Functionalized Phenanthrene Imide-Based Polymers for n-Type Organic Thin-Film Transistors

High-performing n-type polymers are crucial for the advance of organic electronics field, however strong electron-deficient building blocks with optimized physicochemical properties for constructing them are still limited. The imide-functionalized polycyclic aromatic hydrocarbons (PAHs) with extended π-conjugated framework, high electron deficiency and good solubility serve as promising candidates for developing high-performance n-type polymers. Among the PAHs, phenanthrene (PhA) features a well-delocalized aromatic π-system with multiple modifiable active sites . However, the PhA-based imides are seldom studied, mainly attributed to the synthetic challenge. Herein, we report two functionalized PhAs, CPOI and CPCNI, by simultaneously incorporating imide with carbonyl or dicyanomethylene onto PhA. Notably, the dicyanomethylene-modified CPCNI exhibits a well stabilized LUMO energy level (-3.84 eV), attributed to the synergetic inductive effect from imide and cyano groups. Subsequently, based on CPOI and CPCNI, two polymers PCPOI-Tz and PCPCNI-Tz were developed. Applied to organic thin-film transistors, owing to the strong electron-deficiency of CPCNI, polymer PCPCNI-Tz shows an improved electron mobility and largely decreased threshold voltage compared with PCPOI-Tz. This work affords two structurally novel electron-deficient building blocks and highlights the effectiveness of dual functionalization of PhAs with strong electron-withdrawing groups for devising n-type polymers.

High-performance n-type organic thermoelectrics enabled by modulating cyano-functionalized polythiophene backbones

The scarcity of n-type polymers with high electrical conductivity (σ) and power factor (PF) is the major challenge for organic thermoelectrics (OTEs). By integrating cyano functionalities and an intramolecular conformation lock, we herein synthesize a new electron-deficient building block, CNg4T2, bearing long 1,4,7,10-tetraoxahendecyl side chains, and then further develop two n-type polythiophene derivatives, CNg4T2-2FT and CNg4T2-CNT2, with 3,4-difluorothiophene and 3,3'-dicyano-2,2'-bithiophene as co-units, respectively. Compared with CNg4T2-2FT, CNg4T2-CNT2 features a deeper-positioned lowest unoccupied molecular orbital (LUMO) while maintaining a high degree of backbone coplanarity. As a consequence, the CNg4T2-CNT2 film with molecular dopant N-DMBI delivered an impressive σ of 13.2 S cm-1 and a high PF of up to 10.84 μW m-1 K-2, significantly outperforming CNg4T2-2FT and benchmark n-type polymer N2200 films. To the best of our knowledge, this PF of CNg4T2-CNT2 devices is the highest value for n-type polythiophenes in OTEs. Further characterizations indicate that the high performance of CNg4T2-CNT2-based devices is attributed to the high doping efficiency and ordered packing of polymer chains. Our study demonstrates that CNg4T2 is a highly appealing electron-deficient building block for n-type OTE polymers and also suggests that fine-tuning of the polymer backbone is a powerful approach to accessing high-performance n-type polymers for OTE devices.

PC71BM as Morphology Regulator for Highly Efficient Ternary Organic Solar Cells with Bulk Heterojunction or Layer-by-Layer Configuration

The ternary strategy is one of the effective methods to regulate the morphology of the active layer in organic solar cells (OSCs). In this work, the ternary OSCs with bulk heterojunction (BHJ) or layer-by-layer (LbL) active layers are prepared by using the polymer donor PM6 and the non-fullerene acceptor L8-BO as the main system and the fullerene acceptor PC71BM as the third component. The power conversion efficiencies (PCEs) of BHJ OSCs and LbL OSCs are increased from 17.10% to 18.02% and from 17.20% to 18.20% by introducing PC71BM into the binary active layer, respectively. The in situ UV-vis absorption spectra indicate that the molecular aggregation and crystallization process can be prolonged by introducing PC71BM into the PM6:L8-BO or PM6/L8-BO active layer. The molecular orientation and molecular crystallinity in the active layer are optimized by introducing the PC71BM into the binary BHJ or LbL active layers, which can be confirmed by the experimental results of grazing incidence wide-angle X-ray scattering. This study demonstrates that the third component PC71BM can be used as a morphology regulator to regulate the morphology of BHJ or LbL active layers, thus effectively improving the performance of BHJ and LbL OSCs.

Multi-Selenophene Incorporated Thiazole Imide-Based n-Type Polymers for High-Performance Organic Thermoelectrics

Developing polymers with high electrical conductivity (σ) after n-doping is a great challenge for the advance of the field of organic thermoelectrics (OTEs). Herein, we report a series of thiazole imide-based n-type polymers by gradually increasing selenophene content in polymeric backbone. Thanks to the strong intramolecular noncovalent N⋅⋅⋅S interaction and enhanced intermolecular Se⋅⋅⋅Se interaction, with the increase of selenophene content, the polymers show gradually lowered LUMOs, more planar backbone, and improved film crystallinity versus the selenophene-free analogue. Consequently, polymer PDTzSI-Se with the highest selenophene content achieves a champion σ of 164.0 S cm-1 and a power factor of 49.0 μW m-1  K-2 in the series when applied in OTEs after n-doping. The σ value is the highest one for n-type donor-acceptor OTE materials reported to date. Our work indicates that selenophene substitution is a powerful strategy for developing high-performance n-type OTE materials and selenophene incorporated thiazole imides offer an excellent platform in enabling n-type polymers with high backbone coplanarity, deep-lying LUMO and enhanced mobility/conductivity.

High-Performance n-Type Polymeric Mixed Ionic-Electronic Conductors: The Impacts of Halogen Functionalization

Developing high-performance n-type polymer mixed ionic-electronic conductors (PMIECs) is a grand challenge, which largely determines their applications in vaious organic electronic devices, such as organic electrochemical transistors (OECTs) and organic thermoelectrics (OTEs). Herein, two halogen-functionalized PMIECs f-BTI2g-TVTF and f-BTI2g-TVTCl built from fused bithiophene imide dimer (f-BTI2) as the acceptor unit and halogenated thienylene-vinylene-thienylene (TVT) as the donor co-unit are reported. Compared to the control polymer f-BTI2g-TVT, the fluorinated f-BTI2g-TVTF shows lower-positioned lowest unoccupied molecular orbital (LUMO), improved charge transport property, and greater ion uptake capacity. Consequently, f-BTI2g-TVTF delivers a state-of-the-art µC* of 90.2 F cm-1 V-1 s-1 with a remarkable electron mobility of 0.41 cm2 V-1 s-1 in OECTs and an excellent power factor of 64.2 µW m-1 K-2 in OTEs. An OECT-based inverter amplifier is further demonstrated with voltage gain up to 148 V V-1 , which is among the highest values for OECT inverters. Such results shed light on the impacts of halogen atoms on developing high-performing n-type PMIECs.

