In situ Visualization of Gene Expression Using Polymer‐Coated Quantum–Dot–DNA Conjugates

Imaging of specific mRNA targets in cells is of great importance in understanding gene expression and cell signaling processes. Subcellular localization of mRNA is known as a universal mechanism for cells to sequester specific mRNA for high production of required proteins. Various gene expressions in Drosophila cells are studied using quantum dots (QDs) and the fluorescence in situ hybridization (FISH) method. The excellent photostability and highly luminescent properties of QDs compared to conventional fluorophores allows reproducible obtainment of quantifiable mRNA gene expression imaging. Amine‐modified oligonucleotide probes are designed and covalently attached to the carboxyl‐terminated polymer‐coated QDs via EDC chemistry. The resulting QD–DNA conjugates show sequence‐specific hybridization with target mRNAs. Quantitative analysis of FISH on the Diptericin gene after lipopolysaccharide (LPS) treatment shows that the intensity and number of FISH signals per cell depends on the concentration of LPS and correlates well with quantitative real‐time PCR results. In addition, our QD–DNA probes exhibit excellent sensitivity to detect the low‐expressing Dorsal‐related immunity factor gene. Importantly, multiplex FISH of Ribosomal protein 49 and Actin 5C using green and red QD–DNA conjugates allows the observation of cellular distribution of the two independent genes simultaneously. These results demonstrate that highly fluorescent and stable QD–DNA probes can be a powerful tool for direct localization and quantification of gene expression in situ.     

Multiplexed Nucleic Acid Hybridization Assays Using Single‐FRET‐Pair Distance‐Tuning

Multiplexed photoluminescence (PL) detection plays an important role in chemical and biological sensing. Here, it is shown that time‐gated (TG) detection of a single terbium‐donor‐based Förster resonance energy transfer (FRET) pair can be used to selectively quantify low nanomolar concentrations of multiple DNAs or microRNAs in a single sample. This study demonstrates the applicability of single‐TG‐FRET‐pair multiplexing for molecular (Tb‐to‐dye) and nanoparticle (Tb‐to‐quantum‐dot) biosensing. Both systems use acceptor‐sensitization and donor‐quenching for quantifying biomolecular recognition and modification of the donor–acceptor distance for tuning the PL decays. TG intensity detection provides extremely low background noise and a quick and simple one‐step assay format. Single‐TG‐FRET‐pair multiplexing can be combined with spectral and spatial resolution, paving the way for biosensing with unprecedented high‐order multiplexing capabilities.     

Hybrid PbS Quantum‐Dot‐in‐Perovskite for High‐Efficiency Perovskite Solar Cell

In this study, a facile and effective approach to synthesize high‐quality perovskite‐quantum dots (QDs) hybrid film is demonstrated, which dramatically improves the photovoltaic performance of a perovskite solar cell (PSC). Adding PbS QDs into CH₃NH₃PbI₃ (MAPbI₃) precursor to form a QD‐in‐perovskite structure is found to be beneficial for the crystallization of perovskite, revealed by enlarged grain size, reduced fragmentized grains, enhanced characteristic peak intensity, and large percentage of (220) plane in X‐ray diffraction patterns. The hybrid film also shows higher carrier mobility, as evidenced by Hall Effect measurement. By taking all these advantages, the PSC based on MAPbI₃‐PbS hybrid film leads to an improvement in power conversion efficiency by 14% compared to that based on pure perovskite, primarily ascribed to higher current density and fill factor (FF). Ultimately, an efficiency reaching up to 18.6% and a FF of over ≈0.77 are achieved based on the PSC with hybrid film. Such a simple hybridizing technique opens up a promising method to improve the performance of PSCs, and has strong potential to be applied to prepare other hybrid composite materials.     

NIR‐Emitting Quantum Dot‐Encoded Microbeads through Membrane Emulsification for Multiplexed Immunoassays

NIR‐emitting CdSeTe/CdS/ZnS core/shell/shell QD‐encoded microbeads are combined with common flow cytometry with one laser for multiplexed detection of hepatitis B virus (HBV). A facile one‐pot synthetic route is developed to prepare CdSeTe/CdS/ZnS core/shell/shell QDs with high photoluminescence quantum yield and excellent stability in liquid paraffin, and a Shirasu porous glass (SPG) membrane emulsification technique is applied to incorporate the QDs into polystyrene–maleic anhydride (PSMA) microbeads to obtain highly fluorescent QD‐encoded microbeads. The relatively wide NIR photoluminescence full width half maximum of the CdSeTe/CdS/ZnS QDs is used to develop a ‘single wavelength’ encoding method to obtain different optical codes by changing the wavelengh and emission intensity of the QDs incorporated into the microbeads. Moreover, a detection platform combining NIR‐emitting CdSeTe/CdS/ZnS QD‐encoded microbeads and Beckman Coulter FC 500 flow cytometry with one laser of 488 nm is successfully used to conduct a 2‐plex hybridization assay for hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and a 3‐plex hybridization assay for hepatitis B surface antibody (HBsAb), hepatitis B e antibody (HBeAb), and hepatitis B core antibody (HBcAb), which suggests the promising application of NIR QD‐encoded microbeads for multiplex immunoassays.     

