Host Poly Research Articles

Fabrication of free standing nano-SiO2 incorporated solid polymer electrolytes based on poly(vinyl) chloride

AbstractFree standing nanocomposite polymer electrolytes (NCPEs) based on the polymer host poly(vinyl) chloride (PVC) were successfully prepared using the solution casting technique. Lithium nitrate (LiNO3) and nano-sized silica (SiO2) (< 100 nm) were employed as the electrolyte and filler, respectively. Impedance studies revealed a maximum ionic conductivity value of 1.226 × 10−4 S/cm at room temperature for the PVC/LiNO3 with 5 wt.% nano-SiO2. X-ray diffraction (XRD) analysis verified the sample’s amorphous nature. Dielectric permittivity and relaxation time values were consistent with impedance results. Additionally, parameters such as diffusion coefficient, mobile concentration, and mobility were evaluated for the prepared samples. Differential scanning calorimetry (DSC) studies confirmed a change in glass transition temperature (Tg) of PVC/LiNO3/SiO2 sample. The scanning electron micrograph (SEM) images revealed a honeycomb morphology, indicating ease of Li+ ion transportation.

Type III secretion system effector YfiD inhibits the activation of host poly(ADP-ribose) polymerase-1 to promote bacterial infection

Modulation of cell death is a powerful strategy employed by pathogenic bacteria to evade host immune clearance and occupy profitable replication niches during infection. Intracellular pathogens employ the type III secretion system (T3SS) to deliver effectors, which interfere with regulated cell death pathways to evade immune defenses. Here, we reveal that poly(ADP-ribose) polymerase-1 (PARP1)-dependent cell death restrains Edwardsiella piscicida’s proliferation in mouse monocyte macrophages J774A.1, of which PARP1 activation results in the accumulation of poly(ADP-ribose) (PAR) and enhanced inflammatory response. Moreover, E. piscicida, an important intracellular pathogen, leverages a T3SS effector YfiD to impair PARP1’s activity and inhibit PAR accumulation. Once translocated into the host nucleus, YfiD binds to the ADP-ribosyl transferase (ART) domain of PARP1 to suppress its PARylation ability as the pharmacological inhibitor of PARP1 behaves. Furthermore, the interaction between YfiD and ART mainly relies on the complete unfolding of the helical domain, which releases the inhibitory effect on ART. In addition, YfiD impairs the inflammatory response and cell death in macrophages and promotes in vivo colonization and virulence of E. piscicida. Collectively, our results establish the functional mechanism of YfiD as a potential PARP1 inhibitor and provide more insights into host defense against bacterial infection.

Efficient Near‐Infrared Organic Light‐Emitting Diodes with Emission Peak Above 900 nm Enabled by Enhanced Photoluminescence Quantum Yields and Out‐Coupling Efficiencies

AbstractNear‐infrared organic light‐emitting diodes (NIR OLEDs) with emission peak above 900 nm are attractive for many emerging applications, spanning from bioimaging to light detection and ranging. However, the device performance of NIR OLEDs is generally limited by the low quantum efficiency of emitters because of the fast nonradiative transition process imposed by energy‐gap law and aggregation quenching. So far, only a few Pt(II) complexes delivering external quantum efficiency (EQE) over 1% are reported, while there is no comparable electroluminescence in heavy‐metal‐free fluorescent organic emitters. Here, NIR OLEDs centered at 934 nm by blending an acceptor–donor–acceptor type molecule Y11 into a polymer host poly[(9,9‐dioctylfluorenyl‐2,7‐diyl)‐alt‐(4,4′‐(N‐(4‐sec‐butylphenyl)diphenylamine) (TFB) are reported. The OLEDs show a remarkably high EQE of 1.72%. Moreover, owing to a low turn‐on voltage (≈0.9 V), the resultant NIR OLEDs have an electricity‐to‐light power efficiency surpassing 20 mW W−1. The improved device performance can be attributed to enhanced photoluminescence quantum yields (PLQYs) of the blends owing to suppressed aggregation quenching, and favorable light extraction from the emissive layer. Such values are the highest among fluorescent OLEDs with electroluminescence above 900 nm.

CCR4-NOT differentially controls host versus virus poly(a)-tail length and regulates HCMV infection.