Selenophene Substitution Enabled High-Performance n-Type Polymeric Mixed Ionic-Electronic Conductors for Organic Electrochemical Transistors and Glucose Sensors

High-performance n-type polymeric mixed ionic-electronic conductors (PMIECs) are essential for realizing organic electrochemical transistors (OECTs)-based low-power complementary circuits and biosensors, but their development still remains a great challenge. Herein, by devising two novel n-type polymers (f-BTI2g-SVSCN and f-BSeI2g-SVSCN) containing varying selenophene contents together with their thiophene-based counterpart as the control, it is demonstrated that gradually increasing selenophene loading in polymer backbones can simultaneously yield lowered lowest unoccupied molecular orbital levels, boosted charge-transport properties, and improved ion-uptake capabilities. Therefore, a remarkable volumetric capacitance (C*) of 387.2 F cm-3 and a state-of-the-art OECT electron mobility (µe,OECT ) of 0.48 cm2 V-1 s-1 are synchronously achieved for f-BSeI2g-SVSCN having the highest selenophene content, yielding an unprecedented geometry-normalized transconductance (gm,norm ) of 71.4 S cm-1 and record figure of merit (µC*) value of 191.2 F cm-1 V-1 s-1 for n-type OECTs. Thanks to such excellent performance of f-BSeI2g-SVSCN-based OECTs, a glucose sensor with a remarkably low detection limit of 10 nMm and decent selectivity is further implemented, demonstrating the power of selenophene substitution strategy in enabling high-performance n-type PMIECs for biosensing applications.

Self-Powering Sensory Device with Multi-Spectrum Image Realization for Smart Indoor Environments

The development of organic-based optoelectronic technologies for the indoor Internet of Things market, which relies on ambient energy sources, has increased, with organic photovoltaics (OPVs) and photodetectors (OPDs) considered promising candidates for sustainable indoor electronic devices. However, the manufacturing processes of standalone OPVs and OPDs can be complex and costly, resulting in high production costs and limited scalability, thus limiting their use in a wide range of indoor applications. This study uses a multi-component photoactive structure to develop a self-powering dual-functional sensory device with effective energy harvesting and sensing capabilities. The optimized device demonstrates improved free-charge generation yield by quantifying charge carrier dynamics, with a high output power density of over 81 and 76 µW cm-2 for rigid and flexible OPVs under indoor conditions (LED 1000 lx (5200 K)). Furthermore, a single-pixel image sensor is demonstrated as a feasible prototype for practical indoor operating in commercial settings by leveraging the excellent OPD performance with a linear dynamic range of over 130 dB in photovoltaic mode (no external bias). This apparatus with high-performance OPV-OPD characteristics provides a roadmap for further exploration of the potential, which can lead to synergistic effects for practical multifunctional applications in the real world by their mutual relevance.

Ground-state electron transfer in all-polymer donor:acceptor blends enables aqueous processing of water-insoluble conjugated polymers

Water-based conductive inks are vital for the sustainable manufacturing and widespread adoption of organic electronic devices. Traditional methods to produce waterborne conductive polymers involve modifying their backbone with hydrophilic side chains or using surfactants to form and stabilize aqueous nanoparticle dispersions. However, these chemical approaches are not always feasible and can lead to poor material/device performance. Here, we demonstrate that ground-state electron transfer (GSET) between donor and acceptor polymers allows the processing of water-insoluble polymers from water. This approach enables macromolecular charge-transfer salts with 10,000× higher electrical conductivities than pristine polymers, low work function, and excellent thermal/solvent stability. These waterborne conductive films have technological implications for realizing high-performance organic solar cells, with efficiency and stability superior to conventional metal oxide electron transport layers, and organic electrochemical neurons with biorealistic firing frequency. Our findings demonstrate that GSET offers a promising avenue to develop water-based conductive inks for various applications in organic electronics.

On the Conformation of Dimeric Acceptors and Their Polymer Solar Cells with Efficiency over 18

The determination of molecular conformations of oligomeric acceptors (OAs) and their impact on molecular packing are crucial for understanding the photovoltaic performance of their resulting polymer solar cells (PSCs) but have not been well studied yet. Herein, we synthesized two dimeric acceptor materials, DIBP3F-Se and DIBP3F-S, which bridged two segments of Y6-derivatives by selenophene and thiophene, respectively. Theoretical simulation and experimental 1D and 2D NMR spectroscopic studies prove that both dimers exhibit O-shaped conformations other than S- or U-shaped counter-ones. Notably, this O-shaped conformation is likely governed by a distinctive "conformational lock" mechanism, arising from the intensified intramolecular π-π interactions among their two terminal groups within the dimers. PSCs based on DIBP3F-Se deliver a maximum efficiency of 18.09 %, outperforming DIBP3F-S-based cells (16.11 %) and ranking among the highest efficiencies for OA-based PSCs. This work demonstrates a facile method to obtain OA conformations and highlights the potential of dimeric acceptors for high-performance PSCs.

Stable organic electrochemical neurons based on p-type and n-type ladder polymers

Organic electrochemical transistors (OECTs) are a rapidly advancing technology that plays a crucial role in the development of next-generation bioelectronic devices. Recent advances in p-type/n-type organic mixed ionic-electronic conductors (OMIECs) have enabled power-efficient complementary OECT technologies for various applications, such as chemical/biological sensing, large-scale logic gates, and neuromorphic computing. However, ensuring long-term operational stability remains a significant challenge that hinders their widespread adoption. While p-type OMIECs are generally more stable than n-type OMIECs, they still face limitations, especially during prolonged operations. Here, we demonstrate that simple methylation of the pyrrole-benzothiazine-based (PBBT) ladder polymer backbone results in stable and high-performance p-type OECTs. The methylated PBBT (PBBT-Me) exhibits a 25-fold increase in OECT mobility and an impressive 36-fold increase in μC* (mobility × volumetric capacitance) compared to the non-methylated PBBT-H polymer. Combining the newly developed PBBT-Me with the ladder n-type poly(benzimidazobenzophenanthroline) (BBL), we developed complementary inverters with a record-high DC gain of 194 V V-1 and excellent stability. These state-of-the-art complementary inverters were used to demonstrate leaky integrate-and-fire type organic electrochemical neurons (LIF-OECNs) capable of biologically relevant firing frequencies of about 2 Hz and of operating continuously for up to 6.5 h. This achievement represents a significant improvement over previous results and holds great potential for developing stable bioelectronic circuits capable of in-sensor computing.

High-Performance n-Type Organic Thermoelectrics Enabled by Synergistically Achieving High Electron Mobility and Doping Efficiency

n-Doped polymers with high electrical conductivity (σ) are still very scarce in organic thermoelectrics (OTEs), which limits the development of efficient organic thermoelectric generators. A series of fused bithiophene imide dimer-based polymers, PO8, PO12, and PO16, incorporating distinct oligo(ethylene glycol) side-chain to optimize σ is reported here. Three polymers show a monotonic electron mobility decrease as side-chain size increasing due to the gradually lowered film crystallinity and change of backbone orientation. Interestingly, polymer PO12 with a moderate side-chain size delivers a champion σ up to 92.0 S cm-1 and a power factor (PF) as high as 94.3 µW m-1 K-2 in the series when applied in OTE devices. The PF value is among the highest ones for the solution-processing n-doped polymers. In-depth morphology studies unravel that the moderate crystallinity and the formation of 3D conduction channel derived from bimodal orientation synergistically contribute to high doping efficiency and large charge carrier mobility, thus resulting in high performance for the PO12-based OTEs. The results demonstrate the great power of simple tuning of side chain in developing n-type polymers with substantial σ for improving organic thermoelectric performance.

