Flourescent-endcap PLGA from PolySciTech used to investigate whole-body imaging biodistribution methodologies

Use of fluorescently-tagged PLGA allows for generated nanoparticles to be tracked using imaging systems. However, circumstances such as self-quenching can alter the results unless the research is performed in a careful and controlled manner. These situations can lead to erroneous results and alter the apparent uptake of nanoparticles into tumor sites relative to those up-taken by clearance through the liver, spleen, or kidneys. Recently, researchers at Purdue University use PLGA-Rhodamine (PolyVivo AV011), PLGA (AP020), and near-IR dye (FPI749) from PolySciTech (www.polyscitech.com) to evaluate the bio-distribution assays used to determine nanoparticle fate. This research holds promise to improve assessments of bio-distribution of nanoparticles in the future thus aiding in development of cancer therapies. Read more: Meng, Fanfei, Jianping Wang, Qineng Ping, and Yoon Yeo. "Quantitative Assessment of Nanoparticle Biodistribution by Fluorescence Imaging, Revisited." ACS nano (2018). https://pubs.acs.org/doi/abs/10.1021/acsnano.8b02881

“Abstract: Fluorescence-based whole body imaging is widely used in the evaluation of nanoparticles (NPs) in small animals, often combined with quantitative analysis to indicate their spatiotemporal distribution following systemic administration. An underlying assumption is that the fluorescence label represents NPs and the intensity increases with the amount of NPs and/or the labeling dyes accumulated in the region of interest. We prepare DiR-loaded poly(lactic-co glycolic acid) (PLGA) NPs with different surface layers (polyethylene glycol with and without folate terminus) and compare the distribution of fluorescence signals in a mouse model of folate receptor expressing tumor by near infrared fluorescence whole body imaging. Unexpectedly, we observe that fluorescence distribution patterns differ far more dramatically with DiR loading than with the surface ligand, reaching opposite conclusions with the same type of NPs (tumor-specific delivery vs. predominant liver accumulation). Analysis of DiR-loaded PLGA NPs reveal that fluorescence quenching, dequenching and signal saturation, which occur with the increasing dye content and local NP concentration, are responsible for the conflicting interpretations. This study highlights the critical need for validating fluorescence labeling of NPs in the quantitative analysis of whole body imaging. In light of our observation, we make suggestions for future whole body fluorescence imaging in the in vivo evaluation of NP behaviors. Keywords: Whole body imaging; fluorescence quenching; fluorescence saturation; nanoparticles; biodistribution”

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