Rapid Self-Assembly of Au Nanoparticles on Rigid Mesoporous Yeast-Based Microspheres for Sensitive Immunoassay

Abstract

A simple, rapid, inexpensive, eco-friendly, and high-throughput biological strategy for the preparation of functional microspheres on a yeast-cell platform was introduced. Microspheres prepared through the treatment of yeast cells with formaldehyde and decoating buffer exhibited excellent characteristics, such as superior mechanical strength, high sulfhydryl group content, and mesoporous structure. Au nanoparticles (NPs) easily and rapidly self-assembled onto the surfaces of the yeast-based microspheres within 5 min to form rigid yeast@Au microspheres with high monodispersity and uniformity. The rapid formation of yeast@Au microspheres mainly involved the enhancement of sulfhydryl groups and mesoporosity. The yeast@Au microspheres were successfully used in a flow cytometry immunoassay to detect Pseudorabies viral infection events. Signal-to-noise ratio was enhanced by approximately 49.4-fold. The presence of Au NPs on the yeast-based microspheres greatly improved sensitivity by decreasing noise through reducing nonspecific adsorption, highly enhancing the fluorescence signal caused by the surface plasmon resonance effect, and increasing the coupling efficiency of the capture protein. The presented method was used to analyze 81 clinical swine serum specimens. The results obtained by this developed method were compared to those of commercial diagnostic kits. The sensitivity, specificity, and efficiency of the developed method were 92.31, 88.24, and 88.89%, respectively. The excellent characteristics of the yeast@Au microspheres illustrate its great potential for high-throughput immunoassay applications in the fields of disease diagnosis, environmental analysis, and food safety.

Microorganism@UiO-66-NH2 Composites for the Detection of Multiple Colorectal Cancer-Related microRNAs with Flow Cytometry

“…As shown in Figure B, it can be confirmed that the presence of – COOH groups (3306 and 1652 cm –1 ), −NH 2 groups (1652 and 1539 cm –1 ), – OH groups (3306, 2927, and 1049 cm –1 ), and −SH groups (1049 and 700 cm –1 ) on the yeast cell wall. The presence of various functional groups on the surface of yeast will provide a wide range of fixed sites to stabilize various metals (e.g., Zr 4+ ) and molecules . After the formation of yeast@UiO-66-NH 2 composites, red-shift and blue-shift occurred at multiple peaks.…”

“…As one of the most commonly used multiplex technologies, microsphere-based flow-cytometry (e.g., suspension array) has attracted considerable interest in modern diagnostics for precise medicine. , The preparation of encoded microspheres with homogeneous physiochemical properties and enhanced sensitivities is essential for microsphere-based analysis methods in basic and technological research . To date, there are two main coding systems, including spectroscopic, − and graphical encoding − that have been presented to provide a sufficient number of identification codes for microspheres.…”

“…In our previous works, we have presented the use of microorganisms with a rigid shell such as bacillus spore and yeast cell for the preparation of functional microspheres in flow-cytometry detection. , The use of microorganisms for producing encoded microspheres meets some of the present sustainability challenges due to low cost, easy, availability, and environmental benignity. In principle, microorganisms are ideal coding materials, because there are millions of them with different morphologies and compositions in nature, which can be distinguished by using flow cytometry.…”

“…This feature indicates that microorganisms can be used for morphological coding in suspension array. Moreover, the surface of microorganism is rich in functional groups, such as −COOH, – NH 2 , −SH, and −OH, which make them compatible to conjugate with several nanoscale materials such as SiO 2 , TiO 2 , AuNPs, halloysite nanotubes and so on, to form innovative composites. ,− These composites exhibit attractive application prospects in scientific research and technologically important areas, such as cell therapy, sensors, electronic devices, and biocatalysis. ,,− The research on microorganism-based morphology coding technology is still very limited and practical applications have not been reported yet. To use microorganisms as morphology coding microspheres in suspension array assay, the following obstacles should be addressed: (1) Most microorganisms do not have a rigid cell wall, which leads microorganism-based microspheres to a loss of coding ability owing to breakage during application and storage.…”

“…1,2 The preparation of encoded microspheres with homogeneous physiochemical properties and enhanced sensitivities is essential for microsphere-based analysis methods in basic and technological research. 3 To date, there are two main coding systems, including spectroscopic, 4−7 and graphical encoding 8−10 that have been presented to provide a sufficient number of identification codes for microspheres. The latter for suspension arrays that use a set of visually distinguishable patterns such as embedded barcodes 9,11 or physical shapes 12 to identify different assay particles.…”