Synthesis and in vivo fate of zwitterionic near-infrared fluorophores

Discrete bimodal probes for thrombus imaging

Here we report a generalizable solid/solution-phase strategy for the synthesis of discrete bimodal fibrin-targeted imaging probes. A fibrin-specific peptide was conjugated with two distinct imaging reporters at the C- and N-termini. In vitro studies demonstrated retention of fibrin affinity and specificity. Imaging studies showed that these probes could detect fibrin over a wide range of probe concentrations by optical, magnetic resonance, and positron emission tomography imaging.

Bone flap perfusion assessment using near-infrared fluorescence imaging

BACKGROUND

Microsurgical vascularized bone flaps are a versatile technique for reconstructing large bone defects. However, the assessment of perfusion is challenging, because clinical examination is difficult intraoperatively and often not possible postoperatively. Therefore, it is important to develop techniques to assess the perfusion of vascularized bone flaps and potentially improve the surgical outcomes. Near-infrared (NIR) fluorescence imaging has previously been shown to provide real-time, intraoperative evaluation of vascular perfusion. The present pilot study investigated the ability of NIR imaging to assess the perfusion of vascularized bone flaps.

METHODS

Vascularized bone flaps were created in female Yorkshire pigs using well-established models for porcine forelimb osteomyocutaneous flap allotransplantation (n = 8) and hindlimb fibula flaps (n = 8). Imaging of the bone flaps was performed during harvest using the FLARE intraoperative fluorescence imaging system after systemic injection of indocyanine green. Perfusion was also assessed using the standard of care by clinical observation and Doppler ultrasonography. NIR fluorescence perfusion assessment was confirmed by intermittent clamping of the vascular pedicle.

RESULTS

NIR fluorescence imaging could identify bone perfusion at the cut end of the osteotomy site. When the vascular pedicle was clamped or ligated, NIR imaging demonstrated no fluorescence when injected with indocyanine green. With clamp removal, the osteotomy site emitted fluorescence, indicating bone perfusion. The results using fluorescence imaging showed 100% agreement with the clinical observation and Doppler findings.

CONCLUSIONS

Vascularized bone transfers have become an important tool in reconstructive surgery; however, no established techniques are available to adequately assess perfusion. The results of our pilot study have indicated that NIR imaging can provide real-time, intraoperative assessment of bone perfusion.

Fluorescent nanoprobes dedicated to in vivo imaging: from preclinical validations to clinical translation

With the fast development, in the last ten years, of a large choice of set-ups dedicated to routine in vivo measurements in rodents, fluorescence imaging techniques are becoming essential tools in preclinical studies. Human clinical uses for diagnostic and image-guided surgery are also emerging. In comparison to low-molecular weight organic dyes, the use of fluorescent nanoprobes can improve both the signal sensitivity (better in vivo optical properties) and the fluorescence biodistribution (passive “nano” uptake in tumours for instance). A wide range of fluorescent nanoprobes have been designed and tested in preclinical studies for the last few years. They will be reviewed and discussed considering the obstacles that need to be overcome for their potential everyday use in clinics. The conjugation of fluorescence imaging with the benefits of nanotechnology should open the way to new medical applications in the near future.

Self-fluorescence of chemically crosslinked MRI nanoprobes to enable multimodal imaging of therapeutic cells

Old chemistry for novel materials: Self-fluorescent high-relaxivity T(2)-weighted magnetic resonance imaging (MRI) contrast agents are produced. They are a novel type of MR/optical dual-modality in vivo imaging nanoprobe using glutaraldehyde crosslinking chemistry, and they are used to label and monitor therapeutic cells both in vitro and in vivo.

Rapid and Facile Microwave-Assisted Surface Chemistry for Functionalized Microarray Slides

We describe a rapid and facile method for surface functionalization and ligand patterning of glass slides based on microwave-assisted synthesis and a microarraying robot. Our optimized reaction enables surface modification 42-times faster than conventional techniques and includes a carboxylated self-assembled monolayer, polyethylene glycol linkers of varying length, and stable amide bonds to small molecule, peptide, or protein ligands to be screened for binding to living cells. We also describe customized slide racks that permit functionalization of 100 slides at a time to produce a cost-efficient, highly reproducible batch process. Ligand spots can be positioned on the glass slides precisely using a microarraying robot, and spot size adjusted for any desired application. Using this system, we demonstrate live cell binding to a variety of ligands and optimize PEG linker length. Taken together, the technology we describe should enable high-throughput screening of disease-specific ligands that bind to living cells.

Water-soluble, deep-red fluorescent squaraine rotaxanes

Eight fluorescent squaraine rotaxanes with deep-red absorption/emission wavelengths were prepared and assessed for chemical stability and suitability as water-soluble, fluorescent tracers. The most stable squaraine rotaxanes have four large stopper groups attached to the ends of the encapsulated squaraine, and two members of this structural class have promise as highly fluorescent tracers with rapid renal clearance and very low tissue uptake in living mice.

Near infrared active heptacyanine dyes with unique cancer-imaging and cytotoxic properties

Three near-infrared fluorescent heptacarbocyanine dyes have been synthesized using a facile one-pot synthetic approach. The reaction methodology afforded a mixture of three symmetric and unsymmetric heptacyanines containing various N-indolenine substituents, a dicarbocyclic acid (DA), a monoester (ME), and a diester (DE). These compounds were isolated, purified, characterized and biologically investigated for tumor cell cytotoxicity and uptake selectivity. Using cell viability and in vitro proliferation assays, we found that the esterified dyes (monoester, ME and diester, DE) were selectively cytotoxic to cancer cells and spared normal fibroblast cells. Additionally, confocal fluorescence imaging confirmed selective uptake of these dyes in cancer cells, thus suggesting tumor cell targeting.