Single CuTCNQ charge transfer complex nanowire as ultra high responsivity photo-detector

We report ultra large photo responsivity ℜ (ratio of photo-generated current to absorbed power) in a single nanowire (NW) device made from a single strand of a nanowire (diameter ~30nm and length ~200nm) of an organomettalic semiconducting charge transfer complex material of CuTCNQ. The device shows responsivity of 8x10(4) A/Watt at 1 volt applied bias with an enhancement over the dark current exceeding 10(5) at zero bias. The observed photo current has a spectral dependence that strongly follows the main absorption peak (close to 405 nm) showing the primary role of absorbed photo-generated carriers.

Polymer optoelectronic structures for retinal prosthesis

This commentary highlights the effectiveness of optoelectronic properties of polymer semiconductors based on recent results emerging from our laboratory, where these materials are explored as artificial receptors for interfacing with the visual systems. Organic semiconductors based polymer layers in contact with physiological media exhibit interesting photophysical features, which mimic certain natural photoreceptors, including those in the retina. The availability of such optoelectronic materials opens up a gateway to utilize these structures as neuronal interfaces for stimulating retinal ganglion cells. In a recently reported work entitled "A polymer optoelectronic interface provides visual cues to a blind retina," we utilized a specific configuration of a polymer semiconductor device structure to elicit neuronal activity in a blind retina upon photoexcitation. The elicited neuronal signals were found to have several features that followed the optoelectronic response of the polymer film. More importantly, the polymer-induced retinal response resembled the natural response of the retina to photoexcitation. These observations open up a promising material alternative for artificial retina applications.

Solution processable benzooxadiazole and benzothiadiazole based D-A-D molecules with chalcogenophene: field effect transistor study and structure property relationship

We present here the physicochemical characterization of a series of D-A-D type molecules which comprise benzooxadiazole (BDO) and benzothiadiazole (BDT) core symmetrically linked to two aromatic-heterols (furan (F), thiophene (T) and selenophene (Se)) at 4 and 7-positions. The molecular structures of four compounds 2 (T-BDO-T), 3 (Se-BDO-Se), 5 (T-BDT-T), and 6 (Se-BDT-Se) were determined by single-crystal X-ray diffraction. The combination of chalcogen atoms of benzochalcogenadiazole and chalcogenophene in D-A-D molecules has significant impact on their molecular packing in crystal structures. Structural analyses and theoretical calculations showed that all the molecules are nearly planar. Crystal structures of 2, 3, 5, and 6 showed significant short range interactions such as π···π, CH···π, S···π, Se···π, N···H, O···H, S···H, Se···H, S···O, and Se···N interactions, which influence crystal packing and orientation of the capped aromatic-heterol rings with respect to the central BDO or BDT unit. The π-stacking interactions have been observed via intermolecular overlap of the donor with acceptor units of the adjacent molecules which facilitate the charge transport process. Good thermal stability and solubility in common organic solvents make them good candidate for flexible electronics. Interestingly, the molecules 2, 3, and 6 have the propensity to form ordered crystallites when sheared during the drying process in the thin films. Devices based on these solution processable all organic FETs demonstrated hole mobility as high as 0.08 cm(2) V(-1) s(-1) and Ion/Ioff ratio of 10(4).

Morphology and electrostatics play active role in neuronal differentiation processes on flexible conducting substrates

This commentary discusses and summarizes the key highlights of our recently reported work entitled "Neuronal Differentiation of Embryonic Stem Cell Derived Neuronal Progenitors Can Be Regulated by Stretchable Conducting Polymers." The prospect of controlling the mechanical-rigidity and the surface conductance properties offers a unique combination for tailoring the growth and differentiation of neuronal cells. We emphasize the utility of transparent elastomeric substrates with coatings of electrically conducting polymer to realize the desired substrate-characteristics for cellular development processes. Our study showed that neuronal differentiation from ES cells is highly influenced by the specific substrates on which they are growing. Thus, our results provide a better strategy for regulated neuronal differentiation by using such functional conducting surfaces.

