Search Results (6)

Aflatoxin B₁ (AFB₁) is highly toxic and difficult to prevent. It is mainly produced by fungi and exists in plants and animals and is classified by the World Health Organization as a class I carcinogen, posing a serious threat to human and animal health. Therefore, it is important to establish an efficient, sensitive, and on-site detection method for AFB₁ to protect human health. The immunochromatographic test strip method is simple, sensitive, and can achieve real-time detection. However, traditional immunochromatographic test strips have low sensitivity due to their relatively weak optical properties. In this study, Nb-G8 was biotinylated using a chemical method. Two sizes of gold nanoflowers (AuNFs) were prepared and combined with biotinylated G8 and streptavidin to form two types of probes. These probes were sprayed on gold standard pads and expanded pads, respectively, to enhance the signals through the high affinity interaction between streptavidin and biotin. Under the optimal experimental conditions, the half maximal inhibitory concentration (IC₅₀) of this method was 5.0 ng/mL and the limit of detection (IC₁₀) was 0.03 ng/mL, which increased the sensitivity of the test strip by four-fold compared with that of the traditional biotinylated nanoantibody immunochromatography test strip and had a wider detection range. In conclusion, the use of a high-affinity amplification signal between biotin and streptavidin is a valuable method for the detection of aflatoxin. Full article

In the realm of analysis, the lateral flow immunoassay (LFIA) is frequently utilized due to its capability to be fast and immediate. However, the biggest challenge of the LFIA is its low detection sensitivity and tolerance to matrix interference, making it impossible to enable accurate, qualitative analyses. In this study, we developed a new LFIA with higher affinity and sensitivity, based on a nanobody (G8-DIG) and CuS nanoflowers-Au (CuS NFs-Au), for the detection of aflatoxin B₁ (AFB₁) in maize. We synthesized the immunoprobe G8-DIG@CuS NFs-Au, stimulated the in situ development of Au nanoparticles (Au NPs) on Cu NFs by electrical displacement, and obtained Cu NFs-Au for fixing the G8-DIG. G8-DIG@CuS NFs-Au probe-based LFIAs may, in ideal circumstances, use a strip chromatography reader to accomplish sensitive quantitative detection and qualitative visualization. AFB₁ has a detection range of 2.82–89.56 µg/L and a detection limit of 0.87 µg/L. When compared with an LFIA based on CuS NFs, this sensitivity is increased by 2.76 times. The practical application of this method in corn flour demonstrated a recovery rate of 81.7% to 117%. Therefore, CuS NFs-Au show great potential for detecting analytes. Full article

Glutathione peroxidase 4 (GPX4) plays an important effect on ferroptosis. Down-regulating the expression of GPX4 mRNA can decrease the content of GPX4. In this work, a gold nanoflare (AuNF) probe loaded with anti-sense sequences targeting for GPX4 mRNA was designed to monitor and down-regulate intracellular GPX4 mRNA using fluorescence imaging in situ and using anti-sense technology. The results revealed that there was a marked difference for the expression of GPX4 mRNA in different cell lines, and the survival rate of cancer cells was not significantly effected when the relative mRNA and protein expression levels of GPX4 was down-regulated by AuNF probes. However, when co-treated with AuNF probes, the low expression of GPX4 strengthened erastin-induced ferroptosis, and this synergy showed a better effect on inhibiting the proliferation of cancer cells. Full article

