Two-Photon Tracer for Human Epidermal Growth Factor Receptor-2: Detection of Breast Cancer in a Live Tissue

PyrPeg, a Blood-Brain-Barrier-Penetrating Two-Photon Imaging Probe, Selectively Detects Neuritic Plaques, Not Tau Aggregates

Amyloid-β (Aβ) tracers have made a significant contribution to the treatment of Alzheimer's disease (AD) by allowing a definitive diagnosis in living patients. Unfortunately, they also detect tau and other protein aggregates that compromise test accuracy. In AD research, there has been a growing need for in vivo Aβ imaging by two-photon microscopy, which enables deep-brain-fluorescence imaging. There is no suitable neuritic Aβ probe for two-photon microscopy. Here we report PyrPeg, a novel two-photon fluorescent probe that can selectively target insoluble Aβ rather than tau and α-synuclein aggregates in the AD model brain and postmortem brain. When injected intravenously, PyrPeg detects the neuritic plaques in the brain and olfactory bulb of the AD model. PyrPeg may serve as a useful blood-brain-barrier-penetrating diagnostic tool for optical and functional monitoring of insoluble forms of Aβ aggregates in the living AD brain.

Two-photon probes for the endoplasmic reticulum: its detection in a live tissue by two-photon microscopy

BER-blue and FER-green can detect the endoplasmic reticulum in a live tissue by two-photon microscopy.

Two-Photon Probe for TNF-α. Assessment of the Transmembrane TNF-α Level in Human Colon Tissue by Two-Photon Microscopy

We developed Pyr1-infliximab: a two-photon probe for TNF-α. Pyr1-infliximab showed absorption maxima at 280 and 438 nm and an emission maximum at 610 nm in an aqueous buffer and effective two-photon action cross-section values of (520-2830) × 10^-50 cm⁴s/photon in RAW 264.7 cells. After this probe was labeled, it was possible to detect Pyr1-infliximab-transmembrane TNF-α complexes in a live cell and to determine the relative proportion of these complexes in human colon tissues. This proportion among healthy, possibly inflamed, and inflamed tissues of patients with ulcerative colitis was found to be 1.0/4.5/10. This probe may find useful applications for selective detection of transmembrane TNF-α in a live cell or tissue, for quantification of inflammation in human colon tissue or of antidrug antibodies in patients who stop responding to anti-TNF therapy, and for monitoring of the response to this therapy.

Two-Photon Probes for Golgi Apparatus: Detection of Golgi Apparatus in Live Tissue by Two-Photon Microscopy

We have developed blue- and yellow-emitting two-photon probes (BGolgi-blue and PGolgi-yellow) from 6-(benzo[ d]oxazol-2-yl)-2-naphthalylamine and 2,5-bis(benzo[ d]oxazol-2-yl)pyrazine derivatives as the fluorophores and trans-Golgi-network peptide (SDYQRL) as the Golgi-apparatus-targeting moiety. HeLa cells labeled with BGolgi-blue and PGolgi-yellow emitted two-photon-excited fluorescence at 462 and 560 nm, respectively, with effective two-photon-action cross-section values of 1860 and 1600 × 10^-50 cm⁴·s/photon, respectively. The probes can detect the Golgi apparatus in live cells and deep inside live tissue via two-photon microscopy at widely separated wavelength regions with high selectivity and minimal pH interference, and they are photostable and have low cytotoxicity.

Bispecific affibody molecule targeting HPV16 and HPV18E7 oncoproteins for enhanced molecular imaging of cervical cancer

High-risk human papillomavirus (HPV16 and HPV18) are now widely recognized as responsible for cervical cancer, which remains to be the most common gynecologic malignancy in women worldwide. It is well known that viral oncoproteins E6/E7 play key roles in HPV-associated cervical carcinogenesis. Thus, in vivo detection of the two oncoproteins may provide important diagnostic information influencing patient management. More recently, affibody molecules have been demonstrated to be a promising candidate for development as molecular imaging probes. Based on the two monomeric affibody molecules (Z_HPV16E7 and Z_HPV18E7) generated in our laboratory, here, we used a peptide linker (Gly₄Ser)₃ to link Z_HPV16E7 and Z_HPV18E7 to develop a novel heterodimeric affibody Z_HPV16E7-(Gly₄Ser)₃-Z_HPV18E7. Both biosensor and immunofluorescence assays have proved that the heterodimeric affibody molecule targeted simultaneously HPV16 and HPV18E7 proteins by binding to the viral oncoproteins. In vivo tumor-imaging experiments using the Dylight755-labeled heterodimeric affibody revealed that strongly high-contrast tumor retention of the heterodimers occurred in both HPV16- and HPV18-derived tumors of nude mice 0.5 h post-injection. The accumulation of Dylight755-labeled heterodimers in tumors was achieved over 48 h. Therefore, we believe that this novel heterodimeric affibody molecule has great potential utility in molecular imaging in vivo and diagnosis of HPV-associated cervical cancers.

Affibody Molecules in Biotechnological and Medical Applications

Affibody molecules are small (6.5-kDa) affinity proteins based on a three-helix bundle domain framework. Since their introduction 20 years ago as an alternative to antibodies for biotechnological applications, the first therapeutic affibody molecules have now entered clinical development and more than 400 studies have been published in which affibody molecules have been developed and used in a variety of contexts. In this review, we focus primarily on efforts over the past 5 years to explore the potential of affibody molecules for medical applications in oncology, neurodegenerative, and inflammation disorders, including molecular imaging, receptor signal blocking, and delivery of toxic payloads. In addition, we describe recent examples of biotechnological applications, in which affibody molecules have been exploited as modular affinity fusion partners.

A two-photon ratiometric fluorescent probe for the synergistic detection of the mitochondrial SO2/HClO crosstalk in cells and in vivo

We report herein a mitochondria-targeted two-photon ratiometric fluorescent probe to respectively or successively detect HSO₃⁻/HClO in cells and zebrafish.