Rhodamine-123: Therapy for Hormone Refractory Prostate Cancer, A Phase I Clinical Trial

Rhodamine-123, a lipophilic, cationic, rhodocyanine dye, has been reported to have carcinoma selective toxicity in vitro and in vivo. This phase I clinical trial established the safety and pharmacokinetics of Rhodamine-123 administered to men with hormone refractory prostate cancer. A single dose toxicity study of Rhodamine-123 determined the maximum tolerated dose. A multiple dose toxicity study assessed the safety of Rhodamine-123 at the maximum tolerated dose level. Transient and variable toxicities noted following Rhodamine-123 infusion resolved within 6 hours following infusion. Pharmacokinetic analyses of sera showed no accumulation of drug with repeated monthly administrations. Drug retention was confirmed in prostatic tissue following Rhodamine-123 administration. PSA doubling times lengthened variably suggesting drug efficacy but the data were not statistically significant. The maximum tolerated dose of Rhodamine-123 is 96 mg/m2. The drug can be safely administered at monthly intervals without detectable drug accumulation in serum. Rhodamine-123 is retained by prostatic tumor tissue.

Neuronal differentiation of embryonic stem cell derived neuronal progenitors can be regulated by stretchable conducting polymers

Electrically conducting polymers are prospective candidates as active substrates for the development of neuroprosthetic devices. The utility of these substrates for promoting differentiation of embryonic stem cells paves viable routes for regenerative medicine. Here, we have tuned the electrical and mechanical cues provided to the embryonic stem cells during differentiation by precisely straining the conducting polymer (CP) coated, elastomeric-substrate. Upon straining the substrates, the neural differentiation pattern occurs in form of aggregates, accompanied by a gradient where substrate interface reveals a higher degree of differentiation. The CP domains align under linear stress along with the formation of local defect patterns leading to disruption of actin cytoskeleton of cells, and can provide a mechano-transductive basis for the observed changes in the differentiation. Our results demonstrate that along with biochemical and mechanical cues, conductivity of the polymer plays a major role in cellular differentiation thereby providing another control feature to modulate the differentiation and proliferation of stem cells.

Retention of power conversion efficiency--from small area to large area polymer solar cells

A light harvesting device geometry is implemented for polymer solar cells that retain efficiency when the device area is scaled up. Patterning devices and incorporating suitable fluorescent dye doped polymers in the spaces between the patterns leads to 12% efficiency enhancement. Vacuum free deposition of electrodes is carried out using meltable alloys giving rise to device efficiency of 6%. The fluorescent layer along with the electrode serves as an active encapsulant leading to improved device stability.

High-Resolution Photocurrent Imaging of Bulk Heterojunction Solar Cells

Images obtained from photocurrent scanning of organic bulk heterojunction solar cell devices provide a direct measure of correlation of the morphology to the performance parameters. The peripheral photocurrent induced from light coupled to probe tips in the near-field regime of bulk heterojunction layers permits in situ scanning of active solar cells with asymmetric electrodes. We present a methodology involving a combination of atomic force microscopy, near-field optical microscopy, and near-field photocurrent microscopy to decipher the carrier generation and transport regions in the bulk heterojunction layer. The angular Fourier transformation technique is implemented on these images to rationalize the optimum blend concentration in crystalline and amorphous donor systems and provide insights into the role of the bulk heterojunction morphology.

