Single-Layer ZnO Hollow Hemispheres Enable High-Performance Self-Powered Perovskite Photodetector for Optical Communication.

The carrier transport layer with reflection reduction morphology has attracted extensive attention for improving the utilization of light. Herein, we introduced single-layer hollow ZnO hemisphere arrays (ZHAs) behaving light trapping effect as the electron transport layer in perovskite photodetectors (PDs). The single-layer hollow ZHAs can not only reduce the reflection, but also widen the angle of the effective incident light and especially transfer the distribution of the optical field from the ZnO/FTO interface to the perovskite active layer confirmed by the 3D finite-difference time-domain simulation. These merits benefit for the generation, transport and separation of carriers, improving the light utilization efficiency. Finally, our optimized FTO/ZHA/CsPbBr3/carbon structure PDs showed high self-powered performance with a linear dynamic range of 120.3 dB, a detectivity of 4.2 × 1012 Jones, rise/fall time of 13/28 µs and the f-3 dB of up to 28 kHz. Benefiting from the high device performance, the PD was demonstrated to the application in the directional transmission of encrypted files as the signal receiving port with super high accuracy. This work uniquely utilizes the features of high-performance self-powered perovskite PDs in optical communication, paving the path to wide applications of all-inorganic perovskite PDs.

[Construction, expression and identification of chimeric foot-and-mouth disease virus-like particles].

To improve the specific recognition and presentation of virus-like particle (VLPs), and to develop immune-targeted VLPs vaccine, the gene fragment encoding OVA257₋264 peptide was inserted into the VP3 gene of foot-and-mouth disease virus (FMDV) between the 171th and 172th amino acids (aa) or 173th and 174th aa by reverse PCR. The recombinant proteins were expressed by using Escherichia coli and assembled into chimeric VLP (VLP(OVA)) in vitro after purification. The VLP(OVA) was measured by dynamic light scattering and transmission electron microscopy. The recombinant protein and the assembled VLPs were evaluated by Western blotting, enzyme-linked immunosorbent assay and laser scanning confocal microscopy to confirm the insertion of OVA257₋264 peptide into VP3 and its location. The results show that insertion of OVA257₋264 into the 173th and 174th aa of FMDV VP3 did not affect the assembly of VLPs. The VLP(OVA) in size was larger than VLPs, and the OVA257₋264 peptide was located on the surface of VLP(OVA).

Welding Perovskite Nanowires for Stable, Sensitive, Flexible Photodetectors.

Compared with a single nanowire (NW) or NW array, the simpler preparation process of an NW network (NWN) enables it to be fabricated in large-scale, flexible, and wearable applications of photodetectors (PDs). However, the NWN behaves many microinterfaces (MIs) between NWs, seriously limiting the device performance and stability. Here, we demonstrate a welding strategy for an MAPbI3 NWN, which enhances the crystallinity of the NWN and enhances the radial transmission of photogenerated carriers, leading to a better device performance with ultrahigh stability. Our NWN PDs fabricated by using the welding strategy showed ultrahigh performance with an on/off ratio and detectivity of 2.8 × 104 and 4.16 × 1012 Jones, respectively, which are the best performance for reported metal-semiconductor-metal (MSM) perovskite NWN PDs and are comparable to those of single-NW or NW array PDs. More importantly, our unpackaged NWN PDs show ultrahigh storage stability in air with a humidity of 55-65%, and the flexible NWN PDs can enable 250 bending cycles at different bending radii and 1000 bending cycles at fixed bending radii with no performance degradation being observed. These results indicate our welding strategy is very powerful for improving the performance of the NW device with applications in the wearable field.

All-Inorganic Halide Perovskite Alloy Nanowire Network Photodetectors with High Performance.

Organic-inorganic hybrid lead halide perovskites have attracted much attention in the photoelectric field due to their excellent characteristics, such as a tunable band gap, simple fabrication process, and high photoelectric conversion efficiency. However, the commercialization of the perovskite-based devices still faces many challenges, one of which is the inclusion of the toxic lead. Herein, we demonstrated a two-step solution method for synthesizing tin-based perovskite nanowires (NWs) with their application in photodetectors (PDs). By changing the halide exchange time and the Sn content in the precursor, the dark current of the CsPbxSn1-x(BryI1-y)3 perovskite NW PDs increased with increasing content of tin and decreased with increasing Br concentration, and the lowest dark current with a value of 0.672 nA at 1 V was achieved for the perovskite alloy NW PDs synthesized with 0.5 mg mL-1 SnI2. Our optimized perovskite alloy NW PDs showed high performance with a linear dynamic range of up to 120 dB, a rising/falling time of 4.25/4.82 ms, and a detectivity of 2 × 1010 Jones. In addition, our Sn-based perovskite NW devices could maintain good performance after storing in air for 30 days. These results demonstrated good practical application for the Sn-based perovskite NW devices.

