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A widely used component of high-efficiency perovskite solar cells (PSCs) is the molecular hole-transport material (HTM) spiro-OMeTAD. This organic solid needs to be p-doped to acquire sufficient hole conductivity. However, the conventional doping method using LiTFSI in the air is slow, sensitive to the environment, and may lead to the deterioration of the PSCs by unintended oxidation or dopant migration. It is thus highly desirable to develop fast doping approaches that avoid exposing the PSC to ambient air and easy-to-move dopant ions. We report here that light absorption by spiro-OMeTAD itself triggers redox photochemistry that has so far been ignored. Strikingly, we found that Y(III) or La(III)-tBP complexes catalyze the symmetry-breaking charge separation of photo-excited spiro-OMeTAD, resulting in the efficient p-doping of the HTM. Using this photo-redox process, we realize PSCs with superior stability over cells using conventional doping that show no degradation under continuous illumination over 1,000 h.

Background: The development of molecular imaging agents targeting epidermal growth factor receptor (EGFR) with L858R mutation may help with the selection of non-small cell lung carcinoma (NSCLCL) patients who may benefit from EFGR tyrosine kinase inhibitor (TKI) therapy.Objective: In this study, we developed 99mTc STHHYYP-GHEG-ECGK-tetramethylrhodamine (STHHYYP-ECGK-TAMRA) to target EGFR with L858R mutation in NSCLC tumors and verified its probability as a molecular imaging agent.Methods: Fmoc solid-phase peptide synthesis was used to synthesize STHHYYP-ECGKTAMRA. 99mTc labelled STHHYYP-ECGK-TAMRA was prepared. Gamma imaging, fluorescent imaging and biodistribution were performed in murine models bearing NCI-H1975 and NCI-H1650 tumors.Results: The binding affinity value (Kd) of 99mTc STHHYYP-ECGK-TAMRA was estimated to be 130.6 ± 29.2 nM in NCI-H1975 cells. The gamma camera images showed a substantial uptake of 99mTc STHHYYP-ECGK-TAMRA in the NCI-H1975 tumor. The % injected dose/gram of the NCI-H1975 tumor tissue was 2.77 ± 0.70 and 3.48 ± 1.01 at 1 and 3 h, respectively.Conclusion: Specific binding of 99mTc STHHYYP-ECGK-TAMRA to L858R-mutated EGFRpositive NCI-H1975 cells and tumors was demonstrated in in vivoand in vitrostudies. The results suggest that 99mTc STHHYYP-ECGK-TAMRA is a good candidate agent for dualmodality imaging targeting EGFR with L858R mutation.

A novel rotary-type atomic layer deposition (ALD) process for coating platinum thin film on three-dimensional (3D) substrates is demonstrated. High uniformity and conformability of the platinum thin-film deposition on 3D substrates were confirmed, ensuring the controllability of the new ALD technique. The results for this technique surpassed those of the conventional wet method and ordinary atomic layer deposition, which both have a limited specific surface area. To demonstrate the application of this new technology, Pt nano-film coated γ-Al2O3was produced using the rotary-type ALD and applied to diesel oxidation catalysts (DOCs). The produced DOCs showed high Pt content when the number of ALD cycles was increased, and thereby exhibited more complete combustion of gaseous pollutants, such as CO, C3H8, and NO, even at lower temperatures. Pt nano-film deposition by the rotary-type ALD process was first optimised on Si wafer substrates. The process was controlled by four parameters: processing temperature, number of ALD cycles, precursor pulse time, and reactant pulse time. Deposition of the Pt nano-film was mainly determined by the processing temperature and the number of ALD cycles. The average growth per cycle and density of the Pt nano-film were found to be 0.8 Å/cycle and 21.0 g/cm3, respectively. The same procedure and conditions were applied to 3D γ-Al2O3powder substrates for DOCs, which demonstrated greater conversion performance compared with conventional Pt-used DOCs.

Conventional antiferroelectric materials with atomic-scale anti-aligned dipoles undergo a transition to a ferroelectric (FE) phase under strong electric fields. The moiré superlattice formed in the twisted stacks of van der Waals crystals exhibits polar domains alternating in moiré length with anti-aligned dipoles. In this moiré domain antiferroelectic (MDAF) arrangement, the distribution of electric dipoles is distinguished from that of two-dimensional FEs, suggesting dissimilar domain dynamics. Here we performed an operando transmission electron microscopy investigation on twisted bilayer WSe2to observe the polar domain dynamics in real time. We find that the topological protection, provided by the domain wall network, prevents the MDAF-to-FE transition. As one decreases the twist angle, however, this transition occurs as the domain wall network disappears. Exploiting stroboscopic operando transmission electron microscopy on the FE phase, we measure a maximum domain wall velocity of 300 μm s–1. Domain wall pinnings by various disorders limit the domain wall velocity and cause Barkhausen noises in the polarization hysteresis loop. Atomic-scale analysis of the pinning disorders provides structural insight on how to improve the switching speed of van der Waals FEs.