Nonplanar Perylene Diimides as Potential Alternatives to Fullerenes in Organic Solar Cells

Perylene diimides (PDIs) are attractive alternatives to fullerenes as electron transporters because of their optoelectronic properties, durability, and ease of synthesis. Belying this promise, devices that utilize PDIs as electron acceptors have low efficiencies. The primary deficiency in such cells is the low short circuit current density (JSC), which is traceable to the crystallinity of PDIs. Therefore, disrupting the crystallinity without adversely impacting the charge-transfer properties of PDIs is proposed as an important design principle. This has been achieved using a nonplanar perylene. In combination with a hole transporting polymer, a device efficiency of 2.77% has been achieved. A 10-fold increase in JSC is observed in comparison with a planar PDI, resulting in one of the highest JSC values for a solution processed device featuring a PDI. Indeed, this is one of the highest efficiencies for devices featuring a nonfullerene as the electron transporter.

Characteristic noise features in light transmission across membrane protein undergoing photocycle

We demonstrate a technique based on noise measurements which can be utilized to study dynamical processes in protein assembly. Direct visualization of dynamics in membrane protein system such as bacteriorhodopsin (bR) upon photostimulation are quite challenging. bR represents a model system where the stimulus-triggered structural dynamics and biological functions are directly correlated. Our method utilizes a pump-probe near field microscopy method in the transmission mode and involves analyzing the transmittance fluctuations from a finite size of molecular assembly. Probability density distributions indicating the effects of finite size and statistical correlations appear as a characteristic frequency distribution in the noise spectra of bR whose origin can be traced to photocycle kinetics. Valuable insight into the molecular processes were obtained from the noise studies of bR and its mutant D96N as a function of external parameters such as temperature, humidity or presence of an additional pump source.

Monitoring intermediate states of bacteriorhodopsin monolayers using near-field optical microscopy

We demonstrate single-molecule-level features using near-field optical microscopy on bacteriorhodopsin (bR), a membrane protein that functions as a light-driven proton pump. The photophysical properties of bR are utilized in this imaging technique, using a combination of photoexcitation sources, to accurately identify the active regions and quantify the optical parameters. The studies of bR monolayers are carried out on inert quartz substrates as well as active conducting polymer (polyaniline) substrates. The substrate also plays an important role in the photocycle quantum efficiencies. We speculate on mechanisms governing the higher near-field absorption strength of bR molecules.

Observation of Bessel beams from electric-field-induced patterns on polymer surfaces

We report the observation of Bessel-like beams from periodic patterns induced on viscoelastic polymer surfaces by electric field. The patterns resembling a microaxicon array originate from electrohydrodynamic instabilities in polymer films, where the feature dimensions can be easily controlled. The output beam characteristics from these patterns revealed characteristic traits of Bessel beams.

Electric-field-induced patterns in soft viscoelastic films: from long waves of viscous liquids to short waves of elastic solids

We show that the electric field driven surface instability of viscoelastic films has two distinct regimes: (1) The viscoelastic films behaving like a liquid display long wavelengths governed by applied voltage and surface tension, independent of its elastic storage and viscous loss moduli, and (2) the films behaving like a solid require a threshold voltage for the instability whose wavelength always scales as approximately 4xfilm thickness, independent of its surface tension, applied voltage, loss and storage moduli. Wavelength in a narrow transition zone between these regimes depends on the storage modulus.

Opto-electrical processes in a conducting polymer–bacteriorhodopsin system

In this report, we highlight the opto-electrical processes at a conducting polymer-bacteriorhodopsin (bR) interface in presence of a voltage bias. Oriented bR on a conducting polymer substrate forms a unique hybrid system where the oxidation state of the polymer controls the optically activated proton gradient in the bR side. The internal conversion of the intermediate deprotonated M-state and the proton transfer/transport of bR at the interface can be controlled by the electrostatic environment and leads to interesting device features in this process.

Lymphocytic infiltration of bladder after local cellular immunotherapy

BACKGROUND

This is a case report of a patient who received cellular immunotherapy, in the form of local injections of autologous stimulated lymphocytes (ASL) into individual tumors in the urinary bladder. A major consideration in cellular immunotherapy being the ability of immune cells to reach all target areas, we hypothesized that direct delivery of effector cells into individual bladder tumors might assure such access.