Ultrasmall Particle Sizes of Walnut‐Like Mesoporous Silica Nanospheres with Unique Large Pores and Tunable Acidity for Hydrogenating Reaction

The large particle sizes, inert frameworks, and small pore sizes of mesoporous silica nanoparticles greatly restrict their application in the acidic catalysis. The research reports a simple and versatile approach to synthesize walnut‐like mesoporous silica nanospheres (WMSNs) with large tunable pores and small particle sizes by assembling with Beta seeds. The as‐synthesized Beta‐WMSNs composite materials possess ultrasmall particulate sizes (70 nm), large radial mesopores (≈30 nm), and excellent acidities (221.6 mmol g^?1). Ni₂P active phase is supported on the surface of Beta‐WMSNs composite materials, and it is found that the obtained composite spherical materials can reduce the Ni₂P particle sizes from 8.4 to 4.8 nm with the increasing amount of Beta seeds, which can provide high accessibilities of reactants to the active sites. Furthermore, the unique large pores and ultrasmall particle sizes of Beta‐WMSNs samples facilitate the reduction of the diffusion resistance of reactants due to the short transporting length, thus the corresponding Ni₂P/Beta‐WMSNs composite catalysts show the excellent hydrogenating activity compared to the pure Ni₂P/WMSNs catalyst.     

Silver‐Quantum‐Dot‐Modified MoO3 and MnO2 Paper‐Like Freestanding Films for Flexible Solid‐State Asymmetric Supercapacitors

Free‐standing paper‐like thin‐film electrodes have great potential to boost next‐generation power sources with highly flexible, ultrathin, and lightweight requirements. In this work, silver‐quantum‐dot‐ (2–5 nm) modified transition metal oxide (including MoO₃ and MnO₂) paper‐like electrodes are developed for energy storage applications. Benefitting from the ohmic contact at the interfaces between silver quantum dots and MoO₃ nanobelts (or MnO₂ nanowires) and the binder‐free nature and 0D/1D/2D nanostructured 3D network of the fabricated electrodes, substantial improvements on the electrical conductivity, efficient ionic diffusion, and areal capacitances of the hybrid nanostructure electrodes are observed. With this proposed strategy, the constructed asymmetric supercapacitors, with Ag quantum dots/MoO₃ “paper” as anode, Ag quantum dots/MnO₂ “paper” as cathode, and neutral Na₂SO₄/polyvinyl alcohol hydrogel as electrolyte, exhibit significantly enhanced energy and power densities in comparison with those of the supercapacitors without modification of Ag quantum dots on electrodes; present excellent cycling stability at different current densities and good flexibility under various bending states; offer possibilities as high‐performance power sources with low cost, high safety, and environmental friendly properties.     

A Vesicle Supra‐Assembly Approach to Synthesize Amine‐Functionalized Hollow Dendritic Mesoporous Silica Nanospheres for Protein Delivery

Intracellular delivery of proteins is a promising strategy of intervention in disease, which relies heavily on the development of efficient delivery platforms due to the cell membrane impermeability of native proteins, particularly for negatively charged large proteins. This work reports a vesicle supra‐assembly approach to synthesize novel amine‐functionalized hollow dendritic mesoporous silica nanospheres (A‐HDMSN). An amine silica source is introduced into a water–oil reaction solution prior to the addition of conventional silica source tetraethylorthosilicate. This strategy favors the formation of composite vesicles as the building blocks which further assemble into the final product. The obtained A‐HDMSN have a cavity core of ≈170 nm, large dendritic mesopores of 20.7 nm in the shell and high pore volume of 2.67 cm³ g^?1. Compared to the calcined counterpart without amine groups (C‐HDMSN), A‐HDMSN possess enhanced loading capacity to large negative proteins (IgG and β‐galactosidase) and improved cellular uptake performance, contributed by the cationic groups. A‐HDMSN enhance the intracellular uptake of β‐galactosidase by up to 5‐fold and 40‐fold compared to C‐HDMSN and free β‐galactosidase, respectively. The active form of β‐galactosidase delivered by A‐HDMSN retains its intracellular catalytic functions.     

A Colloidal‐Quantum‐Dot‐Based Self‐Charging System via the Near‐Infrared Band

A novel self‐charging platform is proposed using colloidal‐quantum‐dot (CQD) photovoltaics (PVs) via the near‐infrared (NIR) band for low‐power electronics. Low‐bandgap CQDs can convert invisible NIR light sources to electrical energy more efficiently than wider spectra because of reduced thermalization loss. This energy‐conversion strategy via NIR photons ensures an enhanced photostability of the CQD devices. Furthermore, the NIR wireless charging system can be concealed using various colored and NIR‐transparent fabric or films, providing aesthetic freedom. Finally, an NIR‐driven wireless charging system is demonstrated for a wearable healthcare bracelet by integrating a CQD PVs receiver with a flexible lithium‐ion battery and entirely embedding them into a flexible strap, enabling permanent self‐charging without detachment.     

Silica fluorescent nanospheres containing a large amount of quantum dots prepared using liposomes as templates

Quantum dot (QD) fluorescent spheres have captivated many scientists because of their many potential applications in biomedical research. In this work, QD nanospheres were prepared using a novel method: incorporating QDs into nano-liposomes and then synthesising a silica shell using a lipid membrane as the template. The results showed that the nanocomposites obtained were spherical in shape, and each nanosphere contained a silica shell and the cores consisted of a large amount of QDs. Ultrathin sections of the spheres showed that the thickness of the silica shell was about 50–60?nm. Because the QD cores were coated with liposome and thick silica shell, the bright field of the silica sphere suspension was close to milk white in colour, which was different from that of the red-coloured QD solution. Although the quantum yield of the silica spheres (2.27%) was lower than that of the QDs (23.52%), these nanospheres still emitted a bright fluorescence, and there was no obvious difference between the fluorescent colour of the nanosphere suspension and the QD solution.