An enzyme-free biosensor for sensitive detection of Salmonella using curcumin as signal reporter and click chemistry for signal amplification

Abstract

In this study, an enzyme-free biosensor was developed for sensitive and specific detection of Salmonella typhimurium (S. typhimurium) using curcumin (CUR) as signal reporter and 1,2,4,5-tetrazine (Tz)-trans-cyclooctene (TCO) click chemistry for signal amplification.Methods: Nanoparticles composed of CUR and bovine serum albumin (BSA) were formulated and reacted with Tz and TCO to form Tz-TCO-CUR conjugates through Tz-TCO click chemistry. Then, the Tz-TCO-CUR conjugates were functionalized with polyclonal antibodies (pAbs) against S. typhimurium to form CUR-TCO-Tz-pAb conjugates. Magnetic nanoparticles (MNPs) conjugated with monoclonal antibodies (mAbs) against S. typhimurium through streptavidin-biotin binding were used to specifically and efficiently separate S. typhimurium from the background by magnetic separation. CUR-TCO-Tz-pAb conjugates were reacted with the magnetic bacteria to form CUR-Tz-TCO bacteria. Finally, CUR was released quickly from the CUR-Tz-TCO bacteria in the presence of NaOH, and the color change was measured at the characteristic wavelength of 468 nm for bacteria quantification.Results: A linear relationship between absorbance at 468 nm and concentration of S. typhimurium from 102 to 106 CFU/mL was found. The lower detection limit was calculated to be as low as 50 CFU/mL and the mean recovery was 107.47% for S. typhimurium in spiked chicken samples.Conclusion: This biosensor has the potential for practical applications in the detection of foodborne pathogens.

pH-Sensitive Dye-Based Nanobioplatform for Colorimetric Detection of Heterogeneous Circulating Tumor Cells

“…Given these facts, we deduce that the nanotags can be used to realize the colorimetric detection of heterogeneous CTCs. Based on the standard curves, the loading amounts of TP and CUR on MoS 2 are about 79.8 and 82.1%, respectively (Figure S6), which are comparable to these in literatures. , …”

“…Based on the standard curves, the loading amounts of TP and CUR on MoS 2 are about 79.8 and 82.1%, respectively (Figure S6), which are comparable to these in literatures. 35,36 Optimization of Experimental Conditions. Before evaluating the performance of colorimetric detection, a series of experimental parameters need to be optimized.…”

Self-Assembly of All-Inclusive Allochroic Nanoparticles for the Improved ELISA

“…In the first method, using nanomaterials as carriers for loading many more enzymes is an effective approach for signal amplification. − Also, newly designed nanozymes have been chosen as robust alternatives in place of the natural enzyme, where catalytic efficiencies were enhanced by morphology and component-dependent signal amplification. − Another way is to achieve a high loading capacity of signal molecules by taking advantage of the reservoir function of nanomaterial characterized by large specific surface area, controllable morphology features and reliable biocompatibility. As a result of the external stimulus, including pH, light, and substrate of the enzymatic reaction, the signal molecules were released rapidly, delivering relevant colorimetric and fluorescent responses for signal amplification. ,, For example, many groups have developed a series of improved ELISA using nanomaterials with large specific surface area as carriers to load hydrophobic allochroic molecules (such as phenolphthalein, thymolphthalein, curcumin et al) through hydrophobic interaction. ,,− After incubation with acid or basic solution, the hydrophobic allochroic molecules can be rapidly released from nanocarrier, leading to a distinct color change. Note that the sensitivity of these ELISA was highly dependent on the loading capacity of signal molecules.…”

Detection of Bacterial Pathogens and Antibiotic Residues in Chicken Meat: A Review

“…The binding of antibodies against E. coli and E. coli K12 on the gold surface was determined with the detection limit of 10 3 cfu mL −1 . Huang et al [ 125 ] developed an enzyme-free biosensor for precise and targeted detection of Salmonella typhimurium with the help of curcumin (CUR) and 1,2,4,5-tetrazine (Tz)–trans-cyclooctene (TCO) acting as a signal reporter and a signal amplifier, respectively. For fabricating this biosensor, nanoparticles containing bovine serum albumin (BSA) and CUR were reacted with TCO and Tz to synthesize Tz-TCO-CUR conjugates.…”