ABSTRACT
BACKGROUND: Gold nanorods show a surface plasmon resonance (SPR) band at the near infra-red (NIR) region which enables them to produce heat on irradiation with a NIR laser. As a result of this, gold nanorods have the potential to be used as thermal therapeutic agents for selective damage to cancer cells, bacterial cells, viruses, and DNA. METHODS: Gold nanorods with an aspect ratio of approximately 5 were prepared by exploiting the normal micellar route of a water/dioctyl sulfosuccinate (Aerosol-T)/hexane system. The shape and size of the gold nanorods were characterized by surface plasmon bands at 520 nm and 980 nm, and by atomic force microscopy and transmission electron microscopy. RESULTS: The length of the gold nanorods was 100 nm and their diameter was 20 nm. X-ray diffraction analysis demonstrated that the gold nanorods formed were metallic in nature. The gold nanorods showed good photothermolysis activity. CONCLUSION: Gold nanorods injected subcutaneously and irradiated with 980 nm laser caused injury to rat tissue, demonstrating that gold nanorods may be used to kill cancerous cells in tumor tissue.
Subject(s)
Gold/chemistry , Laser Therapy/instrumentation , Nanotubes/chemistry , Skin/radiation effects , Animals , Gold/pharmacology , Histocytochemistry , Micelles , Microscopy , Necrosis , Particle Size , Photochemical Processes , Rats , Rats, Wistar , Skin/drug effects , X-Ray DiffractionABSTRACT
Hollow nanoshells of gold entrapping an enzyme, horseradish peroxidase (HRP), in the cavity of the nanoshell have been prepared in the reverse micelles by leaching out silver chloride (AgCl) from Au(shell)AgCl(core) nanoparticles with dilute ammonia solution. The particles have been characterised by dynamic laser light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and electron diffraction. The particle size is below 100 nm diameter, depending upon the size of the aqueous core of reverse micelles in which these particles have been prepared. This soft-chemical method for the preparation of such particles allows the entrapped enzyme to remain active inside the hollow gold nanoparticles. Small substrate molecules such as o-dianisidine can easily enter through the pores of the nanoshell and can undergo enzymatic oxidation by H2O2. The enzyme kinetics follows Michaelis-Menten mechanism. When the substrate is chemically conjugated with dextran molecule (10 kDa), the enzymatic reaction is practically completely prevented perhaps by the inability of dextran-o-dianisidine conjugate to penetrate the pores of the nanoshells. However, HRP did not show any activity when trapped inside solid gold nanoparticles.
Subject(s)
Gold/chemistry , Horseradish Peroxidase/chemistry , Nanostructures/chemistry , Nanotechnology/methods , Ammonia/chemistry , Crystallization , Dextrans/chemistry , Dianisidine/chemistry , Drug Compounding , Electrons , Enzymes/chemistry , Hydrogen Peroxide/chemistry , Kinetics , Light , Macromolecular Substances/chemistry , Micelles , Microscopy, Electron, Transmission , Models, Chemical , Nanotubes/chemistry , Particle Size , Scattering, Radiation , Silver Compounds/chemistry , Spectrophotometry , X-Ray DiffractionABSTRACT
The interference of colloidal tin oxides on the biodistribution of (99m)Technetium radiolabeled chitosan nanoparticles has been overcome by using sodium borohydride instead of commonly used stannous salts as reducing agent for the reduction of (99m)Tc (VII) to lower valency states. Biodistribution of radiolabeled chitosan nanoparticles prepared by using stannous chloride method revealed localization of the radioactivity mainly in the liver and spleen while that of radiolabeled chitosan nanoparticles prepared by using sodium borohydride method manifested the presence of radioactivity in blood up to an extent of 10% even after 2 h. Interestingly, the reduction of radioactivity in the latter case with the progress of time was not manifested through an increase in activity in the liver. Rather, a time dependent increased accumulation of radioactive materials was observed in the stomach. From the results it has been concluded that the biodistribution is strongly influenced by the presence of colloidal particles of tin oxides and (99m)Tc labeled chitosan nanoparticles are RES evading and long circulating in blood when Tc (VII) is reduced by sodium borohydride and not by stannous chloride during radiolabeling process.
Subject(s)
Colloids/pharmacology , Isotope Labeling/methods , Nanostructures/chemistry , Organotechnetium Compounds/chemistry , Organotechnetium Compounds/metabolism , Tin Compounds/pharmacology , Tissue Distribution , Animals , Borohydrides/blood , Borohydrides/chemistry , Borohydrides/pharmacology , Chitosan/blood , Chitosan/chemistry , Chitosan/pharmacology , Colloids/chemistry , Colloids/metabolism , Drug Evaluation, Preclinical/methods , Isotope Labeling/trends , Mice , Mice, Inbred Strains , Organotechnetium Compounds/pharmacology , Rabbits , Technetium , Technology, Pharmaceutical/methods , Technology, Pharmaceutical/trends , Tin Compounds/blood , Tin Compounds/chemistry , Tin Compounds/metabolismABSTRACT
Doxorubicin (DXR) commonly used in cancer therapy produces undesirable side effects such as cardiotoxicity. To minimize these, attempts have been made to couple the drug with dextran (DEX) and then to encapsulate this drug conjugate in hydrogel nanoparticles. By encapsulation of the drug conjugate in biodegradable, biocompatible long circulating hydrogel nanoparticles, we further improved the therapeutic efficacy of the conjugate. The size of these nanoparticles as determined by quasi-elastic light scattering, was found to be 100+/-10 nm diameter, which favors the enhanced permeability and retention effect (EPR) as observed in most solid tumors. The antitumor effect of these DEX-DXR nanoparticles, was evaluated in J774A.1 macrophage tumor cells implanted in Balb/c mice. The in vivo efficacy of these nanoparticles as antitumor drug carriers, was determined by tumor regression and increased survival time as compared to drug conjugate and free drug. These results suggest that encapsulation of the conjugate in nanoparticles not only reduces the side effects, but also improves its therapeutic efficacy in the treatment of solid tumors.
