^99mTc‐human serum albumin nanocolloids: particle sizing and radioactivity distribution

Abstract

Several parameters affect the biodistribution of administered nanocolloids (NC) for Sentinel Lymph Node (SLN) detection: particle size distribution, number of Tc atoms per particle and specific activity (SA). Relatively few data are available with frequently conflicting results. (99m)Tc-NC-human serum albumin (HSA) Nanocoll®, Nanoalbumon® and Nanotop® were analysed for particles' dimensional and radioactivity distribution, and a mathematical model was elaborated to estimate the number of particles involved. Commercially available kits were reconstituted at maximal SA of 11 MBq/µg HSA. Particles size distribution was evaluated by Dynamic Light Scattering. These data were related to the radioactivity distribution analysis passing labelled NC through three polycarbonate filters (15-30-50-nm pore size) under vacuum. Highest radioactivity was carried by 30-50 nm particles. The smallest ones, even though most numerous, carried only the 10% of (99m)Tc atoms. Nanocoll and Nanotop are not significantly different, while Nanoalbumon is characterized by largest particles (>30 nm) that carried the most of radioactivity (80%). Smallest particles could saturate the clearing capacity of macrophages; therefore, if the tracer is used for SLN detection, more node tiers could be visualized, reducing accuracy of SLN mapping. Manufacturers could implement technical leaflets with particle size distribution and could improve the labelling protocol to provide clinicians useful information.

Chemical and Physical Characterisation of Human Serum Albumin Nanocolloids: Kinetics, Strength and Specificity of Bonds with 99mTc and 68Ga

“…Persico et al calculated the NC size and particle number statistically present in a vial of NanoAlbumon ® and the number of Human Serum Albumin molecules forming a single nanocolloid particle [ 12 ]. The further step was to evaluate the amount of 99m Tc and 68 Ga binding each nanocolloid particle, and hence also each Human Serum Albumin molecule within a single nanoparticle.…”

“…A better understanding of pH influence could be helpful for developing an efficient labelling procedure. In fact, amino acid residues are strongly affected by pH changes, and the de/protonation of the residues involved in isotopes binding could negatively impact on the labelling reactions [ 12 ].…”

Co-delivery of Cyclopamine and Doxorubicin Mediated by Bovine Serum Albumin Nanoparticles Reverses Doxorubicin Resistance in Breast Cancer by Down-regulating P-glycoprotein Expression

“…In addition, Figure 5D showed that metastasis of cervical lymph node occurred during the progression of breast cancer, and BSA-CYC-DOX NPs accumulated obviously in tumor and metastatic lymph node. Albumin nanoparticles were often used for lymph node detection as radiolabeled agents 44. They transferred to the sentinel lymph node from tumor sites though lymphatic channels, and then were gulfed by the lymph node macrophages resulting in a long period retention 45.…”

Sentinel Node Identification in Melanoma: Current Clinical Impact, New Emerging SPECT Radiotracers and Technological Advancements. An Update of the Last Decade

“…Examples of 99m Tc-labeled colloids include Sulphur colloid (TechneScan ® , TechneColl ® ), Antimony trisulphide (Lymph-Flo ® ), Sulphide nanocolloid (Lymphoscint ® ), Nanocolloidal albumin (Nanocoll ® , Nanoalbumon ® , Nanotop ® ) and Rhenium sulphide (Nanocis ® ) [ 5 , 65 ]. In the clinical setting, the choice of the radiopharmaceutical is influenced by the local availability, with 99m Tc-albumin nanocolloids being present in Europe, 99m Tc-antimony trisulphide in Australia and Canada and 99m Tc-sulphur colloid in the United States [ 5 ].…”

“…Persico et al . evaluated Nanocoll ® , Nanoalbumon ® and Nanotop ® demonstrating that the highest radioactivity is vehiculated by particles with size ranging from 30 to 50 nm (representing only 0.02-0.05% of the total) [ 65 ].…”