Hongkwan Park

Enhanced thermoelectric properties of PEDOT:PSS nanofilms by a chemical dedoping process

We report that a simple chemical dedoping treatment of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) nanofilms enhances the thermoelectric properties of the polymer nanofilms. The dedoping process was done by over-coating a mixture of dimethyl sulfoxide (DMSO) and hydrazine (HZ), a strong chemical reducing agent, onto the PEDOT:PSS nanofilms. This additional step led to the removal of excess PSS chains and the formation of neutral states of PEDOT chains, resulting in an improvement in the Seebeck coefficient, from 30 μV K−1 to 142 μV K−1, and a decrease in the electrical conductivity from 726 S cm−1 to 2 S cm−1. By controlling the concentration of HZ, we obtained an optimized power factor of 112 μW m−1 K−2 at 0.0175 wt% of HZ in DMSO at room temperature. The corresponding electrical conductivity and Seebeck coefficient under optimized conditions were 578 S cm−1 and 67 μV K−1, respectively. We expect that this simple dedoping process can be applied to general thermoelectric nanofilms based on chemically doped polymers in order to enhance the power factor.

Transparent and flexible organic semiconductor nanofilms with enhanced thermoelectric efficiency

Sequential doping and dedoping increased the conductivity and optimized the oxidation level of transparent and flexible poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonic acid) (PEDOT:PSS) films, resulting in an improvement in the thermoelectric figure of merit ZT. The electrical conductivity (σ) increased from 970 to 1260 S cm−1 and the power factor from 66.5 to 70.7 μW mK−2 at the optimum concentration of the chemical dopant p-toluenesulfonic acid monohydrate (TSA). Then, the doped PEDOT:PSS films were treated with hydrazine/DMSO solutions with different hydrazine concentrations to precisely control the oxidation level. During the hydrazine/DMSO treatment (dedoping), σ of the films continuously decreased from 1647 to 783 S cm−1 due to a decrease in the carrier concentration, whereas the Seebeck coefficient (S) steeply increased from 28 to 49.3 μV K−1 at the optimum oxidation level. A power factor of 318.4 μW mK−2 (σ = 1310 S cm−1, S = 49.3 μV K−1), the highest among all existing thermoelectric nanofilms, was achieved while maintaining polymer film flexibility and transparency (88.3% of optical transmittance). In addition, the thermal conductivity (κ) of the PEDOT:PSS films decreased from 0.38 to 0.30 W mK−1 upon removal of PSS. At the lowest κ value, a high ZT value of 0.31 was achieved at room temperature.

Ionically crosslinked Ad/chitosan nanocomplexes processed by electrospinning for targeted cancer gene therapy.

For effective cancer gene therapy, systemic administration of tumor-targeting adenoviral (Ad) complexes is critical for delivery to both primary and metastatic lesions. Electrospinning was used to generate nanocomplexes of Ad, chitosan, poly(ethylene glycol) (PEG), and folic acid (FA) for effective FA receptor-expressing tumor-specific transduction. The chemical structure of the Ad/chitosan-PEG-FA nanocomplexes was characterized by NMR and FT-IR, and the diameter and surface charge were analyzed by dynamic light scattering and zeta potentiometry, respectively. The average size of Ad/chitosan-PEG-FA nanocomplexes was approximately 140 nm, and the surface charge was 2.1 mV compared to -4.9 mV for naked Ad. Electron microscopy showed well-dispersed, individual Ad nanocomplexes without aggregation or degradation. Ad/chitosan nanocomplexes retained biological activity without impairment of the transduction efficiency of naked Ad. The transduction efficiency of Ad/chitosan-PEG-FA was increased as a function of FA ratio in FA receptor-expressing KB cells, but not in FA receptor-negative U343 cells, demonstrating FA receptor-targeted viral transduction. In addition, the transduction efficiency of Ad/chitosan-PEG-FA was 57.2% higher than chitosan-encapsulated Ad (Ad/chitosan), showing the superiority of FA receptor-mediated endocytosis for viral transduction. The production of inflammatory cytokine, IL-6 from macrophages was significantly reduced by Ad/chitosan-PEG-FA nanocomplexes, implying the potential for use in systemic administration. These results clearly demonstrate that cancer cell-targeted viral transduction by Ad/chitosan-PEG-FA nanocomplexes can be used effectively for metastatic tumor treatment with reduced immune reaction against Ad.

