Low-cost screen-printed electrodes based on electrochemically reduced graphene oxide-carbon black nanocomposites for dopamine, epinephrine and paracetamol detection.

A green approach for the preparation of carbon black (CB) and electrochemically reduced graphene oxide composite (ERGO) is described based on screen printed carbon electrodes (SPCEs) fabricated on poly(ethylene terephthalate) (PET) as electrochemical sensors. This approach leads to a heterogeneous hydrophilic surface with high concentration of defect sites according to scanning electron microscopy, contact angle and Raman spectroscopy measurements. The SPCE/CB-ERGO sensor was tested with dopamine (DA), epinephrine (EP) and paracetamol (PCM), exhibiting an enhanced electrocatalytic performance compared to the bare SPCE. It displayed a wider linear range, lower limit of detection and a remarkably higher analytical sensitivity, viz. 1.5, 0.13 and 0.028 A L mol-1 for DA, EP and PCM, respectively, being also capable of simultaneous determination of the three analytes. Such high performance is demonstration that SPCE/CB-ERGO may serve as generic platform for cost-effective flexible electrochemical sensors.

Glycocinnamoylspermidines, a new class of antibiotics. V. Antibacterial evaluation of the isopropyl derivative of LL-BM123gamma.

Isopropyl LL-BM123gamma, a novel semisynthetic glycocinnamoylspermidine antibiotic, was active in vitro against both Gram-negative and Gram-positive bacteria with broad spectrum bactericidal activity against clinically important Gram-negative strains. In parallel tests, it was equal to or more potent than reference aminoglycoside antibiotics against Escherichia coli, Proteus, Enterobacter-Klebsiella, Serratia, Salmonella, and Acinetobacter strains. Against clinical isolates of Pseudomonas aeruginosa, isopropyl LL-BM123gamma compared favorably with gentamicin, verdamicin and amikacin but was less potent than tobramycin. Isopropyl LL-BM123gamma was active against many Gram-negative bacteria that were relatively resistant to aminoglycosides. It was rapidly absorbed following subcutaneous administration in mice and showed greater potency than gentamicin on both dosage and plasma concentration bases against several experimental infections.

Glycocinnamoylspermidines, a new class of antibiotics. II. Isolation, physiocochemical and biological properties of LL-BM123beta, gamma1 and gamma2.

LL-BM123beta, gamma1 and gamma2 are three new antibiotics produced by fermentation of an unidentified species of Nocardia. These strongly basic, water soluble compounds were isolated from the culture filtrate by CM-Sephadex ion-exchange and carbon chromatography. All three antibiotics are active against both gram-positive and gram-negative bacteria. A mixture of LL-BM123 gamma1 and gamma2 is more active than the beta component but generally less active than gentamicin.