title: Modification of PLGA nanoparticles for improved properties as a 99mTc-labeled agent in sentinel lymph node detection.
abstract: We have earlier reported on the possible application of poly [lactide (co-glycolide)] (PLGA) nanoparticles of suitable size to serve as a (99m)Tc-labeled diagnostic tracer in sentinel lymph node detection (SLND). Additional efforts have now been made to improve both the radiolabeling yield and the biological efficacy by modifying the PLGA particles. Two approaches were taken, one based on in situ loading of mebrofenin inside PLGA nanoparticles and the second one based on functionalization of existing terminal carboxylic acid groups on the nanoparticle surface with p-aminobenzyl diethylenetriamine pentaacetic acid (p-NH2-Bz-DTPA) for enhanced availability of functional groups suitable for (99m)Tc complexation. The modified PLGA derivatives were purified and characterized. Radiolabeling of the modified PLGA nanoparticles was carried out with (99m)Tc using stannous chloride as the reducing agent. Mebrofenin encapsulated PLGA nanoparticles (mebrofenin-PLGA) did not show any significant improvement in the radiolabeling yield in comparison to the earlier reported "plain" PLGA nanoparticles, probably due to inaccessibility of the mebrofenin moiety to (99m)Tc upon encapsulation. DTPA-conjugated PLGA nanoparticles (DTPA-PLGA) showed appreciable improvement in radiolabeling yield under more moderate reaction conditions and better stability. In the biological evaluation performed in Wistar rat model, (99m)Tc-DTPA-PLGA nanoparticles showed a considerable increase in uptake in the sentinel node and the percentage popliteal extraction of the preparation was also higher. (99m)Tc-mebrofenin-PLGA did not show any improvement in SLN uptake over plain PLGA nanoparticles. The above results suggest that surface modification of PLGA by covalently coupling DTPA to PLGA nanoparticles prior to (99m)Tc labeling appears to be a superior approach to achieve a suitable (99m)Tc-labeled PLGA nanoparticle preparation for SLND.
authors.affiliation: 1 Radiopharmaceutical Evaluation Section, Radiopharmaceuticals Division, Bhabha Atomic Research Centre (BARC) , Trombay, Mumbai, India .
authors.forename: Suresh
authors.initials: S
authors.lastname: Subramanian
authors.forename: Usha
authors.initials: U
authors.lastname: Pandey
authors.forename: Dalapathi
authors.initials: D
authors.lastname: Gugulothu
authors.forename: Vandana
authors.initials: V
authors.lastname: Patravale
authors.forename: Grace
authors.initials: G
authors.lastname: Samuel
mesh_terms: D000818:Animals; D005260:Female; D007553:Isotope Labeling / Q000379:methods; D019344:Lactic Acid / Q000737:chemistry*; D008198:Lymph Nodes / Q000000981:diagnostic imaging* / Q000473:pathology; D053758:Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011877:Radionuclide Imaging / Q000379:methods; D051381:Rats; D017208:Rats, Wistar; D021701:Sentinel Lymph Node Biopsy / Q000379:methods*; D016284:Technetium Tc 99m Pentetate / Q000737:chemistry*
chemical_list: D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D016284:Technetium Tc 99m Pentetate