Surface acoustic waves (SAW) devices are used in several domains varying from telecommunication and mechanics to chemical and biological sensing. Their ability to function in either liquid or gaseous environments make them devices of choice for the detection of several types of analytes (DNA, antibodies/antigens, gases, pesticides, heavy metals …) in real time and without labeling. Compared to other chemical and biological sensors, the SAW ones are highly sensitive and can achieve very low limits of detection. Among the large variety of acoustic devices, SAW sensors are the most promising ones, as their operating frequencies can be varied from several hundred MHz to a few GHz. However, they are still the subject of constant development; therefore, simulation becomes a powerful tool to design optimised structure for highly sensitive devices. This study concerns 3D Finite Element Method (FEM) simulation of SAW sensors using COMSOL Multiphysics software. A SAW delay line was designed on 36°lithium tantalate (LiTaO₃) piezoelectric substrate. Interdigital transducers (IDTs) were patterned in Cr/Au (20 nm/80 nm) layers with the same periodicity of λ = 40 μm. A metallized Cr/Au (20 nm/80 nm) sensing area of 80 µm length separates the input and output IDTs. The corresponding frequency is thus of order of 104 MHz. Simulations were made on well-known structure to define a model that can account for and predict the electrical behaviour of SAW transducers for the future optimisations. The results show good agreement between COMSOL numerical simulation and experimental S21 spectra. Accordingly, we can use the built model for simulations intended to optimize the structure of devices, mainly for increasing their sensitivity.

Molecularly imprinted polymers (MIPs) are attracting considerable attention nowadays, due to their “relative easy” concept and to the possibility of their use in several applications varying from drug release, protein and DNA sensing, to quenchers in SERS experiments or molecules and ions extraction. Molecular imprinting principal is based on the creation of specific and selective cavities in a 3D-polymeric network, which are complementary in size and shape of a target species, and which provide interaction points and a coordination sphere around the template molecule. In this work, we have designed and realized a MIP based electrochemical biosensor for the selective detection of prostate specific antigen (PSA). Pyrrole was chosen as functional monomer to realize the polymeric matrix. Several reasons have motivated our choice, mainly the fact that polypyrrole (PPy) is biocompatible and the fact that it can be used in aqueous and at neutral pH media. Choosing the most appropriate supporting electrolyte is another key element which can affect the MIP morphology, and thus the corresponding electrochemical response. Here, we have tested several kinds of electrolytes: NaCl, KCl and LiClO4 at a concentration of 0,1 M in either aqueous or PBS media. Electrochemical results indicate that the MIPs realized in PBS have better responses (in terms of current intensity values) than those realized in aqueous media, and that LiClO4 counter ions permit to obtain the most reproductible and stable films. Atomic force microscopy was investigated to determine the morphological structures of the realized MIPs. Results indicate that the films realized in PBS and in presence of LiClO4 are more uniform than all the other ones, confirming thus the electrochemical results.

Due to the holes high transport mobility, anthracene derivates are widely used for the elaboration of OLEDs and other organic thin-layer-based electronic, such as transistors and photovoltaic cells. This study aims to investigate the electric properties of two new anthracene derivatives: 9-{[4-({[4-(9 anthrylmethoxy)phenyl]sulfanyl}methyl)] methyl]anthracene (TDP-AN) and 4-(9-anthrylmethoxy) benzyl[4-(9-anthrylmethoxy)phenyl]sulfone (BPS-AN). The main difference between them is related to the functional group between the two central phenyls. Conductance measurements results show a frequency-independent behaviour, for low frequencies ranging between 0.1 and 100 KHz, while they exhibit a power law model for higher ones. BPS-AN was found more conductive than the TDP-AN. Impedance spectroscopy (IS) was then investigated to understand the charge carrier mechanisms in both TDP-AN and BPS-AN molecules. Measurements were carried out in the frequency range 100 Hz – 10 MHz at different bias voltages (from 0 V to 3 V). The obtained results permitted to confirm that the conductivity of BPS-AN is superior to that of TDP-AN.

