Deep, noninvasive imaging and surgical guidance of submillimeter tumors using targeted M13-stabilized single-walled carbon nanotubes

Abstract

Highly sensitive detection of small, deep tumors for early diagnosis and surgical interventions remains a challenge for conventional imaging modalities. Second-window near-infrared light (NIR2, 950-1,400 nm) is promising for in vivo fluorescence imaging due to deep tissue penetration and low tissue autofluorescence. With their intrinsic fluorescence in the NIR2 regime and lack of photobleaching, single-walled carbon nanotubes (SWNTs) are potentially attractive contrast agents to detect tumors. Here, targeted M13 virus-stabilized SWNTs are used to visualize deep, disseminated tumors in vivo. This targeted nanoprobe, which uses M13 to stably display both tumor-targeting peptides and an SWNT imaging probe, demonstrates excellent tumor-to-background uptake and exhibits higher signal-to-noise performance compared with visible and near-infrared (NIR1) dyes for delineating tumor nodules. Detection and excision of tumors by a gynecological surgeon improved with SWNT image guidance and led to the identification of submillimeter tumors. Collectively, these findings demonstrate the promise of targeted SWNT nanoprobes for noninvasive disease monitoring and guided surgery.cancer imaging | fluorescence-guided surgery | M13 bacteriophage I n clinical oncology, in vivo fluorescence imaging has emerged as a valuable tool for improving diagnosis, staging tumors, monitoring response to therapy, and detecting recurrent or residual disease. Compared with existing imaging modalities, fluorescence imaging offers a low-cost, portable, and safe alternative (i.e., nonionizing radiation), with key advantages including realtime imaging, superior resolution, and high specificity for small tumor nodules during diagnostic and intraoperative surgical procedures (1, 2). Although efforts have focused on using visible and short near-infrared (NIR1, 650-900 nm) wavelength fluorescent dyes as contrast agents for delineating tumor margins in both preclinical cancer models (2, 3) and human patients (4), these agents are suboptimal for noninvasive, reflectance-based imaging due to limited penetration depth (3-5 mm) and high tissue autofluorescence. During intraoperative surgery, these dyes may additionally undergo photobleaching, thereby reducing the ability of the surgeon to readily locate and resect tumors. Alternative approaches to specifically permit noninvasive imaging and limited photobleaching would be highly desirable for diagnostic and surgical applications.Single-walled carbon nanotubes (SWNTs) hold great promise as fluorescence imaging agents due to the large interband difference between their excitation and emission wavelengths, resulting in minimal spectral overlap and tissue autofluorescence. In particular, the low tissue autofluorescence observed with SWNTs greatly enhances target-to-background ratios (TBRs) necessary for improved detection of small tumor nodules in confined anatomic regions. SWNT emission at longer wavelengths in the near-infrared second window (NIR2, 950-1,400 nm) results in less optical scattering and deeper tissue p...

Layer-by-layer assembled fluorescent probes in the second near-infrared window for systemic delivery and detection of ovarian cancer

“…Fluorescence imaging is categorized according to the spectral regions of the detected signal, including visible (400-750 nm), the first near-infrared window (NIR-I, 750-1,000 nm), and the second near-infrared window (NIR-II; 1,000-1,700 nm). NIR-II fluorescence imaging features deeper penetration and outperforms the others for in vivo investigations owing to the reduced absorption, scattering, and autofluorescence by biological tissues (6,7).…”

“…Current NIR-II emissive materials, including rare-earthbased down-conversion nanoparticles (DCNPs), quantum dots (QDs), single-walled carbon nanotubes (SWNTs), and small organic molecules, have been incorporated into diagnostic probes using a single lipid, polymer, protein, or bacteriophage (6)(7)(8)(9)(10)(11)(12). However, these delivery carriers lack the modularity and versatility to include drugs effectively for theranostic platforms and do not as readily enable the incorporation of complex or multiple drug payloads.…”

Genetically Engineered Phages: a Review of Advances over the Last Decade

“…M13-functionalized SWNTs have been used as effective probes for noninvasive fluorescence imaging of prostate tumors in mice (207), as well as to target SPARC and to visualize deep, disseminated tumors in mouse models of human ovarian cancers (222). By attachment of an antibacterial antibody to the p3 minor coat protein of the M13-SWNT complex, probes were made that could be used to image bacterial infections in vivo (223).…”

30 years of advances in functionalization of carbon nanomaterials for biomedical applications: a practical review

“…We discuss examples of the Belcher group's work [Figs. 4(a)-4(c), 7(a), 7(b) and 8(g)] on the use of a biological template (M13 bacteriophage), as a scaffold for noncovalent functionalization of carbon nanotubes for detection of cancers 32,33 and infectious diseases, 34 and also the use of physical or chemical modification to functionalize graphene oxide (GO) for biosensing applications 35 involving cell capture from whole blood; using the same metrics described above. The goal of this Review is to provide an objective, quantitative (wherever possible) comparison of these parameters, to help researchers make an informed decision while choosing a functionalization technique for their desired application.…”