Novel advancements in nanomaterials-based contrast agents across multimodal imaging and theranostic applications.

Nanomaterials offer significant potential for non-invasive multimodal imaging due to their multifunctionality and tunable nanoscale features. Advances in their design and conjugation with organic and inorganic materials have enhanced their production and utility. Functionalizing nanoparticles (NPs) with imaging agents enables high-contrast imaging with spatial precision. Plasmonic NPs, lanthanide NPs, semiconductor-based quantum dots (QDs), and biogenic NPs have been employed as contrast agents for sensitive and specific imaging. Diseases such as cancer, neurological, gastrointestinal, and cardiovascular conditions demand early diagnosis for effective therapy. Therefore, functionalized NPs are employed to enhance molecular imaging by penetrating cells and targeting biomolecules thereby improving imaging modalities like positron emission tomography (PET), X-ray computed tomography (CT), near-infrared fluorescence (NIRF), magnetic resonance imaging (MRI), and photoacoustic imaging (PAI). This review highlights novel NP applications for image-guided surgery and treatment, emphasizing their role in combining imaging techniques for precision diagnostics. Challenges such as clinical translation and toxicity are discussed, underscoring the need for further research. NP-based contrast agents have emerged as an effective tool for bridging the gap between traditional diagnostics and personalized treatments, enabling real-time therapeutic monitoring and early stage theranostics.