In situwireless monitoring for cell proliferation and detachment kinetics was conducted using pH-responsive zwitterionic polymer dots (Z-PDs), based on changes in electrochemical signals derived from Z-PD-coated substrates viathe interaction of charges transferred between Z-PDs and cells. Z-PD-coated substrates were found to be a potent means to monitor and manipulate cell adhesion and detachment because of their high sensitivity over a wide range of pH conditions, and modification of the coated substrates was confirmed using a wireless system. At neutral pH, Z-PD-coated wireless sensors exhibited π–π stacking involving aromatic rings with hydrophobic interactions, thereby promoting cell proliferation; consequently, an increase in the measured resistance was observed. In contrast, Z-PD-coated substrates triggered by acidic and basic conditions promoted cell detachment, which induced an increase in the resistance compared with Z-PD substrates at pH 6.8, as a result of charges transferred to support Z-PD internalization through cell membranes after detachment. Therefore, as a wireless biosensor with excellent pH responsiveness that facilitates cell proliferation and detachment and whose electrochemical signals could be additionally acquired viaa smartphone, Z-PD biosensors demonstrated a more favorable approach for monitoring cell–surface interactions than conventional optically based methods.

This study investigated a selective and sensitive theragnosis system for the specific targeting of the membrane and nuclei based on visible-light and pH-responsive TiO2-integrated cross-linked carbon dot (C-CD/TiO2) for tumor detection and controllable photothermal therapy. The cross-linking system was formed by boronate ester linkages between the TiO2-immobilized Dopa-decyl (D-CD) and zwitterionic-formed CD (Z-CD) for nuclear targeting, which showed fluorescence “off” at physiological pH. The fluorescence recovered to the “on” state in acidic cancer cells owing to cleavages of the boronate ester bonds, resulting in the disruption of the Förster resonance energy transfer that generated different CDs useful for tumor-selective biosensors and therapy. D-CD, which is hydrophobic, can penetrate the hydrophobic sites of the cell membrane; it caused a loss in the hydrophobicity of these sites after visible-light irradiation. This was achieved by the photocatalytic activity of the TiO2modulating energy bandgap, whereas the Z-CD targeted the nucleus, as confirmed by merged confocal microscopy images. D-CD augmented by photothermal heat also exhibited selective anticancer activity in the acidic tumor condition but showed only minimal effects at a normal site at pH 7.4. After C-CD/TiO2injection to an in vivotumor model, C-CD/TiO2efficiently ablated tumors under NIR light irradiation. The C-CD/TiO2group showed up-regulation of the pro-apoptotic markers such as P53and BAXin tumor. This material exhibited its potential as a theragnostic sensor with excellent biocompatibility, high sensitivity, selective imaging, and direct anticancer activity via photothermal therapy.

Recently, a great deal of research has focused on the study of self-healing hydrogels possessing electronic conductivity due to their wide applicability for use in biosensors, bioelectronics, and energy storage. The low solubility, poor biocompatibility, and lack of effective stimuli-responsive properties of their sp2carbon-rich hybrid organic polymers, however, have proven challenging for their use in electroconductive self-healing hydrogel fabrication. In this study, we developed stimuli-responsive electrochemical wireless hydrogel biosensors using ureidopyriminone-conjugated gelatin (Gel-UPy) hydrogels that incorporate diselenide-containing carbon dots (dsCD) for cancer detection. The cleavage of diselenide groups of the dsCD within the hydrogels by glutathione (GSH) or reactive oxygen species (ROS) initiates the formation of hydrogen bonds that affect the self-healing ability, conductivity, and adhesiveness of the Gel-UPy/dsCD hydrogels. The Gel-UPy/dsCD hydrogels demonstrate more rapid healing under tumor conditions (MDA-MB-231) compared to that observed under physiological conditions (MDCK). Additionally, the cleavage of diselenide bonds affects the electrochemical signals due to the degradation of dsCD. The hydrogels also exhibit excellent adhesiveness and in vivocancer detection ability after exposure to a high concentration of GSH or ROS, and this is comparable to results observed in a low concentration environment. Based on the combined self-healing, conductivity, and adhesiveness properties of the Gel-UPy/dsCD, this hydrogel exhibits promise for use in biomedical applications, particularly those that involve cancer detection, due to its selectivity and sensitivity under tumor conditions.