METHODS

ASL were generated by exposing the patient's PBL to phytohemagglutinin and culturing them in the presence of IL-2 to expand the population. ASL were injected into the base of individual bladder tumors three times at intervals of 3 weeks.

RESULTS

The patient died of a myocardial infarct, unrelated to cell therapy, 20 days after the third injection. An autopsy was performed. Histological sections of the bladder showed extensive lymphocytic infiltration of virtually the entire organ.

DISCUSSION

No conclusions about the therapeutic efficacy of local immunotherapy using ASL are possible. Nevertheless, the observations reported, taken together with reports of therapeutic efficacy of other immunotherapy regimens in the management of bladder cancer, suggest that ready access of stimulated lymphocytes to all regions of the organ may account, in part, for the relatively high rate of therapeutic success reported for various immunotherapy regimens for this malignancy.

Three-dimensional growth patterns of various human tumor cell lines in simulated microgravity of a NASA bioreactor

Growth patterns of a number of human tumor cell lines that from three-dimensional structures of various architectures when cultured without carrier beads in a NASA rotary cell culture system are described and illustrated. The culture system, which was designed to mimic microgravity, maintained cells in suspension under very low-shear stress throughout culture. Spheroid (particulate) production occurred within a few hours after culture was started, and spheroids increased in size by cell division and fusion of small spheroids, usually stabilizing at a spheroid diameter of about 0.5 mm. Architecture of spheroids varied with cell type. Cellular interactions that occurred in spheroids resulted in conformation and shape changes of cells, and some cell lines produced complex, epithelial-like architectures. Expression of the cell adhesion molecules, CD44 and E cadherin, was upregulated in the three-dimensional constructs. Coculture of fibroblast spheroids with PC3 prostate cancer cells induced tenascin expression by the fibroblasts underlying the adherent prostate epithelial cells. Invasion of the fibroblast spheroids by the malignant epithelium was also demonstrated.

Induction of apoptosis in myocardial infarction and its possible relationship to nitric oxide synthase in macrophages

Activated macrophages produce nitric oxide through the inducible form of nitric oxide synthase (iNOS). Previously, a significant increase of iNOS activity in macrophages in infarcted rabbit heart tissue was observed. The present study is concerned with the induction of apoptosis in macrophages and cardiomyocytes in infarcted rabbit heart tissue. The left anterior descending artery of rabbits was ligated. The heart was excised five hours, one, two, three, ten and twenty days later, and DNA was extracted from infarcted and non-infarcted region and subjected to electrophoresis. Terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) was carried out, and iNOS activity was measured by conversion of L-[14C]-arginine to L-[14C]-citrulline. Positive staining by TUNEL was seen in some cardiomyocytes five hours after coronary ligation and on postoperative day (POD) 1; internucleosomal DNA fragmentation was not noted. On POD 2 and 3, many infiltrating cells, immunohistochemically identified as macrophages, were positively stained by TUNEL; DNA fragmentation was also present. Apoptosis was not found on POD 10 and 20. The peak activity of iNOS was noted on POD 3, which corresponded with the induction of apoptosis. It is tempting to speculate that a causal relationship exists between increased iNOS formation and induction of apoptosis in macrophages in infarcted rabbit heart tissue.

Studies of rhodamine-123: effect on rat prostate cancer and human prostate cancer cells in vitro

The effect of the lipophilic, cationic dye, Rhodamine-123 (Rh-123), on prostate cancer in rats, and on three tumor cell lines in vitro is reported here. The general toxicity of Rh-123 in mice has been found to be minimal. Lobund-Wistar (L-W) rats with the autochthonous prostate cancer of Pollard were treated for six doses with Rh-123 at a dose of 15 mg/kg subcutaneously every other day. Microscopic examination of the tumors revealed cellular and acinar destruction. The effectiveness of Rh-123 as a cytotoxic agent was tested by clonogenic and viability assays in vitro with three human prostate cancer cell lines. Severe (60-95%) growth inhibition was observed following Rh-123 exposure for 2-5 days at doses as low as 1.6 micrograms/ml in all three prostate cancer cell lines.

