ABSTRACT
Aims: To develop block copolymer crosslinked nanoassemblies (CNAs) that co-entrap an imaging dye (Acridine Yellow: AY) and therapeutic agent (doxorubicin: DOX) as novel nanoparticle drug carriers for a combined application of drug delivery-based therapy and diagnostic imaging technologies (theranostics). Study Design: Physicochemical properties of AY-CNAs, such as molecular weight, particle size, surface charge, drug entrapment yield, and drug release profiles, were characterized prior to determining intracellular uptake profile, in vitro cytotoxicity, and in vivo tissue distribution patterns of the particles. Place and Duration of Study: Department of Pharmaceutical Sciences (University of Kentucky), between June 2012 and January 2013. Methodology: The AY-crosslinked CNAs (CNAs) were synthesized from biocompatible poly(ethylene glycol)-poly(aspartate) block copolymers by using AY as a crosslinker while DOX was physically entrapped in the particle through an ionic interaction. AY-CNAs and AY-CNAs with DOX were characterized to determine their particle properties (molecular weight, size, and optical properties), intracellular uptake and cytotoxicity in an in vitro cell culture system using human colon HT29 and lung A549 cancer cell lines, and tissue accumulation and tumor-preferential drug delivery efficiency ex vivo with a xenograft mouse tumor model. Results: AY-CNAs maintained nanoscale particle sizes (< 20 nm), fluorescence optical properties, and negative surface charge before and after drug entrapment. AY-CNAs with DOX were confirmed to kill cancer cells as effectively as free drug formulations, and to enhance intracellular uptake in vitro and tumor accumulation ex vivo. Conclusion: These results demonstrate that block copolymer nanoassemblies crosslinked with an imaging dye are promising platforms for the development of theranostic nanoparticle drug carriers.
ABSTRACT
We describe the development of nanoscale polymer drug carriers for the combinational delivery of an anticancer drug (doxorubicin: DOX) along with super paramagnetic iron oxide nanoparticles (IONPs). The drug molecules were electrostatically loaded into both block copolymer self-assembled nanoassemblies (SNAs) and cross-linked nanoassemblies (CNAs). Both nanoassemblies entrapped DOX and IONPs either individually or in tandem, maintaining sub-100 nm diameter. The IONP-loaded nanoassemblies generated heat in the presence of an alternating magnetic field (AMF). Incorporation of the drug payload, DOX, showed no adverse effects on the heating profile. Drug release from the SNAs and CNAs was accelerated as temperature increased from the normal body temperature (37°C) to a mild hyperthermic condition (40 42°C). CNAs released DOX faster than SNAs regardless of an incubation temperature. CNAs co-entrapped IONPs and DOX were more stable than SNAs in aqueous solutions for five days. These results suggest that block copolymer cross-linked nanoassemblies provide viable delivery platforms for combination delivery of inorganic molecules, anticancer drugs, and potentially other various biologically active substances.
ABSTRACT
Disulfide crosslinked nanoassemblies (ssCNAs) were characterized in this study to assess their reductant-dependent degradation patterns for future development of redox-responsive smart nanomaterials in biomedical applications. The nanoassemblies were prepared from poly(ethylene glycol)-poly(aspartate) block copolymers, crosslinked with cystamine through an amidation reaction, generating 25 nm particles that have a disulfide crosslinked core enveloped with a poly(ethylene glycol) shell. ssCNAs remained unexpectedly stable in the presence of glutathione, a natural reductant overexpressing inside cells to cleave disulfide compounds. Further investigation revealed that ssCNAs underwent none, partial, and complete degradation in aqueous solutions at 37 °C for 48 h, depending on the molecular weight (MW), Connolly surface excluded volume (SEV), and charged state (net negative, neutral, and positive) of a reductant. Among six reductants tested, 2-aminoethanethiol (MW = 77.2, SEV = 52.2 Å3, net positive) was the most efficient for complete degradation of ssCNAs in 1 h, whereas another reductant, similar in structure except the charged state, 2-mercaptoethanol (MW = 78.1, SEV = 50.3 Å3, net neutral), took 4 h for complete nanoassembly degradation. These results indicate that degradation patterns of ssCNAs can be fine-tuned in a reductant-dependent manner, providing a better understanding of chemical stability of disulfide-crosslinked nanoassemblies.
ABSTRACT
facile and reliable method to perform pilot pharmacokinetic (PK) and biodistribution studies is necessary for expediting the overall development and clinical translation of novel nanoparticle drug carriers. In this study, we compared two common analytical techniques, fluorescence spectrometry using a microplate reader and liquid chromatography/mass spectrometry (LC/MS), demonstrating the quantification of a model anticancer drug (doxorubicin: DOX) in its free drug and nanoparticle formulations in vivo. Drug-loaded nanoparticle formulations were prepared from poly(ethylene glycol)-poly(aspartate) block copolymers, which formed two model drug carriers with different particle stability, self-assembled polymer micelles (DOX-micelles) and cross-linked nanoassemblies (DOX-CNAs). These three DOX formulations were injected into tumor-bearing mice at a DOX equivalent concentration. DOX levels in liver, spleen, and tumors were found to be comparable regardless of the analytical methods. LC/MS showed lower serum level than spectrometry with a microplate reader, which is consistent with the fact that DOX metabolites are present mainly in the serum.These results demonstrate that, in comparison to the LC/MS method, spectrometry using a microplate reader would be a viable and more facile method to perform pilot PK and biodistribution studies of various potential nanoparticle drug carriers using DOX as a model drug.