Novel metal enhanced dual-mode fluorometric and SERS aptasensor incorporating a heterostructure nanoassembly for ultrasensitive T-2 toxin detection.

Fluorescent gold (Au) nanostructures have emerged as burgeoning materials to fabricate nanomaterial assemblies which play a vital role in improving the detection sensitivity and specificity for various biomolecules. In this work, a fluorescence labelled (Rhodamine-B-Isothiocyanate) silica shell with Au metal core (AuNPs@PVP@RITC@SiO2) and a graphene-Au nanostar nanocomposite (rGO-AuNS) are presented as a metal enhanced fluorescence (MEF) material and Raman signal enhancer, respectively. Their composite (AuNPs@PVP@RITC@SiO2NPs/rGO-AuNS) was employed as a dual-mode fluorescence (FL) and surface-enhanced Raman scattering (SERS) nanoprobe for selective and sensitive detection of T-2 toxin. To comprehend the dual-modality, a core-shell nanostructure, AuNPs@PVP@RITC@SiO2, was functionalized with an aptamer (donor) and adsorbed on the surface of rGO-AuNS through electrostatic forces and π-π stacking which act as a FL quencher and SERS signal enhancer. When exposed to T-2 toxin, the apt-AuNPs@PVP@RITC@SiO2NPs move away from the surface of rGO-AuNS, resulting in the restoration of FL and reduction of the SERS signal. There was distinct linearity between the T-2 toxin concentration and the dual FL and SERS signals with lower limits of detection (LOD) of 85 pM and 12 pM, as compared to the previous methods, respectively. The developed FL and SERS aptasensor presented excellent recovery ratio and RSD in wheat and maize, respectively, as compared with the standard ELISA method. The complementary performances of the developed stratagem revealed a high correlation between the FL and SERS sensing modes with exquisite detection properties.

Advances in sustainable approaches utilizing orange peel waste to produce highly value-added bioproducts.

Orange peel waste (OPW), a discarded part of orange fruit, is a rich source of essential constituents that can be transformed into highly value-added bioproducts. OPW is being generated in million tonnes globally and returns to the environment without complete benefit. Thus, a high volume of annually produced OPW in the industry requires effective valorization. In this regard, limited data is available that summarizes the broader spectrum for the sustainable fate of OPW to produce value-added bioproducts. The main objective of this treatise is to explore the sustainable production of bioproducts from OPW. Therefore, this review covers all the aspects of OPW, from its production to complete valorization. The review encompasses the extraction technologies employed for extracting different valuable bioactive compounds, such as: essential oil (EO), pectin, and carotenoids, from OPW. Furthermore, the suitability of bioconversion technologies (digestion/fermentation) in transforming OPW to other useful bioproducts, such as: biochemicals (lactic acid and succinic acid), biopolysaccharides (xanthan and curdlan gum), and bioenergy (biomethane and bioethanol) is discussed. Also, it includes the concept of OPW-based biorefineries and their development that shall play a definite role in future to cover demands for: food, chemicals, materials, fuels, power, and heat. Lastly, this review focuses on OPW-supplemented functional food products such as: beverages, yogurts, and extruded products. In conclusion, insights provided in this review maximize the potential of OPW for commercial purposes, leading to a safe, and waste-free environment.

A novel bioassay based on aptamer-functionalized magnetic nanoparticle for the detection of zearalenone using time resolved-fluorescence NaYF4: Ce/Tb nanoparticles as signal probe.

Zearalenone (ZEN) is a non-steroidal estrogenic mycotoxin produced by fungi on stored grains. The earlier detection methods used for ZEN rely on expensive equipment, time-consuming sample preparation and temperature sensitive antibodies. The current work, proposed a novel strategy based on ZEN aptamer labeled with amine-functionalized magnetic nanoparticle (MNPs) as a capture probe and time-resolved fluorescence (TRFL) nanoparticles labeled with complementary DNA (cDNA) as a signal probe. Under the optimized conditions, TRFL intensity at 544 nm was used to measure ZEN (R2 = 0.9920) in the range of 0.001-10 ng mL-1 and limits of detection (LOD) for proposed method was 0.21 pg mL-1. The specificity of bioassay was also determined by using other mycotoxins (OTA, AFB2, DON and Patulin) and results showed that the aptamer are specific to recognize only ZEN. The analytical applications of the present bioassay in maize and wheat samples were also examined and results were compared with existing methods. Based on these findings, it is suggested to use current rapid and simple bioassay for the determination of ZEN in food and agricultural products.