Highly Emitting Perovskite Nanocrystals with 2-Year Stability in Water through an Automated Polymer Encapsulation for Bioimaging

Abstract

Lead-based halide perovskite nanocrystals are highly luminescent materials, but their sensitivity to humid environments and their biotoxicity are still important challenges to solve. Here, we develop a stepwise approach to encapsulate representative CsPbBr 3 nanocrystals into water-soluble polymer capsules. We show that our protocol can be extended to nanocrystals coated with different ligands, enabling an outstanding high photoluminescence quantum yield of ∼60% that is preserved over two years in capsules dispersed in water. We demonstrate that this on-bench strategy can be implemented on an automated platform with slight modifications, granting access to a faster and more reproducible fabrication process. Also, we reveal that the capsules can be exploited as photoluminescent probes for cell imaging at a dose as low as 0.3 μg Pb /mL that is well below the toxicity threshold for Pb and Cs ions. Our approach contributes to expanding significantly the fields of applications of these luminescent materials including biology and biomedicine.

Stable and Recyclable Photocatalysts of CsPbBr3@MSNs Nanocomposites for Photoinduced Electron Transfer RAFT Polymerization

“…For the CsPbBr 3 @MSNs nanocomposites, the relative PL intensity after irradiation at 460 nm maintained 90% of the initial value after 120 h. On irradiation at 365 nm and visible light for 120 h, over 80% and 95% of the initial PL intensities were retained, respectively. The greatly improved stability is consistent with the conceptual design that the perovskite nanocrystals are spatially isolated by the MSN pore walls, preventing fusion between NCs by heat or light, which has been similarly demonstrated by other encapsulation methods using inorganic or polymer matrixes (Figure c). ,, …”

“…The greatly improved stability is consistent with the conceptual design that the perovskite nanocrystals are spatially isolated by the MSN pore walls, preventing fusion between NCs by heat or light, which has been similarly demonstrated by other encapsulation methods using inorganic or polymer matrixes (Figure 4c). 31,35,46 As was mentioned, the CsPbBr 3 @MSNs nanocomposites could be easily separated from the polymerization reaction mixture via centrifugation (Figures S18 and S19) and be reused for successive polymerization. After the second cycle of polymerization, a slight catalytic efficiency decrease (78.3% conversion) was observed, resulting in a lower conversion rate with comparable M n and PDI (Figure 4d).…”

Biomolecules incorporated in halide perovskite nanocrystals: synthesis, optical properties, and applications

“…Complete surface coverage is difficult to achieve with discrete small molecules due to steric hindrance, thus the most successful surface coatings have been polymer or silicabased. 147,[184][185][186][187][188][189][190][191][192][193][194][195] Interestingly, phospholipid-based surface coatings have also been quite successful for generating aqueous dispersions and maintaining PL intensity, despite being small molecules, as previously mentioned in section 2.6. 112,147 For a more in-depth discussion on the use of coatings to generate HPNCs relevant for biological applications, readers are referred to the review of Lian et al 196…”

“…147,187 At present, there are a handful of proof-ofconcept demonstrations of HPNCs used as fluorescent imaging probes in a variety of mammalian cell lines, as well as in E. coli, and most of these do not employ biomolecules as ligands or during synthesis. 112,147,184,185,187,188,191,192,194,[232][233][234][235][236][237][238][239][240] Currently, the main focus of these studies is to demonstrate cellular uptake with minimal toxicity from Pb 2+ leaching and good imaging contrast. Nearly all the reports utilize UV and blue light for excitation, and acquire the images using the green emissions from CsPbBr 3 or red emissions from CsPbI 3 , demonstrating the viability of using HPNCs for basic optical bioimaging.…”

Highly water-stable, luminescent, and monodisperse polymer-coated CsPbBr3 nanocrystals for imaging in living cells with better sensitivity

“…[53][54][55] Different bio-compatible polymer-coated perovskite NCs were oen preferred to ensure low cytotoxicity, higher stability, and easy uptake in the cells. [56][57][58][59] Polyvinylpyrrolidone (PVP) polymer contains strongly hydrophilic pyrrolidone moiety and hydrophobic alkyl groups that prevent the aggregation of NCs due to their repulsive forces. 60,61 PVP forms an ultrathin shell around the NCs surface via adsorption which can easily detach under external stress.…”