Immunohistochemistry in the identification of nitric oxide synthase isoenzymes in myocardial infarction

OBJECTIVE

Inducible nitric oxide synthase (iNOS) activity, as measured by conversion of L-14C-arginine to L-14C-citrulline is significantly increased in infarcted rabbit myocardium as compared to healthy myocardium 48 h after coronary occlusion. The aim of this study was to localise the nitric oxide synthase (NOS) isoforms in normal myocardium and compare these findings with NOS activity in cells of the infarcted region.

METHODS

Activities of NOS isoforms were enzymatically assayed in normal and infarcted myocardium. Localisation of NOS was performed on identical sections using specific monoclonal IgG antibodies against endothelial constitutive (cNOS) and macrophage inducible (iNOS) nitric oxide synthase. In addition, macrophages were identified using fluorescein conjugated ChromPure rabbit IgG, Fc fragment.

RESULTS

iNOS activity increased significantly in infarcted as compared to normal myocardium [0.42(SEM 0.03) v 0.85(0.08) fmol.microgram-1.min-1, P = 0.02, respectively]. However, cNOS did not increase significantly in infarcted regions [0.18(0.04) v 0.24(0.06) fmol.microgram-1.min-1; P = 0.16, respectively]. cNOS was immunohistochemically localised in endothelial and endocardial cells in normal and infarcted tissues. The presence of iNOS activity in macrophages in infarcted myocardium was identified immunohistochemically. Cardiomyocytes and neutrophils did not label with the antibodies to cNOS and iNOS.

CONCLUSIONS

(1) Infiltrating macrophages are the main site of increased iNOS activity in infarcted rabbit myocardium. (2) cNOS activity is not significantly increased in infarcted tissues as compared to normal myocardium. (3) Neutrophils and cardiomyocytes do not express NOS immunoreactivity in infarcted and normal rabbit myocardium.

Cytokine production from freshly harvested human mononuclear cells attached to plastic beads

The release of tumor necrosis factor (TNF), interleukin-1 beta (IL-1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) from freshly harvested monocytes and lymphocytes attached to plastic beads was investigated. Previous studies had shown that freshly harvested endothelial cells attached to microcarrier beads release an endothelium-derived relaxing factor. Attachment of freshly harvested lymphocytes and monocytes to plastic beads created a dense network, consisting of 25% monocytes and 75% lymphocytes as shown by flow cytometry. Viability of cells was 90%. Monocytes were characterized by phagocytosis and non-specific esterase stain. Freshly harvested cells stimulated with lipoprotein lipase (LPS) released TNF and IL-1. Non-stimulated cells also produced GM-CSF five hours after collection of blood.

Release of prostacyclin, endothelium-derived relaxing factor and endothelin by freshly harvested cells attached to microcarrier beads

Cultured endothelial cells have been used in the past as a source of endothelium-derived relaxing factor (EDRF) and of prostacyclin (PGI2). Although cell cultures are essential for observation of prolonged exposure to media or when there is delayed response, they are time consuming and sterile conditions are essential. In the present study, we report that endothelial cells, freshly harvested from bovine aortas, readily attached themselves to cytodex-3 microcarrier beads and released an endothelium-derived relaxing factor (EDRF), prostacyclin (PGI2) and increased the amount of cyclic GMP in vascular smooth muscle. Attachment to microcarrier beads was essential since it increased the surface area and the number of attached cells and permitted collection of cell free filtrates because of the formation of dense networks of cells and beads. As a result superfusion of cells and beads on the filter did not dislodge bound cells which remain on the filter. Conditioned filtrates from freshly harvested endothelial cells attached to microcarrier beads caused marked relaxation of endothelium-deprived bovine pulmonary artery strips. The degree of relaxation depended on the number of cells; maximal relaxation occurred with 50 million cells at ED50 of 14 million. High values of cyclic GMP were found in vascular smooth muscle exposed to conditioned filtrate. The calcium ionophore A23187 further increased the amount of cyclic GMP. Large amounts of PGI2 were released by freshly harvested endothelial cells particularly after stimulation with the calcium ionophore. In contrast, endothelin production by freshly harvested cells attached to microcarrier beads was barely detectable after 30 min incubation and was beyond the limit of detection by bioassay procedures. Freshly harvested endothelial cells attached to microcarrier beads appear to be a useful adjunct to tissue cultures under specific experimental conditions.

