Bandwidth Optimisation and Frequency Tuning of Plasmonic Functionalised Metasurfaces for Optical Sensing of Chemical and Biological Substances

This paper reports on a method to optimise the sensitivity of plasmonics sensors based on functionalised metasurfaces of 2D-array of Al NanoAntennas (NA) deposited on a SiO2 substrate operating in the visible region of the electromagnetic spectrum. Moreover, we analysed the characteristics of a double layer metasurface configuration where two different NA 2D-arrays are separated by a dielectric spacer. The optical properties of both the metasurface configurations have been studied analysing how their maximum transmittance and Full-Width-at-Half-Maximum (FWHM) of the transmission curve are related to the variations of the NA geometrical parameters and dielectric spacer thickness. The tailoring of the FWHM is particular important for improving the plasmonic sensors sensitivity in probing the presence of chemical/biological substances absorbed on the NA surface when their absorption curve is superimposed with the metasurface transmission curve. In particular, better is this superposition better will be the plasmonic sensor sensitivity in probing variations of small concentrations of the adsorbed substances. The simulation results of the optical response of the designed plasmonic sensors suggest a methodology in choosing the NA parameters able to modify the bandwidth of the metasurface transmittance so fitting the absorption curve of chemical/biological substances absorbed on them. As a case-example, we simulated the response of a plasmonic sensor on which has been deposited a 3nm-thick layer of Rhodamine-6G (R6G) proving that is possible to increase the sensor detection sensitivity of about two orders of magnitude in the measurement of the R6G absorbance. Furthermore we proved the capability of the double layer plasmonic sensors to tune the transmission curve peak wavelength without changing the main optical characteristics

Optimisation of the Detection Sensitivity of Plasmonic Nanoantenna Based Sensors for Mid-infrared Spectroscopy

AbstractIn this paper we report on the optimisation of the optical characteristics of 2D-arrays of plasmonic gold nanoantennas (NA) that can be used as high sensitivity mid-infrared spectroscopic sensor for the detection of chemical/biological substances by using the Surface Enhanced Infrared Absorption (SEIRA) technique. This approach allows to detect the presence of a substance adsorbed on the NA by measuring its optical absorption under the conditions for which the maximum of the reflectivity response of the 2D-array occurs at the same wavelength of the substance maximum absorption peak. In particular, by acting on the 2D-array periodicity, NA shape, size and thickness, numerical simulations of the 2D-array detection response, based on Finite Element Method (FEM), demonstrate that is possible to obtain an increase in the detection sensitivity of more than three orders of magnitude with respect to that one achievable if the same substance is deposited on an unstructured planar metal surface, independently from the wavelength at which the substance absorption occurs. Moreover, we present the results of an analysis of the dependence of the 2D-array maximum reflectivity and peak wavelength on the geometrical parameters characterising the NA and the 2D-array

Attenuation of doxorubicin-induced cardiotoxicity by mdivi-1: a mitochondrial division/mitophagy inhibitor

Doxorubicin is one of the most effective anti-cancer agents. However, its use is associated with adverse cardiac effects, including cardiomyopathy and progressive heart failure. Given the multiple beneficial effects of the mitochondrial division inhibitor (mdivi-1) in a variety of pathological conditions including heart failure and ischaemia and reperfusion injury, we investigated the effects of mdivi-1 on doxorubicin-induced cardiac dysfunction in naïve and stressed conditions using Langendorff perfused heart models and a model of oxidative stress was used to assess the effects of drug treatments on the mitochondrial depolarisation and hypercontracture of cardiac myocytes. Western blot analysis was used to measure the levels of p-Akt and p-Erk 1/2 and flow cytometry analysis was used to measure the levels p-Drp1 and p-p53 upon drug treatment. The HL60 leukaemia cell line was used to evaluate the effects of pharmacological inhibition of mitochondrial division on the cytotoxicity of doxorubicin in a cancer cell line. Doxorubicin caused a significant impairment of cardiac function and increased the infarct size to risk ratio in both naïve conditions and during ischaemia/reperfusion injury. Interestingly, co-treatment of doxorubicin with mdivi-1 attenuated these detrimental effects of doxorubicin. Doxorubicin also caused a reduction in the time taken to depolarisation and hypercontracture of cardiac myocytes, which were reversed with mdivi-1. Finally, doxorubicin caused a significant elevation in the levels of signalling proteins p-Akt, p-Erk 1/2, p-Drp1 and p-p53. Co-incubation of mdivi-1 with doxorubicin did not reduce the cytotoxicity of doxorubicin against HL-60 cells. These data suggest that the inhibition of mitochondrial fission protects the heart against doxorubicin-induced cardiac injury and identify mitochondrial fission as a new therapeutic target in ameliorating doxorubicin-induced cardiotoxicity without affecting its anti-cancer properties

The Role of Transporters in the Pharmacokinetics of Orally Administered Drugs

Drug transporters are recognized as key players in the processes of drug absorption, distribution, metabolism, and elimination. The localization of uptake and efflux transporters in organs responsible for drug biotransformation and excretion gives transporter proteins a unique gatekeeper function in controlling drug access to metabolizing enzymes and excretory pathways. This review seeks to discuss the influence intestinal and hepatic drug transporters have on pharmacokinetic parameters, including bioavailability, exposure, clearance, volume of distribution, and half-life, for orally dosed drugs. This review also describes in detail the Biopharmaceutics Drug Disposition Classification System (BDDCS) and explains how many of the effects drug transporters exert on oral drug pharmacokinetic parameters can be predicted by this classification scheme

CBPP T144/T1SR vaccine induced immune response in vaccinated cattle

The Gambia experienced a sudden epidemic outbreak of Contagious bovine pleuropneumonia (CBPP) in cattle in August 2012 after its last reported cases in 1971. The objective of this study was to monitor the immunological response in terms of antibody detection in vaccinated cattle against CBPP using freeze-dried live attenuated T144 or T1SR strains.Blood samples were collected from 136 cattle 2 days before vaccination, 135 cattle 2 weeks post vaccination, and 114 cattle at 3 months post-vaccination. The extracted serum samples were tested for the presence of antibodies against Mycoplasma mycoides subsp mycoides Small Colony variant (MmmSC) using IDEXX Contagious Bovine Pleuropneumonia enzyme immunoassay Antibody Test Kit.Results show that the proportion of cattle with detectable antibodies against CBPP antigens were 15% (9 – 22%), 67% (59 – 75%), and 28% (20 – 37%) at 2 days before vaccination, 2 weeks post vaccination, and 3 months post vaccination, respectively. The proportion of animals with detectable antibodies postvaccinationwas significantly higher (p < 0.05) than pre-vaccination stage. The seroprevalence of CBPP in the monitored cattle before vaccination was 15% (9 – 22%).Based on the results obtained, it could be concluded that the vaccinated animals have responded well to the vaccination. Assuming that CBPP vaccine efficacy could be associated to detection of antibodies 2 weeks post-vaccination, then this vaccine’s efficacy could be in the range of 59 - 75%. In order to prolong the protection of vaccinated animals, it is recommended that animals should be re-vaccinated 12 months post-vaccination. A longer and more robust longitudinal study involving more animals should be undertaken to determine CBPP vaccine efficacy under local conditions.Keywords: Contagious bovine pleuropneumonia, cattle, ELISA, The Gambi