Lead halide perovskite nanocrystals (LHP NCs) exhibit remarkable optical and optoelectronical properties but greatly suffer from poor stability in standard ambient and in-use conditions. These stability issues hinder their utilization in many technological applications and in their integration within industrial processes. Herein, we report a polymeric nano-encapsulation method of these NCs based on a spray-drying process, with the aim of using them as light down-converting materials in LED devices. CsPbBr3 NCs were encapsulated in acrylate-based polymers to form NCs / polymer nano-composite beads, with an average diameter lower than 500 nm. Structural and optical characterizations demonstrated good preservation of the NC properties after the spraydrying despite quite harsh process conditions. Specific acrylate-based polymers were selected in order to match native surface ligands from our NCs. This was necessary to obtain an effective encapsulation within the beads. To evaluate the encapsulated NCs photostability under in-use conditions, bare NCs and encapsulated NCs were deposited on the chip of a blue LED down-converter to compare their luminescence stability. We observed that under continuous blue photon excitation, the NCs / polymer nano-composite beads exhibit a much better resistance to photobleaching compared to bare NCs.

BackgroundIn nanomedicine, gold nanoparticles (AuNPs) have demonstrated versatile therapeutic efficiencies and, in particular, have been developed for the treatment of various cancers due to their high selectivity in killing cancer, not healthy, cells.MethodsIn this study, AuNPs were conjugated with the cell-penetrating peptide Cys-(Arg)8-Asp-Ser (CRRRRRRRRGDS) by direct cross-linking of the cysteine’s thiol group to the gold surface and a fibronectin-derived RGD group was also used due to its efficacy toward cancer cell targeting and possible promotion of healthy fibroblast functions.ResultsUltraviolet–visible absorbance spectrum and transmission electron microscope images of the synthesized peptide-capped AuNPs (PEP-AuNPs) validated the formation of AuNP aggregates. The presence of peptides on AuNPs was confirmed by Fourier transform infrared spectroscopy and quantified by a bicinchoninic acid assay. After being modified with the arginine-rich peptide, the AuNPs possessed a positive charge, as their zeta potential increased from −23.81±8.43 mV to 8 mV on average. In this manner, an easy method to conjugate AuNPs was shown here. Further, MTS assays were performed using healthy human dermal fibroblasts. After 24 hours of treatment with PEP-AuNPs, the cell density increased dramatically to around 25,000 cells/cm2. Results further showed a very high half-maximal inhibitory concentration of 69.2 µM for the PEP-AuNPs (indicating low toxicity).ConclusionThe results showed for the first time the ability of PEP-AuNPs to promote human dermal fibroblast cell viability, which after further investigation, may show an ability to replace cancerous tissue with healthy soft tissue.

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