A narrow bandgap, strong donor‐acceptor polymer semiconductor is presented. This “transistor paint” material exhibits hole mobilities as high as 0.41 cm2/Vs. Importantly, the semiconductor yields ...high reproducible mobility values of 0.28 cm2/Vs ± 0.019 for a range of channel lengths when measured from several transistors on different days.
is an opportunistic fungal pathogen that causes meningitis in >152,000 immunocompromised individuals annually, leading to 112,000 yearly deaths. The four classes of existing antifungal agents target ...plasma membrane sterols (ergosterol), nucleic acid synthesis, and cell wall synthesis. Existing drugs are not highly effective against
, and antifungal drug resistance is an increasing problem. A novel antimicrobial compound, a eumelanin-inspired indoylenepheyleneethynylene, EIPE-1, was synthesized and has antimicrobial activity against Gram-positive bacteria, including methicillin-resistant
(MSRA), but not towards Gram-negative organisms. Based on EIPE-1's antibacterial activity, we hypothesized that EIPE-1 could have antifungal activity. For these studies, we tested EIPE-1 against
strain H99 and 6 additional cryptococcal clinical isolates. We examined antifungal activity, cytotoxicity, effects on fungal gene expression, and mechanism of action of EIPE-1. Results showed that EIPE-1 has fungicidal effects on seven cryptococcal strains with MICs ranging from 1.56 to 3.125 μg/mL depending on the strain, and it is non-toxic to mammalian cells. We conducted scanning and transmission electron microscopy on the exposed cells to examine structural changes to the organism following EIPE-1 treatment. Cells exposed displayed structural changes to their cell wall and membranes, with internal contents leaking out of the cells. To understand the effect of EIPE-1 on fungal gene expression, RNA sequencing was conducted. Results showed that EIPE-1 affects several processes involved stress response, ergosterol biosynthesis, capsule biosynthesis, and cell wall attachment and remodeling. Therefore, our studies demonstrate that EIPE-1 has antifungal activity against
which affects both cellular structure and gene expression of multiple fungal pathways involved in cell membrane stability and viability.
Herein are reported the syntheses of poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PF), poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT), and ...poly(9,9-bis(3′-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene) (PFN) by employing catalytic mechanochemical Suzuki polymerization in a ball mill. This mechanochemical synthesis technique can yield soluble functionalized polyfluorenes and its derivatives in 30 min or less. Furthermore, the polymer light emitting diode and photovoltaic interfacial electrolyte, poly(9,9-bis(3′-(N,N-dimethyl)-N-ethylammoinium-propyl-2,7-fluorene)-alt-2,7-(9,9-dioctylfluprene))dibromide (PFN-Br), was obtained via a facile mechanochemical quaternization reaction at the terminal amino groups of PFN.
Advancements in electrode technologies to both stimulate and record the central nervous system's electrical activities are enabling significant improvements in both the understanding and treatment of ...different neurological diseases. However, the current neural recording and stimulating electrodes are metallic, requiring invasive and damaging methods to interface with neural tissue. These electrodes may also degrade, resulting in additional invasive procedures. Furthermore, metal electrodes may cause nerve damage due to their inherent rigidity. This paper demonstrates that novel electrically conductive organic fibers (ECFs) can be used for direct nerve stimulation. The ECFs were prepared using a standard polyester material as the structural base, with a carbon nanotube ink applied to the surface as the electrical conductor. We report on three experiments: the first one to characterize the conductive properties of the ECFs; the second one to investigate the fiber cytotoxic properties in vitro; and the third one to demonstrate the utility of the ECF for direct nerve stimulation in an in vivo rodent model.
The mechanism of Ullmann-type biaryl formation between benzo-1,2-b:4,5-b′dithiophene-1,1,5,5-tetraoxide (BDTT) and iodobenzene (ArI) was computationally studied in the presence of CuI, ...phenanthroline (Phen), K3PO4 (as a base), and Ag2CO3 (as an additive). It is shown that base and additive play critical roles in each step of the reaction, such as (a) the I-to-base exchange in complex (Phen)CuI, (b) substrate deprotonation via the acid–base mechanism, and (c) Ar–I activation and DBT–Ar coupling. It is shown that (a) the presence of sulfonyl oxygens in DBT is essentialit plays an anchoring role and brings substrate and base closer to each other. In the presence of K3PO4 and in the absence of additive Ag2CO3, the Ph-I activation and C–C coupling occurs via a Cu-mediated nucleophilic substitution mechanism and requires a significant free energy barrier. However, the addition of Ag2CO3 to the reaction mixture not only accelerates the DBT and PhI coupling by reducing the rate-limiting Ph-I activation barrier but also switches the mechanism of the reaction from a Cu-mediated nucleophilic substitution to a Ag(I)-promoted oxidative addition-reductive elimination. These findings are important for development of the next generation reaction conditions for Ullmann-type of coupling reactions.
Typically, Suzuki couplings used in polymerizations are performed at raised temperatures in inert atmospheres. As a result, the synthesis of aromatic materials that utilize this chemistry often ...demands expensive and specialized equipment on an industrial scale. Herein, we describe a bimetallic methodology that exploits the distinct reactivities of palladium and copper to perform high yielding aryl–aryl dimerizations and polymerizations that can be performed on a benchtop under ambient conditions. These couplings are facile and can be performed by simple mixing in the open vessel. To demonstrate the utility of this method in the context of polymer synthesis: polyfluorene, polycarbazole, polysilafluorene, and poly(6,12-dihydro-dithienoindacenodithiophene) were created at ambient temperature and open to air.
Lightweight conductive polymers are considered for lightning strike mitigation in composites by synthesizing intrinsically conductive polymers (ICPs) and by the inclusion of conductive fillers in ...insulating matrices. Conductive films based on polyaniline (PANI) and graphene have been developed to improve through‐thickness conductivity of polymer composites. The result shows that the conductivity of PANI enhanced by blending polyvinylpyrrolidone (PVP) and PANI in 3:1 ratio. Conductive composite thin films are prepared by dispersing graphene in PANI. The conductivity of composite films was found to increase by 40× at 20 wt% of graphene inclusion compared with PVP and PANI blend. Fourier‐transform‐infrared (FTIR) spectra confirmed in situ polymerization of the polymer blend. The inclusion of graphene also exhibits an increase in Tg by 21°C. Graphene additions also showed an increase in thermal stability by approximately 148°C in the composite films. The mechanical result obtained from DMA shows that inclusion of graphene increases the tensile strength by 48% at 20 wt% of graphene reinforcement. A thin, highly conductive surface that is compatible with a composite resin system can enhance the surface conductivity of composites, improving its lightning strike mitigation capabilities.
A Diverse View of Science to Catalyse Change Urbina-Blanco, César A; Jilani, Safia Z; Speight, Isaiah R ...
Journal of the American Chemical Society,
08/2020, Letnik:
142, Številka:
34
Journal Article
PDF
