Researcher: Melissa Cadena
Collaborator: Dr. Robert Dickson
Virus-like particles (VLPs) are versatile platforms for vaccines and drug delivery due to their nanoscale structure, biocompatibility, and ability to be chemically modified. They can be functionalized with imaging agents, antigens, or therapeutic molecules, and their accumulation in lymph nodes is critical for eliciting strong immune responses. However, the dynamics of VLP trafficking in lymphatic tissues remain poorly understood, and conventional imaging methods such as IVIS or MRI are limited in depth, resolution, and sensitivity. Ultrasound-guided photoacoustic (US/PA) imaging provides a powerful alternative by combining ultrasound’s deep tissue penetration and resolution with optical contrast from light-absorbing agents.
In this study, Cy7-labeled VLPs were synthesized and characterized to enable noninvasive imaging of particle trafficking. (A) A schematic illustrates the Cy7-VLP structure, while (B) UV–Vis absorbance confirmed successful conjugation. (C) Size distribution analysis showed uniform particles with an average diameter of ~35 nm. Using US/PA imaging, Cy7-VLPs were tracked in vivo, where signal was detected in the draining lymph node 24 hours post-injection (D). Imaging also captured hemoglobin and oxygenation maps, providing functional context alongside VLP distribution. These results demonstrate that US/PA imaging can monitor both VLP delivery and lymph node localization, supporting their potential role in vaccine and therapeutic applications.
Together, these findings highlight US/PA imaging as a minimally invasive tool for studying the in vivo behavior of engineered particles. By integrating structural and functional information—including oxygenation, hemoglobin levels, and vascular features—this approach offers a more comprehensive assessment of particle trafficking than traditional endpoint methods. The ability to track VLP delivery and lymph node accumulation in real time provides valuable insights for optimizing vaccine design, improving therapeutic particle formulations, and advancing the clinical translation of VLP-based technologies.
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