Unlike most RNA and DNA viruses that broadly stimulate mRNA decay and interfere with host gene expression, human cytomegalovirus (HCMV) extensively remodels the host translatome without producing an mRNA decay enzyme. By performing a targeted loss-of-function screen in primary human fibroblasts, we here identify the host CCR4-NOT deadenylase complex members CNOT1 and CNOT3 as unexpected pro-viral host factors that selectively regulate HCMV reproduction. We find that the scaffold subunit CNOT1 is specifically required for late viral gene expression and genome-wide host responses in CCR4-NOT-disrupted cells. By profiling poly(A)-tail lengths of individual HCMV and host mRNAs using nanopore direct RNA sequencing, we reveal poly(A)-tails of viral messages to be markedly longer than those of cellular mRNAs and significantly less sensitive to CCR4-NOT disruption. Our data establish that mRNA deadenylation by host CCR4-NOT is critical for productive HCMV replication and define a new mechanism whereby herpesvirus infection subverts cellular mRNA metabolism to remodel the gene expression landscape of the infected cell. Moreover, we expose an unanticipated host factor with potential to become a therapeutic anti-HCMV target.

Structural basis for cloverleaf RNA-initiated viral genome replication.

The genomes of positive-strand RNA viruses serve as a template for both protein translation and genome replication. In enteroviruses, a cloverleaf RNA structure at the 5' end of the genome functions as a switch to transition from viral translation to replication by interacting with host poly(C)-binding protein 2 (PCBP2) and the viral 3CDpro protein. We determined the structures of cloverleaf RNA from coxsackievirus and poliovirus. Cloverleaf RNA folds into an H-type four-way junction and is stabilized by a unique adenosine-cytidine-uridine (A•C-U) base triple involving the conserved pyrimidine mismatch region. The two PCBP2 binding sites are spatially proximal and are located on the opposite end from the 3CDpro binding site on cloverleaf. We determined that the A•C-U base triple restricts the flexibility of the cloverleaf stem-loops resulting in partial occlusion of the PCBP2 binding site, and elimination of the A•C-U base triple increases the binding affinity of PCBP2 to the cloverleaf RNA. Based on the cloverleaf structures and biophysical assays, we propose a new mechanistic model by which enteroviruses use the cloverleaf structure as a molecular switch to transition from viral protein translation to genome replication.

Composition-Driven Polarization Distribution in Poly(vinylidene fluoride)-Based Copolymer Blends for High Power Density Capacitors

High power density capacitors have been highly demanded in modern electronics and pulsed power systems. Yet the long-standing challenge that restricts achieving high power in capacitors lies in the inverse relationship between the breakdown strength and permittivity of dielectric materials. Here, we introduce poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFE) into the host poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) to produce PVDF-based copolymer blends, resulting in composition-driven 0-3 type microstructures, featuring nanospheres of P(VDF-TrFE) lamellar crystals dispersed homogeneously in a P(VDF-HFP) matrix together with crystalline phase evolution from the γ-phase to the α-phase. At the critical composition, the TrFE/HFP mole ratio is equal to 1, and the blend film achieves maximum energy storage performance with discharged energy density (Udis) ∼ 24.3 J/cm3 at 607 MV/m. Finite element analyses reveal the relationship between microstructures, compositions, and the distribution of local electric field and polarization, which provide an in-depth understanding of the microscopic mechanism of the enhancement in energy storage capability of the blend films. More importantly, in a practical charge/discharge circuit, the blend film could deliver an ultrahigh energy density of 20.4 J/cm3, i.e., 88.3% of the total stored energy to 20 kΩ load in 2.8 μs (τ0.9), resulting a high power density of 7.29 MW/cm3, outperforming the reported dielectric polymer-based composites and copolymer films in both energy and power densities. The study thus demonstrates a promising strategy to develop high-performance dielectrics for high power capacitors.

