Ps-Pt nanozyme-based synergistic signal amplification biosensor for highly sensitive colorimetric detection of protein

Design of U-shaped peptides with long-lasting antifouling efficacy: Toward a feasible electrochemical aptasensor for robust detection in human serum

BACKGROUND

Developing biosensors with antifouling properties is essential for accurately detecting low-concentration biomarkers in complex biological matrix, which is imperative for effective disease diagnosis and treatment. Herein, an antifouling electrochemical aptasensor qualifying for probing targets in human serum was explored based on newly-devised peptides that could form inverted U-shaped structures with long-term stability.

RESULTS

The inverted U-shaped peptides (U-Pep) with two terminals of thiol groups grafted onto the Au-modified electrode showcase superior antifouling properties in terms of high stability against enzymatic hydrolysis and long acting against biofouling in actual biofluids. The construction of the outlined antifouling electrochemical aptasensor just involved the fabrication of Au-deposited poly(3,4 ethylenedioxythiophene) (Au/PEDOT) modified electrode, followed by one-step co-incubation in the peptides and the aptamer probes with the Au/PEDOT electrode. Taking a typical biomarker of alpha-fetoprotein (AFP) for detection, this elegant antifouling aptasenor demonstrated a nice response for probing the target AFP with a low detection limit of 0.27 pg/mL and a wide linear scope of 1.0 pg/mL to 1.0 μg/mL, and furthermore qualified for assaying of AFP in human serum samples with satisfactory accuracy and feasibility.

SIGNIFICANCE

This engineering strategy of U-Pep with long-lasting antifouling efficacy opens a new horizon for high-performance antifouling biosensors suitable for detection in complex bifluids, and it could spark more inspiration for a follow-up exploration of other featured antifouling biomaterials.

A novel chemiluminescence sensor for alpha-fetoprotein detection based on an aptamer-luminol modified magnetic graphene oxide and copper-based MOF composite

Herein, an aptamer-luminol modified magnetic graphene oxide and copper-based MOF composite was prepared and used to build a novel target-triggered "turn on" chemiluminescence (CL) sensor for alpha-fetoprotein (AFP) detection. Magnetic graphene oxide (MGO) was functionalized with the complementary sequence of the AFP aptamer (cDNA), and then MGO-cDNA was linked to aptamer modified luminol (Apt-luminol) through the complementary base pairing effect. The functionalized magnetic graphene oxide (MGO-cDNA/Apt-luminol) was prepared as a specific magnetic separation and signal switch material. ZnONPs-Au@CuMOFs shows excellent catalytic performance and was used as a catalyst for the luminol-H2O2 reaction. AFP will specifically recognize and bind to Apt on MGO-cDNA/Apt-luminol when AFP is present, which causes luminol release and triggers the CL reaction. The released luminol encounters ZnONPs-Au@CuMOFs and produces strong CL intensity. Therefore, a novel target-triggered "turn on" CL method with high selectivity and sensitivity for detecting AFP has been established. The linear range and detection limit were 1.0 × 10-4-50 ng mL-1 and 4.2 × 10-5 ng mL-1, respectively. The sensor also exhibited good selectivity, reproducibility and stability, and was finally used for AFP detection in serum samples.

Multi-functional nanozyme-based colorimetric, fluorescence dual-mode assay for Salmonella typhimurium detection in milk

Rapid and high-sensitive Salmonella detection in milk is important for preventing foodborne disease eruption. To overcome the influence of the complex ingredients in milk on the sensitive detection of Salmonella, a dual-signal reporter red fluorescence nanosphere (RNs)-Pt was designed by combining RNs and Pt nanoparticles. After being equipped with antibodies, the immune RNs-Pt (IRNs-Pt) provide an ultra-strong fluorescence signal when excited by UV light. With the assistance of the H2O2/TMB system, a visible color change appeared that was attributed to the strong peroxidase-like catalytic activity derived from Pt nanoparticles. The IRNs-Pt in conjunction with immune magnetic beads can realize that Salmonella typhimurium (S. typhi) was captured, labeled, and separated effectively from untreated reduced-fat pure milk samples. Under the optimal experimental conditions, with the assay, as low as 50 CFU S. typhi can be converted to detectable fluorescence and absorbance signals within 2 h, suggesting the feasibility of practical application of the assay. Meanwhile, dual-signal modes of quantitative detection were realized. For fluorescence signal detection (emission at 615 nm), the linear correlation between signal intensity and the concentration of S. typhi was Y = 83C-3321 (R2 = 0.9941), ranging from 103 to 105 CFU/mL, while for colorimetric detection (absorbamce at 450 nm), the relationship between signal intensity and the concentration of S. typhi was Y = 2.9logC-10.2 (R2 = 0.9875), ranging from 5 × 103 to 105 CFU/mL. For suspect food contamination by foodborne pathogens, this dual-mode signal readout assay is promising for achieving the aim of convenient preliminary screening and accurate quantification simultaneously.

The combination of DNA nanostructures and materials for highly sensitive electrochemical detection

Due to the wide range of electrochemical devices available, DNA nanostructures and material-based technologies have been greatly broadened. They have been actively used to create a variety of beautiful nanostructures owing to their unmatched programmability. Currently, a variety of electrochemical devices have been used for rapid sensing of biomolecules and other diagnostic applications. Here, we provide a brief overview of recent advances in DNA-based biomolecular assays. Biosensing platform such as electrochemical biosensor, nanopore biosensor, and field-effect transistor biosensors (FET), which are equipped with aptamer, DNA walker, DNAzyme, DNA origami, and nanomaterials, has been developed for amplification detection. Under the optimal conditions, the proposed biosensor has good amplification detection performance. Further, we discussed the challenges of detection strategies in clinical applications and offered the prospect of this field.