DNMT1 determines osteosarcoma cell resistance to apoptosis by associatively modulating DNA and mRNA cytosine-5 methylation.

Cellular apoptosis is a central mechanism leveraged by chemotherapy to treat human cancers. 5-Methylcytosine (m5C) modifications installed on both DNA and mRNA are documented to regulate apoptosis independently. However, the interplay or crosstalk between them in cellular apoptosis has not yet been explored. Here, we reported that promoter methylation by DNMT1 coordinated with mRNA methylation by NSun2 to regulate osteosarcoma cell apoptosis. DNMT1 was induced during osteosarcoma cell apoptosis triggered by chemotherapeutic drugs, whereas NSun2 expression was suppressed. DNMT1 was found to repress NSun2 expression by methylating the NSun2 promoter. Moreover, DNMT1 and NSun2 regulate the anti-apoptotic genes AXL, NOTCH2, and YAP1 through DNA and mRNA methylation, respectively. Upon exposure to cisplatin or doxorubicin, DNMT1 elevation drastically reduced the expression of these anti-apoptotic genes via enhanced promoter methylation coupled with NSun2 ablation-mediated attenuation of mRNA methylation, thus rendering osteosarcoma cells to apoptosis. Collectively, our findings establish crosstalk of importance between DNA and RNA cytosine methylations in determining osteosarcoma resistance to apoptosis during chemotherapy, shedding new light on future treatment of osteosarcoma, and adding additional layers to the control of gene expression at different epigenetic levels.

Fabrication of biodegradable hollow microsphere composites made of polybutylene adipate co-terephthalate/polyvinylpyrrolidone for drug delivery and sustained release.

Sustained drug release has attracted increasing interest in targeted drug therapy. However, existing methods of drug therapy suffer drug action time, large fluctuations in the effective concentration of the drug, and the risk of side effects. Here, a biodegradable composite of polybutylene adipate co-terephthalate/polyvinylpyrrolidone (PBAT/PVP) consisting of electrospun hollow microspheres as sustained-released drug carriers is presented. The as-prepared PBAT/PVP composites show faster degradation rate and drug (Erlotinib) release than that of PBAT. Furthermore, PBAT/PVP composites loaded with Erlotinib provide sustained release effect, thus achieving a better efficacy than that after the direct injection of erlotinib due to the fact that the composites allow a high drug concentration in the tumor for a longer period. Hence, this work provides a potential effective solution for clinical drug therapy and tissue engineering using drug microspheres with a sustained release.

Reducing Open-Circuit Voltage Deficit in Perovskite Solar Cells via Surface Passivation with Phenylhydroxylammonium Halide Salts.

Suppressing non-radiative recombination via passivating surface defects of perovskite films has demonstrated an excellent strategy for high-performance perovskite solar cells (PSCs). However, it is still hard to realize both high open-circuit voltage (Voc ) of >1.2 V and high power conversion efficiency (PCE) of >22%, because the optimized bandgap of perovskite films is less than 1.60 eV for efficient light harvesting and Voc deficit is generally unavoidable due to carriers recombination. Here, the surface of the perovskite film is treated with a series of phenylhydroxylammonium halide salts and it is found that all of them can remarkably prolong the carrier lifetime owing to their excellent capability of surface defects passivation. The best PSC with phenylbutylammonium bromide treatment realizes a PCE of 22.67% with a Voc of 1.216 V, corresponding to a small Voc deficit of ≈344 mV.

Lateral Photodetectors Based on Double-Cable Polymer/Two-Dimensional Perovskite Heterojunction.

Double-cable conjugated polymers and two-dimensional (2D) perovskites are both promising materials for next-generation photodetectors (PDs) due to their solution processibility and tunable optoelectronic properties. In this work, a lateral PD is designed by layering a double-cable conjugated polymer film atop a 2D Ruddlesden-Popper perovskite film. Compared to the corresponding single-layer polymer and perovskite PDs, the heterojunction device exhibits greatly improved performance with a high responsivity of 27.06 A W-1, an on/off ratio of 1379, and a short rise/decay time of 3.53/3.78 ms. In addition, a flexible device using polyimide as the substrate is successfully fabricated and exhibits comparable performance with the device on glass. This work demonstrates the great potential of double-cable polymer/2D perovskite heterojunctions in future flexible optoelectronics.

An Efficient Trap Passivator for Perovskite Solar Cells: Poly(propylene glycol) bis(2-aminopropyl ether).

