TY - JOUR
T1 - Side-chain modification of collagen-targeting peptide prevents dye aggregation for improved molecular imaging of arthritic joints
AU - Michie, Megan S.
AU - Xu, Baogang
AU - Sudlow, Gail
AU - Springer, Luke E.
AU - Pham, Christine T.N.
AU - Achilefu, Samuel
N1 - Funding Information:
Kexian Liang is thanked for assistance with peptide synthesis and Rui Tang for help with spectroscopic studies. This study was supported by grants from the National Institutes of Health (R01 CA260855, U54 CA199092, R01 EB030987, R01 EB021048, P30 CA091842, P30 CA091842-19S3, P30 AR073752, R01 AR067491, S10 OD027042, S10 OD016237, S10 RR031625, and S10 OD020129), the Department of Defense Breast Cancer Research Program (W81XWH-16-1-0286), and the Siteman Investment Program Research Development Award.
Publisher Copyright:
© 2021
PY - 2022/2/1
Y1 - 2022/2/1
N2 - Near-infrared (NIR) dye-peptide conjugates are widely used for tissue-targeted molecular fluorescence imaging of pathophysiologic conditions. However, the significant contribution of both dye and peptide to the net mass of these bioconjugates implies that small changes in either component could alter their photophysical and biological properties. Here, we synthesized and conjugated a type I collagen targeted peptide, RRANAALKAGELYKCILY, to either a hydrophobic (LS1000) or hydrophilic (LS1006) NIR fluorescent dye. Spectroscopic analysis revealed rapid self-assembly of both LS1000 and LS1006 in aqueous media to form stable dimeric/H aggregates, regardless of the free dye's solubility in water. We discovered that replacing the cysteine residue in LS1000 and LS1006 with acetamidomethyl cysteine to afford LS1001 and LS1107, respectively, disrupted the peptide's self-assembly and activated the previously quenched dye's fluorescence in aqueous conditions. These results highlight the dominant role of the octadecapeptide, but not the dye molecules, in controlling the photophysical properties of these conjugates by likely sequestering or extruding the hydrophobic or hydrophilic dyes, respectively. Application of the compounds for imaging collagen-rich tissue in an animal model of inflammatory arthritis showed enhanced uptake of all four conjugates, which retained high collagen-binding affinity, in inflamed joints. Moreover, LS1001 and LS1107 improved the arthritic joint-to-background contrast, suggesting that reduced aggregation enhanced the clearance of these compounds from non-target tissues. Our results highlight a peptide-driven strategy to alter the aggregation states of molecular probes in aqueous solutions, irrespective of the water-solubilizing properties of the dye molecules. The interplay between the monomeric and aggregated forms of the conjugates using simple thiol-modifiers lends this peptide-driven approach to diverse applications, including the effective imaging of inflammatory arthritis joints.
AB - Near-infrared (NIR) dye-peptide conjugates are widely used for tissue-targeted molecular fluorescence imaging of pathophysiologic conditions. However, the significant contribution of both dye and peptide to the net mass of these bioconjugates implies that small changes in either component could alter their photophysical and biological properties. Here, we synthesized and conjugated a type I collagen targeted peptide, RRANAALKAGELYKCILY, to either a hydrophobic (LS1000) or hydrophilic (LS1006) NIR fluorescent dye. Spectroscopic analysis revealed rapid self-assembly of both LS1000 and LS1006 in aqueous media to form stable dimeric/H aggregates, regardless of the free dye's solubility in water. We discovered that replacing the cysteine residue in LS1000 and LS1006 with acetamidomethyl cysteine to afford LS1001 and LS1107, respectively, disrupted the peptide's self-assembly and activated the previously quenched dye's fluorescence in aqueous conditions. These results highlight the dominant role of the octadecapeptide, but not the dye molecules, in controlling the photophysical properties of these conjugates by likely sequestering or extruding the hydrophobic or hydrophilic dyes, respectively. Application of the compounds for imaging collagen-rich tissue in an animal model of inflammatory arthritis showed enhanced uptake of all four conjugates, which retained high collagen-binding affinity, in inflamed joints. Moreover, LS1001 and LS1107 improved the arthritic joint-to-background contrast, suggesting that reduced aggregation enhanced the clearance of these compounds from non-target tissues. Our results highlight a peptide-driven strategy to alter the aggregation states of molecular probes in aqueous solutions, irrespective of the water-solubilizing properties of the dye molecules. The interplay between the monomeric and aggregated forms of the conjugates using simple thiol-modifiers lends this peptide-driven approach to diverse applications, including the effective imaging of inflammatory arthritis joints.
KW - Fluorescence imaging
KW - Fluorescent probe
KW - Inflammatory arthritis
KW - Peptide-fluorophore conjugate
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U2 - 10.1016/j.jphotochem.2021.113624
DO - 10.1016/j.jphotochem.2021.113624
M3 - Article
C2 - 36406204
AN - SCOPUS:85118491292
SN - 1010-6030
VL - 424
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
M1 - 113624
ER -