M13 Phage-Functionalized Single-Walled Carbon Nanotubes for Molecularly Targeted Imaging of Tumors Using Second Near-Infrared Fluorescence

Technology   

In the clinic, non-invasive, real-time and deep tissue imaging greatly facilitates early, accurate diagnoses and surgical procedures. Fluorescence in vivo imaging using second near-infrared (NIR) window light is attractive due to greater penetration of light through tissue. Single-walled carbon nanotubes (SWNTs) show great promise as in vivo imaging agents in the second NIR window, ensuring deeper penetration of light and low autofluorescence. Although SWNTs have previously been used for live cell imaging in vitro and in vivo whole animal imaging, actively targeting in vivo fluorescence imaging has not been achieved, as it is challenging to add targeting moieties to the small coating molecules while keeping the stability of the SWNTs strong enough. Here, multiple capsid proteins of M13 phage were created through independent genetic engineering of M13 phage for in vivo fluorescence imaging of targeted tumors. SWNTs are bound along the length of the phage, while one of the minor coat proteins, p3, of the SWNT-binding phage· is genetically modified to express either peptide ligands or peptide handles for site specific conjugation of antibodies for targeting. By genetically engineering the major coat protein of M13 for stabilizing SWNTs and the minor coat protein for targeting functionality independently, targeting capability was successfully incorporated into the probe without compromising the in vivo stability or the fluorescence of SWNTs.

Problem Addressed

This technology introduces a new method to address the challenge of non-invasive diagnosis and can be used as a tool for clinical procedures requiring immediate feedback, such as intraoperative surgery.  

Advantages

• Targeting capability is incorporated into the probe without compromising the in vivo stability of the fluorescence of SWNTs
• Due to the interchangeability of its components, potentially, any identified targeting ligands or antibody can be readily exchanged onto the imaging probe for molecular recognition of various cancers and bacterial infections
• Targeted fluorescence imaging of tumors is in the longer wavelength window, ensuring greater penetration depth and lower tissue autofluorescence