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The use of affinity peptide displaying on the surface of M13 phage has emerged as a promising alternative to antibody-based detection methods owing to its diverse structure, mass production, easy purification, and genetic manipulation, as well as excellent stability. In this study, we aimed to identify highly selective and sensitive peptide-displayed M13 phage for thrombin detection using phage display technology. Phage display was conducted using two different phage libraries (linear and cyclic forms of peptides), which displayed affinity peptides capable of binding specifically to thrombin. Throughout the biopanning process, two phage clones that displayed both peptides (WGQSFWGYQHYS and CWKLLTPWC) were selected. After the characterization of their binding abilities using enzyme-linked immunosorbent assay, whole phage particles were covalently attached to a gold electrode using MUA-EDC/NHS coupling chemistry. The thrombin detection mechanism was based on signal inhibition, and the results revealed that the specific interactions between the phage-tethered gold electrode and thrombin are critical factors affecting the decrease in the peak current of the sensor. In addition, under optimal conditions, the fabricated phage-based electrochemical sensors were capable of highly sensitive and specific thrombin detection with a good binding affinity (Kd = 17 nM for 12mer 3–17 and 14 nM for C7C 3–5) and limit of detection (4 nM for 12mer 3–17 and 10 nM for C7C 3–5), resulting in good reproducibility, even in artificial human plasma samples. This study may provide an alternative and more efficient method of detecting thrombin with desirable sensitivity, selectivity, and feasibility for the diagnosis and prognosis of coagulation disorder-related diseases. [ABSTRACT FROM AUTHOR]

This paper reports the development of a highly sensitive and selective electrochemical peptide-based biosensor for the detection of the inflammatory disease biomarker, interleukin-1beta (IL-1β). To this end, flower-like Au–Ag@MoS 2 -rGO nanocomposites were used as the signal amplification platform to achieve a label-free biosensor with a high sensitivity and selectivity. First, a high-affinity peptide for IL-1β was identified through biopanning with M13 random peptide libraries, and was newly designed by incorporating cysteine at the C-terminus. An IL-1β specific binding peptide was used as the bio-receptor, and the interaction between the IL-1β binding peptide and IL-1β was confirmed via enzyme-linked immunosorbent assay and various physicochemical and electrochemical analyses. Under optimal conditions, the biosensor achieved an ultrasensitive and specific IL-1β detection in a wide linear concentration range of 0–250 ng/mL with a picomolar-level detection limit (∼2.4 pM), low binding constant (∼0.62 pM), and a low coefficient of variation (<1.65 %). The biosensor was successfully utilized for IL-1β determination in the serum of Crohn's disease patients with a good correlation coefficient. In addition, the detection performance was comparable to that of commercially available IL-1β ELISA kit. This indicates that the electrochemical peptide-based biosensor may offer a potentially valuable platform for the clinical diagnosis of various inflammatory disease biomarkers. [Display omitted] • A novel affinity peptide-tethered Au–Ag–MoS 2 -rGO nanocomposite electrode for the detection of IL-1β. • The peptide-tethered Au–Ag–MoS 2 -rGO nanocomposite electrode exhibited good conductivity and improved electrochemical activity. • The proposed biosensor has a good linear range with a picomolar detection limit and low coefficient variation. • The detection ability of the developed sensor is comparable to that of a commercial IL-1β ELISA kit. [ABSTRACT FROM AUTHOR]