Cross-Linked Polyacrylic-Based Hydrogel Polymer Electrolytes for Flexible Supercapacitors.

Hydrogel polymer electrolytes (GPEs), as an important component of flexible energy storage devices, have gradually received wide attention compared with traditional liquid electrolytes due to their advantages of good mechanical, bending, and safety properties. In this paper, two cross-linked GPEs of poly(acrylic acid-co-acrylamide) or poly(acrylic acid-co-N-methylolacrylamide) with NaNO3 aqueous solution (P(AA-co-AM)/NaNO3 or P(AA-co-HAM)/NaNO3) were successfully prepared using radical polymerization, respectively, using acrylic acid (AA) as the monomer, N-methylolacrylamide (HAM) or acrylamide (AM) as the comonomer, and N, N-methylenebisacrylamide (MBAA) as the cross-linking agent. We investigated the morphology, glass transition temperature (Tg), ionic conductivities, mechanical properties, and thermal stabilities of the two GPEs. By comparison, P(AA-co-HAM)/NaNO3 GPE exhibits a higher ionic conductivity of 2.00 × 10-2 S/cm, lower Tg of 152 °C, and appropriate mechanical properties, which are attributed to the hydrogen bonding between the -COOH and -OH, and moderate cross-linking. The flexible symmetrical supercapacitors were assembled with the two GPEs and two identical activated carbon electrodes, respectively. The results show that the flexible supercapacitor with P(AA-co-HAM)/NaNO3 GPE shows good electrochemical performance with a specific capacitance of 63.9 F g-1 at a current density of 0.2 A g-1 and a capacitance retention of 89.4% after 3000 charge-discharge cycles. Our results provide a simple and practical design strategy of GPEs for flexible supercapacitors with wide application prospects.

Inhibiting MEK1 R189 citrullination enhances the chemosensitivity of docetaxel to multiple tumour cells.

Drug resistance is still a big challenge for cancer patients. We previously demonstrated that inhibiting peptidylarginine deiminase 2 (PADI2) enzyme activity with Cl-amine increases the efficacy of docetaxel (Doc) on tamoxifen-resistant breast cancer cells with PADI2 expression. However, it is not clear whether this effect applies to other tumour cells. Here, we collected four types of tumour cells with different PADIs expression and fully evaluated the inhibitory effect of the combination of PADIs inhibitor (BB-Cla) and Doc in vitro and in vivo on tumour cell growth. Results show that inhibiting PADIs combined with Doc additively inhibits tumour cell growth across the four tumour cells. PADI2-catalysed citrullination of MEK1 Arg 189 exists in the four tumour cells, and blocking the function of MEK1 Cit189 promotes the anti-tumour effect of Doc in these tumour cells. Further analysis shows that inhibiting MEK1 Cit189 decreases the expression of cancer cell stemness factors and helps prevent cancer cell stemness maintenance. Importantly, this combined treatment can partially restore the sensitivity of chemotherapy-resistant cells to docetaxel or cisplatin in tumour cells. Thus, our study provides an experimental basis for the combined therapeutic approaches using docetaxel- and PADIs inhibitors-based strategies in tumour treatment. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

PARP1-catalyzed PARylation of YY1 mediates endoplasmic reticulum stress in granulosa cells to determine primordial follicle activation.

Although only a small number of primordial follicles are known to be selectively activated during female reproductive cycles, the mechanisms that trigger this recruitment remain largely uncharacterized. Misregulated activation of primordial follicles may lead to the exhaustion of the non-renewable pool of primordial follicles, resulting in premature ovarian insufficiency. Here, we found that poly(ADP-ribose) polymerase 1 (PARP1) enzymatic activity in the surrounding granulosa cells (GCs) in follicles determines the subpopulation of the dormant primordial follicles to be awakened. Conversely, specifically inhibiting PARP1 in oocytes in an in vitro mouse follicle reconstitution model does not affect primordial follicle activation. Further analysis revealed that PARP1-catalyzed transcription factor YY1 PARylation at Y185 residue facilitates YY1 occupancy at Grp78 promoter, a key molecular chaperone of endoplasmic reticulum stress (ERS), and promotes Grp78 transcription in GCs, which is required for GCs maintaining proper ERS during primordial follicle activation. Inhibiting PARP1 prevents the loss of primordial follicle pool by attenuating the excessive ERS in GCs under fetal bisphenol A exposure. Together, we demonstrate that PARP1 in GCs acts as a pivotal modulator to determine the fate of the primordial follicles and may represent a novel therapeutic target for the retention of primordial follicle pool in females.

Tightly intercalated Ti3C2Tx/MoO3-x/PEDOT:PSS free-standing films with high volumetric/gravimetric performance for flexible solid-state supercapacitors.