Antibacterial activity of chitosan and zinc oxide impregnated in PVA-based membranes

The development of alternatives to conventional antibiotics against superbugs represents an important step to avoid the increasing resistance of bacteria observed in conventional treatments. Herein, it was evaluated the influence of different combinations of two active antibacterial components (chitosan and zinc oxide) and a host poly (vinyl alcohol - PVA) in membranes produced by the solvent casting technique. Those systems were evaluated in terms of the biofilm inactivation, kill-time assays and inhibition haloes against S. aureus (ATCC 25923) in membranes that must release reactive components while preserving their integrity and favoring the generation of reactive species to improve the antibacterial activity. The results suggest the potential of the combination of chitosan, zinc oxide and poly (vinyl alcohol) to inhibit the growth of S. aureus colonies since the PVA improved the dispersion of the components, whereas chitosan-ZnO chelate improves the mutual activity of the metal oxide and the natural polymer template.

Effective photodegradation of antibiotics by guest-host synergy between photosensitizer and bismuth vanadate: Underlying mechanism and toxicity assessment

The removal of antibiotics in wastewater has attracted increasing attention. Herein, a superior photosensitized photocatalytic system was developed with acetophenone (ACP) as the guest photosensitizer, bismuth vanadate (BiVO4) as the host catalyst and poly dimethyl diallyl ammonium chloride (PDDA) as the bridging complex, and used for the removal of sulfamerazine (SMR), sulfadiazine (SDZ) and sulfamethazine (SMZ) in water under simulated visible light (λ > 420 nm). The obtained ACP-PDDA-BiVO4 nanoplates attained a removal efficiency of 88.9%–98.2% for SMR, SDZ and SMZ after 60 min reaction and achieved kinetic rate constant approximately 10, 4.7 and 13 times of BiVO4, PDDA-BiVO4 and ACP-BiVO4, respectively, for SMZ degradation. In the guest-host photocatalytic system, ACP photosensitizer was found to have a great superiority in enhancing the light absorption, promoting the surface charge separation-transfer and efficient generation of holes (h+) and superoxide radical (·O2−), greatly contributing to the photoactivity. The SMZ degradation pathways were proposed based on the identified degradation intermediates, involving three main pathways of rearrangement, desulfonation and oxidation. The toxicity of intermediates was evaluated and the results demonstrated that the overall toxicity was reduced compared with parent SMZ. This catalyst maintained 92% photocatalytic oxidation performance after five cyclic experiments and displayed a co-photodegradation ability to others antibiotics (e.g., roxithromycin, ciprofloxacin et al.) in effluent water. Therefore, this work provides a facile photosensitized strategy for developing guest-host photocatalysts, which enabling the simultaneous antibiotics removal and effectively reduce the ecological risks in wastewater.

Thermally Stable PVDF-HFP-Based Gel Polymer Electrolytes for High-Performance Lithium-Ion Batteries.

The development of gel polymer electrolytes (GPEs) for lithium-ion batteries (LIBs) has paved the way to powering futuristic technological applications such as hybrid electric vehicles and portable electronic devices. Despite their multiple advantages, non-aqueous liquid electrolytes (LEs) possess certain drawbacks, such as plasticizers with flammable ethers and esters, electrochemical instability, and fluctuations in the active voltage scale, which limit the safety and working span of the batteries. However, these shortcomings can be rectified using GPEs, which result in the enhancement of functional properties such as thermal, chemical, and mechanical stability; electrolyte uptake; and ionic conductivity. Thus, we report on PVDF-HFP/PMMA/PVAc-based GPEs comprising poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) and poly(methyl methacrylate) (PMMA) host polymers and poly(vinyl acetate) (PVAc) as a guest polymer. A physicochemical characterization of the polymer membrane with GPE was conducted, and the electrochemical performance of the NCM811/Li half-cell with GPE was evaluated. The GPE exhibited an ionic conductivity of 4.24 × 10−4 S cm−1, and the NCM811/Li half-cell with GPE delivered an initial specific discharge capacity of 204 mAh g−1 at a current rate of 0.1 C. The cells exhibited excellent cyclic performance with 88% capacity retention after 50 cycles. Thus, this study presents a promising strategy for maintaining capacity retention, safety, and stable cyclic performance in rechargeable LIBs.

