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A competitive electrochemical aptamer biosensor for the selective detection of Pb2+ was developed in this study. The PAMAM@Au hybrid materials and the bioprobe MB-GNPs-ssDNA were synthesized with chemical methods. Modified electrode with carboxylated graphene oxide was prepared via electrodeposition. PAMAM@Au was immobilized on the modified electrode using the EDC/NHS crosslinker, and aptamer (Apt) was bound to PAMAM@Au hybrid materials using the glutaraldehyde crosslinker. The assembly of MB-GNPs-ssDNA/Apt/PAMAM@Au/GO/SPCE biosensors was achieved through immobilizing bioprobe onto electrodes, based on the theory of aptamer-complementary chain reactions. The fabricated biosensor was characterized through electrochemical experiments, SEM, AFM, TEM, XPS and FTIR. The biosensor's performance was evaluated in a series of Pb2+ aqueous solutions by differential pulse voltammetry (DPV), and the results demonstrated this biosensor had excellent repeatability, stability, and specificity. The detection range spanned from 0.5 pM/L to 500 nM/L, with a detection limit of 5 fM/L. Consequently, the proposed biosensor can serve as a reliable analytical tool for the sensitive detection of lead ions. • A novel competitive electrochemical aptamer biosensor for detecting lead ions was Designed. • The polyamidoamine (PAMAM) dendrimer encapsulated with nanogold was innovatively synthesized. • A biosignal probe MB-GNPs-ssDNA for enhancing the detection signal of biosensor was synthesized. • The redox property of methylene blue was employed to generate a detectable electrical signal. [ABSTRACT FROM AUTHOR]

Meat adulteration is a growing concern for consumers and researchers, necessitating the development of a simple and robust method for identifying animal sources in meat products. In this study, a double-tailed recombinase polymerase amplification (RPA) integrated with surface-enhanced Raman scattering (SERS) based two-color lateral flow nucleic acid hybridization strip (LFNAHS) was established for simultaneous detection of pork and horse meat. Magenta and cyan gold nanoparticles functionalized with specific probes and Raman dyestuff were used to color the LFNAHS based on RPA amplification products. The assay successfully detected colored test lines for horse and pork adulteration, with quantitative analysis achieved through Raman intensity measurements. The method showed a high specificity with no cross-reactivity and a detection limit of 0.01 % (wt%). Authenticity testing of 40 donkey products yielded results consistent with PCR-agarose gel electrophoresis. This assay can be extended to identify other meat sources by replacing the specific primer sets. This versatile method can be adapted for identifying other meat sources, making it a valuable tool for accurate, sensitive, and quantitative meat authentication in resource-limited settings. [Display omitted] • A new double tailed mRPA with a RPA-SERS-LFNAHS was developed for donkey authentication. • Magenta spherical and cyan urchin AuNPs were synthesized as multicolor labels in the RPA-SERS-LFNAHS. • The specific RPA primers are uniquely designed with tail sequence and a spacer C9. • The detectability of this mRPA-mNAH-LFS assay for horse meat and pork were 0.01 %. • This assay was successfully applied to the authentication of real donkey products. [ABSTRACT FROM AUTHOR]

We propose a visual strategy for simultaneous detection of chicken and duck ingredients in mutton by integration of a double tailed multiplex recombinase polymerase amplification (mRPA) assay with a multicolor nucleic acid hybridization lateral flow strip (mNAH-LFS) assay. Two colored gold nanoparticles (AuNPs), including gold nanospheres (red) and gold nanoflowers (blue), were synthesized and functionalized with the corresponding nucleic acid probe to target each analyte. The RPA product was analyzed by this two-colored mNAH-LFS assay which includes a red T 1 line for chicken adulteration and a blue T 2 line for duck adulteration. In this RPA reaction, special Spacer9 and tail nucleotide sequence-tagged primers (Tag+Spacer9+F-primer, Tag+Spacer9+R-primer) were used to obtain double-stranded amplicons with specific wobbled sequences that can directly bind with AuNPs-labeled probes (AuNSs-cT 1 hybridized with T 1 , AuNFs-cT 4 hybridized with T 4) and solid-phase probes (biotin-cT 2 hybridized with T 2 , biotin-cT 3 hybridized with T 3) on the mNAH-LFS producing a red or/and cyan color on the T lines. The detection limits of this mRPA-mNAH-LFS assay for chicken and duck were 0.01 % and 0.01 %, respectively. Finally, this mRPA-mNAH-LFS assay was successfully used to authenticate 59 commercial meat products. In conclusion, this mRPA-mNAH-LFS is a sensitive, accurate, and cost-effective approach for meat quality assurance and traceability. • A new double tailed mRPA with a mNAH-LFS was developed for mutton authentication. • Red AuNSs and blue AuNFs were synthesized as multicolor labels in the mNAH-LFS. • The specific RPA primers are uniquely designed with tail sequence and a spacer C9. • The sensitivity of this mRPA-mNAH-LFS assay for chicken and duck were 0.01 %. • This assay was successfully applied to the authentication of real mutton products. [ABSTRACT FROM AUTHOR]

Meat adulteration is becoming increasingly prominent in the global market. Therefore, a robust, sensitive, and affordable rapid detection strategy for identifying meat species is urgently needed. In this study, we developed a novel strategy using chicken-specific recombinase polymerase amplification (RPA) coupled with nucleic acid hybridization lateral flow strip (NAH-LFS) for the rapid detection of chicken adulteration. In an isothermal RPA reaction, chicken mitochondrial DNA (as target) was amplified at 39 °C for 15 min. Both the forward and reverse primers contained three parts, namely the specific binding region, a special abasic spacer 9 (iSp9), and the tag sequence (forward primer tag, F-tag, and reverse primer tag, R-tag). The specific binding region and tag sequences were linked by iSp9, which could also inhibit extension by DNA polymerase, producing a double-stranded amplicon with two tag sequences (F-tag and R-tag) at the two opposite ends. The F-tag and R-tag can complementarily hybridize with probes on AuNPs and the test line, respectively, showing red color on the test line. This visual detection strategy does not require expensive equipment, and the entire detection procedure can be performed within 20 min. Specificity tests with 10 other animal samples showed no cross-reactivity. The RPA-NAH-LFS strategy could detect 0.01% (w/w) chicken in the chicken/beef meat mixture. To verify its utility, this assay was used to authenticate 30 commercial beef samples; the results were 100% consistent with those obtained using the PCR- agarose gel electrophoresis (AGE). In conclusion, the RPA-NAH-LFS assay serves as an accurate, sensitive, and cost-effective method to evaluate chicken adulteration and traceability in meat. • A visual method based on RPA-NAH-LFS was developed to detect chicken adulteration. • Unique chicken-specific primers were designed with spacer9 and tail sequence. • This visual detection strategy did not require expensive experimental equipment. • The RPA-NAH-LFS could be observed by non-expert operators within 20 min at 39 °C. • The detection limit of this RPA-NAH-LFS assay for chicken adulteration was 0.01%. [ABSTRACT FROM AUTHOR]