Biselenophene Imide: Enabling Polymer Acceptor with High Electron Mobility for High-Performance All-Polymer Solar Cells

The shortage of narrow band gap polymer acceptors with high electron mobility is the major bottleneck for developing efficient all-polymer solar cells (all-PSCs). Herein, we synthesize a distannylated electron-deficient biselenophene imide monomer (BSeI-Tin) with high purity/reactivity, affording an excellent chance to access acceptor-acceptor (A-A) type polymer acceptors. Copolymerizing BSeI-Tin with dibrominated monomer Y5-Br, the resulting A-A polymer PY5-BSeI shows a higher molecular weight, narrower band gap, deeper-lying frontier molecular orbital levels and larger electron mobility than the donor-acceptor type counterpart PY5-BSe. Consequently, the PY5-BSeI-based all-PSCs deliver a remarkable efficiency of 17.77 % with a high short-circuit current of 24.93 mA cm-2 and fill factor of 75.83 %. This efficiency is much higher than that (10.70 %) of the PY5-BSe-based devices. Our study demonstrates that BSeI is a promising building block for constructing high-performance polymer acceptors and stannylation of electron-deficient building blocks offers an excellent approach to developing A-A type polymers for all-PSCs and even beyond.

Semiconducting Polymers Based on Simple Electron-Deficient Cyanated trans-1,3-Butadienes for Organic Field-Effect Transistors

Developing high-performance but low-cost n-type polymers remains a significant challenge in the commercialization of organic field-effect transistors (OFETs). To achieve this objective, it is essential to design the key electron-deficient units with simple structures and facile preparation processes, which can facilitate the production of low-cost n-type polymers. Herein, by sequentially introducing fluorine and cyano functionalities onto trans-1,3-butadiene, we developed a series of structurally simple but highly electron-deficient building blocks, namely 1,4-dicyano-butadiene (CNDE), 3-fluoro-1,4-dicyano-butadiene (CNFDE), and 2,3-difluoro-1,4-dicyano-butadiene (CNDFDE), featuring a highly coplanar backbone and deep-positioned lowest unoccupied molecular orbital (LUMO) energy levels (-3.03-4.33 eV), which render them highly attractive for developing n-type semiconducting polymers. Notably, all these electron-deficient units can be easily accessed by a two-step high-yield synthetic procedure from low-cost raw materials, thus rendering them highly promising candidates for commercial applications. Upon polymerization with diketopyrrolopyrrole (DPP), three copolymers were developed that demonstrated unipolar n-type transport characteristics in OFETs with the highest electron mobility of >1 cm2  V-1  s-1 . Hence, CNDE, CNFDE, and CNDFDE represent a class of novel, simple, and efficient electron-deficient units for constructing low-cost n-type polymers, thereby providing valuable insight for OFET applications.

Target Therapy for Buried Interface Enables Stable Perovskite Solar Cells with 25.05% Efficiency

The buried interface in perovskite solar cells (PSCs) is pivotal for achieving high efficiency and stability. However, it is challenging to study and optimize the buried interface due to its non-exposed feature. Here, a facile and effective strategy is developed to modify the SnO2 /perovskite buried interface by passivating the buried defects in perovskite and modulating carrier dynamics via incorporating formamidine oxalate (FOA) in SnO2 nanoparticles. Both formamidinium and oxalate ions show a longitudinal gradient distribution in the SnO2 layer, mainly accumulating at the SnO2 /perovskite buried interface, which enables high-quality upper perovskite films, minimized defects, superior interface contacts, and matched energy levels between perovskite and SnO2 . Significantly, FOA can simultaneously reduce the oxygen vacancies and tin interstitial defects on the SnO2 surface and the FA+ /Pb2+ associated defects at the perovskite buried interface. Consequently, the FOA treatment significantly improves the efficiency of the PSCs from 22.40% to 25.05% and their storage- and photo-stability. This method provides an effective target therapy of buried interface in PSCs to achieve very high efficiency and stability.

Over 18.1% Efficiency of Layer-by-Layer Polymer Solar Cells by Enhancing Exciton Utilization near the ITO Electrode

In this work, layer-by-layer (LbL) polymer solar cells (PSCs) are constructed without/with the incorporation of a dissociation strengthening layer (DSL) on the basis of the wide-bandgap donor D18-Cl, as well as the narrow-bandgap nonfullerene acceptor Y6. The efficiency of LbL PSCs is enhanced from 17.62 to 18.15% through introducing a DSL, originating from the enhanced dissociation of D18-Cl excitons near the ITO electrode. Meanwhile, the interfacial energy between D18-Cl and Y6 layers is decreased by incorporating a DSL, which should facilitate molecular interdiffusion for more adequate exciton dissociation in LbL active layers. This work offers a simple and resultful way for realizing power conversion efficiency (PCE) improvement of LbL PSCs with maximized exciton utilization in LbL active layers. The universality of the DSL incorporation strategy on performance improvement can be further confirmed with a boosted PCE from 17.39 to 18.03% or from 17.13 to 17.61% for D18-Cl/L8-BO- or D18-Cl/N3-based LbL PSCs by incorporating a DSL.

Terminal Cyano-Functionalized Fused Bithiophene Imide Dimer-Based n-Type Small Molecular Semiconductors: Synthesis, Structure-Property Correlations, and Thermoelectric Performances

n-Doped small molecular organic thermoelectric materials (OTMs) hold advantages of high Seebeck coefficient and better performance reproducibility over their polymeric analogues; however, high-performance n-type small molecular OTMs are severely lacking. We report here a class of small molecular OTMs based on terminal cyanation of a bithiophene imide-based ladder-type heteroarene BTI2. It was found that the cyanation could effectively lower the lowest unoccupied molecular orbital (LUMO) level from -2.90 eV (BTI2) to -4.14 eV (BTI2-4CN) and thus lead to significantly improved n-doping efficiency. Additionally, terminal cyano-functionalization can maintain the close packing and efficient intermolecular charge transfer between these cyanated molecules, thus yielding high electron mobilities of up to 0.40 cm2 V-1 s-1. Benefiting from its low LUMO-enabled efficient n-doping and high electron mobility, an encouraging n-type electrical conductivity of 0.43 S cm-1 and power factor (PF) of 6.34 μW m-1 K-2 were achieved for tetracyanated BTI2-4CN, significantly outperforming those of its noncynated BTI2 (<10-7 S cm-1, PF undetectable) and dicyanated BTI2-2CN (0.24 S cm-1, 1.78 μW m-1 K-2). These results suggest the great potential of the terminal cyanation strategy of ladder-type heteroarenes for developing high-performance small molecular OTMs.

Synergistic Contribution of Oligo(ethylene glycol) and Fluorine Substitution of Conjugated Polymer Photocatalysts toward Solar Driven Sacrificial Hydrogen Evolution

To separately explore the importance of hydrophilicity and backbone planarity of polymer photocatalyst, a series of benzothiadiazole-based donor-acceptor alternating copolymers incorporating alkoxy, linear oligo(ethylene glycol) (OEG) side chain, and backbone fluorine substituents is presented. The OEG side chains in the polymer backbone increase the surface energy of the polymer nanoparticles, thereby improving the interaction with water and facilitating electron transfer to water. Moreover, the OEG-attached copolymers exhibit enhanced intermolecular packing compared to polymers with alkoxy side chains, which is possibly attributed to the self-assembly properties of the side chains. Fluorine substituents on the polymer backbone produce highly ordered lamellar stacks with distinct π-π stacking features; subsequently, the long-lived polarons toward hydrogen evolution are observed by transient absorption spectroscopy. In addition, a new nanoparticle synthesis strategy using a methanol/water mixed solvent is first adopted, thereby avoiding the screening effect of surfactants between the nanoparticles and water. Finally, hydrogen evolution rate of 26 000 µmol g^-1  h^-1 is obtained for the copolymer incorporated with both OEG side chains and fluorine substituents under visible-light irradiation (λ > 420 nm). This study demonstrates how the glycol side chain strategy can be further optimized for polymer photocatalysts by controlling the backbone planarity.

