Joo Yeon Park

Graphene-based nanosheets for delivery of chemotherapeutics and biological drugs ☆

Graphene-based nanosheets (GNS), including graphenes, graphene oxides and reduced graphene oxides, have properties suitable for delivery of various molecules. With their two-dimensional structures, GNS provide relatively high surface areas and capacity for non-covalent π-π stacking and hydrophobic interactions with various drug molecules. Currently, GNS-based delivery applications extend to chemotherapeutics as well as biological drugs, including nucleic acid drugs, proteins, and peptides. Surfaces of GNS have been modified with various polymers, such as polyethylene glycol and biopolymers, which enhance biocompatibility and increase drug loading. Anticancer drugs are prominent among chemotherapeutic agents tested, and have been loaded onto GNS with relatively high loading capacities compared with other nanocarriers. For enhanced distribution to specific tissues, GNS have been covalently or non-covalently modified with targeting ligands, including folic acid, transferrins, and others. In this review, we cover the current status of GNS for delivery of anticancer chemotherapeutics and biological drugs, with a focus on nucleic acid drugs. Remaining challenges for the application of GNS for drug-delivery systems and future perspectives are also addressed.

Polyaptamer DNA nanothread-anchored, reduced graphene oxide nanosheets for targeted delivery

Here, we report reduced graphene oxide (rGO) nanosheets anchoring receptor-specific polyaptamer nanothreads for targeted drug delivery. DNA polyaptamer nanothreads of protein tyrosine kinase 7 receptor (PTK7) were synthesized by rolling cycle amplification. To strengthen the anchoring of polyaptamer nanothreads onto rGO, oligoT bridge domain was introduced between each repeating PTK7 aptamer sequence. As compared to PTK7 polyaptamer nanothreads alone, PTK7 polyaptamer nanothreads with 22-mer oligoT bridges (PNT) showed higher anchoring capacity onto rGO nanosheets. Nanothread-coated surface morphology of PNTrGO was observed. Coating of PNT did not affect the sizes of rGO, but reduced the zeta potential. In PTK7-negative Ramos cells, the uptake of PNT-anchored rGO (PNTrGO) did not differ from that of oligoT-bridged scrambled polyaptamer-anchored rGO (SNTrGO). However, in CCRF-CEM leukemia cells overexpressing PTK7, the uptake of PNTrGO was 2.1-fold higher than that of SNTrGO after 15 min pulse. In vivo distribution to CCRF-CEM tumor tissues was 2.8-fold higher in PNTrGO than in SNTrGO at 48 h post-injection. In CCRF-CEM xenografted mice, intravenously administered doxorubicin (Dox)-loaded PNTrGO showed the higher antitumor activity than other groups, reducing the tumor weight down to 12% of tumor weights of untreated mice. These results suggest the potential of PNTrGO for target-specific drug delivery nanoplatform.

Biomimetic DNA nanoballs for oligonucleotide delivery

Here, we designed biomimetic DNA nanoballs for delivery of multiple antisense oligonucleotides (ASOs). DNA templates with ASOs-complementary sequences were amplified by rolling circle amplification (RCA). RCA products were loaded with two types of ASOs by hybridization, condensed using adenovirus-derived Mu peptide, and coated with hyaluronic acid (HA) for delivery into CD44-overexpressing tumor cells. HA-coated, Mu peptide-condensed, dual ASO-loaded DNA nanoballs (HMA nanoballs) showed considerable cellular entry of Cy5-incorporated RCA product DNA and fluorescent ASOs, whereas Mu peptide-condensed, dual ASO-loaded DNA nanoballs (MA nanoballs) revealed limited uptake. Dual ASOs, Dz13 and OGX-427, delivered by HMA nanoballs could reduce the levels of protein targets and exert anticancer effects. Enhanced tumor distribution was observed for fluorescent HMA nanoballs than the corresponding MA nanoballs. Upon intravenous co-administration with doxorubicin, HMA nanoballs exerted the greatest anti-tumor effects among the groups. These results suggest HMA nanoballs as a nanoplatform for sequence-specific delivery of multiple ASOs and other functional oligonucleotides.

