Formulation and Characterization of Patent Blue Dye Nanoliposome Labeled with 99m Tc-HMPAO and In Vivo Evaluation by Sentinel Lymph Node Mapping

Abstract

Objective(s):

Sentinel lymph node (SLN) mapping commonly involves presurgical administration of a radioactive colloid and intraoperative injection of a blue dye near the tumor. Combining gamma scintigraphy and visual inspection could reduce false-negative rates. This study introduces novel imaging agents—radioactive nanoliposomes (NLs) encapsulating patent blue dye—for lymph node scintigraphy.

Materials and Methods:

PEGylated (PEG-NLs) and non-PEGylated (non-PEG-NLs) NLs were prepared using the thin-film hydration method with patent blue dye and labeled with ^99mTc-hexamethylpropylene-amine-oxime (^99mTc-HMPAO). Lymphatic drainage of the radiolabeled liposomes was assessed in BALB/c mice following subcutaneous footpad injections. Planar imaging was performed at 0.5 and 1 hour postinjection.

Results:

The mean diameter, zeta potential, and polydispersity index of the PEG-NLs were 130.7 ± 0.348 nm (n = 3), −22.4 ± 0.54 mV, and 0.118 ± 0.12, respectively. These values for the non-PEG-NLs were 120.46 ± 0.506 nm (n = 3), 7.5 ± 0.65 mV, and 0.055 ± 0.009, respectively. ^99mTc-HMPAO-PEG-NLs had a significantly higher lymph node uptake at earlier times after injection (28.27 ± 5.22% ID/g at 1 hour and 16.65 ± 4.23% ID/g at 2 hours), which was followed by fast washout at 4 hours postinjection and showed fast migration of PEGylated NLs through lymphatic system. ^99mTc-HMPAO-non-PEG-NLs had an increased lymph node accumulation through entire time after injection (11.95 ± 0.8% ID/g, 22.95 ± 4.56% ID/g, 29.71 ± 2.16% ID/g at 1, 2, and 4 hours, respectively). Encapsulation efficiency of patent blue dye was determined to be 1.26 ± 0.1%.

Conclusion:

^99mTc-HMPAO PEG-NLs and non-PEG-NLs containing Paten Blue dye are promising agents for SLN mapping, offering distinct advantages in uptake kinetics and retention for lymphatic imaging and visual detection.