Regulation of Polymer Configurations Enables Green Solvent-Processed Large-Area Binary All-Polymer Solar Cells With Breakthrough Performance and High Efficiency Stretchability Factor

With the great potential of the all-polymer solar cells for large-area wearable devices, both large-area device efficiency and mechanical flexibility are very critical but attract limited attention. In this work, from the perspective of the polymer configurations, two types of terpolymer acceptors PYTX-A and PYTX-B (X = Cl or H) are developed. The configuration difference caused by the replacement of non-conjugated units results in distinct photovoltaic performance and mechanical flexibility. Benefiting from a good match between the intrinsically slow film-forming of the active materials and the technically slow film-forming of the blade-coating process, the toluene-processed large-area (1.21 cm² ) binary device achieves a record efficiency of 14.70%. More importantly, a new parameter of efficiency stretchability factor (ESF) is proposed for the first time to comprehensively evaluate the overall device performance. PM6:PYTCl-A and PM6:PYTCl-B yield significantly higher ESF than PM6:PY-IT. Further blending with non-conjugated polymer donor PM6-A, the best ESF of 3.12% is achieved for PM6-A:PYTCl-A, which is among the highest comprehensive performances.

Thiazole Imide-Based All-Acceptor Homopolymer with Branched Ethylene Glycol Side Chains for Organic Thermoelectrics

n-Type semiconducting polymers with high thermoelectric performance remain challenging due to the scarcity of molecular design strategy, limiting their applications in organic thermoelectric (OTE) devices. Herein, we provide a new approach to enhance the OTE performance of n-doped polymers by introducing acceptor-acceptor (A-A) type backbone bearing branched ethylene glycol (EG) side chains. When doped with 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI), the A-A homopolymer PDTzTI-TEG exhibits n-type electrical conductivity (σ) up to 34 S cm^-1 and power factor value of 15.7 μW m^-1  K^-2 . The OTE performance of PDTzTI-TEG is far greater than that of homopolymer PBTI-TEG (σ=0.27 S cm^-1 ), indicating that introducing electron-deficient thiazole units in the backbone further improves the n-doping efficiency. These results demonstrate that developing A-A type polymers with EG side chains is an effective strategy to enhance n-type OTE performance.

Ferroelectric Polymer Drives Performance Enhancement of Non-fullerene Organic Solar Cells

Enhancing the built-in electric field to promote charge dynamitic process is of great significance to boost the performance of the non-fullerene organic solar cells (OSCs), which has rarely been concerned. In this work, we introduced a cheap ferroelectric polymer as an additive into the active layers of non-fullerene OSCs to improve the device performance. An additional and permanent electrical field was produced by the polarization of the ferroelectric dipoles, which can substantially enhance the built-in electric field. The promoted exciton separation, significantly accelerated charge transport, reduced the charge recombination, as well as the optimized film morphology were observed in the device, leading to a significantly improved performance of the PVDF-modified OSCs with various active layers, such as PM6 : Y6, PM6 : BTP-eC9, PM6 : IT-4F and PTB7-Th : Y6. Especially, a record efficiency of 17.72 % for PM6 : Y6-based OSC and an outstanding efficiency of 18.17 % for PM6 : BTP-eC9-based OSC were achieved.

Boosted efficiency over 18.1% of polymer solar cells by employing large extinction coefficients material as the third component

Series of binary and ternary polymer solar cells (PSCs) were successfully fabricated with PM6 as donor, m-BTP-PhC6 and Y6 as acceptor. The optimal ternary PSCs achieve a power conversion efficiency (PCE) of 18.14% by incorporating 20 wt% Y6 in acceptors, benefiting from the increased short circuit current density (J_SC ) of 26.53 mA cm^-2 and fill factor (FF) of 78.51% in comparison with the J_SC s (25.05 mA cm^-2 and 25.65 mA cm^-2 ) and the FFs (77.13% and 76.55%) of binary PSCs with m-BTP-PhC6 or Y6 as acceptor. The photon harvesting ability of ternary active layers can be enhanced by incorporating appropriate Y6, which can be confirmed from the EQE spectral difference of the optimized ternary and binary PSCs, especially in the wavelength range from 680 nm to 800 nm. The refractive index and extinction coefficients of binary and ternary blend films were measured, which can well support the effect of Y6 incorporation on photon harvesting ability in different wavelength range. Meanwhile, the appropriate Y6 incorporation with large extinction coefficients can be considered as morphology regulator, which can be confirmed from the enhanced FF and the more balanced charge transport in the optimal ternary PSCs. Photogenerated exciton distribution in active layers was simulated by transmission matrix method based on the Beer-Lambert law. The photogenerated exciton density can be enhanced in the middle of active layers by incorporating 20 wt% Y6 in acceptors, which is conducive to charge collection by individual electrode, resulting in the simultaneously enhanced J_SC and FF of the optimal ternary PSCs. This work indicates that an appropriate third component will play versatile roles in improving the performance of PSCs via enhancing photon harvesting and optimizing photogeneration exciton distribution for better charge collection. This article is protected by copyright. All rights reserved.

Smart Ternary Strategy in Promoting the Performance of Polymer Solar Cells Based on Bulk-Heterojunction or Layer-By-Layer Structure

Although the rapid development of polymer solar cells (PSCs) has been achieved, it is still a great challenge to explore efficient ways for improving power conversion efficiency (PCE) of PSCs from materials and device engineering. Ternary strategy has been confirmed as an efficient way to improve PCE of PSCs by employing three kinds of materials. In this work, one polymer donor PM6, and two non-fullerene materials N3 and MF1 are selected to prepare ternary PSCs with layer-by-layer (LbL) or bulk-heterojunction (BHJ) structure. The LbL and BHJ-PSCs exhibit PCEs of 16.75% and 16.76% with 15 wt% MF1 content in acceptors, corresponding to over 5% or 4% PCE improvement compared with N3-based binary PSCs with LbL or BHJ structure. The PCE improvement is mainly attributed to the fill factor enhancement from 73.29% to 76.95% for LbL-PSCs or from 74.13% to 77.51% for BHJ-PSCs by employing the ternary strategy. This work indicates that ternary strategy has great potential in preparing highly efficient LbL-PSCs via simultaneously optimizing molecular arrangement and the thickness of each layer.

Approaching 18% efficiency of ternary organic photovoltaics with wide bandgap polymer donor and well compatible Y6 : Y6-1O as acceptor

A series of ternary organic photovoltaics (OPVs) are fabricated with one wide bandgap polymer D18-Cl as donor, and well compatible Y6 and Y6-1O as acceptor. The open-circuit-voltage (VOC ) of ternary OPVs is monotonously increased along with the incorporation of Y6-1O, indicating that the alloy state should be formed between Y6 and Y6-1O due to their excellent compatibility. The energy loss can be minimized by incorporating Y6-1O, leading to the VOC improvement of ternary OPVs. By finely adjusting the Y6-1O content, a power conversion efficiency of 17.91% is achieved in the optimal ternary OPVs with 30 wt% Y6-1O in acceptors, resulting from synchronously improved short-circuit-current density (JSC ) of 25.87 mA cm-2, fill factor (FF) of 76.92% and VOC of 0.900 V in comparison with those of D18-Cl : Y6 binary OPVs. The JSC and FF improvement of ternary OPVs should be ascribed to comprehensively optimal photon harvesting, exciton dissociation and charge transport in ternary active layers. The more efficient charge separation and transport process in ternary active layers can be confirmed by the magneto-photocurrent and impedance spectroscopy experimental results, respectively. This work provides new insight into constructing highly efficient ternary OPVs with well compatible Y6 and its derivative as acceptor.