Integrative RNA profiling of TBEV-infected neurons and astrocytes reveals potential pathogenic effectors

Tick-borne encephalitis virus (TBEV), the most medically relevant tick-transmitted flavivirus in Eurasia, targets the host central nervous system and frequently causes severe encephalitis. The severity of TBEV-induced neuropathogenesis is highly cell-type specific and the exact mechanism responsible for such differences has not been fully described yet. Thus, we performed a comprehensive analysis of alterations in host poly-(A)/miRNA/lncRNA expression upon TBEV infection in vitro in human primary neurons (high cytopathic effect) and astrocytes (low cytopathic effect). Infection with severe but not mild TBEV strain resulted in a high neuronal death rate. In comparison, infection with either of TBEV strains in human astrocytes did not. Differential expression and splicing analyses with an in silico prediction of miRNA/mRNA/lncRNA/vd-sRNA networks found significant changes in inflammatory and immune response pathways, nervous system development and regulation of mitosis in TBEV Hypr-infected neurons. Candidate mechanisms responsible for the aforementioned phenomena include specific regulation of host mRNA levels via differentially expressed miRNAs/lncRNAs or vd-sRNAs mimicking endogenous miRNAs and virus-driven modulation of host pre-mRNA splicing. We suggest that these factors are responsible for the observed differences in the virulence manifestation of both TBEV strains in different cell lines. This work brings the first complex overview of alterations in the transcriptome of human astrocytes and neurons during the infection by two TBEV strains of different virulence. The resulting data could serve as a starting point for further studies dealing with the mechanism of TBEV-host interactions and the related processes of TBEV pathogenesis.

The SARS-CoV-2 Nsp3 macrodomain reverses PARP9/DTX3L-dependent ADP-ribosylation induced by interferon signaling

SARS-CoV-2 nonstructural protein 3 (Nsp3) contains a macrodomain that is essential for coronavirus pathogenesis and is thus an attractive target for drug development. This macrodomain is thought to counteract the host interferon (IFN) response, an important antiviral signalling cascade, via the reversal of protein ADP-ribosylation, a posttranslational modification catalyzed by host poly(ADP-ribose) polymerases (PARPs). However, the main cellular targets of the coronavirus macrodomain that mediate this effect are currently unknown. Here, we use a robust immunofluorescence-based assay to show that activation of the IFN response induces ADP-ribosylation of host proteins and that ectopic expression of the SARS-CoV-2 Nsp3 macrodomain reverses this modification in human cells. We further demonstrate that this assay can be used to screen for on-target and cell-active macrodomain inhibitors. This IFN-induced ADP-ribosylation is dependent on PARP9 and its binding partner DTX3L, but surprisingly the expression of the Nsp3 macrodomain or the deletion of either PARP9 or DTX3L does not impair IFN signaling or the induction of IFN-responsive genes. Our results suggest that PARP9/DTX3L-dependent ADP-ribosylation is a downstream effector of the host IFN response and that the cellular function of the SARS-CoV-2 Nsp3 macrodomain is to hydrolyze this end product of IFN signaling, rather than to suppress the IFN response itself.

Host Poly(A) Polymerases PAPD5 and PAPD7 Provide Two Layers of Protection That Ensure the Integrity and Stability of Hepatitis B Virus RNA

ABSTRACTNoncanonical poly(A) polymerases PAPD5 and PAPD7 (PAPD5/7) stabilize hepatitis B virus (HBV) RNA via the interaction with the viral posttranscriptional regulatory element (PRE), representing new antiviral targets to control HBV RNA metabolism, hepatitis B surface antigen (HBsAg) production, and viral replication. Inhibitors targeting these proteins are being developed as antiviral therapies; therefore, it is important to understand how PAPD5/7 coordinate to stabilize HBV RNA. Here, we utilized a potent small-molecule AB-452 as a chemical probe, along with genetic analyses to dissect the individual roles of PAPD5/7 in HBV RNA stability. AB-452 inhibits PAPD5/7 enzymatic activities and reduces HBsAg both in vitro (50% effective concentration [EC50] ranged from 1.4 to 6.8 nM) and in vivo by 0.94 log10. Our genetic studies demonstrate that the stem-loop alpha sequence within PRE is essential for both maintaining HBV poly(A) tail integrity and determining sensitivity toward the inhibitory effect of AB-452. Although neither single knockout (KO) of PAPD5 nor PAPD7 reduces HBsAg RNA and protein production, PAPD5 KO does impair poly(A) tail integrity and confers partial resistance to AB-452. In contrast, PAPD7 KO did not result in any measurable changes within the HBV poly(A) tails, but cells with both PAPD5 and PAPD7 KO show reduced HBsAg production and conferred complete resistance to AB-452 treatment. Our results indicate that PAPD5 plays a dominant role in stabilizing viral RNA by protecting the integrity of its poly(A) tail, while PAPD7 serves as a second line of protection. These findings inform PAPD5-targeted therapeutic strategies and open avenues for further investigating PAPD5/7 in HBV replication.IMPORTANCE Chronic hepatitis B affects more than 250 million patients and is a major public health concern worldwide. HBsAg plays a central role in maintaining HBV persistence, and as such, therapies that aim at reducing HBsAg through destabilizing or degrading HBV RNA have been extensively investigated. Besides directly degrading HBV transcripts through antisense oligonucleotides or RNA silencing technologies, small-molecule compounds targeting host factors such as the noncanonical poly(A) polymerase PAPD5 and PAPD7 have been reported to interfere with HBV RNA metabolism. Herein, our antiviral and genetic studies using relevant HBV infection and replication models further characterize the interplays between the cis element within the viral sequence and the trans elements from the host factors. PAPD5/7-targeting inhibitors, with oral bioavailability, thus represent an opportunity to reduce HBsAg through destabilizing HBV RNA.