Fabrication of cross-linked alginate beads using electrospraying for adenovirus delivery

Cross-linked alginate beads containing adenovirus (Ad) were successfully fabricated using an electrospraying method to achieve the protection and release of Ad in a controlled manner. An aqueous alginate solution containing Ad was electrosprayed into an aqueous phase containing a cross-linking agent (calcium chloride) at different process variables (voltages, alginate concentrations, and flow rates). Alginate beads containing Ad were used for transduction of U343 glioma cells and the transduction efficiency of the alginate beads was measured by quantification of gene expression using a fluorescence-activated cell sorter at different time points. In vitro results of gene expression revealed that the Ad encapsulated in the alginate beads with 0.5 wt% of alginate concentration exhibited a high activity for a long period (over 7 days) and was released in a sustained manner from the alginate beads. The Ad-encapsulating alginate beads could be promising materials for local delivery of Ad at a high concentration into target sites.

Novel solution-processable, dedoped semiconductors for application in thermoelectric devices

The thermoelectric performance of poly(3,4-ethylenedioxythiophene) complexed with a poly(4-styrenesulfonic acid) (PEDOT:PSS) film was enhanced by a three-step process. First, ultrafiltration was applied to remove non-complexed PSS from PEDOT:PSS grains. The ultrafiltration treatment leads to an improvement in the power factor (S2σ) from 54.9 to 83.2 μW m−1 K−2 and a decrease in the thermal conductivity (κ) from 0.330 to 0.170 W m−1 K−1. Second, the fully de-doped PEDOT:PSS solution was prepared by addition of hydrazine, which acted as a reducing agent. Third, the two PEDOT:PSS solutions (ultrafiltered and hydrazine-treated) were mixed in different ratios by simple ultrasonication blending without any post-treatment. The optimal S2σ value of 115.5 μW m−1 K−2 (∼10 times higher than that of the pristine PEDOT:PSS film) and ZT value of 0.2 were recorded at 33 wt% of the hydrazine-treated, ultrafiltered PEDOT:PSS in the blend.

Aqueous chemical synthesis of tellurium nanowires using a polymeric template for thermoelectric materials

We report the simple synthesis of tellurium nanowires (TeNWs) by a one-pot scale-up hydrothermal process. A clean wet-chemical method, employing telluric acid (Te(OH)6) as a source of tellurium, ascorbic acid as a weak reducing agent, and a linear polymer as a template, has been developed for the synthesis of TeNWs with a diameter of 30–140 nm and a length of several micrometers at 105 °C. A possible explanation for the one-dimensional growth of TeNWs is the linear polymer template. The effects of the concentration of the polymeric template on the nanowire morphology were investigated. Evaluation of the thermoelectric properties indicated a high Seebeck coefficient and a power factor of about 568 μV K−1 and 8.44 μW mK−2, respectively, of the optimized TeNW films, and these values were about 80 times larger than those of the TeNW films formed without a polymeric template. We expect this simple process to be widely applicable for large-scale production of one-dimensional inorganic nanomaterials for energy harvesting and electronic devices.

THU0431 Delta Neutrophil Index for the Differential Diagnosis between Adult-Onset Still's Disease and Sepsis in the Early Phase