A-D-A Type Semiconducting Small Molecules with Bis(alkylsulfanyl)methylene Substituents and Control of Charge Polarity for Organic Field-Effect Transistors

In this study, we synthesize four different kinds of bis(alkylsulfanyl)methylene-substituted 4,9-dihydro-s-indaceno[1,2-b:5,6-b']dithiophene (IDT)-based acceptor-donor-acceptor (A-D-A) type small molecules (IDSIC, IDSIC-4F, IDSIC-4Cl, and IDSTIC) by incorporating electron-withdrawing halogen atoms or electron-releasing thiophene spacers. Herein, enhanced structural planarity and crystalline intermolecular packing are induced by the sp²-hybridized C═C double bond side chains and sulfur-sulfur chalcogen interactions. The fine control of intramolecular charge transfer modulates the electrochemical characteristics and the resulting carrier polarity in organic field-effect transistors (OFETs). Well-balanced ambipolar, n-dominant, and p-dominant charge transport properties are successfully demonstrated in OFETs by modulating the electron-donating or withdrawing strength based on the A-D-A structural motif, resulting in hole/electron mobilities of 0.599/0.553, 0.003/0.019, 0.092/0.897, and 0.683/0.103 cm²/V·s for IDSIC, IDSIC-4F, IDSIC-4Cl, and IDSTIC respectively, after thermal annealing at 200 °C. Thermal annealing of the as-cast films improves the intermolecular packing in an edge-on fashion, which is investigated in detail by grazing incidence X-ray scattering. Finally, complementary logic circuits, i.e., NOT, NAND, and NOR, are fabricated by assembling p-dominant IDSTIC and n-dominant IDSIC-4Cl OFETs. Therefore, a simple and efficient molecular design strategy for fine tuning the charge polarity and charge transport properties of OFET devices is presented.

Modeling and Staging of Osteoarthritis Progression Using Serial CT Imaging and Arthroscopy

OBJECTIVE

The objective of this study was to describe in life methods by which osteoarthritis can be staged in order to time therapeutic interventions that are relevant to osteoarthritis (OA) clinical trials.

METHODS

Twenty-two sheep underwent arthroscopic meniscal destabilization to induce OA. Serial computed tomography (CT) imaging and arthroscopy were used to monitor osteoarthritis progression at 3-month intervals over 9 months. Eleven sheep received 1 intra-articular injection of hyaluronate 3 months after OA induction and another group of 11 received saline. A linear mixed model was used to define the trajectory of shape change in the medial joint compartment. Ordinal logistic regression was used to investigate the association between morphological changes and sclerosis.

RESULTS

Three months after meniscal destabilization there were early bipolar chondral lesions in the medial compartment of the knee, as well as osteophytes and bone remodeling. Superficial fissures and cartilage cracks progressed to discrete areas of cartilage thinning and fibrillation on the medial tibial plateau by 6 months that became cartilage erosions by nine months. A linear mixed effect model demonstrated significant change in medial compartment length and width with over time (P < 0.05) for both groups. A significant association between severity of sclerosis and medial compartment morphology was also observed.

CONCLUSIONS

The induction of osteoarthritic lesions with meniscal release model can be followed using noninvasive and minimally invasive procedures allowing for real-time decisions about redosing therapies, or other changes such as extending trial timelines without sacrificing animals to conduct assessments.

Anomalous muscles and nerves in the hand of a 94-year-old cadaver-A case report

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The additional flexor muscle (Flexor Digiti Minimi Longus m.) passing through Guyon’s canal is the first to be described.

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The anomalous first lumbrical muscle with three origins is the first to be described.

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Berretini’s and Kaplan’s anastomosis was also noted.

Introduction

During an anatomical dissection of the distal upper extremities, numerous muscular and nervous anomalies were found in the forearm and hand of a 94-year-old cadaver. These anomalies are clinically relevant with regard to medical or surgical interventions.

Presentation of case

The presence of a “flexor digiti minimi longus” muscle was observed passing through Guyon’s canal; to our knowledge this passageway has never been previously reported. An aberrant first lumbrical with three origins was noted. Additionally, numerous atypical nerves were found innervating the hand; the dorsal branch of the ulnar nerve contributed to cutaneous innervation of the palm of the hand (Kaplan’s anastomosis), the superficial ulnar nerve provided muscular innervation to the flexor digiti minimi brevis muscle, and two connections between the common palmar digital branches of the median and superficial ulnar nerves were observed (Berrettini anastomosis).

Discussion

Here, we describe an extranumerary muscle associated with the hypothenar group of muscles. We also describe unusual origins of the first lumbrical muscle, and atypical cutaneous and muscular innervation to the palm of the hand.

Conclusion

Clinically, understanding the existence of these anatomical variations may influence medical care or surgical procedures.

Small hypoxia-primed mesenchymal stem cells attenuate graft-versus-host disease

Mesenchymal stem cells (MSCs) are of particular interest for the treatment of immune-related diseases due to their immunosuppressive capacity. Here, we show that Small MSCs primed with Hypoxia and Calcium ions (SHC-MSCs) exhibit enhanced stemness and immunomodulatory functions for treating allogeneic conflicts. Compared with naïve cultured human umbilical cord blood-derived MSCs, SHC-MSCs were resistant to passage-dependent senescence mediated via the monocyte chemoattractant protein-1 and p53/p21 cascade and secreted large amounts of pro-angiogenic and immunomodulatory factors, resulting in suppression of T-cell proliferation. SHC-MSCs showed DNA demethylation in pluripotency, germline, and imprinted genes similarly to very small embryonic-like stem cells, suggesting a potential mutual relationship. Genome-wide DNA methylome and transcriptome analyses indicated that genes related to immune modulation, cell adhesion, and the cell cycle were up-regulated in SHC-MSCs. Particularly, polo-like kinase-1 (PLK1), zinc-finger protein-143, dehydrogenase/reductase-3, and friend-of-GATA2 play a key role in the beneficial effects of SHC-MSCs. Administration of SHC-MSCs or PLK1-overexpressing MSCs significantly ameliorated symptoms of graft-versus-host disease (GVHD) in a humanized mouse model, resulting in significantly improved survival, less weight loss, and reduced histopathologic injuries in GVHD target organs compared with naïve MSC-infused mice. Collectively, our findings suggest that SHC-MSCs can improve the clinical treatment of allogeneic conflicts, including GVHD.

Optimization of culture conditions for rapid clinical-scale expansion of human umbilical cord blood-derived mesenchymal stem cells

Background

Mesenchymal stem cells (MSCs) have broad-spectrum therapeutic effects in various diseases, and thus have many clinical applications. However, it is difficult to produce sufficient numbers of MSCs for clinical use, and improved culture systems are required. Here, we report the effects of calcium (Ca²⁺) and hypoxia on the proliferation of human umbilical cord blood-derived MSCs (hUCB-MSCs). In addition, we determined the optimal conditions of these two factors for the large-scale culture of hUCB-MSCs.

Methods

hUCB-MSCs were maintained under hypoxic conditions (3% O₂) with 1.8 mM Ca²⁺ during long-term culture, and their proliferation was evaluated. To characterize the underlying mechanisms, the effects on hypoxia-inducible factor (HIF)-1α and the extracellular signal-regulated kinase (ERK) signaling pathways were investigated. The therapeutic effects in a mouse emphysema model were analyzed and compared with those of naive MSCs.