Great enhancement of two photon absorption cross section value by intramolecular charge transfer in newly synthesized triphenylamine-BODIPY derivative

Novel borondipyrromethene (BODIPY) compound without a −8 (meso) substituent containing triphenylamine moieties via Suzuki-Miyaura coupling was designed and synthesized to enhance two photon absorption (TPA) property. The effect of π-expanded triphenylamine moieties and absence of meso substitution in BODIPY core on charge transfer dynamics as well as two photon absorption properties were investigated by utilizing ultrafast transient absorption spectroscopy measurements and open aperture (OA) Z-scan experiments in the environment of both in solution and host poly (methyl methacrylate) (PMMA) polymer film. The BODIPY compound with triphenylamine moieties has intramolecular charge transfer characteristics from electron donating moieties to BODIPY core due to its strong electron donating property and long conjugation length. The BODIPY compound with triphenylamine moieties demonstrates higher TPA cross section compared to reference compound based on the OA Z-scan experiments attributed to the strong coupling between the highest occupied molecular orbitals of BODIPY and 4-N,N-diphenylaminobiphenyl moieties. TPA cross section values were found to be 58 GM and 688 GM at 800 nm wavelength for reference BODIPY (BDP-1) and BODIPY-triphenylamine (BDP-2) compounds, respectively. BODIPY-triphenylamine compound has one of the greatest TPCS value among of the studied BODIPY compounds in the literature and may be a good candidate for photodynamic therapy and bio-imaging applications due to the free heavy atom nature.

Optical and thermal studies of host Poly (methyl methacrylate) (PMMA) based nanocomposites: A review

Advancements and Ascendancy in the use of Poly (methyl methacrylate) (PMMA) polymer has uncloaked the broad applications in nanotechnological field. There is a requirement to converge these advances in terms of review article for better comprehension and easy approach with a special focus on optical and thermal property related issues. This review article provides accurate and deep understandings into the capabilities offered by the PMMA polymer when coupled with the different nanoparticles. Incorporation of different nanoparticles into host Poly (methyl methacrylate) (PMMA) can enhances the optical and thermal properties. These properties of the nanocomposites can be regulate by controlling the different parameters such as sample preparation techniques, type of solvent used, nanoparticles loading concentration, and nanocomposite film thickness. This review article also reveals optical and thermal properties of different nanocomposite films of PMMA/CuO, PMMA/ZnO, PMMA/TiO2 and PMMA/SiO2.

Improved stability of blue TADF organic electroluminescent diodes via OXD-7 based mixed host.

Thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) have been demonstrated in applications such as displays and solid-state lightings. However, weak stability and inefficient emission of blue TADF OLEDs are two key bottlenecks limiting the development of solution processable displays and white light sources. This work presents a solution-processed OLED using a blue-emitting TADF small molecule bis[4-(9,9-dimethyl-9,10-dihydroacridine) phenyl]sulfone (DMAC-DPS) as an emitter. We comparatively investigated the effects of single host poly(N-vinylcarbazole) (PVK) and a co-host of 60% PVK and 30% 2,2'-(1,3-phenylene)-bis[5-(4-tert-butylphenyl)-1,3,4-oxadiazole] (OXD-7) on the device performance (the last 10% is emitter DMAC-DPS). The co-host device shows lower turn-on voltage, similar maximum luminance, and much slower external quantum efficiency (EQE) rolloff. In other words, device stability improved by doping OXD-7 into PVK, and the device impedance simultaneously and significantly reduced from 8.6 × 103 to 4.2 × 103 Ω at 1000 Hz. Finally, the electroluminescent stability of the co-host device was significantly enhanced by adjusting the annealing temperature.

