title: Block co-polymer nanoparticles with degradable cross-linked core and low-molecular-weight PEG corona for anti-tumour drug delivery.
abstract: Biodegradable/bioeliminable, core-cross-linked, block co-polymer nanoparticles have been synthesized as a potential anti-tumour drug-delivery system. Methacrylate-modified poly(ethylene glycol)-b-poly(D,L-lactide) (PEG-b-PDLLA) composed of low-molecular-weight polymer blocks (<5 kg/mol) were synthesized by ring-opening polymerization and post-polymerization chemical modifications. Nanoparticles with a diameter of 110 ± 20 nm were formed from methacrylate-modified PEG(45)-b-PDLLA(41) in a THF/water mixture (1:3). The particles were then core-cross-linked using a new, highly acid-labile ketal cross-linker. The cross-linked particles had a hydrodynamic diameter of 104 ± 20 nm (in THF/water, 1:3), as determined by DLS. The particles in THF exhibited a similar hydrodynamic diameter. Doxorubicin as a model anti-tumour drug was loaded into the nanoparticles (25-31 wt%). The particles released 50% of the loaded drug slowly approximately in 2 days at pH 5.5 and in 5 days at pH 7.4. The particles degraded to bioeliminable polymer fragments (<40 kg/mol) after the hydrolysis of the ketal cross-links at pH 5.5 in seven days, as determined by GPC. Doxorubicin-loaded cross-linked particles (9.3 μM doxorubicin/2.5 μM polymer) inhibited the viability of human neuroblastoma SH-EP cells, whilst the particles without drug at the same concentration were non-toxic, as determined by an Alamar Blue assay. Flow cytometry experiments revealed that the doxorubicin-loaded cross-linked particles were taken up by SH-EP cells in quantities comparable with free doxorubicin. Overall the results support the value of the cross-linked particles for further investigation as a carrier for anti-tumour drugs.
authors.affiliation: Centre for Advanced Macromolecular Design, School of Chemical Sciences and Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
authors.forename: Ginu
authors.initials: G
authors.lastname: Abraham
authors.forename: Josh
authors.initials: J
authors.lastname: McCarroll
authors.forename: Frances
authors.initials: F
authors.lastname: Byrne
authors.forename: Sureyya
authors.initials: S
authors.lastname: Saricilar
authors.forename: Maria
authors.initials: M
authors.lastname: Kavallaris
authors.forename: Volga
authors.initials: V
authors.lastname: Bulmus
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004317:Doxorubicin / Q000008:administration & dosage* / Q000737:chemistry / Q000494:pharmacology; D004337:Drug Carriers / Q000737:chemistry*; D006801:Humans; D053758:Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D000970:Antineoplastic Agents; D004337:Drug Carriers; D011108:Polymers; D011092:Polyethylene Glycols; D004317:Doxorubicin