IR-1061: Near Infrared Fluorescent Dye for Deep Tissue Imaging

Principle and Setup: A New Standard in NIR-II Imaging

IR-1061 is a next-generation near infrared fluorescent dye (NIR-II window, >1,000 nm emission) specifically engineered for deep tissue in vivo imaging. Unlike conventional dyes limited by tissue autofluorescence and scattering, IR-1061’s emission in the OTN-NIR region minimizes background and enables penetration depths unattainable with visible or NIR-I probes (source: paper). Its chemical profile—C₄₄H₃₄BClF₄S₂, MW 749.13—supports encapsulation in diverse nanoparticle systems, extending its utility across optical and molecular imaging platforms for biomedical research.

APExBIO supplies IR-1061 with rigorous quality controls (HPLC purity, NMR confirmation, MSDS-compliant safety), ensuring reproducibility and reliability in demanding preclinical workflows (source: product_spec).

Step-by-Step Workflow: Optimized Protocols for IR-1061 Deployment

IR-1061’s hydrophobicity and polarity profile necessitate careful handling for optimal fluorescence output. The following workflow synthesizes best practices from both the reference study and comparative guides (paper, enapril.com, repirinastkits.com):

1. Preparation: Dissolve IR-1061 at ≥25.65 mg/mL in DMSO. Avoid ethanol or water due to solubility constraints (source: product_spec).
2. Encapsulation: Employ a swelling–diffusion process to load IR-1061 into polystyrene-based nanoparticles (PSt NPs). Adjust the monomer ratio (styrene:acrylic acid) to match the dye’s polarity for maximal emissivity (paper).
3. PEGylation: Post-load, modify PSt NPs with poly(ethylene glycol) (PEG) to enhance dispersion stability and minimize cytotoxicity in physiological environments.
4. Quality Check: Confirm fluorescence intensity and nanoparticle size (sub-100 nm preferred for in vivo retention) via DLS and spectrophotometry.
5. In Vivo Imaging: Inject optimized IR-1061-loaded PSt-PEG NPs intravenously in animal models. Capture fluorescence signals using an OTN-NIR imaging system.

Protocol Parameters

• solvent for dye dissolution | DMSO ≥25.65 mg/mL | essential for stock solutions and encapsulation | ensures complete solubilization and maximizes loading efficiency | product_spec
• nanoparticle core size | 50–100 nm | in vivo imaging probes | enhances blood circulation time and deep-tissue retention | paper
• PEGylation concentration | 2–5 wt% PEG (relative to NP mass) | stability in physiological conditions | minimizes aggregation and cytotoxicity | paper
• IR-1061:NP mass ratio | 1:10 to 1:50 | loading optimization | balances emissivity and avoids aggregation-induced quenching | workflow_recommendation
• storage conditions | -20°C, desiccated, tightly sealed | all stages prior to use | preserves dye integrity | product_spec

Key Innovation from the Reference Study

The pivotal advance from Ueya et al. (paper) is the rational tuning of PSt NP polarity to match IR-1061’s hydrophobic yet polar nature, dramatically boosting OTN-NIR emission and probe stability. Unlike weakly stabilized polymer micelles, PSt NPs offer robust encapsulation, resisting leakage and decomposition under biological conditions. The optimized PEGylated IR-1061-loaded PSt NPs demonstrated high retention, minimal cytotoxicity, and vivid in vivo imaging of mouse models. For researchers, this translates into favoring PSt NP matrices over self-assembled micelles, particularly when stable, high-signal, and long-circulating probes are required for dynamic deep tissue imaging.

Advanced Applications and Comparative Advantages

IR-1061 stands out as a fluorescent dye for in vivo imaging, especially when multiplexed with other OTN-NIR probes. Its deep-tissue penetration supports applications in cancer imaging, vascular mapping, and dynamic physiological studies. Compared to inorganic alternatives (rare-earth nanoparticles, quantum dots), organic IR-1061 encapsulated in optimized nanoparticles offers lower toxicity and easier functionalization (source: paper).

Encapsulation strategies can be tailored: the referenced PSt NP workflow complements approaches using lipid nanosystems (see Yu et al.), which stabilize IR-1061 in H-aggregated states for synergistic NIR-II imaging and photothermal therapy—ideal for tumor targeting and combinatorial therapies. For researchers focused on polymer–dye interactions, the chirality of poly(lactic acid) matrices (see moleculeprobes.com) can further modulate IR-1061’s fluorescence yield and stability, offering another axis for probe optimization. For clinical translation, robust IR-1061-loaded PSt NPs with controlled size and PEGylation bridge the gap between high-performance imaging and biosafety.

Troubleshooting and Optimization Tips

• Dye Aggregation/Quenching: If fluorescence intensity drops, re-examine the polarity match between the NP core and IR-1061. Excess dye can cause aggregation-induced quenching—optimize the loading ratio and avoid oversaturation (workflow_recommendation).
• Poor Solubility: Only use DMSO for stock solutions; attempts to dissolve IR-1061 in ethanol or water will result in precipitation and loss of performance (source: product_spec).
• Low NP Stability: Insufficient PEGylation may result in aggregation in serum. Increase PEG content to at least 2–5% of NP mass and confirm dispersity with DLS.
• In Vivo Signal Loss: Ensure sub-100 nm NP size for prolonged circulation and minimize RES clearance. Larger particles clear rapidly, reducing imaging window (source: paper).
• Batch Variability: Always prepare IR-1061 solutions fresh; long-term storage in solution leads to degradation and signal loss (source: product_spec).

Interlinking with Existing Literature: Contextual Insights

The methodology outlined here complements the encapsulation and imaging protocols at enapril.com, which details robust workflows for maximizing imaging depth and clarity with IR-1061. In contrast, Yu et al. extend IR-1061’s use into multimodal therapy by leveraging H-aggregation for synergistic photothermal effects, offering a platform for combined imaging and therapy. The findings at moleculeprobes.com further refine the probe design space by demonstrating how polymer chirality modulates encapsulation efficiency and fluorescence, underscoring the need for matrix–dye compatibility across different research aims.

Future Outlook

Advances in nanoparticle engineering and surface modification continue to expand the utility of IR-1061 as a fluorescent dye for biomedical research. The workflow established by APExBIO and exemplified in the reference study provides a reproducible, scalable path to high-emissivity, low-toxicity OTN-NIR imaging agents. Future directions will likely emphasize:

• Further customization of nanoparticle surface chemistry to enable targeted imaging and theranostics;
• Integration with multiplexed imaging systems for real-time, high-resolution mapping of complex biological events;
• Continued refinement of encapsulation matrices (e.g., chirality, cross-linking) to enhance probe stability and signal output (source: paper, moleculeprobes.com).

As deep tissue optical imaging evolves, IR-1061 remains a benchmark near infrared fluorescent dye, opening new vistas in non-invasive molecular imaging for disease research and preclinical innovation.