Enhanced survival of transplanted human adipose-derived stem cells by co-delivery with liposomal apoptosome inhibitor in fibrin gel matrix.

To improve the survival of transplanted human adipose-derived stem cells (ADSCs), a liposome preparation containing the apoptosome inhibitor, NS3694, was formulated and co-delivered with ADSCs in fibrin gel scaffolds. Liposomes provided enhanced effect on ADSC proliferation in vitro as compared to free drug. Exposure of ADSCs to liposomal NS3694 for 7 days did not affect the surface marker expression profile. NS3694 encapsulated in negatively charged liposomes composed of phosphatidylcholine, phosphatidylglycerol, and cholesterol was evaluated in vivo following subcutaneous transplantation in mice. Survival of ADSCs co-delivered with liposomal NS3694 was significantly higher than that of untreated ADSCs or ADSCs treated with free NS3694 or empty liposomes. An immunohistochemical analysis revealed a higher number of human nucleus-positive cells after treatment with liposomal NS3694 than following treatment with free NS3694. Similarly, liposomal NS3694 significantly enhanced survival of transplanted ADSCs in rabbits compared to other treatments. Taken together, our results indicate the potential of liposomal NS3694 co-delivered with ADSCs using fibrin gel systems as an in vivo-survival enhancer.

Pharmaceutical Applications of Graphene-based Nanosheets

Graphene-based nanosheets (GNS) are atomic-thickness monolayers of hexagonally arranged, graphite-derived carbon atoms that may be composed of graphene, graphene oxide, or reduced graphene oxide. They have attracted tremendous interest for their potential in pharmaceutical applications, due to their unique physical, chemical, and mechanical properties GNS exhibit highly uniform surface areas and may have hydroxyl (-OH), epoxide (-O-), and carboxyl functional groups at their basal surfaces and plane edges, depending on their oxidized and reduced surface properties. GNS show high-level optical absorption of near infrared (NIR) light and elevate the temperature of nearby environments. Furthermore, they can be loaded with anticancer drugs via hydrophobic interactions, π-π stacking, or electrostatic binding. Given these properties, GNS can be used in chemotherapy, photodynamic therapy, photothermal therapy, and theranostics. However, although GNS appear to have far-reaching potential in the field of biomedical research, their widespread pharmaceutical application has been limited by issues such as poor stability in physiological buffers, undefined mechanisms of cellular uptake, toxicity problems, and a lack of standard preparation methods. Here, we review the current pharmaceutical applications of GNS, focusing on chemotherapy, phototherapy, combo therapy and theranostic applications with challenging issues.

Nanoformulation-based sequential combination cancer therapy

&NA; Although combining two or more treatments is regarded as an indispensable approach for effectively treating cancer, the traditional cocktail‐based combination therapies are seriously limited by coordination issues that fail to account for differences in the pharmacokinetics and action sites of each drug. The careful manipulation of dosing regimens, such as by the sequential application of combination treatments, may satisfy the temporal and spatial needs of each drug and achieve successful combination antitumor therapy. Nanotechnology‐based carriers might be the best tools for sequential combination therapy, as they can be loaded with multiple cargos and may provide targeted and sustained delivery to target tumor cells. Single nanoformulations capable of sequentially releasing drugs have shown synergistic anticancer activity, such as by sensitizing tumor cells through cascaded drug delivery or remodeling the tumor vasculature and microenvironment to enhance the tumor distribution of nanotherapeutics. This review highlights the use of nanotechnology‐based multistage drug delivery for cancer treatment, focusing on the ability of such formulations to enhance antitumor efficacy by applying sequential treatment and modulating dosing regimens, which are challenges currently being faced in the clinic. Graphical abstract Figure. No caption available.