Quencher‐Enhanced Raman Scattering Probes With Large Scattering Cross‐Section for NIR‐II Surgical Navigation and Postsurgical Site Infection Management

Why It Matters

QERS delivers high‑contrast, NIR‑II Raman imaging and on‑demand photothermal therapy without metal nanostructures, addressing key safety and performance gaps in image‑guided surgery and infection control.

Key Takeaways

• QERS probes exhibit Raman cross‑section of 1.27 × 10⁻¹⁹ cm².
• Photothermal conversion efficiency reaches 60.5 % under 1064 nm excitation.
• Fluorescence background suppressed to quantum yield of 0.0001.
• Enables Raman‑guided tumor resection and bacterial ablation in mice.
• Plasmon‑free design offers superior photostability compared with metal‑based probes.

Pulse Analysis

Raman spectroscopy has emerged as a label‑free imaging modality capable of delivering molecular fingerprints without the need for external contrast agents. Yet, conventional plasmon‑free Raman probes suffer from weak scattering signals and competing fluorescence, especially in the second near‑infrared window (NIR‑II, 1000‑1350 nm) where tissue attenuation is minimal. The newly reported quencher‑enhanced Raman scattering (QERS) strategy tackles these bottlenecks by employing non‑fluorescent diammonium building blocks that boost rigid electronic resonance while extinguishing fluorescence background. This design creates a bright, NIR‑II‑compatible Raman probe that operates without metallic nanoparticles, sidestepping cytotoxicity concerns associated with metal nanostructures.

The QERS probes demonstrate a Raman cross‑section of 1.27 × 10⁻¹⁹ cm², a value orders of magnitude higher than typical organic Raman tags. Their ultra‑low fluorescence quantum yield (0.0001) ensures a clean spectral baseline, while photostability tests show negligible signal decay after prolonged 1064 nm illumination. Remarkably, the same nanostructure converts up to 60.5 % of absorbed NIR‑II light into heat, enabling efficient photothermal therapy. In vivo imaging showed signal‑to‑noise ratios exceeding 15:1, confirming clinical relevance and allowing precise, real‑time Raman‑guided tumor excision and simultaneous bacterial eradication in animal models.

From a translational perspective, QERS probes could redefine intra‑operative navigation by providing surgeons with high‑contrast, molecular‑level feedback in the NIR‑II window, where deeper tissue penetration and reduced scattering are critical. The dual functionality—optical imaging and photothermal disinfection—addresses the persistent challenge of postoperative site infections, particularly those caused by drug‑resistant pathogens. As the medical device market increasingly values multimodal, plasmon‑free platforms, QERS technology is poised for rapid adoption in image‑guided surgery suites and wound‑care applications, driving research into scalable production and regulatory clearance. Early safety studies reported no observable toxicity over a two‑week observation period, supporting translational viability.