Immunosensor with two modules for the detection of kojic acid using specific monoclonal antibodies (2023)

Food Chemistry, Volume 413, 2023, Article 135553

Inspired by the biomineralization behavior, we prepared an artificial nanoflower-like clickase (i.e., LCN clickase) for a portable and sensitive click SERS immunoassay of foodborne bacterial pathogens. Motivated by its high click-catalytic activity for initiating Cu(I)-catalyzed azide-alkyne cycloaddition reactions, LCN clickase has been successfully achieved to establish new click SERS immunoassays. The developed method not only effectively eliminates the interference between the Raman reporter gene and the biological species, but also reduces the interference of the complex sample matrix. Compared with traditional immunoassays based on CuAAC, the established method avoids the redundant process of dissolving the nanocatalyst and does not require a reducing agent during the detection process, which shortens the detection time and improves the detection reliability. It is impressive that the proposed method is effective for detectionSalmonella entericaSerotype paratyphi B, with a low LOD of 20 CFU/mL, showed great potential for the detection of foodborne bacterial pathogens in food samples.

Colloids and Surfaces B: Biological Interfaces, Volume 210, 2022, Article 112236

Currently, carbon dots (CDs) with exceptional phosphorescence have attracted much attention due to their wider application. Here, we have successfully synthesized room temperature phosphorescent (RTP) CD doped with N, P elements by a facile microwave method using metformin as a carbon source. It should be noted that the RTP emission of CD occurs when the solution is immobilized on the filter paper. Specifically, hydrogen bonds formed between the CD and the filter paper, resulting in limited rotation and movement of the molecules. Likewise, the rate of nonradiative decay of excited triplet states is reduced by stiffening the entire system, thus suppressing nonradiative transitions and increasing their RTP emission of CDs. Interestingly, the proposed CDs can be used as RTP inks for drawing various patterns and preparing CD-PVA films with fluorescence and phosphorescence. Furthermore, both the fluorescence and phosphorescence of these CDs were significantly enhanced by the introductionbig- Tryptophan, thus creating an innovative two-channel testbig-trp. In addition, the detection mechanism was also investigated, and the increased hydroxyl group enhanced CD fluorescence via radiative recombination.big-trp, while phosphorescence is enhanced by narrowing the energy gap (ΔOther_Yingshi), thereby facilitating singlet-to-triplet intersystem crossing (ISC).

Sensors and Actuators B: Chemistry, Volume 377, 2023, Issue 133087

Here, a dual-response ratiometric fluorescence sensor was developed for highly sensitive and precise detection of Ce⁴⁺and ascorbic acid (AA) by modulating Ce oxidase mimic activity⁴⁺Based on nanocomposites. Complexation with fluorescent polydopamine nanoparticles (FPDA NP) and N-2-hydroxyethylpiperazine-N'-ethanesulfonic acid (HEPES) buffer enhances Ce oxidase mimic activity⁴⁺, greatly facilitated the catalytic oxidation of 1,2-diaminobenzene (OPD) to the yellow-emitting fluorescent 2,3-diaminophenazine (DAP). Meanwhile, the fluorescence of FPDA NPs with blue emission is effectively suppressed due to the electron transfer effect and internal filtering effect. In contrast, the addition of AA, Ce⁴⁺is chemically reduced to Ce³⁺No oxidase mimic activity and quenching properties for FPDA NPs. Therefore, the ratio of DAP to FPDA NP emission should be displayed as a Ce signal⁴⁺and AA disclosure. Thanks to the ratiometric fluorescence technique of the double response with inversely variable curves and the controlled catalytic oxidation activity of the nanocomposite, the good efficiency of Ce⁴⁺Detection of AA in solution and real samples was achieved. This work not only expands the applications of the FPDA NP fluorescent sensor, but also opens new horizons for artificial enzyme research.

Food Chemistry, Volume 407, 2023, Article 135175

Production of high affinity and specific antibodies against small molecules with molecular weight (MW) below 200 Da is challenging. Here, we designed a new hapten called hapten H6 for the detection of 3-methyl-quinoxaline-2-carboxylic acid (MQCA, MW 189 Da), an important veterinary residue marker of the antibiotic olaquindox. Hapten H6 retains all the structural features of MQCA, especially with regard to the Mulliken atomic charge distribution. A monoclonal antibody (mAb) called 8C9 was then obtained by IC₅₀The value was 0.2 µg/L, which was 15.5 to 88.5 times higher than previously prepared MQCA-specific antibodies. Furthermore, mAb 8C9 showed negligible cross-reactivity with other structural analogs. Finally, a highly sensitive and specific indirect competitive ELISA based on mAb 8C9 was developed for the detection of MQCA in pork muscle and liver samples with detection limits of 0.04 µg/kg and 0.09 µg/kg, respectively.

Enzyme and Microbial Technology, Volume 92, 2016, Pages 1-8

Escherichia coliCells with auto-display of the Z domain were used in immunoassays for specific target analytes. In this study, magnetite suspension was used in the washing step of the immunoassayEscherichia coliCells with automatically displayed Z fields. This method improves the washing conditions for these immunoassays by determining (1) the optimal magnetite suspension concentration and (2) the recovery capacity of magnetite suspension-based washing methodsEscherichia colicells and (3) the activity level of the Z field that is automatically displayed. In an immunoassay for C-reactive protein (CRP), an immunoassay involving a magnetite suspension-based wash showed much higher sensitivity and detection limits than conventional centrifuge-based washes. The results show that the immunoassay combined with the washing method based on magnetite suspension is effective for medical diagnostics based on the CRP test.

Biosensors and Bioelectronics, Volume 148, 2020, Article 111780

Estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2) are three important biomarkers for the clinical diagnosis of breast cancer. Sensitive and accurate detection of ER, PR and HER2 is of great importance for the diagnosis of breast cancer. Here, via a simple solvent-induced self-assembly process, some hydrophobic pH indicator molecules were used to prepare self-encapsulated heterochromatic nanoparticles for a heterochromatic NPs-linked immunosorbent assay (named ALISA) for ER, PR and HER2, respectively. ). Meanwhile, the introduction of bovine serum albumin (BSA) and antibody (Ab) enhanced the dispersion of self-assembled nanoparticles as signaling labels. Due to the ultra-high loading and efficient release of the pH indicator, ALISA showed satisfactory selectivity and sensitivity, showing great potential in early diagnosis and postoperative monitoring of breast cancer. In addition, the introduction of smartphones in combination with ALISA for point-of-care testing shows high feasibility in practical applications.