Aptamer-based assembly systems for SARS-CoV-2 detection and therapeutics.

Nucleic acid aptamers are oligonucleotide chains with molecular recognition properties. Compared with antibodies, aptamers show advantages given that they are readily produced via chemical synthesis and elicit minimal immunogenicity in biomedicine applications. Notably, aptamer-encoded nucleic acid assemblies further improve the binding affinity of aptamers with the targets due to their multivalent synergistic interactions. Specially, aptamers can be engineered with special topological arrangements in nucleic acid assemblies, which demonstrate spatial and valence matching towards antigens on viruses, thus showing potential in the detection and therapeutic applications of viruses. This review presents the recent progress on the aptamers explored for SARS-CoV-2 detection and infection treatment, wherein applications of aptamer-based assembly systems are introduced in detail. Screening methods and chemical modification strategies for aptamers are comprehensively summarized, and the types of aptamers employed against different target domains of SARS-CoV-2 are illustrated. The evolution of aptamer-based assembly systems for the detection and neutralization of SARS-CoV-2, as well as the construction principle and characteristics of aptamer-based DNA assemblies are demonstrated. The typically representative works are presented to demonstrate how to assemble aptamers rationally and elaborately for specific applications in SARS-CoV-2 diagnosis and neutralization. Finally, we provide deep insights into the current challenges and future perspectives towards aptamer-based nucleic acid assemblies for virus detection and neutralization in nanomedicine.

A sensitive photoelectrochemical aptasensor for enrofloxacin detection based on plasmon-sensitized bismuth-rich bismuth oxyhalide.

Highly sensitive detection of enrofloxacin (ENR) is crucial for contaminant detection and environmental protection. A sensitive and selective photoelectrochemical (PEC) aptasensor was assembled by Au nanoparticles sensitized Bi24O31Br10 (Au/Bi24O31Br10) composites for detecting ENR. Due to the synergistic effect of bismuth-rich strategy and surface plasmon resonance (SPR) effect, Au/Bi24O31Br10 possessed promoted visible light absorption capacity further enhancing PEC performance and detection sensitivity of the constructed PEC aptasensor. By chemically adsorption effect between the sulfhydryl modified aptamer and Au nanoparticles, the ENR-aptamer was introduced into the PEC sensor to achieve highly selective detection of ENR. The PEC ENR aptasensor based on Au/Bi24O31Br10 composites possessed a broad linear detection scope (0.72-36000 ng L-1), satisfactory limit of detection (0.30 ng L-1, S/N = 3), high selectivity and stability. This work provides a new way for the trace detection of antibiotics in environmental analysis field.