Improving the signal-to-noise ratio (SNR) by amplifying the outputting signal or reducing nonspecific binding (NSB) are the key techniques in multiple immunoassay. Aiming at these issues, this paper presents an improved multiple indirect competitive immune surface-enhanced Raman scattering (ci-SERS) assay for the rapid screening of highly toxic rodenticides in food and biological samples, which ensured remarkable accuracy, ultra-sensitivity and reproducibility. The non-fouling polymer brush grafted magnetic beads (the MB@P-CyM) were prepared as multiple competitive recognition substrates after conjugating triplex haptens (the MB@P-CyM-hap). It was demonstrated that the particular 3D hair-like structures of P-CyM not only facilitate conjugate high-density hapten but reduce the steric hindrance from SERS probes recognition, thus enhancing SNB. On the other hand, Au nanoflowers (AuNFs) of high SERS activity were synthesized using a simple one-pot hydrazine reduction. For simultaneously detecting three highly toxic rodenticides, i.e., diphacinone (DPN), bromadiolone (BRD) and tetramine (TET), the obtained AuNFs were fabricated as a SERS-encoded nanoprobe cocktail after successively labeling mono-antibodies/Raman probes. By integrating the MB@P-CyM-hap with the SERS-encoded cocktail, a highly sensitive multiple SERS assay was achieved in less than 2 h with a limit of detection of 0.62 ng mL⁻¹ for BRD, 0.42 ng mL⁻¹ for TET and 1.37 ng mL⁻¹ for DPN, respectively. The recoveries of these rodenticides in spiked food and biological samples were determined and ranged from 72 to 123%. Above all, the proposed modifications show remarkable improvements for high efficient multiple chemical toxin immunoassay. Full article

Pigmentary manifestations can represent an early clinical sign in children affected by Neurofibromatosis type 1 (NF1), Legius syndrome, and other neurocutaneous disorders. The differential molecular diagnosis of these pathologies is a challenge that can now be met by combining next generation sequencing of target genes with concurrent second-level tests, such as multiplex ligation-dependent probe amplification and RNA analysis. We clinically and genetically investigated 281 patients, almost all pediatric cases, presenting with either NF1 (n = 150), only pigmentary features (café au lait macules with or without freckling; (n = 95), or clinical suspicion of other RASopathies or neurocutaneous disorders (n = 36). The causative variant was identified in 239 out of the 281 patients analyzed (85.1%), while 42 patients remained undiagnosed (14.9%). The NF1 and SPRED1 genes were mutated in 73.3% and 2.8% of cases, respectively. The remaining 8.9% carried mutations in different genes associated with other disorders. We achieved a molecular diagnosis in 69.5% of cases with only pigmentary manifestations, allowing a more appropriate clinical management of these patients. Our findings, together with the increasing availability and sharing of clinical and genetic data, will help to identify further novel genotype–phenotype associations that may have a positive impact on patient follow-up. Full article

Trace detection of common pesticide residue is necessary to assure safety of fruit and vegetables, given that the potential health risk to consumers is attributed to the contamination of the sources. A simple, rapid and effective means of finding the residue is however required for household purposes. In recent years, the technique in association with surface-enhanced Raman scattering (SERS) has been well developed in particular for trace detection of target molecules. Herein, gold nanoparticles (Au NPs) were integrated with sol-gel spin-coated Zirconia nanofibers (ZrO₂ NFs) as a chemically stable substrate and used for SERS application. The morphologies of Au NPs/ZrO₂ NFs were adjusted by the precursor concentrations (_X, X = 0.05–0.5 M) and the effect of SERS on Au NPs/ZrO₂ NFs_X was evaluated by different Raman laser wavelengths using rhodamine 6G as the probe molecule at low concentrations. The target pesticides, phosmet (P1), carbaryl (C1), permethrin (P2) and cypermethrin (C2) were thereafter tested and analyzed. Au NPs/ZrO₂ NFs_0.3 exhibited an enhancement factor of 2.1 × 10⁷, which could detect P1, C1, P2 and C2 at the concentrations down to 10⁻⁸, 10⁻⁷, 10⁻⁷ and 10⁻⁶ M, respectively. High selectivity to the organophosphates was also found. As the pesticides were dip-coated on an apple and then measured on the diluted juice containing sliced apple peels, the characteristic peaks of each pesticide could be clearly identified. It is thus promising to use NPs/ZrO₂ NFs_0.3 as a novel SERS-active substrate for trace detection of pesticide residue upon, for example, fruits or vegetables. Full article