Results

The proliferation of Ca²⁺/hypoxia-treated hUCB-MSCs was increased compared with that observed using either calcium or hypoxia culture alone, without loss of stem cell marker expression or differentiation ability. The enhancement of the proliferation capacity of hUCB-MSCs by the synergistic effects of Ca²⁺ and hypoxia was dependent on the expression of HIF-1α and the ERK signaling pathway. The proliferation of Ca²⁺/hypoxia-treated hUCB-MSCs resulted in a delayed senescence phenotype and increased the expression levels of stemness genes such as Oct4 and Nanog compared to those observed in conventional culture conditions. In addition, Ca²⁺/hypoxia-treated MSCs transplantation in the mouse emphysema model showed the same therapeutic effects as observed with naive MSCs.

Conclusions

These findings suggest that a Ca²⁺/hypoxia-based expansion system has applications for the large-scale production of MSCs for therapeutic purposes.

Electronic supplementary material

The online version of this article (doi:10.1186/s40169-017-0168-z) contains supplementary material, which is available to authorized users.

Autocrine Action of Thrombospondin-2 Determines the Chondrogenic Differentiation Potential and Suppresses Hypertrophic Maturation of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

Previous studies have shown that mesenchymal stem cell (MSC)-based therapies have varying efficacies for the treatment of various diseases, including cartilage defects. In this study, we demonstrated that the chondrogenic differentiation potential of human umbilical cord blood-derived MSCs (hUCB-MSCs) obtained from different individual donors varies, and we investigated the molecular basis for this variation. Microarray gene expression analysis identified thrombospondin-2 (TSP2) as a candidate gene underlying the interindividual variation in the chondrogenic differentiation potential of hUCB-MSCs. To assess the association between TSP-2 and the differentiation potential, we evaluated chondrogenic differentiation of hUCB-MSCs treated with TSP2 siRNA. In addition, we studied the effect of supplementing exogenous recombinant TSP-2 on TSP2 siRNA-treated hUCB-MSCs. We found that TSP-2 autocrinally promoted chondrogenic differentiation of hUCB-MSCs via the Notch signaling pathway, which was confirmed in MSCs from other sources such as bone marrow and adipose tissue. Interestingly, we observed that TSP-2 attenuated hypertrophy, which inevitably occurs during chondrogenic differentiation of hUCB-MSCs. Our findings indicated that the variable chondrogenic differentiation potential of MSCs obtained from different donors is influenced by the TSP-2 level in the differentiating cells. Thus, the TSP-2 level can be used as a marker to select MSCs with superior chondrogenic differentiation potential for use in cartilage regeneration therapy.

Association between information provision and decisional conflict in cancer patients

BACKGROUND

In this study, we aimed to identify demographic and clinical variables that correlate with perceived information provision among cancer patients and determine the association of information provision with decisional conflict (DC).

PATIENTS AND METHODS

We enrolled a total of 625 patients with cancer from two Korean hospitals in 2012. We used the European Organization for Research and Treatment of Cancer (EORTC) quality-of-life questionnaire (QLQ-INFO26) to assess patients' perception of the information received from their doctors and the Decisional Conflict Scale (DCS) to assess DC. To identify predictive sociodemographic and clinical variables for adequate information provision, backward selective logistic regression analyses were conducted. In addition, adjusted multivariate logistic regression analyses were carried out to identify clinically meaningful differences of perceived level of information subscales associated with high DC.

RESULTS

More than half of patients with cancer showed insufficient satisfaction with medical information about disease (56%), treatment (73%), other services (83%), and global score (80%). In multiple logistic regression analyses, lower income and education, female, unmarried status, type of cancer with good prognosis, and early stage of treatment process were associated with patients' perception of inadequate information provision. In addition, Information about the medical tests with high DCS values clarity [adjusted odds ratio (aOR), 0.54; 95% confidence interval (CI) 0.30-0.97] and support (aOR, 0.53; 95% CI 0.33-0.85) showed negative significance. For inadequate information perception about treatments and other services, all 5 DCS scales (uncertainty, informed, values clarity, support, and effective decision) were negatively related. Global score of inadequate information provision also showed negative association with high DCS effective decision (aOR, 0.43; 95% CI 0.26-0.71) and DCS uncertainty (aOR, 0.46; 95% CI 0.27-0.77).

CONCLUSION

This study found that inadequate levels of perceived information correlated with several demographic and clinical characteristics. In addition, sufficient perceived information levels may be related to low levels of DC.

Thrombospondin-2 secreted by human umbilical cord blood-derived mesenchymal stem cells promotes chondrogenic differentiation

Increasing evidence indicates that the secretome of mesenchymal stem cells (MSCs) has therapeutic potential for the treatment of various diseases, including cartilage disorders. However, the paracrine mechanisms underlying cartilage repair by MSCs are poorly understood. Here, we show that human umbilical cord blood-derived MSCs (hUCB-MSCs) promoted differentiation of chondroprogenitor cells by paracrine action. This paracrine effect of hUCB-MSCs on chondroprogenitor cells was increased by treatment with synovial fluid (SF) obtained from osteoarthritis (OA) patients but was decreased by SF of fracture patients, compared to that of an untreated group. To identify paracrine factors underlying the chondrogenic effect of hUCB-MSCs, the secretomes of hUCB-MSCs stimulated by OA SF or fracture SF were analyzed using a biotin label-based antibody array. Among the proteins increased in response to these two kinds of SF, thrombospondin-2 (TSP-2) was specifically increased in only OA SF-treated hUCB-MSCs. In order to determine the role of TSP-2, exogenous TSP-2 was added to a micromass culture of chondroprogenitor cells. We found that TSP-2 had chondrogenic effects on chondroprogenitor cells via PKCα, ERK, p38/MAPK, and Notch signaling pathways. Knockdown of TSP-2 expression on hUCB-MSCs using small interfering RNA abolished the chondrogenic effects of hUCB-MSCs on chondroprogenitor cells. In parallel with in vitro analysis, the cartilage regenerating effect of hUCB-MSCs and TSP-2 was also demonstrated using a rabbit full-thickness osteochondral-defect model. Our findings suggested that hUCB-MSCs can stimulate the differentiation of locally presented endogenous chondroprogenitor cells by TSP-2, which finally leads to cartilage regeneration.

Distant metastatic lesions in patients with differentiated thyroid carcinoma. Clinical implications of radioiodine and FDG uptake

AIM

Many investigators have reported an inverse relationship between iodine and glucose utilization of differentiated thyroid carcinoma (DTC) according to its degree of differentiation; however, not every DTC is compatible with this phenomenon. This study was conducted to evaluate the clinical implication of iodine and glucose uptake at distant metastatic lesions in DTC patients.

PATIENTS, METHODS

64 DTC patients (women 47; mean age 49.9 ± 16.4 years) with distant metastasis who underwent post (131)I treatment whole-body scan (RxWBS) and FDG PET/CT were included in the study. Radioiodine (RAI) and FDG uptake of metastatic lesions were evaluated. TSH stimulated serum thyroglobulin (s-Tg) were obtained.

