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Ultrasmall dual-modality silica nanoparticle drug conjugates: Design, synthesis, and characterization.

ABSTRACT: The physicochemical design and synthesis of effective cancer-directed and particle-based nanotherapeutic imaging agents remains a challenging task. Of critical importance is the ability to demonstrate maximum delivery, retention, and treatment efficacy for platforms designed to deposit their cargo at sites of disease without attendant dose-limiting toxicity. In this work, we describe dual-modality nanoparticle drug conjugates (NDCs) which utilize protease sensitive linkers to attached drug compounds and imaging labels to a clinically translated class of ultrasmall silica nanoparticle (C' dots). We describe the synthesis and characterization of these linker-drug constructs. Linkers incorporating dipeptide enzyme substrates are attached to analogs of a prototypical epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), through a cleavable amide bond or para-aminobenzyloxycarbonyl (PABC) group. These constructs are conjugated onto C' dots leading to the desired NDCs. These NDCs exhibit fast and predictable release kinetics in the presence of model proteases, and are stable in various biological media. Finally, in vitro assays show NDCs to be highly active in reducing phosphorylated EGFR levels in H1650 cells, a human tumor-derived cell line. The data suggests that NDCs exhibit desirable properties that warrant further development toward oncological therapy.

SUBMITTER: Yoo B

PROVIDER: S-EPMC4842310 | biostudies-literature | 2015 Nov

REPOSITORIES: biostudies-literature

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Ultrasmall dual-modality silica nanoparticle drug conjugates: Design, synthesis, and characterization.

Yoo Barney B Ma Kai K Zhang Li L Burns Andrew A Sequeira Sonia S Mellinghoff Ingo I Brennan Cameron C Wiesner Ulrich U Bradbury Michelle S MS

Bioorganic & medicinal chemistry 20151011 22

The physicochemical design and synthesis of effective cancer-directed and particle-based nanotherapeutic imaging agents remains a challenging task. Of critical importance is the ability to demonstrate maximum delivery, retention, and treatment efficacy for platforms designed to deposit their cargo at sites of disease without attendant dose-limiting toxicity. In this work, we describe dual-modality nanoparticle drug conjugates (NDCs) which utilize protease sensitive linkers to attached drug compo ...[more]

PMID: 26462054

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Project description:The combination of radionuclide-based imaging modalities such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) with magnetic resonance imaging (MRI) is likely to become the next generation of clinical scanners. Hence, there is a growing interest in the development of SPECT- and PET-MRI agents. To this end, we report a new class of dual-modality imaging agents based on the conjugation of radiolabeled bisphosphonates (BP) directly to the surface of superparamagnetic iron oxide (SPIO) nanoparticles. We demonstrate the high potential of BP-iron oxide conjugation using (??m)Tc-dipicolylamine(DPA)-alendronate, a BP-SPECT agent, and Endorem/Feridex, a liver MRI contrast agent based on SPIO. The labeling of SPIOs with (??m)Tc-DPA-alendronate can be performed in one step at room temperature if the SPIO is not coated with an organic polymer. Heating is needed if the nanoparticles are coated, as long as the coating is weakly bound as in the case of dextran in Endorem. The size of the radiolabeled Endorem (??m)Tc-DPA-ale-Endorem) was characterized by TEM (5 nm, Fe?O? core) and DLS (106 ± 60 nm, Fe?O? core + dextran). EDX, Dittmer-Lester, and radiolabeling studies demonstrate that the BP is bound to the nanoparticles and that it binds to the Fe?O? cores of Endorem, and not its dextran coating. The bimodal imaging capabilities and excellent stability of these nanoparticles were confirmed using MRI and nanoSPECT-CT imaging, showing that (??m)Tc and Endorem co-localize in the liver and spleen In Vivo, as expected for particles of the composition and size of (??m)Tc-DPA-ale-Endorem. To the best of our knowledge, this is the first example of radiolabeling SPIOs with BP conjugates and the first example of radiolabeling SPIO nanoparticles directly onto the surface of the iron oxide core, and not its coating. This work lays down the basis for a new generation of SPECT/PET-MR imaging agents in which the BP group could be used to attach functionality to provide targeting, stealth/stability, and radionuclides to Fe?O? nanoparticles using very simple methodology readily amenable to GMP.

Project description:The use of dexamethasone for eye disease treatment is limited by its low solubility, bioavailability, and rapid elimination when applied topically. The covalent conjugation of dexamethasone with polymeric carriers is a promising strategy to overcome existing drawbacks. In this work, amphiphilic polypeptides capable of self-assembly into nanoparticles were proposed as potential delivery systems for intravitreal delivery. The nanoparticles were prepared and characterized using poly(L-glutamic acid-co-D-phenylalanine) and poly(L-lysine-co-D/L-phenylalanine) as well as poly(L-lysine-co-D/L-phenylalanine) covered with heparin. The critical association concentration for the polypeptides obtained was in the 4.2-9.4 μg/mL range. The hydrodynamic size of the formed nanoparticles was between 90 and 210 nm, and they had an index of polydispersity between 0.08 and 0.27 and an absolute zeta-potential value between 20 and 45 mV. The ability of nanoparticles to migrate in the vitreous humor was examined using intact porcine vitreous. Conjugation of DEX with polypeptides was performed by additional succinylation of DEX and activation of carboxyl groups introduced to react with primary amines in polypeptides. The structures of all intermediate and final compounds were verified by 1H NMR spectroscopy. The amount of conjugated DEX can be varied from 6 to 220 µg/mg of polymer. The hydrodynamic diameter of the nanoparticle-based conjugates was increased to 200-370 nm, depending on the polymer sample and drug loading. The release of DEX from the conjugates due to hydrolysis of the ester bond between DEX and the succinyl moiety was studied both in a buffer medium and a vitreous/buffer mixture (50/50, v/v). As expected, the release in the vitreous medium was faster. However, the release rate could be controlled in the range of 96-192 h by varying the polymer composition. In addition, several mathematical models were used to assess the release profiles and figure out how DEX is released.

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Ultrasmall dual-modality silica nanoparticle drug conjugates: Design, synthesis, and characterization.

Publications

Ultrasmall dual-modality silica nanoparticle drug conjugates: Design, synthesis, and characterization.

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