Spray‐Assisted Coil–Globule Transition for Scalable Preparation of Water‐Resistant CsPbBr₃@PMMA Perovskite Nanospheres with Application in Live Cell Imaging

Abstract

Despite their impressive optical properties, lead halide perovskite quantum dots (PQDs) have not realized their potential, especially in bioimaging applications, as they suffer from poor moisture and thermal stability, solvent incompatibility, and significant toxicity. Here, a spray‐assisted coil–globule transition method for encapsulating CsPbBr3 (CPB) PQDs into poly(methyl methacrylate) (PMMA) polymer nanospheres is reported. Polyvinylpyrrolidone‐capped CPB PQDs are synthesized via the ligand assisted reprecipitation method in dichloromethane. After dissolving PMMA, the above precursor solution is sprayed into petroleum ether under high pressure N2. High‐pressure nebulization restricts the interactions between PMMA polymer chains, resulting in the formation of ≈112 nm nanoscale composite spheres after a coil–globule transition. The CPB@PMMA nanospheres not only possess 73% quantum yields but retain 81% of fluorescence intensity after the exposure to water for over 80 days. Due to their confined size and biocompatible encapsulation, they are readily available for cellular uptake and exhibit no toxicity on live HeLa cells. Furthermore, the PMMA surface allows for functional surface modification, carrying the possibility of targeting specific biological species and processes.

Effective Singlet Oxygen Generation in Silica‐Coated CsPbBr3 Quantum Dots through Energy Transfer for Photocatalysis

“…CsPbBr 3 QDs have no significant aggregation in the SiO 2 matrix, and the dispersion is better. It should be noted that the particles are easily aggregated if CsPbBr 3 PQDs are used directly in the post‐processing step without the protection of PS . CsPbBr 3 QDs/silica composites have a lattice distance of 0.412 nm, corresponding to the (1 1 0) crystal plane of the cubic phase perovskite (Figure d and the inset), suggesting that silica encapsulation preserves the size and structure of CsPbBr 3 QDs.…”

“…It is observed that the average diameter of silica-coated CsPbBr 3 QDs is 8.2 nm, size deviation is 0.1 nm, and there was no significant change before and after coating.C sPbBr 3 QDs have no significant aggregation in the SiO 2 matrix, and the dispersion is better.I t should be noted that the particles are easily aggregated if CsPbBr 3 PQDs are used directly in the post-processing step without the protection of PS. [20] CsPbBr 3 QDs/silica composites have al attice distance of 0.412 nm, corresponding to the (110) crystal plane of the cubic phase perovskite (Figure 2d and the inset),s uggesting that silica encapsulationp reserves the size and structure of CsPbBr 3 QDs. The presenceo fC s, Pb, Br,S i, and Oi nt he CsPbBr 3 QDs/silica composites was confirmed by energy-dispersive X-ray spectroscopy (EDX) mapping (Figure 2e).…”

“…However, there are still some limitations to stabilizeh alide PQDs in the above methods. Av ariety of methods have recently been developed to enhancet he colloidal and chemical stability of perovskitesb yl igands, [17,18] polymere ncapsulation, [19,20] and silica protecting layers. [21,22] Am ethod of silica encapsulation can be used to maintain the desired perovskite morphologya nd phase.…”

Hairy Fluorescent Nanospheres Based on Polyelectrolyte Brush for Highly Sensitive Determination of Cu(II)

“…Recently, many groups have been devoted to preparing FNs by different methods, such as encapsulating fluorescent molecules or quantum dots into the matrix spheres [16][17][18] and placing nanoparticles on the surface of matrix spheres [19,20]. In consideration of differentiated application environments, FNs are fabricated based on different matrices, including polystyrene [21], polymethyl methacrylate [22], silica [23], polylactic acid [24], melamine formaldehyde [25], sodium alginate [26], conjugated microporous polymers [27] and nanocellulose [28]. Each type of matrix spheres and preparation methods has advantages and disadvantages, with respect to the cost-effectiveness, properties and stability of FNs, as shown in Table 1.…”

Magneto‐Fluorescent Perovskite Nanocomposites for Directed Cell Motion and Imaging

“…These excellent attributes make perovskite nanocrystals particularly attractive for applications in fluorescent biotagging or related biotechnologies. Presently, however, their use as biotagging or magneto‐fluorescent agents remain limited primarily due to their instability toward polar solvents, such as water or ethanol, of which are essential in the Stöber process needed for forming an encapsulating silica shell. While there have been reports of works describing the stabilization of perovskite nanoparticles through formation of silica shells via modified Stöber processes, these amorphous and typically porous shells are insufficient in providing protection toward water.…”