Background Several classification criteria for Adult-onset Still’s disease (AOSD) have been suggested, but there have been no objective laboratory tests established for its diagnosis. Especially in the early phase, it is more difficult to discriminate AOSD from infection due to their indistinguishable symptoms and laboratory findings. Delta neutrophil index (DNI) is an automatically calculated parameter that reflects the ratio of immature granulocytes (IGs) over total neutrophil count in the peripheral circulation. DNI has been reported to be more specific for sepsis severity and prognosis than the traditional markers. With these reasons, it can be speculated that DNI may be helpful to discriminate AOSD from sepsis in the confusing early phase before the report of microbial culture studies, but its clinical application has not been reported to date. Objectives To investigate the clinical usefulness of DNI to discriminate AOSD from sepsis in the early phase. Methods We investigated the medical records of 13 patients with AOSD and 33 sex- and age- matched patients with sepsis. DNI and other laboratory values were assessed two or three times during the first 3 days and represented by their mean levels. In all subjects, microbial tests were performed to exclude or confirm sepsis. DNI was calculated by the automatic cell analyzer (ADVIA 2120 Hematology System, Siemens Healthcare Diagnostics, Forchheim, Germany). DNI was calculated using the following formula: DNI = [the neutrophil sub fraction and the eosinophil sub fraction measured in the MPO channel by the cytochemical MPO reaction] - [the PMN sub fraction measured in the nuclear lobularity channel by the reflected light beam]. Results Mean age of AOSD patients (male 3, female 10) was 43.9 ± 13.4 years old and that of sepsis patients (male 8, female 25) was 48.8 ± 11.0 years old. There were no significant differences in white blood cell counts, neutrophil proportion, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) between two groups. AOSD patients had notably lower DNI than sepsis patients regardless of the presence of bacteremia or not (1.8 ±1.0% vs. 9.9 ± 8.9% and 1.8 ±1.0% vs. 7.9 ± 3.7%, respectively)(Figure 1). Although the usefulness of DNI did not surpass that of ferritin for the differential diagnosis of the two diseases, the area under the receiver operating characteristic curve of DNI was slightly higher than that of ferritin. When we set DNI of 2.75% as the cut-off value for differential diagnosis of the two diseases, eleven (84.6%) of AOSD patients had a DNI value below 2.75% and 2 (15.4%) of them had a DNI over 2.75%. In contrast, in sepsis patients only 1 (3.0%) had a DNI below 2.75%. And the relative risk for predicting sepsis was 176 (p < 0.001, 95% confidential interval 14.501–2136.176). Conclusions AOSD patients had significantly lower DNI than sepsis patients regardless of the presence of bacteremia. Also DNI over 2.75 showed a high risk for sepsis in patients suspected of both AOSD and sepsis (RR=176.0). Thus, we suggest that DNI may help physicians to discriminate AOSD from sepsis in the confusing early phase before the report of microbial culture studies. Disclosure of Interest None Declared

THU0084 The relationship between serum leptin: Adiponectin ratio, insulin resistance, and carotid atherosclerosis in patients with rheumatoid arthritis

Background Cardiovascular (CV) morbidity and mortality are increased in patients with rheumatoid arthritis (RA). A growing set of evidence shows the relationship between inflammation and CV risk. Insulin resistance (IR) is not only associated with the increased CV risk, but also involved in inflammatory process by adipocytokines. Carotid intima-media thickness (IMT), and carotid resistive index (RI) have been used as indictors for carotid atherosclerosis. While carotid IMT has been reported in patients with RA in many studies, the RI has not been studied yet. Objectives We assessed the relationship between adipocytokines, insulin resistance and carotid atherosclerosis in RA via carotid IMT, plaque and RI to examine the hypothesis that adipocytokines affect insulin resistance and atherosclerosis. Methods Common carotid IMT, common carotid RI, and carotid plaque were measured by high-resolution ultrasonography in 192 patients with RA. Patients who have overt diabetes were excluded. Insulin resistance was assayed by homeostasis model assessment for insulin resistance (HOMA-IR). Serum adipocytokine (adiponectin, leptin, resistin, TNF-α, IL-6) concentrations were determined. Results Common carotid RI was independently associated with common carotid IMT after adjusting sex, conventional cardiovascular and metabolic risk factors (p=0.031); smoking, systolic blood pressure (SBP), waist circumference, glucose, triglycerides, HDL and LDL cholesterol. RI was also significantly associated with carotid plaque number (p=0.015) and estimated total plaque volume (p=0.033) after adjustment. Increased leptin:adiponectin ratio (p=0.021) was significantly related with higher HOMA-IR even after adjusting age, sex, and conventional risk. Resistin, TNF-α, IL-6, showed no significant association with HOMA-IR. Age, male sex, smoking, SBP, waist circumference, triglycerides, LDL cholesterol, and HOMA-IR were associated with increased carotid IMT by linear regression analysis. HOMA-IR was not associated with IMT after adjustment, nor with carotid plaque number, nor with plaque volume. Age, waist circumference, HOMA-IR and leptin:adiponectin ratio were related with increased carotid RI. Even after adjusting age, sex, conventional risk, and HOMA-IR, leptin:adiponectin ratio was the independent predictor for carotid RI (p=0.018). Conclusions Common carotid RI was significantly associated with common carotid IMT, plaque number, and plaque volume. Leptin:adiponectin ratio was independently related with HOMA-IR and carotid RI. Leptin and adpiponectin might be involved in the pathogenesis of accelerated atherogenetic process in RA. References Gremese E, Ferraccioli G. The metabolic syndrome: The crossroads between rheumatoid arthritis and cardiovascular risk. Autoimmun Rev 2011;10:582-9. Vicenzini E, Ricciardi MC, Puccinelli F, Altieri M, Vanacore N, Di Piero V, Lenzi GL. Common carotid artery intima-media thickness determinants in a population study. J Ultrasound Med 2007;26:427-432. Disclosure of Interest None Declared