Target specific aptamer-induced self-assembly of fluorescent graphene quantum dots on palladium nanoparticles for sensitive detection of tetracycline in raw milk

The excessive use of tetracyclines (TCs), a bacteriostaticantibiotic, in food products, has led to the accumulation of TCs residues in the human body, affecting human health seriously. Therefore, the development of a highly sensitive method to detect TCs in food is of utmost importance. This study reports a novel sensing strategy using aptamer-induced fluorescence fluctuation of graphene quantum dots (GQDs) and palladium nanoparticles (Pd NPs) for the rapid and label-free detection of tetracycline with a limit of detection of 45 ng.mL^-1. A novel single-step synthesis of positively charged Pd NPs and one-step green synthesis of GQDs directly from graphite has been developed. The proposed strategy provides an efficient way to detect low traces of TCs and a new technique for the development of aptamer-based sensors.

Supraparticles: Functionality from Uniform Structural Motifs

Under the right process conditions, nanoparticles can cluster together to form defined, dispersed structures, which can be termed supraparticles. Controlling the size, shape, and morphology of such entities is a central step in various fields of science and technology, ranging from colloid chemistry and soft matter physics to powder technology and pharmaceutical and food sciences. These diverse scientific communities have been investigating formation processes and structure/property relations of such supraparticles under completely different boundary conditions. On the fundamental side, the field is driven by the desire to gain maximum control of the assembly structures using very defined and tailored colloidal building blocks, whereas more applied disciplines focus on optimizing the functional properties from rather ill-defined starting materials. With this review article, we aim to provide a connecting perspective by outlining fundamental principles that govern the formation and functionality of supraparticles. We discuss the formation of supraparticles as a result of colloidal properties interplaying with external process parameters. We then outline how the structure of the supraparticles gives rise to diverse functional properties. They can be a result of the structure itself (emergent properties), of the colocalization of different, functional building blocks, or of coupling between individual particles in close proximity. Taken together, we aim to establish structure-property and process-structure relationships that provide unifying guidelines for the rational design of functional supraparticles with optimized properties. Finally, we aspire to connect the different disciplines by providing a categorized overview of the existing, diverging nomenclature of seemingly similar supraparticle structures.

Sensitive detection of acid phosphatase based on graphene quantum dots nanoassembly

Mechanism for the detection of ACP based on the aggregation of GQDs.