Ultra-Sensitive Near-Infrared Imaging of Micro-Neuroinflammation with Surface-Engineered Silver Indium Selenide Quantum Dots

Encephalitis, a severe inflammatory brain condition, poses significant diagnostic challenges due to its heterogeneous symptoms and the limitations of conventional imaging techniques, such as magnetic resonance imaging (MRI), which often fail to detect early or subtle lesions. To address this clinical need, herein, a near-infrared (NIR) optical imaging strategy using engineered silver indium selenide quantum dots (QDs) was developed for precise and early detection of microencephalitic lesions. The QDs were synthesized via a robust aqueous-phase method with optimized NIR emission intensity through suppression of nonradiative recombination pathways. Surface modification with carboxyl-terminated poly(ethylene glycol) (carboxyl-PEG) enhanced colloidal stability, biocompatibility, and selective uptake capabilities by disease-associated M1 macrophages, improving localization at inflammatory sites. In vivo studies demonstrated the outstanding imaging performance of QDs, with encephalitis lesions clearly delineated at ultrahigh spatial resolution, enabling reliable detection of microinflammatory foci as small as 4.6 mm × 5.3 mm. This breakthrough capability facilitates early diagnosis by resolving sub-5 mm lesions, surpassing the sensitivity and resolution of conventional methods for the first time. By providing a noninvasive, high-resolution diagnostic tool, this technology holds potential for improving clinical decision-making and patient outcomes in encephalitis and other neuroinflammatory disorders, particularly in resource-limited settings where early diagnosis remains challenging.