The use of microcarrier beads in the production of endothelium-derived relaxing factor by freshly harvested endothelial cells

This study is concerned with the use of freshly harvested bovine endothelial cells attached to microcarrier beads in the production of the endothelium-derived relaxing factor (EDRF). The results are compared to production of EDRF by endothelial cells grown in tissue cultures. We found that freshly harvested cells attach themselves to microcarrier beads within minutes. This results in large surface/area volume ratio and permits superfusion of cells suspension on a filter (pore size of 25-30 microns), resulting in cell free filtrate. When superfusing an endothelium-deprived pulmonary artery strip, the effluent causes relaxation; the response depends on the number of superfused endothelial cells. The number of viable freshly harvested cells attached to microcarrier beads in 5 ml Krebs-Henseleit solution is small (30%), as compared to almost 100% for cultured cells. Despite this difference, percent relaxation induced for the same number of viable cells is identical for both groups. Scanning electromicrographs confirm anchorage of endothelial cells to microcarrier beads. While cultured cells cover the entire surface and are individually attached, freshly harvested cells are anchored as cell aggregates leaving some of the surface free. Attachment of freshly harvested endothelial cells to microcarrier beads offers an alternative for the study of the role of endothelial cells in the production of vasoactive substances.

Lymphocyte metabolism and cytotoxic activity monitored with 31P magnetic resonance spectroscopy

Continuous metabolic monitoring of human lymphocytes and a tumor cell line was achieved by means of nuclear magnetic resonance (NMR) applied to cells suspended in alginate gels. Human peripheral blood lymphocytes cultured in vitro were examined with 31P magnetic resonance spectroscopy (MRS) before and after activation with phytohemagglutinin and interleukin-2 (IL-2). Following the addition of these biological response modifiers, increases in [ATP], phosphomonoesters (PME), and phosphodiesters occurred. These appear to be markers of lymphocyte stimulation. Lymphocyte pH was unchanged. A target tumor cell line (K562) showed 31P NMR spectra that differed significantly from that of lymphocytes. When lymphocytes were mixed with tumor cells (to induce tumor cell death), and monitored by 31P MRS, levels of inorganic phosphate (Pi) increased, [PME] levels fell, and release of H+ was inhibited. 31P MRS may therefore provide a noninvasive assay of lymphocyte-mediated tumor cell killing that will have application in monitoring treatment in patients undergoing this type of therapy.

Growth of a malignant human urothelial cell line (J82) in a serum-free medium (HMRI-1) developed previously for normal human urothelium

A malignant human urothelial cell line (J82) has been cultured in a serum-free medium (HMRI-1) developed specifically for normal human urothelium. Unlike the normal human urothelium which grew as an attached monolayer, the J82 cells proliferated as free floating cellular aggregates. Comparative growth kinetic studies have shown that the J82 cells, unlike normal cultured urothelial cells, did not require epidermal growth factor, bovine pituitary extract or transferrin as single additives in the HMRI-1. However, deletion of certain combinations of these factors markedly reduced growth. It was concluded that the J82 cells had a reduced dependency on the normal urothelial cell growth factors suggesting that the J82 cells had altered nutritional requirements which might possibly be associated with the production of autocrine growth factors.