Highly sensitive and label free on-site monitoring immunosensor for detection of Aflatoxin B1 from real samples.

Aflatoxin B1 (AF-B1) are toxins secreted by secondary metabolites of molds that have adverse effects on humans and animals resulting in huge economic losses. Here we report on field useable, cost effective and direct electrochemical sensor based on conducting polymer composite electrode, Poly (3,4-ethylenedioxythiophene): polystyrene sulphonic acid (PEDOT-PSS) for label-free detection of AF-B1. Structural and morphological characterization of composite electrodes were carried out using XRD and SEM. We compared two different electroanalytical techniques namely, transient capacitance and differential pulse voltammetry, to select the most prominent technique for analyzing the mycotoxin easily. For direct detection of AF-B1, transient capacitance measurement at 77 and 1000 Hz was employed wherein sensor showed linearity in 18.18-300.0 ng mL-1 range at 77 Hz for AF-B1. Best limit of detection (LOD) for AF-B1 was 55.41 ng mL-1 (369 pM) at 77 Hz with very good repeatability. DPV showed linearity in the range 18.18-342.85 ng mL-1 with LOD 435 pM. For demonstration of application of this sensor directly using minimum sample preparation, AF-B1 sensing has been confirmed successfully using white button mushrooms and okra stored at ambient conditions. Sensor response with real samples suggest usefulness of sensor to monitor stored farm products easily.

Thorough evaluation of sweet potato starch and lemon-waste pectin based-edible films with nano-titania inclusions for food packaging applications.

Biodegradable starch-pectin­titanium oxide nanoparticles (TiO2 - NPs) blend edible films were developed by casting filmogenic solution of sweet potato starch and lemon waste pectin incorporated with TiO2 nanoparticles. The effect of incorporating different concentration of TiO2 nanoparticle (0.5-4% wt) on the different properties of starch and pectin based edible film was evaluated. Surface color measurement, light transmission, scanning electron microscopy, fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis techniques were used to characterize the developed films. Increasing the level of TiO2-NPs led to significant decreases in the moisture content, solubility, and moisture uptake of the films. Addition of low concentration of TiO2 - NPs into starch-pectin films significantly improved the mechanical and moisture barrier properties. SEM analysis also revealed that good particles dispersion could be obtained when nano-TiO2 particles content was low (0.5-2% wt). The glass transition temperatures (Tg) shifted to higher temperature with increasing the TiO2 concentrations and the thermal stability of the films was increased. The transmittance percentage was also decreased with increasing the TiO2 concentrations which revealed that with UV prevention capacity, the developed films can be used as food grade UV screening biodegradable packaging material.