RESULTS

53 of 64 patients (82.8%) were RAI(+) group, and 37 patients (57.8%) were FDG(+) group. Patients in the RAI(-) group showed a higher rate of FDG uptake than RAI(+) group (100.0% vs. 49.1%, p = 0.002). Patients in the FDG(-) group showed a higher rate of RAI uptake than FDG(+) group (100.0% vs. 70.3%, p = 0.002). Patients with s-Tg < 100 ng/ml were frequently observed in the FDG(-)/RAI(+) group and the FDG(+)/RAI(-) group (p = 0.023). And patients with s-Tg ≥ 500 ng/ml were more frequently observed in the FDG(+)/RAI(+) group, compared with the FDG(+)/RAI(-) group (p = 0.036). Reduced disease-specific survival (DSS) was observed in patients with RAI(-) (p = 0.003), FDG(+) (p = 0.006), SUVmax > 3.6 (p<0.001), and s-Tg > 75.8 ng/ml (p = 0.009). In multivariate analysis, only a SUVmax > 3.6 was significantly predictive of DSS (p = 0.006).

CONCLUSION

An inverse relationship between RAI and FDG uptake, flip-flop phenomenon, was observed in patients with metastatic lesions of DTC. Reduced disease-specific survival was observed in patients with FDG(+), RAI(-) in metastatic lesions, or high s-Tg value.

Low immunogenicity of allogeneic human umbilical cord blood-derived mesenchymal stem cells in vitro and in vivo

Evaluation of the immunogenicity of human mesenchymal stem cells (MSCs) in an allogeneic setting during therapy has been hampered by lack of suitable models due to technical and ethical limitations. Here, we show that allogeneic human umbilical cord blood derived-MSCs (hUCB-MSCs) maintained low immunogenicity even after immune challenge in vitro. To confirm these properties in vivo, a humanized mouse model was established by injecting isolated hUCB-derived CD34+ cells intravenously into immunocompromised NOD/SCID IL2γnull (NSG) mice. After repeated intravenous injection of human peripheral blood mononuclear cells (hPBMCs) or MRC5 cells into these mice, immunological alterations including T cell proliferation and increased IFN-γ, TNF-α, and human IgG levels, were observed. In contrast, hUCB-MSC injection did not elicit these responses. While lymphocyte infiltration in the lung and small intestine and reduced survival rates were observed after hPBMC or MRC5 transplantation, no adverse events were observed following hUCB-MSC introduction. In conclusion, our data suggest that allogeneic hUCB-MSCs have low immunogenicity in vitro and in vivo, and are therefore "immunologically safe" for use in allogeneic clinical applications.

The influence of hospital volume and surgical treatment delay on long-term survival after cancer surgery

BACKGROUND

We conducted a population-based retrospective cohort study to investigate the influence of hospital volume, delay of surgery, and both together on the long-term survival of postoperative cancer patients.

METHODS

Using information from the Korea Central Cancer Registry from 2001 through 2005 and the National Health Insurance claim database, we determined survival for 147 682 patients who underwent definitive surgery for any of six cancers.

RESULTS

Regardless of cancer site, surgical patients in low- to medium-volume hospitals showed significantly worse survival [adjusted hazard ratio (aHR) = 1.36-1.86] than those in high-volume hospitals in multivariable analyses. Among the latter, treatment delays > 1 month were not associated with worse survival for stomach, colon, pancreatic, or lung cancer but were for rectal [aHR = 1.28; 95% confidence interval (CI), 1.17-1.40] and breast (aHR = 1.59; 95% CI, 1.37-1.84) cancer. For patients in low- to medium-volume hospitals, treatment delay was associated with worse survival for all types of cancer (aHR = 1.78-3.81).

CONCLUSION

Our findings suggest that the effect of hospital volume and surgical treatment delay on overall survival of cancer patients should be considered in formulating or revising national health policy.

Variations in the course of the cervical vagus nerve on thyroid ultrasonography

BACKGROUND AND PURPOSE

Only 1 ultrasonography study that described the variation of the VN had been published at the time our research was begun. The purpose of this study was to evaluate the incidence and type of variation in the course of the cervical VN on thyroid ultrasonography.

MATERIALS AND METHODS

From August 2009 to September 2010, 163 consecutive patients were evaluated by sonography for the screening and characterization of thyroid nodules (mean age, 49.0 ± 14.4 years, male:female, 20:143). Two types of variation were defined as follows: 1) anterior variation, when the course of the VNs changed from the typical location to an anterior location in front of the CCA; and 2) medial variation, when the course of the VNs changed from the typical location to a location medial to the CCA (between CCA and thyroid gland). The incidence of the each variation was studied.

RESULTS

Variation in the course of the VN occurred in 5.5% (18/326) of cases. The anterior variation was observed in 4.3% (14/326, right:left = 4:10), and the medial variation was observed in 1.2% (4/326, right:left = 3:1). For both variations, the VN was close to or nearly abutted the thyroid gland after it changed course.

CONCLUSIONS

Variation in the course of the cervical VN could be assessed by ultrasonography. Two variations were observed in 5.5% of cases. The anterior variation was more common than the medial variation.

Risk factors for device-associated infection related to organisational characteristics of intensive care units: findings from the Korean Nosocomial Infections Surveillance System

Device-associated infections (DAIs) have been the major causes of morbidity and mortality of patients in intensive care units (ICUs). This study evaluated the risk factors for DAIs in ICUs. Ninety-six medical or surgical ICUs of 56 hospitals participated in the Korean Nosocomial Infections Surveillance System between July 2007 and June 2008. The occurrence of catheter-associated urinary tract infection (CAUTI), central line-associated bloodstream infection (CABSI), and ventilator-associated pneumonia (VAP) were monitored and DAI rates were calculated. Data associated with ICU characteristics were collected and Poisson regression was used for statistical analysis. Rates of CAUTI, CABSI, and VAP were 3.87 per 1000 urinary catheter days, 2.23 per 1000 central line days, and 1.89 per 1000 mechanical ventilator days, respectively. Rates of CAUTI were higher in ICUs in Seoul (P=0.032) and ICUs of major teaching hospitals (P=0.010). The ICUs of university-affiliated hospitals showed lower CAUTI rates (P=0.013). CABSI rates were higher in Seoul (P=0.001) and in medical ICUs (P=0.026). VAP rates were lower in ICUs of hospitals with more than 900 beds compared with hospitals with 400-699 beds (P=0.026). VAP rates were higher in surgical ICUs (P<0.0001) and increased 1.13-fold with each 100-unit increase in beds per infection control professional (P=0.003). The organisational and institutional characteristics of ICUs may influence DAI rates and there is a need for improvement in the incidence of VAP, CAUTI or CABSI.

Biocompatible Polyhydroxyethylaspartamide-based Micelles with Gadolinium for MRI Contrast Agents

Biocompatible poly-[N-(2-hydroxyethyl)-d,l-aspartamide]-methoxypoly(ethyleneglycol)-hexadecylamine (PHEA-mPEG-C(16)) conjugated with 1,4,7,10-tetraazacyclododecan-1,4,7,10-tetraacetic acid-gadolinium (DOTA-Gd) via ethylenediamine (ED) was synthesized as a magnetic resonance imaging (MRI) contrast agent. Amphiphilic PHEA-mPEG-C(16)-ED-DOTA-Gd forms micelle in aqueous solution. All the synthesized materials were characterized by proton nuclear magnetic resonance ((1)H NMR). Micelle size and shape were examined by dynamic light scattering (DLS) and atomic force microscopy (AFM). Micelles with PHEA-mPEG-C(16)-ED-DOTA-Gd showed higher relaxivities than the commercially available gadolinium contrast agent. Moreover, the signal intensity of a rabbit liver was effectively increased after intravenous injection of PHEA-mPEG-C(16)-ED-DOTA-Gd.

