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[Display omitted] • A new affinity peptide against β-LG was successfully screened, designed, synthesized, and characterized. • A conductive TA–PEI network was incorporated into electrode for electrochemical sensing of β-LG. • The developed sensor demonstrated a linear correlation range of 50 to 750 ng with a K d value of 213.9 ng. • The sensor could detect β-LG in cow and goat milk, with mean recoveries of 88.5% and 92.2%. Harmful substances that cause food allergies can pose a significant threat to consumers along with food safety. According to the World Health Organization (WHO), approximately 10 % of the global population is currently affected by food allergies. Therefore, there is an urgent need for the development of more accurate and precise biosensors capable of detecting these hazardous substances including beta-lactoglobulin. Although numerous detection and analysis methods have been developed, they still suffer from various limitations. In this study, a tannic acid–polyethyleneimine (TA-PEI) network modified screen-printed electrodes (SPE) are newly developed and the binding sequence of peptide against β-LG was successfully screened using random peptide library. A novel affinity peptide with the desired sequence of S-L-S-P-S-L-W-Q-V-S-M-L-G-G-G-G-E-P-L-Q-L-K-M against β-lactoglobulin (β-LG) is designed and synthesized. The synthesized affinity peptide was immobilized on TA-PEI modified SPE to develop peptide-based sensor against β-LG for the first time. Under successful optimization, the developed sensor exhibited a linear relationship between 50 and 750 ng, with a K d of 213.9 ng. In addition, the sensor was able to detect β-LG in cow and goat milk, with average recoveries of 88.5 % and 92.2 %, respectively. [ABSTRACT FROM AUTHOR]

Saxitoxin (STX), which is produced by certain dinoflagellate species, is a type of paralytic shellfish poisoning toxin that poses a serious threat to human health and the environment. Therefore, developing a technology for the convenient and cost-effective detection of STX is imperative. In this study, we developed an affinity peptide-imprinted polymer-based indirect competitive ELISA (ic-ELISA) without using enzyme–toxin conjugates. AuNP/Co 3 O 4 @Mg/Al cLDH was synthesized by calcining AuNP/ZIF-67@Mg/Al LDH, which was obtained by combining AuNPs, ZIF-67, and flower-like Mg/Al LDH. This synthesized nanozyme exhibited high catalytic activity (K m = 0.24 mM for TMB and 132.5 mM for H 2 O 2). The affinity peptide-imprinted polymer (MIP) was imprinted with an STX-specific template peptide (STX MIP) on a multi-well microplate and then reacted with an STX-specific signal peptide (STX SP). The interaction between the STX SP and MIP was detected using a streptavidin-coated nanozyme (SA-AuNP/Co 3 O 4 @Mg/Al cLDH). The developed MIP-based ic-ELISA exhibited excellent selectivity and sensitivity, with a limit of detection of 3.17 ng/mL (equivalent: 0.317 μg/g). Furthermore, the system was validated using a commercial ELISA kit and mussel tissue samples, and it demonstrated a high STX recovery with a low coefficient of variation. These results imply that the developed ic-ELISA can be used to detect STX in real samples. [ABSTRACT FROM AUTHOR]

Influenza viruses are known to cause pandemic flu through inter-human and animal-to-human transmissions. Neuraminidase (NA), which is a surface glycoprotein of both influenza A and B viruses, is a minor immunogenic determinant; however, it has been proposed as an ideal candidate for a real testing. We successfully identified an affinity peptide which is specific to the influenza H5N1 virus NA via phage display technique and observed initially its binding affinities using enzyme-linked immunosorbent assay (ELISA). In addition, four synthetic peptides were chemically synthesized to develop an affinity peptide-based electrochemical biosensing system. Among all peptides tested, INA BP2 was selected as a potential candidate and subjected to square-wave voltammetry (SWV) for evaluating their detection performance. To enhance analytical performance, a three-dimensional porous bovine serum albumin (BSA)–MXene (BSA/MXene) matrix was applied. The surface morphology of the BSA/MXene film-deposited electrode was analyzed using X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Using SWV measurement, the BSA/MXene nanocomposite-based peptide sensor exhibited significant the dissociation constant (K d = 9.34 ± 1.20 nM) and the limit of detection (LOD, 0.098 nM), resulting in good reproducibility, stability and recovery, even in the presence with spiked human plasma. These results demonstrate an alternative way of new bioanalytical sensing platform for developing more desirable sensitivity in other virus detection. [Display omitted] • Highly sensitive and label-free electrochemical biosensor for detection of H5N1 viral antigen was developed. • 3D porous affinity peptide/BSA/MXene nanocomposite electrode was observed by XPS, SEM, EIS and SWV. • The developed electrochemical biosensor exhibited excellent detection for H5N1 NA protein with high sensitivity, selectivity and stability. [ABSTRACT FROM AUTHOR]