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Antibody-based immunoassays such as the lateral flow immunoassay (LFIA) and enzyme-linked immunosorbent assay (ELISA) are currently indispensable analytical methods widely used in many fields, mainly due to the high sensitivity and specificity of antibodies. However, the high cost of monoclonal antibodies and their susceptibility to high temperature limit the application of immunoassays. Previously, we developed a class of gold nanoparticle (AuNP)-based artificial antibodies, called Goldbody. Goldbodies not only bind antigens as specifically as monoclonal antibodies do but also have far better stability than monoclonal antibodies. To take advantage of the excellent specificity, stability, and easy functionalization of Goldbodies and use them for the substitution of monoclonal antibodies in immunoassays, herein, we synthesize a biotinylated anti-lysozyme Goldbody and successfully construct a competitive LFIA for the detection of lysozyme in the range of 17.98–226.49 ng·mL–1. At the same time, the biotinylated anti-lysozyme Goldbody can easily replace the detection antibody in the commercial BA (biotinylated antibody)-ELISA kit for the detection of lysozyme with a lower detection limit of 0.34 ng·mL–1 and a wider detection range of 0.89–20 ng·mL–1 compared with the commercial BA-ELISA kit. In addition, the biotinylated anti-lysozyme Goldbody has good thermal stability in both assays and can accurately detect spiked samples even after pretreatment at 100 °C, demonstrating the high potential of Goldbodies as a good replacement of monoclonal antibodies in immunoassays. [ABSTRACT FROM AUTHOR]

Herein, a strategy for a metal ion-imprinted artificial antibody with recognition sites tagged by fluorescein was carried out to construct the selective sites with a sensitive optical response signal to the specific metal ion. The synthesized silica nanoparticles were modified by the derivative residue group of 3-aminopropyltriethoxysilane conjugated with a 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) molecule through the hydrolysis and condensation reactions. The as-prepared silica nanoparticles were encapsulated by metal ion (Cu 2+ , Cd 2+ , Hg 2+ , and Pb 2+ )-imprinted polymers with nanostructured layers through the copolymerization of ethyl glycol dimethyl methacrylate (EGDMA) as a cross-linker, AIBN as an initiator, metal ions as template molecules, AA as a functional monomer, and acetonitrile as a solvent. The layers of molecular imprinted polymers (MIPs) with a core-shell structure removed template molecules by EDTA-2Na to retain the cavities and spatial sizes to match the imprinted metal ions. The microsensor arrays were achieved by the self-assembly technique of SiO 2 @MIP nanoparticles on the etched silicon wafer with regular dot arrays. The nanostructured-shell layers with fluorescence-tagged recognition sites rebound metal ions by the driving force of concentration difference demonstrates the high selective recognition and sensitive detection to heavy metal ions through the decline of fluorescence intensity. The LOD concentration for four metal ions is down to 10 -9 mol·L -1 . The method will provide biomimetic synthesis, analyte screen, and detection of highly dangerous materials in the environment for theoretical foundation and technological support.

Small extracellular vesicles (sEVs) are increasingly recognized as noninvasive diagnostic markers for many diseases. Hence, it is highly desirable to isolate sEVs rapidly for downstream molecular analyses. However, conventional methods for sEV isolation (such as ultracentrifugation and immune-based isolation) are time-consuming and expensive and require large sample volumes. Herein, we developed artificial magnetic colloid antibodies (MCAs) via surface imprinting technology for rapid isolation and analysis of sEVs. This approach enabled the rapid, purification-free, and low-cost isolation of sEVs based on size and shape recognition. The MCAs presented a higher capture yield in 20 min with more than 3-fold enrichment of sEVs compared with the ultracentrifugation method in 4 h. Moreover, the MCAs also proposed a reusability benefiting from the high stability of the organosilica recognition layer. By combining with volumetric bar-chart chip technology, this work provides a sensitive, rapid, and easy-to-use sEV detection platform for point-of-care (POC) diagnostics.

Molecular imprinting, which involves the formation of artificial recognition elements or cavities with complementary shape and chemical functionality to the target species, is a powerful method to overcome a number of limitations associated with natural antibodies. An important but often overlooked consideration in the design of artificial biorecognition elements based on molecular imprinting is the nonspecific binding of interfering species to noncavity regions of the imprinted polymer. Here, we demonstrate a universal method, namely, PEGylation of the noncavity regions of the imprinted polymer, to minimize the nonspecific binding and significantly enhance the selectivity of the molecular imprinted polymer for the target biomolecules. The nonspecific binding, as quantified by the localized surface plasmon resonance shift of imprinted plasmonic nanorattles upon exposure to common interfering proteins, was found to be more than 10 times lower compared to the non-PEGylated counterparts. The method demonstrated here can be broadly applied to a wide variety of functional monomers employed for molecular imprinting. The significantly higher selectivity of PEGylated molecular imprints takes biosensors based on these artificial biorecognition elements closer to real-world applications.