A sensitive electrochemical detection of metronidazole in synthetic serum and urine samples using low-cost screen-printed electrodes modified with reduced graphene oxide and C60

Monitoring the concentration of antibiotics in body fluids is essential to optimizing the therapy and minimizing the risk of bacteria resistance,which can be made with electrochemical sensors tailored with appropriate materials.In this paper,we report on sensors made with screen-printed electrodes(SPE)coated with fullerene(C60),reduced graphene oxide(rGO)and Nafion(NF)(C60-rGO-NF/SPE)to determine the antibiotic metronidazole(MTZ).Under optimized conditions,the C60-rGO-NF/SPE sensor exhibited a linear response in square wave voltammetry for MTZ concentrations from 2.5×10^(-7) to 34×10^(-6) mol/L,with a detection limit of 2.1×10^(-7) mol/L.This sensor was also capable of detecting MTZ in serum and urine,with recovery between 94%and 100%,which are similar to those of the standard chromatographic method(HPLC-UV).Because the C60-rGO-NF/SPE sensor is amenable to mass production and allows for MTZ determination with simple principles of detection,it fulfills the requirements of therapeutic drug monitoring programs.

Efficacy of Photogem（Hematoporphyrin Derivative） as a Photoactivatable Larvicide against Aedes aegypti （Diptera： Culicidae） Larvae

Dengue vector is responsible for millions of deaths every year and has caused disastrous impacts on health systems. The continuous use of chemical insecticides, such as carbamates, pyrethroids and organophosphates generates resistant populations of the mosquito, therefore, new control methods must be investigated. The joint action of the population and guidelines for preventing the reproduction of the mosquito associated with the use of photoactivatable insecticides can be the alternative for the control of epidemiological outbreaks in affected regions. In this study, the photo-larvicidal activity of Photogem^（PG）, a derivative of hematoporphyrin, was investigated against 2nd-early 3rd instar of Aedes aegypti larvae （Diptera： Culicidae） under different lighting conditions （artificial lighting system and sunlight）. The dynamics of PG accumulation was characterized by CLSM （confocal laser scanning microscopy） and total time PG eliminationin solution was investigated by ultraviolet-visible spectrophotometry. The maximum photo-activity of PG was observed in 0.5 h under sunlight exposure which achieved 100% larval mortality. Fluorescence images showed a uniform distribution of PG along the digestive tract. PG remained stable in the sunlight for 48 h and in an artificial lighting system for longer periods, therefore, it can be used for the control ofAedes aegypti larvae as a new alternative to chemical insecticides. The method is considered environmentally friendly due to its rapid degradation in the presence of light. Further studies are required, so that the potential of the technique can be explored in real breeding places.

Antimicrobial Efficacy of Curcumin Formulations byPhotodynamic Therapy

URTI （upper respiratory tract infections） are caused by acute, chronic or recurrent infections including pharyngitis andtonsillitis. The etiologic agents involved are bacteria, virus, and fungi. The standard treatment for bacterial infections is the use ofantibiotics. The antibiotic resistance, side effects of drugs and URTI complications indicate the importance of new therapies. PDT（photodynamic therapy） is a treatment option with a fast onset of action, low side effects, and easy administration of PS（photosensitizer） based on this study. The main aim of this study was to develop a new modality for the treatment of infectiouspharyngotonsillitis by photodynamic therapy. In addition, this study aims to evaluate components of the therapy as the PS, curcumin,in two formulations and irradiation conditions in the effectiveness of treatment. The procedure consists of two steps： oraladministration of CFs （curcumin formulations） containing a PS and illumination （450 nm and 0-60 J/cm2）. Bacterial isolates wereobtained from patients in a routine clinical pratice. The new methodology has been developed from the principle ofPI （photodynamicinactivation）. The strain identification number of colony forming units determined the efficacy of PI using each component, lightingand PS. The use of curcumin formulations in PI presented microbial reduction of 5 log.

In Vitro Study of Photodynamic Therapy for Treatment of Bacteremia in Whole Blood

Antibiotic resistance has been compromised hospitalized patients with serious infections. The main cases of bacteremia can be caused by antibiotic resistant pathogens. Photodynamic therapy （PDT） has been shown as an alternative for inactivation of microorganisms in blood. In this therapy photochemical mechanisms occur that may prevent the development of bacteria. This study aims optimization of PDT parameters for blood decontamination. Concentration ofphotosensitizer （PS）, light dose （LD） and incubation time （IT） were studied for hemolysis and cell toxic effects. It was observed that PDT can be used for microbial inactivation in total blood reducing 0.85 log10 CFU/mL ofS. aureus at 15 J/cm^2 and 50μg/mL of Photogem .

Ultrafast synthesis and sintering of materials in a single running experiment approach by using electric fields

Processing of materials in the form of ceramics normally involves several steps including calcination at a relatively low temperature for synthesis of the end-product powder and sintering at a high temperature for densification.The work we have been developing introduces a novel approach enabling synthesis plus sintering of materials in a single running experiment by using electric fields,ending with dense ceramics that display grains noticeably finer than in conventional processing.This new paradigm is fully illustrated with experiments conducted on amorphous CaCu3Ti4O12 precursor powder,shown to experience,on heating,crystallization through intermediate phases,followed by chemical reaction leading to synthesis of the end-product powder,plus densification depending on field adjustment.The processing time and furnace temperature are considerably reduced,demonstrating that enhanced synthesis and sintering rates applied under field input.Similar results found in Bi2/3Cu3Ti4O12are also shown.The different factors that may contribute to this unique scenario,including Joule heating,defect generation,and reduction of free energy for nuclei formation promoted by the applied field,are briefly discussed.Overall,the findings we bring here are exclusive as they show an exploitable way that allows rapid processing of materials with good control over particle and grain coarsening.

Two-photon lithography for integrated photonic packaging

Photonic integrated circuits(PICs)have long been considered as disruptive platforms that revolutionize optics.Building on the mature industrial foundry infrastructure for electronic integrated circuit fabrication,the manufacturing of PICs has made remarkable progress.However,the packaging of PICs has often become a major barrier impeding their scalable deployment owing to their tight optical alignment tolerance,and hence,the requirement for specialty packaging instruments.Two-photon lithography(TPL),a laser direct-write three-dimensional(3-D)patterning technique with deep subwavelength resolution,has emerged as a promising solution for integrated photonics packaging.This study provides an overview of the technology,emphasizing the latest advances in TPL-enabled packaging schemes and their prospects for adoption in the mainstream photonic industry.

Luminescent polymer electrolytes based on chitosan and containing europium triflate

Solid polymer electrolytes based on chitosan and europium triflate were prepared by solvent casting and characterized by X-ray diffraction, scanning electron microscopy （SEM）, atomic force microscopy （AFM）, and photoluminescence spectroscopy. The X-ray diffraction exhibited that the samples were essentially amorphous with organized regions over the whole range of the salt content studied. The AFM analysis demonstrated that the smoother sample had roughness of 4.39 nm. Surface visualization through SEM revealed good homogeneity without any phase separation for more conductive samples and the less conductive showed some im- perfections on the surface. The emission and excitation spectra displayed the characteristic bands of Eu（CF3SO3）3 in addition to broad bands corresponding to the polymer host. The excited state 5D0 lifetime values ranged from 0.29-0.37 ms for the studied samples.