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Hepatic fibrosis, a chronic liver response to injury with potential severe outcomes like cirrhosis and liver cancer, necessitates urgent noninvasive diagnostic techniques to halt disease progression. We herein for the first time developed a single-chain peptide probe targeting pathological collagen for in vivo magnetic resonance imaging (MRI) of hepatic fibrosis. The novel (GhypO) 10 probe, distinguished by its unique monomeric conformation achieved through Pro to (2 S ,4 S )-hydroxyproline (hyp) substitution and subsequent disruption of hydrogen bonding, exhibits selectivity for pathological collagen over its intact counterpart in connective tissues. Fluorescence imaging of liver specimens from fibrotic models displayed a discernible relationship between pathological collagen levels and fibrosis stage. Moreover, T1-weighted MR images post Gd-GhypO administration revealed progressive signal enhancement congruent with fibrosis severity, corroborated by a corresponding increase in the contrast-to-noise ratio (ΔCNR). Biodistribution analysis indicates that Gd-GhypO has low Gd retention in the main organs 24 h postinjection, ensuring the probe's safety for molecular imaging. The Gd-GhypO probe therefore emerges as a potent tool for the precise, noninvasive delineation of hepatic fibrosis stages, offering significant implications for the diagnosis and management of liver fibrosis.

Osteogenesis imperfecta (OI) is a hereditary skeletal disorder characterized by bone fragility and deformities, primarily attributed to defects in type I collagen, the most abundant structural protein in humans. Multiple phosphorylation sites have been detected within collagen, suggesting that phosphorylation may influence mineralization processes, thereby impacting the development of OI. In this study, we investigated the modulation of biomineralization morphology by phosphorylated collagen peptides mimicking Gly-Ser mutations in osteogenesis imperfecta. A series of collagen peptide sequences, including GPO 13 S, GPO 13 pS, GPO 12 S, GPO 12 pS, GPO 11 S, and GPO 11 pS, were synthesized to explore the role of phosphorylation in peptide stability and its templating effect on biomineralization. The CD results indicated that the phosphorylation of Gly-pSer mutants reduces the stability of collagen peptides. SEM images revealed that phosphorylated peptides acted as templates, guiding the morphology of calcium carbonate into either olive-like or spherical structures, depending on their conformational state of the peptides. Non-phosphorylated peptides maintained a calcite crystal structure. The XRD patterns predominantly exhibited peaks associated with calcite and vaterite for GPO 13 pS-CaCO 3 , GPO 12 pS-CaCO 3 , and GPO 11 pS-CaCO 3 , and peaks associated with calcite for GPO 13 S-CaCO 3 , GPO 12 S-CaCO 3 , and GPO 11 S-CaCO 3 , indicating a transformation of mesocrystals influenced by peptide phosphorylation. Our findings elucidate the crucial role of phosphorylated collagen peptides in mediating biomineralization morphology and polymorph selection, offering insights into the complex pathophysiology of OI.

We herein report the construction of a robust MRI peptide contrast agent Gd-ICTP with superior selectivity for type I collagen, enabling the accurate and non-invasive detection of hepatic fibrosis in vivo .

The development of novel assays to detect collagen fragments is of utmost importance for diagnostic, prognostic and therapeutic decisions in various collagen-related diseases, and one essential question is to discover probe peptides that can specifically recognize target collagen sequences. Herein we have developed the fluorescence self-quenching assay as a convenient tool to screen the capability of a series of fluorescent probe peptides of variable lengths to bind with target collagen peptides. We have revealed that the targeting ability of probe peptides is length-dependent, and have discovered a relatively short probe peptide FAM-G(POG) 8 capable to identify the target peptide. We have further demonstrated that fluorescence self-quenching assay together with this short probe peptide can be applied to specifically detect the desired collagen fragment in complex biological media. Fluorescence self-quenching assay provides a powerful new tool to discover effective peptides for the recognition of collagen biomarkers, and it may have great potential to identify probe peptides for various protein biomarkers involved in pathological conditions., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We herein report the construction of a robust MRI peptide contrast agent Gd-ICTP with superior selectivity for type I collagen, enabling the accurate and non-invasive detection of hepatic fibrosis in vivo. [ABSTRACT FROM AUTHOR]

Retraction of 'A robust collagen-targeting MRI peptide contrast agent for in vivo imaging of hepatic fibrosis' by Zhao Liu et al., Chem. Commun., 2023, 59, 6068–6071, https://doi.org/10.1039/D3CC01096A. [ABSTRACT FROM AUTHOR]

The precise detection of pathological type I collagen is critical for diagnosing and prognosticating various diseases such as fibrosis and tumors. Surface-enhanced Raman scattering (SERS) is emerging as a promising high-resolution imaging technique, yet the intricate process of covalently modifying antibodies often results in SERS probes with diminished selectivity. We herein for the first time report the development of dual SERS peptide probes, Ag@R1@PCTP (S-P) and Ag@R2@ICTP (S-I), which integrate collagen targeting peptides (CTPs), Raman reporters, and silver nanoparticles (Ag NPs) for specific imaging of pathological type I collagen in connective tissues. The S-P/S-I dual SERS peptide probes displayed distinct peaks at 2154 cm−1 and 2227 cm−1 in the Raman silent region with no overlap, showcasing their capability for multiplex imaging free from cross-interference. The SERS peptide probe S-P is specifically tuned to target pathological collagen, excluding intact collagen, while S-I effectively recognizes type I collagen in both its pathological and healthy states. The S-P/S-I probes have exhibited outstanding effectiveness in identifying pathological type I collagen across various connective tissues and have been successfully applied for imaging this collagen in a variety of cancer tissues. The innovative dual SERS peptide probes offer a highly specific and robust tool for imaging pathological type I collagen in tissues, presenting significant potential for the accurate diagnosis and treatment of a range of collagen-related diseases. • A highly specific sensor for SERS imaging of pathological type I collagen was established. • SERS peptide probes S-P and S-I showed selective identification of pathological collagen and type I collagen, respectively. • Dual SERS peptide probes have been effectively deployed for targeting pathological type I collagen in diverse tissues. [ABSTRACT FROM AUTHOR]