β-D-glucosidase assisted gold dissolution as non-optical and quantifiable detection technique for immunoassays

Plasmon-Based Colorimetric Nanosensors for Ultrasensitive Molecular Diagnostics

Colorimetric detection of target analytes with high specificity and sensitivity is of fundamental importance to clinical and personalized point-of-care diagnostics. Because of their extraordinary optical properties, plasmonic nanomaterials have been introduced into colorimetric sensing systems, which provide significantly improved sensitivity in various biosensing applications. Here we review the recent progress on these plasmonic nanoparticles-based colorimetric nanosensors for ultrasensitive molecular diagnostics. According to their different colorimetric signal generation mechanisms, these plasmonic nanosensors are classified into two categories: (1) interparticle distance-dependent colorimetric assay based on target-induced forming cross-linking assembly/aggregate of plasmonic nanoparticles; and (2) size/morphology-dependent colorimetric assay by target-controlled growth/etching of the plasmonic nanoparticles. The sensing fundamentals and cutting-edge applications will be provided for each of them, particularly focusing on signal generation and/or amplification mechanisms that realize ultrasensitive molecular detection. Finally, we also discuss the challenge and give our future perspective in this emerging field.

Application of the Prunus spp. Cyanide Seed Defense System onto Wheat: Reduced Insect Feeding and Field Growth Tests

Many crops are ill-protected against insect pests during storage. To protect cereal grains from herbivores during storage, pesticides are often applied. While pesticides have an undoubtable functionality, increasing concerns are arising about their application. In the present study, we investigated a bioinspired cyanogenic grain coating with amygdalin as cyanogenic precursor mimicking the feeding-triggered release of hydrogen cyanide (HCN) found for example in bitter almonds. The multilayer coating consisted of biodegradable polylactic acid with individual layers containing amygdalin or β-glucosidase which is capable of degrading amygdalin to HCN. This reaction occurred only when the layers were ruptured, e.g., by a herbivore attack. Upon feeding coated cyanogenic wheat grains to Tenebrio molitor (mealworm beetle), Rhizopertha dominica (lesser grain borer), and Plodia interpunctella (Indianmeal moth), their reproduction as well as consumption rate were significantly reduced, whereas germination ability increased compared to noncoated grains. In field experiments, we observed an initial growth delay compared to uncoated grains which became negligible at later growth stages. The here shown strategy to artificially apply a naturally occurring defense mechanisms could be expanded to other crops than wheat and has the potential to replace certain pesticides with the benefit of complete biodegradability and increased safety during storage.