Biomineralization improves the thermostability of foot-and-mouth disease virus-like particles and the protective immune response induced.

Virus-like particles (VLPs) are an ideal substitute for traditionally inactivated or attenuated viruses in vaccine production. However, given the properties of their native proteins, the thermal stability of VLPs is poor. In this study, calcium mineralization was used to fabricate foot-and-mouth disease virus (FMDV) VLPs as immunogenic core-shell particles with improved thermal stability. The biomineralized VLPs were stably stored at 24 °C and 37 °C for 13 and 11 days, respectively. Animal experiments showed that the biomineralized VLPs induced specific protective immunogenic effects, even after storage at 37 °C for 7 days. The biomineralized VLPs also effectively activated dendritic cells (DCs) to express high levels of surface MHC-II, costimulatory molecules, and proinflammatory cytokines. The DCs activated by the mineralized VLPs rapidly localized to the secondary lymphoid tissues and promoted the activation of the native T-cell population. These results suggest that the biomineralization of VLPs is an effective approach to vaccine production insofar as the mineralized shell provides an adjuvant effect which improves the immunogenicity of the VLPs. Biomineralization can also confer superior heat resistance on VLPs, an advantage in vaccine production. The successful development of thermally stable, biomineralized VLPs will reduce our dependence on cold storage and delivery.

Low-reflection, (110)-orientation-preferred CsPbBr3 nanonet films for application in high-performance perovskite photodetectors.

All-inorganic metal halide perovskites have attracted great interest in recent years due to their good device performance with higher thermal stability than that of their organic-inorganic perovskite counterparts. However, the all-inorganic perovskite polycrystalline films prepared by the conventional spin-coating method possess many pinholes, nonuniform surface with many small crystals, and irregular agglomerates, limiting their device performance. Herein, we introduced a monolayer nano-polystyrene (PS) sphere confined growth method for obtaining CsPbBr3 nanonet films (NFs) with ordered nanostructures grown in the preferred (110) orientation, which is beneficial for the charge carrier transport and the light-harvesting efficiency. The (110) peak intensity of CsPbBr3 NFs increased with the increase of the diameter of the monolayer sphere, while the (001) peak intensity was suppressed greatly, indicating the more preferred (110) oriented growth. The PDs based on (110)-orientation-preferred CsPbBr3 NFs prepared by using 850 nm PS spheres showed the best performance. The best performing device displayed the biggest linear dynamic range of up to 120 dB. In addition, a responsivity of 2.84 A W-1 and a detectivity of 5.47 × 1012 Jones were also achieved.

Retinoic acid synthesis by a population of NG2-positive cells in the injured spinal cord.

Retinoic acid (RA) promotes growth and differentiation in many developing tissues but less is known about its influence on CNS regeneration. We investigated the possible involvement of RA in rat spinal cord injury (SCI) using the New York University (NYU) impactor to induce mild or moderate spinal cord contusion injury. Changes in RA at the lesion site were determined by measuring the activity of the enzymes for its synthesis, the retinaldehyde dehydrogenases (RALDHs). A marked increase in enzyme activity occurred by day 4 and peaked at days 8-14 following the injuries. RALDH2 was the only detectable RALDH present in the control or injured spinal cord. The cellular localization of RALDH2 was identified by immunostaining. In the noninjured spinal cord, RALDH2 was detected in oligodendroglia positive for the markers RIP and CNPase. Expression was also intense in the arachnoid membrane surrounding the spinal cord. After SCI the increase in RALDH2 was independent of the RIP- and CNPase-positive cells, which were severely depleted. Instead, RALDH2 was present in a cell type not previously identified as capable of synthesizing RA, that expressed NG2 and that was negative for markers of astrocytes, oligodendroglia, microglia, neurons, Schwann cells and immature lymphocytes. We postulate that the RALDH2- and NG2-positive cells migrate into the injured sites from the adjacent arachnoid membrane, where the RALDH2-positive cells proliferate substantially following SCI. These findings indicate that close correlations exist between RA synthesis and SCI and that RA may play a role in the secondary events that follow acute SCI.