Flumequine is a synthetic fluoroquinolone antibiotic used to treat bacterial infections. It is a first-generation fluoroquinolone antibacterial that has been removed from clinical use and is no longer being marketed. Flumequine was used in veterinarian medicine for the treatment of enteric infections, as well as to treat cattle, swine, chickens, and fish, but only in a limited number of countries. Several studies have reported the design of chemical sensors for the selective detection of flumequine (Flu). The limits of detection were of order of 15 - 24 µg.L^-1.

Here, we have designed and realized an electrochemical sensor for flumequine detection. For this purpose, a platinum (Pt) electrode was functionalized with a one-step polypyrrole-silver (PPy-Ag) film. Cyclic voltammetry was investigated for PPy-Ag realization, while square-wave voltammetry was used for (Flu) monitoring. The incorporated Ag amount in polypyrrole matrix was optimized. The Flumequine oxidation on both Pt and Ag-PPy was investigated. The limit of detection (LOD) of the designed senor was of order of 2.61 µg.l^-1, one of the lowest values ever reported in literature. The sensitivity (in the semi logarithmic representation) was equal to 19 µA.M^-1. These results pave the way for flumequine track in real media.

The biodeterioration and blackening of vinyl glues before their expiration date of use was studied and shown to be of bacterial origin. Two bacterial isolates, responsible for this alteration were identified as sulfate-reducing bacteria. On the basis of biochemical properties and 16S rRNA gene sequencing, they were identified as Microbacterium oxydans and Alcaligenes faecalis. This is the first report dealing with Microbacterium as a vinyl glue deterioration causal agent. Blackening and deterioration were confirmed after glue artificial contamination using the two isolates. The sensitivity of the two contaminant bacteria to various triaryl butenes derivatives, compared to the commercial large used and large spectra biocide (Preventol D6), was assessed for artificially contaminated vinyl glue at different concentrations. Results showed that triaryl butenes have an interesting conservative potential. This was confirmed in vitro by tests demonstrating the activity of the triaryl butenes against glue contaminants. The water-soluble compound 1,1-bis-[4-(3-dimethylamoniumpropoxy)phenyl]-2-ferrocenyl-but-1-ene dichloride shows the most effective performance against glue spoilage and can be proposed as an ecological and economical alternative to traditional biocide formulations.

A comparative study of the ethanol extract of the leaves of four species of Psidium (P. cattleianum, P. claraense, P. guajava and P. sartorianum) was carried out. The investigation included phytochemical screening, Folin-Ciocalteu method to determine total phenolic content and determination of antioxidant activity by assaying the free radical sequestering activity of 2,2-diphenyl-1-picryl-hydrazyl (DPPH). The phytochemical screening showed a similar composition in the four evaluated species. The phenolic content of the ethanolic extracts of the four species was high, especially in the extract of Psidium sartorianum (17.59 mgEAG / gES) but lower than that obtained for Psidium guajava (19.782 mgEAG / gES) considered a reference species. The ethanolic extracts of the four species of Psidium showed values ​​of DPPH free radical scavenger activity higher than the synthetic antioxidant Butyl hydroxytoluene (BHT) (175.98 μg / mL), highlighting the Psidium sartorianum (17.82 μg / mL).

The cannabis is one of the most widely-consumed drugs in the world. According to the United Nations’ Word drug report, the number of cannabis consumers worldwide was of order of 238 million in 2017 and this number is in constant increase. Certainly, cannabis can be administrated for therapeutic use, and in several medicines; in this case, the administered doses take into account both medical and psychic states of the patients. When consumed as a drug, and depending upon the dose, method of administration and prior experience, cannabis can cause an altered state of consciousness, pulse and heart rate increase, and impaired coordination and concentration. For an equivalent dose of 15 mg of ∆9-tetrahydrocannabinol, the active ingredient of cannabis, the consumer can get attacks of anxiety, hallucinations, delusions and impression of knowing nothing. France has recorded 7 % of fatal accidents involving cannabis’ users drivers. The ∆9-THC, as an example of cannabis, can be detected with its metabolites in the blood, sweat and saliva by chromatographic methods with a limit of detection in the order of 0.4 ng.ml^-1.