Ti3C2Tx-MXenes have extremely promising applications in electrochemistry, but the development of Ti3C2Tx is limited due to severe self-stacking problem. Here, we introduced oxygen vacancy-enriched molybdenum trioxide (MoO3-x) with pseudocapacitive properties as the intercalator of Ti3C2Tx and PEDOT with high electronic conductivity as the co-intercalator and conductive binder of Ti3C2Tx to synthesize Ti3C2Tx/MoO3-x/PEDOT:PSS (TMP) free-standing films by vacuum-assisted filtration and H2SO4 soaking. The tightly intercalated free-standing film structure can effectively improve the self-stacking phenomenon of Ti3C2Tx, expose more active sites and facilitate electron/ion transport, thus making TMP show excellent electrochemical performance. The volumetric and gravimetric capacitance of optimized TMP-2 can reach 1898.5 F cm-3 and 523.0 F g-1 at 1 A g-1 with a rate performance of 90.5% at the current density from 1 A g-1 to 20 A g-1, which is significantly better than those of MXene-based composites reported in the literature. The directly-assembled TMP-2//TMP-2 flexible solid-state supercapacitor displays high energy/power output performances (25.1 W h L-1 at 6383.1 W L-1, 6.9 W h kg-1 at 1758.4 W kg-1) and there is no obvious change after 100 cycles at a bending angle of 180°. As a result, the tightly intercalated TMP-2 free-standing film with high volumetric/gravimetric capacitances is a promising material for flexible energy storage devices.

Spinel LiMn2O4 nanoparticles fabricated by the flexible soft template/Pichini method as cathode materials for aqueous lithium-ion capacitors with high energy and power density.

Spinel LiMn2O4 (LMO) with a three-dimensional structure has become one of the cathode materials that has gained the most interest due to its safety, low price and abundant resources. However, the lithium ion transmission is limited by large particle size and particle agglomeration of LMO. Thus, reducing the particle size and agglomeration of LMO can effectively improve its lithium ion transmission. Here, we synthesized a LMO cathode material with a nanoscale crystal size using the flexible expanded graphite (EG) soft template and Pichini method. EG-controlled particle size and particle agglomeration of LMO is conducive to charge transfer and diffusion of lithium ions between LMO and the electrolyte, meanwhile, there are more redox sites on the nanosized LMO particles, which makes the redox reaction of LMO more thorough during the charge and discharge process, resulting in high capacitance performance. In order to obtain the considerably required lithium-ion capacitors (LICs) with high energy density and power density, we assembled aqueous LMO//activated carbon (AC) LICs with 5 M LiNO3 as the aqueous electrolytes, which are environmentally friendly, safe, low cost and have higher electrical conductivity than organic electrolytes. The optimal LIC has an energy density of 32.63 W h kg-1 at a power density of 500 W kg-1 and an energy density of 8.06 W h kg-1 at a power density of 10 000 W kg-1, which is higher than most of the LMO-based LICs in previous reports. After 2000 cycles, the specific capacitance retention rate was 75.9% at a current density of 3 A g-1. Therefore, our aqueous LMO//AC LICs synthesized by the soft template/Pichini method have wide prospects and are suitable for low-cost, high-safety and high-power applications.

One-step fabrication of nanosized LiFePO4/expanded graphite composites with a particle growth inhibitor and enhanced electrochemical performance of aqueous Li-ion capacitors.

It is reported that olivine-type lithium iron phosphate (LFP) for Li-ion batteries is one of the most widely utilized cathode materials, but its high-power applications are limited due to its intrinsically poor ion transfer rate and conductivity. Therefore, it is highly desired to fabricate LFP Li-ion capacitors (LICs) with high power performance and excellent cyclic reversibility, especially in safe, low cost and environmentally friendly aqueous electrolytes. Here, we fabricate LFP/expanded graphite (EG) nanocomposites by a one-step process, in which polyethylene glycol (PEG) is used as the particle growth inhibitor combined with vacuum infiltration of the LFP precursor into EG as a conductive sub-phase, and further investigate their high-power performance in aqueous LICs. Embedding spherical LFP nanoparticles with well-controlled size and agglomeration into the pores of EG and wrapping LFP nanoparticles by EG films contribute to the rapid electron and ion diffusion in LFP/EG composites, resulting in excellent cyclic reversibility and rate performance of LFP/EG composites. The aqueous LFP/EG//active carbon (AC) LICs were assembled in LiNO3 electrolytes with LFP/EG composites and AC as the positive and negative electrodes, respectively. The optimal LIC shows a power density of 2367.9 W kg-1 at an energy density of 6.5 W h kg-1, dramatically favorable rate characteristics and excellent cycle life with 82.1% capacitance retention of its primary capacitance at 2 A g-1 after 6000 cycles, markedly higher than those of the commercial LFP LIC. The presented aqueous LFP/EG//AC LICs with excellent electrochemical performance are expected to have broad high-power appliances that are cost-sensitive and highly secure.