Two-Dimensional Cs2Pb(SCN)2Br2-Based Photomemory Devices Showing a Photoinduced Recovery Behavior and an Unusual Fully Optically Driven Memory Behavior

The rapid development of Internet of Things and big data has made the conventional storage devices face the need of reforming. Rather than using electrical pulses to store data in one of two states, photomemory exploiting optical stimulation to store light information emerges as a revolutionary candidate for the optoelectronic community. However, fully optically-driven photomemory with fast data transmission speed and outstanding energy saving capability suffers from less exploration. Herein, a transistor-type photomemory using a 2D Cs2Pb(SCN)2Br2/polymer hybrid floating gate is explored and three host polymers, polystyrene (PS), poly(4-vinylphenol) (PVPh), and polyvinylpyrrolidone (PVP), are investigated to understand the relationship between polymer matrix selection and memory performance. All devices show a photo-induced recovery memory behavior but with two distinctly different photomemory behaviors. Besides the demonstration of a regular non-volatile photomemory showing a high on/off ratio of > 106 over 104 s, an unusual fully optically-driven memory behavior is intriguingly accomplished in the Cs2Pb(SCN)2Br2/PVP photomemory. Using white light serving as the driver of programming and blue laser acting as the main performer of erasing, this device can be switched between two distinguishable states and possesses acceptable data discriminability as evidenced by its fully optically-driven writing (programing)-reading-erasing-reading (WRER) switching function that shows an on/off current ratio of 103. This study not only presents the first 2D perovskite-based photomemory but also shows a novel fully optically-driven memory that has been rarely reported in the literature.

Rational Design of Carbazole- and Carboline-Based Polymeric Host Materials for Realizing High-Efficiency Solution-Processed Thermally Activated Delayed Fluorescence Organic Light-Emitting Diode.

Recently, various host materials have been developed for solution-processed thermally activated delayed fluorescent organic light-emitting diodes (TADF-OLEDs). Compared with small-molecule hosts, polymeric hosts are advantageous for inducing a uniform distribution and segregation of dopant molecules in the emissive layer without undesired large-scale phase separation. In this study, new polymer hosts were demonstrated, in which a bipolar conjugative moiety consisting of a carbazole (Cz) donor and an α-carboline (α-Cb) acceptor was bound to the polystyrene backbone through a non-conjugated linker. They exhibited high triplet energies of >2.8 eV, and their emission spectra overlapped with the absorption spectrum of a green TADF emitter, which allowed facile energy transfer from the polymeric host to the small-molecule dopants. High device performance was observed, with external quantum efficiencies (EQEs) of 13.65, 17.09, and 17.48% for solution-processed green TADF-OLEDs using PSCzCz, PSCzCb, and PSCbCz, respectively, as hosts for the EML. The EQEs of bipolar host (PSCzCb and PSCbCz)-based devices were higher than those of unipolar host (poly(N-vinylcarbazole) and PSCzCz)-based devices owing to the well-balanced charge-carrier transport. According to these results, the polymeric host bearing a bipolar Cz and α-Cb coupled moiety is a promising material for solution-processable TADF-OLEDs.

Polylysine modified conjugated polymer nanoparticles loaded with the singlet oxygen probe 1,3-diphenylisobenzofuran and the photosensitizer indocyanine green for use in fluorometricsensing and in photodynamic therapy.