We developed a Tc-99m and fluorescence-labeled peptide, Tc-99m TAMRA-GHEG-ECG-GNQWFI, to target tumor cells, and evaluated the diagnostic performance as a dual-modality imaging agent for tumor in a murine model. TAMRA-GHEG-ECG-GNQWFI was synthesized using Fmoc solid-phase peptide synthesis. Radiolabeling of TAMRA-GHEG-ECG-GNQWFI with Tc-99m was done using ligand exchange via tartrate. Binding affinity and in vitro cellular uptake studies were performed. Gamma camera imaging, biodistribution, and ex vivo imaging studies were performed in murine models with U87MG tumors. Tumor tissue slides were prepared and analyzed with immunohistochemistry using confocal microscopy. After radiolabeling procedures with Tc-99m, Tc-99m TAMRA-GHEG-ECG-GNQWFI complexes were prepared in high yield (> 95%). The Kdof Tc-99m TAMRA-GHEG-ECG-GNQWFI determined by saturation binding was 29.5 ± 4.5 nM. Confocal microscopy images of U87MG cells incubated with TAMRA-GHEG-ECG-GNQWFI showed strong fluorescence in the cytoplasm. Gamma camera imaging revealed substantial uptake of Tc-99m TAMRA-GHEG-ECG-GNQWFI in tumors. Tumor uptake was effectively blocked by the co-injection of an excess concentration of GNQWFI. Specific uptake of Tc-99m TAMRA-GHEG-ECG-GNQWFI was assessed by biodistribution, ex vivo imaging, and immunohistochemistry stain studies. In vivo and in vitro studies revealed substantial and specific uptake of Tc-99m TAMRA-GHEG-ECG-GNQWFI in tumor cells. Tc-99m TAMRA-GHEG-ECG-GNQWFI could be a good candidate dual-modality imaging agent for tumors.

As silicon-based metal oxide semiconductor field effect transistors get closer to their scaling limit, the importance of resistive random-access memory devices increases due to their low power consumption, high endurance and retention performance, scalability, and fast switching speed. In the last couple of years, organic–inorganic lead halide perovskites have been used for resistive switching applications, where they outperformed conventional metal oxides in terms of large on/off ratio and low power consumption. However, there were scarce reports on lead-free perovskites for such applications. In this report, we prepared lead-free Au/A3Bi2I9/Pt/Ti/SiO2/Si (A is either Cs+or Rb+) devices and tested their resistive switching characteristics. They showed a forming step prior to repeating switching, low operating voltage (0.09 V for Rb3Bi2I9and 0.1 V for Cs3Bi2I9), large on/off ratio (>107), relatively high endurance (200 cycles for Rb3Bi2I9and 400 cycles for Cs3Bi2I9cycles), and high retention (1000 s). Such low voltage could be explained by grain boundary-modulated ion drift. Difference in endurance was speculated to be due to the difference in the surface roughness of films because Cs3Bi2I9films are smoother. To get rid of the forming step, 10% of the Bi3+cations were substituted with Na+cations. However, this method only worked on Rb-based structures. This phenomenon was explained by the defect formation energy, which can only be negative in a corner-sharing Rb3Bi2I9structure compared to a face-sharing octahedral Cs3Bi2I9structure. As a result, the forming step was removed, and 100 cycles endurance and 1000 s retention performance were obtained. Similarly, the lower endurance is suspected to be due to the poor surface quality of the film.

Surface passivation of perovskite grains is one of the promising methods to reduce recombination and improve stability of perovskite solar cells (PSCs). We herein report the effect of a melaminium iodide additive on the photovoltaic performance of PSCs based on (FAPbI3)0.875(CsPbBr3)0.125perovskite. Cyclic −C═N– and primary amine in melamine are a good hydrogen bond acceptor and Lewis base, which can interact with both the organic cation and Lewis acidic lead iodide in the perovskite film. Melaminium iodide is synthesized and added to the precursor solution, which is directly spin-coated to form the perovskite film. The presence of melaminium iodide additive reduces the trap density from 1.02 × 1016to 0.645 × 1016cm–3, which leads to the reduction of nonradiative recombination and thereby improving the mean open-circuit voltage and the fill factor from 1.054 to 1.095 V and from 0.693 to 0.725 V, receptively. In addition, photocurrent–voltage hysteresis is reduced by the melaminium iodide additive, which results in an enhanced average power conversion efficiency, obtained from reverse and forward scanned data, from 15.86 to 17.32%. Time-resolved photoluminescence confirms that melaminium iodide plays a more important role in passivating the rear surface of the perovskite layer contacting the hole transporting spiro-MeOTAD layer. An aging test under a relative humidity of 65% reveals that melaminium iodide improves stability because of the suppression of the defect evolved by moisture.

Currently, the most efficient perovskite solar cells (PSCs) mainly use planar and mesoporous titanium dioxide (TiO2) as an electron-transport layer (ETL). However, because of its intrinsic photocatalytic properties, TiO2can decompose perovskite absorber and lead to poor stability under solar illumination (ultraviolet light). Herein, a simplified architectural ETL-free PSC with enhanced efficiency and outstanding photostability is produced by the facile deposition of a bathocuproine (BCP) interlayer. Power conversion efficiency of the ETL-free PSC improves from 15.56 to 19.07% after inserting the BCP layer, which is the highest efficiency reported for PSCs involving an ETL-free architecture, versus 19.03% for the n–i–p full device using TiO2as an ETL. The BCP interlayer has been demonstrated to have several positive effects on the photovoltaic performances of devices, such as “modulation doping” of the perovskite layer, modification of FTO surface work function, and enhancing the charge-transfer efficiency between FTO and perovskite. Moreover, the BCP-based ETL-free devices exhibit outstanding photostability: the unencapsulated BCP-based ETL-free PSCs retain over 90% of their initial efficiencies after 1000 h of storage in air and maintain 92.2% after 450 h of exposure to full solar irradiation (without a UV filter), compared to only 14.1% in the n–i–p full cells under the same condition.