Nonblinking Core–Multishell InP/ZnSe/ZnS Quantum Dot Bioconjugates for Super-resolution Imaging

Abstract

Colloidal quantum dots (QDs) are vital fluorescent probes with several optical features superior to those found in organic dyes for microscopy imaging. However, the emission blinking behavior of a single QD is an intrinsic drawback for stimulated emission depletion microscopy (STED) or structured illumination microscopy techniques. Herein, we present a rational strategy for the synthesis of a type of deterministic, environmentally friendly, small nonblinking core−multishell InP/ZnSe/ZnS QD using a hydrofluoric acid (HF) etching passivation. The strategy includes four steps: synthesis of the InP core, synthesis of oil-phase core− multishell InP/ZnSe/ZnS QDs using hydrogen fluoride and trioctylphosphine etching passivation, promotion of the water solubility of QDs modified by 3-mercaptopropionic acid (MPA), and enhanced biotargeting of core−multishell InP/ZnSe/ZnS QDs by surface coupling technology. The suppressed blinking mechanism was primarily attributed to surface wrapping shells and HF etching passivation of surface dangling bonds, which reduced surface nonradiative recombination. Nonblinking QDs exhibit high fluorescence efficiency (∼90%), good photostability (>20 min), a large Stokes shift (>135 nm), biocompatibility of the cell viability (>90%), and high targeting. Furthermore, super-resolution multifocal structured illumination microscopy imaging of subcellular structures labeled using these QDs confirmed a resolution improvement of greater than 2.6-fold compared to wide-field microscopy. The results indicate that the nonblinking QDs can function as excellent probes for use in the long-term super-resolution visualization of subcellular dynamics.

Nontoxic Fluorescent Nanoprobes for Multiplexed Detection and 3D Imaging of Tumor Markers in Breast Cancer

“…Reid et al [ 144 ] described the synthesis of InP/ZnS NCs with a thick shell that allowed NCs to emit for more than 95% of the time; however, this shell increased the NC size, which was not ideal for biological detection. Another approach to obtaining nonblinking, nontoxic InP-based NCs is to apply a multilayer inorganic shell, e.g., a ZnSe/ZnS shell, and then treat the surface with hydrofluoric acid to reduce the surface nonradiative recombination [ 145 ]. This approach yields nonblinking NCs with a fluorescence QY of about 90% that have almost no effect on cell viability and provides a resolution 2.6 times better than that of wide-field microscopy.…”

Suppressed Auger recombination and enhanced emission of InP/ZnSe/ZnS quantum dots through inner shell manipulation

“…Semiconductor quantum dots (QDs) have been the subject of extensive research in important science domains including solar cells, photodetectors, bioimaging, and light-emitting diodes for their size-tunable emission qualities, higher photostability, and higher photoluminescence quantum yields (PL QYs). [1][2][3][4] In recent years, cadmium chalcogenide QDs have been widely investigated for their superior optical properties to meet the requirements of photoelectric devices. 5,6 However, the toxicity of cadmium severely limits their further commercialization.…”

“…Compared with InP/ZnSe and InP/ZnS core-shell QDs, multishell InP/ZnSe/ ZnS QDs usually exhibit much higher PL QYs and photostability. 2,7,[12][13][14][15] The inner ZnSe shell can passivate the surface of the InP core and reduce the lattice mismatch between InP and ZnS, for that the lattice strain can effectively be relieved at the interfaces (lattice constant: InP = 5.9 Å, ZnSe = 5.7 Å, ZnS = 5.4 Å). 9,13,16,17 However, a thick ZnSe shell will induce more internal traps due to the increased lattice strain.…”

Green Synthesis of Carboxymethyl Chitosan-Based CuInS2 QDs with Luminescent Response toward Pb2+ Ion and Its Application in Bioimaging

“…Therefore, CuInS 2 QDs may provide a way to develop polysaccharide-based QDs to their full potential without worrying about their toxicity in a biological environment. However, so far, few studies have been carried out on the creation and use of PNPs formed by CuInS 2 QDs in the realm of biomedicine. , Thus, there is a growing demand to design “green” polysaccharide-based QDs for constructing biofunctional and nontoxic PNPs with excellent optical properties.…”

“…However, so far, few studies have been carried out on the creation and use of PNPs formed by CuInS 2 QDs in the realm of biomedicine. 20,21 Thus, there is a growing demand to design "green" polysaccharide-based QDs for constructing biofunctional and nontoxic PNPs with excellent optical properties.…”