Conjugated polymer hybrid nanoparticles (NPs) loaded with bothindocyanine green (ICG) and 1,3-diphenylisobenzofuran (DPBF) are described. The NPs are dually functional in thatICG acts as the photosensitizer, and DPBF as a probe for singlet oxygen (1O2 probe). The nanoparticle core consists of the energy donating host poly(9,9-dioctylfluorenyl-2,7-diyl)-co-(2,5-p-xylene) (PFP). The polymer is doped with the energy acceptor DPBF. Ratiometric fluorometric detection of singlet oxygen is accomplished by measurement of fluorescence at wavelengths of 415 and 458nm. In addition, the shell of the positively charged polymeric nanoparticles was modified, via electrostatic interaction, with negatively charged PDT drugs ICG. The integrated nanoparticles of type ICG-DPBF-PFP display effective photodynamic performance under 808-nm laser irradiation. The 1O2 sensing behaviors of samples are evaluated based on the ratiometric fluorescent responses produced by DPBF and PFP. 1O2 can be fluorimetically sensed with a detection limit of 28μM. The multifunctional nanoprobes exhibit effortless cellular uptake, superior photodynamic activity and a rapid ratiometric response to 1O2. Graphical abstractSchematic of a dual-functional nanoplatform for photodynamic therapy (PDT) and singlet oxygen (1O2) feedback. It offers a new strategy for self-monitoring photodynamic ablation. FRET: fluorescence resonance energy transfer. Indocyanine green is attached in the shell of nanoparticles, and 1,3-diphenylisobenzofuran is doped into the energy donating host conjugated polymer.

Strong exciton—photon coupling in anthradithiophene microcavities: from isolated molecules to aggregates

Abstract

The Influential Properties of Polymer Electrolytes on the Performance and Longevity of Solids-State Flexible Supercapacitors

Polymer electrolytes are the key enablers for solid-state energy storage including batteries and supercapacitors. Not only they can provide leakage-free thin and flexible form factors for solid supercapacitors, but also they can reduce and simplify the packaging of the devices to increase the actual energy and power densities. An ideal polymer electrolytes for supercapacitor should have: 1) high ionic conductivity; 2) wide electrochemical stability window and chemical stability without undesirable side reactions; 3) good environmental stability and mechanical properties; and 4) low material and processing cost. While most of the research are focusing on attributes 1) and 2) as well as the enabled solid supercapacitor devices in pristine condition, there are very few studies on the long-term service life and shelf life or the failure mechanisms of the polymer electrolytes. Although many polymer electrolytes have excellent performance at the beginning, they deteriorated rapidly over time. These can be related to the material properties (e.g. the crystallinity of the polymer host), the compatibility of ionic conductors and polymer host, sensitivity of the electrolytes to the environment etc. Fig. 1 compares the conductivities of two pairs of polymer electrolytes over a period of 4 weeks. One pair is a OH- ion conducting polymer electrolytes using the same polymer host poly(vinyl-alcohol) (PVA) but different ionic conductors, KOH or tetraethylammonium hydroxide (TEA-OH). The other set is a neutral pH salt polymer electrolytes that have the same Li2SO4 ionic conductor but different polymer hosts, PVA or polyacrylamide (PAM). PVA-KOH has been the most widely used electrolyte in all solid supercapacitors that need alkaline media. However, despite of its initial good performance, it tends to crystalize and dry out [1]. TEAOH-PVA, on the other hand, has a much longer shelf life. The solid capacitor it enabled was functional for AC-line filtering for over 18 month [2]. The neutral polymer electrolytes using Li2SO4 can reach to 2.0 V in solid symmetric supercapacitor devices [3] , which is very promising to increase energy density. Nonetheless, the same ionic conductor with different polymer hosts led to very different trends in the longevity and device shelf life. These differences in long term stability are the results of the intrinsic properties, degree of hydration within the materials and the conduction and failure mechanisms. In this talk, we will address these issues through the examples to show the influential factors on the performance of the polymer electrolytes at different time and temperature and the impact on the longevity of the solid supercapacitor devices. References Gao, J. Li, and K. Lian, "Alkaline quaternary ammonium hydroxides and their polymer electrolytes for electrochemical capacitors", RSC Advances, 4 (41), 21332-21339, 2014.Gao, J. Li, J. Miller, R. Outlaw, S. Butler, and K. Lian, “Solid-state electric double layer capacitors for ac line-filtering", Energy Storage Materials, 4, 66–70, 2016.Virya and K.Lian, “Li2SO4-Polyacrylamide Polymer Electrolytes for 2.0 V Solid Symmetric Supercapacitors”, Electrochemistry Communications, 81, 52–55， 2017. Figure 1