Perovskite solar cells (PSCs) are regarded as promising candidates for future renewable energy production. High-density defects in the perovskite films, however, lead to unsatisfactory device performances. Here, poly(propylene glycol) bis(2-aminopropyl ether) (PEA) additive is utilized to passivate the trap states in perovskite. The PEA molecules chemically interact with lead ions in perovskite, considerably passivate surface and bulk defects, which is in favor of charge transfer and extraction. Furthermore, the PEA additive can efficiently block moisture and oxygen to prolong the device lifetime. As a result, PEA-treated MAPbI3 (MA: CH3NH3) solar cells show increased power conversion efficiency (PCE) (from 17.18 to 18.87%) and good long-term stability. When PEA is introduced to (FAPbI3)1-x(MAPbBr3)x (FA: HC(NH2)2) solar cells, the PCE is enhanced from 19.66 to 21.60%. For both perovskites, their severe device hysteresis is efficiently relieved by PEA.

Band engineering at the interface of all-inorganic CsPbI2Br solar cells.

An all-inorganic CsPbI2Br perovskite with excellent phase stability and thermal stability has been considered to be a promising candidate for photovoltaic application. However, low efficiency and high moisture sensitivity hinder its advancement. In this work, we exploit 4-bromobenzylamine hydriodate post-treatment on CsPbI2Br thin films to assist the extraction of holes and to block the flow of electrons to the hole transport layer through band engineering at the CsPbI2Br bulk/surface. We found through depth profile analysis that a small amount of BrBeAI permeates into the CsPbI2Br bulk and mainly locates at the CsPbI2Br grain boundaries. This treatment leads to an improved short-circuit current of CsPbI2Br solar cells and an enhanced efficiency from 13.10% to 14.63%. In addition, the incorporation of the hydrophobic organic component into perovskite films effectively enhances the moisture resistance. This result proves that utilizing organic ammonium salt to improve the performance of the device through band alignment is an effective strategy for all-inorganic perovskite solar cell optimization.

High-Performance Planar Perovskite Solar Cells with Negligible Hysteresis Using 2,2,2-Trifluoroethanol-Incorporated SnO2.

An efficient electron transport layer (ETL) between the perovskite absorber and the cathode plays a crucial role in obtaining high-performance planar perovskite solar cells (PSCs). Here, we incorporate 2,2,2-trifluoroethanol (TFE) in the commonly used tin oxide (SnO2) ETL, and it successfully improves the power conversation efficiency (PCE) and suppresses the hysteresis of the PSCs: the PCE is increased from 19.17% to 20.92%, and the hysteresis is largely reduced to be almost negligible. The origin of the enhancement is due to the improved electron mobility and optimized work function of the ETL, together with the reduced traps in the perovskite film. In addition, O2 plasma is employed to treat the surface of the TFE-incorporated SnO2 film, and the PCE is further increased to 21.68%. The concept here of incorporating organic small molecules in the ETL provides a strategy for enhancing the performance of the planar PSCs.

A Simple, Small-Bandgap Porphyrin-Based Conjugated Polymer for Application in Organic Electronics.

A simple, small-bandgap porphyrin-based conjugated polymer with ethylnyl linkers is prepared for application in organic electronics. Beneficial from quinoid resonance form, the polymer showed near-infrared absorption up to 1000 nm and strong photoluminescence emission with a quantum yield of 0.2%. The polymer can be successfully applied to several electronic devices, such as organic field-effect transistors with ambipolar charge transport, organic solar cells with a high external quantum efficiency of 0.58 at 970 nm, and organic photodetectors with high responsibility and detectivity.

Bilayer PbS Quantum Dots for High-Performance Photodetectors.

Due to their wide tunable bandgaps, high absorption coefficients, easy solution processabilities, and high stabilities in air, lead sulfide (PbS) quantum dots (QDs) are increasingly regarded as promising material candidates for next-generation light, low-cost, and flexible photodetectors. Current single-layer PbS-QD photodetectors suffer from shortcomings of large dark currents, low on-off ratios, and slow light responses. Integration with metal nanoparticles, organics, and high-conducting graphene/nanotube to form hybrid PbS-QD devices are proved capable of enhancing photoresponsivity; but these approaches always bring in other problems that can severely hamper the improvement of the overall device performance. To overcome the hurdles current single-layer and hybrid PbS-QD photodetectors face, here a bilayer QD-only device is designed, which can be integrated on flexible polyimide substrate and significantly outperforms the conventional single-layer devices in response speed, detectivity, linear dynamic range, and signal-to-noise ratio, along with comparable responsivity. The results which are obtained here should be of great values in studying and designing advanced QD-based photodetectors for applications in future flexible optoelectronics.