Galectin-3 secreted by human umbilical cord blood-derived mesenchymal stem cells reduces amyloid-beta42 neurotoxicity in vitro

In this study, we found that expression and secretion of galectin-3 (GAL-3) were upregulated by amyloid-beta42 (Abeta42) exposure in human umbilical cord blood-derived mesenchymal stem cell (hUCB-MSC) without cell death. Abeta42-exposed rat primary cortical neuronal cells co-treated with recombinant GAL-3 were protected from neuronal death in a dose-dependent manner. hUCB-MSCs were cocultured with Abeta42-exposed rat primary neuronal cells or the neuroblastoma cell line, SH-SY5Y in a Transwell chamber. Coculture of hUCB-MSCs reduced cell death of Abeta42-exposed neurons and SH-SY5Y cells. This neuroprotective effect of hUCB-MSCs was reduced significantly by GAL-3 siRNA. These data suggested that hUCB-MSC-derived GAL-3 is a survival factor against Abeta42 neurotoxicity.

Functional characterization of mesenchymal stem cells labeled with a novel PVP-coated superparamagnetic iron oxide

Magnetic resonance imaging of cells labeled with superparamagnetic iron oxide (SPIO) could be a valuable tool for tracking transplanted cells in living organisms. Human bone marrow-derived mesenchymal stem cells (hBMMSC) were labeled with a novel polyvinyl pyrrolidone (PVP)-coated SPIO. Prussian blue staining and electron microscopy revealed that almost all of the cells were efficiently labeled with PVP-SPIO nanoparticles. There were no signs of cytotoxicity, even at concentrations of up to 1600 microg Fe/ml of the nanoparticles, and the labeled cells were successfully visualized by in vitro cellular MRI. In addition, there was no significant alteration of the phenotype or the adipo/osteo/chondrogenic differentiation potential of the cells. This was in contrast to Feridex IV labeling that led to the inhibition of hBMMSC chondrogenesis. Following intramuscular injection in a rabbit hind limb ischemia model, the intercellular migration of the labeled cells toward the ablated site was clearly tracked through in vivo MRI. The localization of the transplanted cells observed by MRI correlated well with postmortem histological studies. These results demonstrate that the novel PVP-SPIO nanoparticles appear to be efficient MR contrast agents and may enable non-invasive in vivo tracking of stem cells in experimental and clinical settings during cell therapy.

Synchronous gastric cancer in primary sporadic colorectal cancer patients in Korea

BACKGROUND AND AIMS

Colorectal cancer has been reported to be the malignancy most frequently associated with gastric cancer in Korea. The aim of this study was to define the frequency and clinical characteristics of synchronous gastric cancer detected at preoperative esophagogastroduodenoscopy (EGD) in colorectal cancer patients.

MATERIALS AND METHODS

This prospective study analyzed the EGD results from 1,542 consecutive colorectal cancer patients who underwent surgery from January 2003 to December 2005 at the Center for Colorectal Cancer, National Cancer Center, Korea.

RESULTS

Of the 1,542 cases, 1,155 (74.9%) underwent EGD at our center and 387 underwent EGD at other hospitals within 6 months before surgery. Of the 1,542 cases, synchronous gastric cancers were detected in 31 cases (2.0%). Of these 31 cases, 26 had early gastric cancer (EGC; 83.9%) and 5 had advanced gastric cancer. Ten (38.5%) of the 26 EGC cases were managed using endoscopic mucosal resection. Compared to colorectal cancer patients without synchronous gastric cancer, the group of patients with synchronous gastric cancer was older (65.5+/-9.6 vs 58.4+/-11.3 years, p=0.001) and had a greater proportion of males (77.4 vs 59.4%, p=0.043).

CONCLUSION

This study found that 2% of Korean sporadic colorectal cancer patients had synchronous gastric cancer. A preoperative EGD for colorectal cancer patients is likely to greatly assist in the diagnosis of synchronous gastric cancer at an early stage and the implementation of appropriate minimally invasive treatment.

Aspergillus oryzae palBory encodes a calpain-like protease: homology to Emericella nidulans PalB and conservation of functional regions

We have cloned and sequenced genomic DNA of Aspergillus oryzae palBory, orthologue of Emericella nidulans palB, which encodes a calpain-like protease modulating a signal transduction pathway during alkaline adaptation. The deduced amino acid sequence of PalBory is 70.0% identical to PalB over its entire length. The regions with high similarity revealed possible domains important for their function. This is the first step towards understanding the alkaline adaptation mechanism of A. oryzae, which would be very useful in the fermentation industry.

Controlled release of paclitaxel from microemulsion containing PLGA and evaluation of anti-tumor activity in vitro and in vivo

The main objective of this study was to develop an optimal paclitaxel microemulsion prepared by self-microemulsifying drug delivery system (SMEDDS) which is a mixture of paclitaxel, tetraglycol, Cremophor ELP, and Labrafil 1944 and a paclitaxel microemulsion containing poly(D,L-lactide-co-glycolide) (PLGA) in order to offer controlled release of paclitaxel. To achieve this goal, paclitaxel and PLGA were dissolved by solubilizer like tetraglycol. There was not observed any change in molecular weight of PLGA after being solubilized by tetraglycol. The droplet size for all of the formulation of microemulsion was found in the range of 45-270nm by dynamic light scattering (DLS). It was observed that the droplet size of microemulsion without PLGA was smaller than that of microemulsion containing PLGA by transmission electron microscopy (TEM). The droplet of microemulsion containing PLGA was almost of spherical shape with smooth surface and there was no aggregation or adhesion among droplet of microemulsion by atomic force microscopy (AFM). The release behaviour of paclitaxel from microemulsion containing PLGA having various molecular weights (8K, 33K, and 90K) exhibited a biphasic pattern characterized by a fast initial release during the first 48h, followed by a slower and continuous release for 144h, in contrast that the release of paclitaxel from microemulsion without PLGA was finished during 24h. This result was identical with the result of anti-tumor activity in vitro of paclitaxel from microemulsion containing PLGA against human breast cancer cell line MCF7 and this formulation enhanced anti-tumor activity in vivo compared with microemulsion without PLGA against SKOV-3 human ovarian cancer cells bearing nude mice model.

Use of polyurethane with sustained release dexamethasone in delayed adjustable strabismus surgery

AIM

To determine the effect of polyurethane film with sustained release dexamethasone (SRD) in delayed adjustable strabismus surgery.

METHODS

A prospective, masked observer, controlled study was performed in rabbits. Thirty four rabbit eyes were divided into three groups. After recession of the superior rectus muscle (SRM), polyurethane film with or without SRD, or balanced salt solution was applied beneath and over SRM in the polyurethane-dexamethasone group (group P-D), polyurethane group (group P), and the control group (group C), respectively. Delayed adjustment was performed once on each SRM at 4 and 6 weeks postoperatively by a masked observer. The possible length to adjust and the necessary force required for the adjustment, as well as the degree of any adhesions, were also evaluated.

RESULTS

In the control group, adjustment was impossible in all of the eyes at 4 and 6 weeks postoperatively. In group P-D, adjustment was possible in 11 out of 11 eyes (11/11) 4 weeks postoperatively and in 10/11 eyes 6 weeks postoperatively. In group P, adjustment was possible in 9/11 eyes 4 weeks postoperatively and in 10/12 eyes 6 weeks postoperatively.

CONCLUSIONS

Use of polyurethane film with and without SRD could delay adjustment in most eyes for up to 6 weeks postoperatively. Polyurethane is helpful for delaying adjustment in rabbit eyes until 6 weeks postoperatively without the need for frequent topical instillation of steroids.