In this context, we have developed a new alternative for ∆9-THC detection: an electrochemical immunosensor. To the very best of our knowledge, this is the first study concerning cannabinoid detection with a biosensor. Here, gold electrodes were first functionalized with a self-assembled monolayer (SAM) of mercaptoundecanoid acid (MUDA), a long-chain carboxylic acid-terminating alkanethiol. The acid groups were then activated with the 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) before further grafting of anti-cannabinoid monoclonal antibodies. Cyclic voltammetry (CV) and impedance (EIS) electrochemical techniques were used to follow up ∆9-THC antigen detection. All experiments were carried out in phosphate buffer solution (PBS) containing 1 M KCl and 5 mM [Fe(CN)₆]^-2/-3 redox probe. Electrochemical results showed a wide dynamic range varying between 10^-15 and 1 mg.mL^-1. The limit of detection of the designed sensor, of order of 10^-15 mg/ml, is largely inferior to that obtained with conventional technique techniques. This study paves the way for the development of new analytical devices able to detect cannabis traces in few minutes and in a biological medium.

In recent years, an increase in the consumer interest has been observed for craft beers, which are unpasteurized and unfiltered. Thus, the use of probiotic starters remaining in the craft beers could significantly increase health benefits. Here, the first study on the use of the probiotic Sacharomyces boulardii (Sb) yeast as single starter for craft brewing at 20 L scale is presented. The probiotic biomass growth was studied in bioreactor batch culture and modelled by the logistic and Gompertz equations. Finally, the probiotic biovolume of Sb was estimated from microscopy images. All these experiments were compared with those obtained with a commercial Sacharomyces cerevisiae (Sc) yeast strain, which is commonly utilised in the brewing industry. The result of this study showed that, the craft beer produced with Sb possessed higher antioxidant activity and more acidification, which is very desirable to reduce contamination risks at large-scale production. Furthermore, Sb exhibited faster growth and larger biovolume than Sc, which increases the probiotic value of the final craft beer.

SUMMARY

The plants are a great source for the discovery of new products of medicinal value for the development of drugs. Several chemical products derived from plants are important drugs that are currently used in one or more countries of the world. In this study, we performed a GC-MS analysis on a fraction of the hexane extract from the leaves of Cissus incisa, an endemic plant from Mexico and the southern of The United States. Until the best of our knowledge there are not reports about the phytochemical composition of this plant. As a result of the analysis, five sterols were identified. The stigmastan-3, 5-diene was the most predominant with 74% of the abundance. It has been found that these different active phytochemicals possess a wide range of biological activities.

SUMMARY

Nature is an abundant source of drugs, however, it is estimated that only 5 to 15% of the approximately 250,000 species have been studied worldwide. Of the medicinal plants active ingredients of marked importance in the current investigation are obtained. This century has been characterized by the discovery and development of drugs based on an extensive exploration of natural products. There are several factors that enhance these studies: the increase in the withdrawal of drugs due to serious side effects, the increase in bacterial resistance, the resistance of tumor cells to current anticancer treatments, among others. That is why the pharmaceutical industry and researchers of any area are interested in finding new medicines from natural sources. Our objective is the study of Cissus incisa as a potential source of therapeutic agents. As result of the HPLC analysis of the hexane extract, it is obtained that it contains interesting phytocompounds. These compounds are: phytol, β-Sitosterol, α-Amyrin, β-Amyrin and β-Amyrone. Which have previously been repotted biological properties as antimicrobial and anticancer.