthritis diseases, to the protein-capped NPs. We showed stimuli-responsive release of MTX from the PhG-based nanoconjugates under physiological cues such as temperature and ionic strength. The results of this study stimulate future exploration of biomedical applications of nanoconjugates of PhG NPs.

Phytoglycogen nanoparticles (PhG NPs), a single-molecule highly branched polysaccharide, exhibit excellent water retention, due to the abundance of close-packed hydroxyl groups forming hydrogen bonds with water. Here we report lubrication properties of close-packed adsorbed monolayers of PhG NPs acting as boundary lubricants. Using direct surface force measurements, we show that the hydrated nature of the NP layer results in its striking lubrication performance, with two distinct confinement-controlled friction coefficients. In the weak-to moderate-confinement regime, when the NP layer is compressed down to 8% of its original thickness under a normal pressure of up to 2.4 MPa, the NPs lubricate the surface with a friction coefficient of 10 −3 . In the strong-confinement regime, with 6.5% of the original layer thickness under a normal pressure of up to 8.1 MPa, the friction coefficient was 10 −2 . Analysis of the water content and energy dissipation in the confined NP film reveals that the lubrication is governed by synergistic contributions of unbound and bound water molecules, with the former contributing to lubrication properties in the weak-to moderate-confinement regime and the latter being responsible for the lubrication in the strong-confinement regime. These results unravel mechanistic insights that are essential for the design of lubricating systems based on strongly hydrated NPs.

We prepared a hybrid system composed of a continuous film of a dinuclear lanthanide complex [Ln 2 bpm(tfaa) 6 ] (Ln = Tb or Eu) and upconverting nanoparticles (UCNPs) using a straightforward drop-cast methodology. The system displayed visible emission under near-infrared (NIR) excitation, simultaneously stemming from sub-10 nm UCNPs and [Ln 2 ] complexes, the latter species being otherwise directly excitable only using UV-blue radiation. In light of the results of steady-stateincluding power-dependentand time-resolved optical measurements, we identified the radiative, primarily ligand-mediated nature of the energy transfer from Tm 3+ ions in the UCNPs to Ln 3+ ions in the complexes. Hyperspectral mapping and electron microscopy observations of the surface of the hybrid system confirmed the continuous and concomitant distribution of UCNPs and lanthanide complexes over the extensive composite films. Key features of the hybrid system are the simultaneous UV-blue and NIR light harvesting capabilities and their ease of preparation. These traits render the presented hybrid system a formidable candidate for the development of photoactivated devices capable of operating under multiple excitation wavelengths and to transduce the absorbed light into narrow, well-defined spectral regions.

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