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Polymerase chain reaction (PCR) is one of the most common methods for rapid monitoring of foodborne pathogens; however, it requires purified nucleic acid as a template. Conventional nucleic acid purification is a time-consuming and laborious process. To overcome this, we developed polydopamine nanospheres (PDA NPs)-assisted direct PCR for detecting Escherichia coli O157:H7 (E. coli O157:H7). PDA NPs significantly enhanced PCR efficiency because of their strong interaction with PCR reagents, including polymerase and primers, thereby enabling regulation of the PCR performance. The optimal concentration and diameter for PDA NPs were 0.10 μg/μL and 504 nm, respectively. The PDA NPs-assisted direct PCR exhibited high sensitivity in E.coli O157:H7 detection. The detection limit of PDA NPs-assisted direct PCR was 6.7 × 104 CFU/mL, which was 10-fold lower than that of direct PCR (6.7 × 105 CFU/mL). Moreover, the sensor demonstrated excellent selectivity against E. coli O157:H7, with a negative reaction to eight other common pathogens. Most importantly, the PDA NPs-assisted direct PCR detected the order of 104−5 CFU/mL E.coli O157:H7 in milk, beef, and watermelon samples. No cultural enrichment was required, with the whole process taking <3 h. Therefore, PDA NPs-assisted direct PCR has tremendous potential in the rapid and sensitive detection of pathogens. [Display omitted] • Polydopamine nanospheres-assisted direct PCR was developed. • Direct PCR shortens the detection time due to the DNA extraction step being omitted. • Polydopamine nanospheres can improve PCR efficiency by interaction with PCR reagents. • The sensor was used in real samples for E. coli O157: H7 detection with good results. [ABSTRACT FROM AUTHOR]

Ultrasensitive and facile detection of Acetamiprid (ACE) is of exceptional significance to assess the environmental and biological pollution. In this study, an advanced Bi semimetal/Zeolitic imidazolate frameworks hybrid material-based immunochromatographic strip (Bi/ZIF HM-ICS) sensor was developed for the sensitive detection of ACE. The novel Bi/ZIF HM was prepared through one-pot hydrothermal reduction of Bi nanoparticles on ZIF, which was selected as a signal tag taking advantages of its excellent color intensity, strong affinity with monoclonal antibodies (mAbs), and favorable biocompatibility. Bi/ZIF HM could not only improve the utilization efficiency of mAbs but also boost the sensing performance. Under optimal conditions, the limit of detection (LOD) of the Bi/ZIF HM-ICS was 4.68 pg/mL with the linear range from 0.01 ng/mL to 6 ng/mL, which was 98-fold lower than that of traditional gold nanoparticles-based ICS (0.457 ng/mL), and the recoveries of the Bi/ZIF HM-ICS ranged from 80.27% to 118.52% with the relative standard deviation (RSD) below 3.67% in pear, apple, tomato, and cucumber. Overall, the practical application of the Bi/ZIF HM-ICS in complicated samples was realized for detecting pesticide residue, and expanding its application scope in monitoring environment. [Display omitted] • The Bi semimetal-ZIF hybrid material based immunochromatographic strip was firstly developed for detection of acetamiprid. • The synthesized Bi/ZIF HM possessed excellent color intensity, remarkable monoclonal antibodies coupling efficiency. • The sensor showed a low limit of detection (4.68 pg/mL, 98-fold improvement) and specificity for ACE detection. • The Bi/ZIF HM-ICS in monitoring pesticide residue proves the satisfactory applicability and stability. [ABSTRACT FROM AUTHOR]

• A prussian blue nanocubes decomposition-assisted competitive sensor was developed. • With the dissolution of the nanocubes, a decreased T -line intensity was obtained. • The proposed sensor was highly sensitive and selective with a low detection limit. • Satisfactory analytical results in real samples suggests the sensor's applicability. A prussian blue nanocubes decomposition-assisted signal amplification strategy for competitive lateral flow immunoassay (PBNCD-SALFIA) was innovatively proposed to analyze aflatoxin B 1 (AFB 1) in foodstuffs. The signal was amplified on account of the PBNCs can degrade and fade under alkaline condition, which could weak the color of the test- and control-lines, thereby improving the sensitivity of the sensor. The strategy was technically-simple, just using NaOH as an amplifier can realize signal amplification in the competition assay. Under optimized conditions, the enhanced strip exhibited excellent specificity and sensitivity in AFB 1 monitoring with a detection limit of 23 pg/mL, which was approximately 4- and 8-folds lower than those of PBNCs-LFIA (90 pg/mL) and conventional gold nanoparticles-LFIA (175 pg/mL), respectively. Taking the advantage of the color-fading, this platform revealing the lowest detectable concentration of 0.184, 0.368 and 0.184 μg/kg for AFB 1 in corn, peanut and pumpkin seed within 58 min, separately, showing reliable results. [ABSTRACT FROM AUTHOR]

• The rhombic-like Al nanosupporter (RAlNS) based fluorescence immunochromatographic assay was constructed. • The synthesized RAlNS can label antibodies in one-step stirring, avoiding the use of the complex cross-linkers. • The sensor possessed high sensitivity and specificity for tetracycline (TET). • Significant recovery rates of TET detection in real samples demonstrates the sensor's applicability. Fluorescence-based lateral flow immunoassay (FLFIA) is a prospective technology in detecting tetracycline (TET). However, the existing fluorescent materials (FMs) often require cross-linkers to bind with antibodies (Abs) to form FLFIA FM-Ab probe, which complicates the modification process and may affect the fluorescence intensity of FMs. Herein, the rhombic-like Al nanosupporter (RAlNS) was prepared via a one-step hydrothermal method and used for designing fluorescence nanosupporter for FLFIA to detect TET in real samples. The RAlNS not only possessed excellent water stability, strong fluorescence intensity and favorable thermal stability, but also could adsorb Abs to obtain FMs-Ab probe by simple centrifugation. Under optimal conditions, the limit of detection (LOD) of RAlNS-FLFIA was 0.0516 ng/mL (n = 3), which was 18 times lower than traditional colloidal gold-based LFIA. Meanwhile, the proposed sensor also exhibited high specificity for TET against other antibiotics. Furthermore, the RAlNS-FLFIA was successfully applied to the detection of TET in beef, chicken, milk and honey samples, separately, which demonstrated a significant recovery of 80.40–112.05%. The novel RAlNS-FLFIA provided great potential for the detection of various analytes in food analysis. [ABSTRACT FROM AUTHOR]