Sin-jung Park

Hyaluronic acid-conjugated graphene oxide/photosensitizer nanohybrids for cancer targeted photodynamic therapy

Hyaluronic acid (HA)-graphene oxide (GO) conjugates, with a high loading of photosensitizers (PS; Ce6), were developed as a cancer cell targeted and photoactivity switchable nanoplatform for photodynamic therapy (PDT). HA-GO conjugates with size below 100 nm were first prepared by the chemical conjugation between ADH-modified HA and fractionated GO sheets with size relevant for drug delivery. Before evaluating the drug delivery efficacies, their chemical structure, morphology, and biocompatibility were characterized by 1H NMR, UV, TGA, AFM, DLS and MTT assays. The physical adsorption of Ce6 onto HA-GO nanocarriers was mainly due to the π-π stacking as well as hydrophobic interactions. It was demonstrated by CLSM and FACS that the cellular internalization of the HA-GO/Ce6 nanohybrids was much more effective when compared with free Ce6, which was also found to be significantly influenced by the co-treatment with an excess amount of HA polymers, illustrating their active targeting to HA receptors overexpressed on cancer cells. The photoactivity of Ce6 adsorbed on HA-GO nanocarriers was mostly quenched in aqueous solution to ensure biocompatibility, but was quickly recovered after the release of Ce6 from HA-GO nanocarriers upon cellular uptake. As a result, the PDT efficiency of the HA-GO/Ce6 nanohybrids was remarkably improved ∼10 times more than that of free Ce6, as well demonstrated in both MTT and LIVE/DEAD assays.

Endolysosomal environment-responsive photodynamic nanocarrier to enhance cytosolic drug delivery via photosensitizer-mediated membrane disruption

The endolysosome is a major barrier for the effective intracellular delivery by conventional nanocarriers. Herein, we demonstrate that endolysosome environment-responsive photodynamic nanocarriers (EPNs) are capable of encapsulation of the hydrophobic drug paclitaxel (PTX) and photosensitizer (PS)-mediated ELB disruption for effective cancer therapy. EPNs were self-assembled from PS (chlorin e6, Ce6) or Black Hole Quencher-3 (BHQ3) conjugated covalently to polypeptide-based amphiphilic copolymers [monomethoxy polyethylene glycol-block-poly(β-benzyl-L-aspartic acid), mPEG-pBLA]. EPNs have a spherical shape and a unimodal size distribution below 100 nm. Photoquenching of the EPNs was dependent on the molar ratio of mPEG-pBLA-BHQ3/mPEG-pBLA-Ce6. However, in the presence of the endolysosomal enzyme (e.g., esterase), the benzyl ester bond is cleaved which leads to the structural collapse of EPNs, thus triggering drug release and restoring photoactivity. Live cell imaging studies demonstrated that PS-mediated lipid peroxidation significantly increased the ability of model drug (i.e., Nile red) to overcome the ELB. In comparison with PTX treatment alone, the combined treatment of PTX encapsulated EPNs with laser irradiation synergistically induced the death of HeLa and drug-resistant HCT-8 cells in vitro, and suppressed CT-26 tumor growth in vivo. These results suggest that this approach is a promising platform for cancer treatment. Furthermore, this EPN system offers significant potential for effective cytosolic delivery of chemical and biological therapeutics.

Potential of self-organizing nanogel with acetylated chondroitin sulfate as an anti-cancer drug carrier

In order to obtain feasibility data regarding the possibility of using chondroitin sulfate (CS) in an anti-cancer drug delivery system, CS was chemically modified by a one-step process with acetic anhydride. Although 3 samples with different degrees of acetylation were synthesized, only the sample with the highest degree of acetylation (AC-CS3) was tested as a nanogel because the others (AC-CS1 and 2) dissolved in distilled water (DW) in the test range (1-10 mg/ml). The AC-CS3 nanogel was characterized by fluorescence probe and dynamic light scattering (DLS) techniques. Its critical aggregation concentration (CAC) was <2.0 x 10(-2) mg/ml at 25 degrees C. The partition equilibrium constant, K(v), of the nanogel (7.88 x 10(5)) was similar to that of polymeric micelles, which means that the acetyl group may act as a hydrophobic core controlling pharmacokinetic behavior. The higher surface charge value in the nanogel, above - 40 due to carboxyl and sulfate groups in CS, explains its good stability. The anticancer drug doxorubicin (DOX) loading efficiency of the AC-CS3 nanogel was also superior, at above 90%. Changes in the size of the polydispersion index (PDI) of nanogels loaded with DOX over a 3-week period were negligible. The nanogels interacted with HeLa cells and were internalized together with the entrapped drug within the cytoplasm, probably via an endocytic mechanism exploited by sugar receptors. Based on these results, the AC-CS3 nanogel is expected to prove useful as an anti-cancer drug carrier for chemotherapy.

Photosensitizer-Conjugated Hyaluronic Acid-Shielded Polydopamine Nanoparticles for Targeted Photomediated Tumor Therapy

Photodynamic therapy (PDT) is a widely used clinical option for tumor therapy. However, the clinical utilization of conventional small-molecule photosensitizers (PSs) for PDT has been limited by their low selectivity for disease sites, and undesirable photoactivation. To overcome these limitations, we demonstrated a tumor-specific and photoactivity-controllable nanoparticle photomedicine based on a combination of PS-biomacromolecule conjugates and polydopamine nanoparticles (PD-NP) for an effective tumor therapy. This novel photomedicine consisted of a PD-NP core and a PS-conjugated hyaluronic acid (PS-HA) shell. The PD-NP and the PS-HA play roles as a quencher for PSs and a cancer targeting moiety, respectively. The synthesized PS-HA-shielded PD-NPs (PHPD-NPs) had a relatively narrow size distribution (approximately 130 nm) with uniform spherical shapes. In response to cancer-specific intracellular enzymes (e.g., hyaluronidase), the PHPD-NPs exhibited an excellent singlet oxygen generation capacity for PDT. Furthermore, an efficient photothermal conversion ability for photothermal therapy (PTT) was also shown in the PHPD-NPs system. These properties provide superior therapeutic efficacy against cancer cells. In mice tumor model, the photoactive restorative effects of the PHPD-NPs were much higher in cancer microenvironments compared to that in the normal tissue. As a result, the PHPD-NPs showed a significant antitumor activity in in vivo mice tumor model. The nanoparticle photomedicine design is a novel strategy for effective tumor therapy.

The transfection efficiency of photosensitizer-induced gene delivery to human MSCs and internalization rates of EGFP and Runx2 genes.

To improve the transfection efficiency of non-viral gene vectors to human mesenchymal stem cells (hMSCs), a photosensitizer (PS)-induced gene delivery system was designed by using pheophorbide-a (pheo-a) as a PS. In FACS results, this system showed excellent gene transfection efficiency depending on irradiation power. The result was strongly supported by western blot and real-time quantitative PCR (RT-qPCR) assays. The protein and mRNA expression of enhanced green fluorescent protein (EGFP) in hMSCs treated with 0.9 J/cm(2) irradiation increased 9.8- and 8.7-fold compared with non-irradiated hMSCs, respectively. Furthermore, the internalization of PEI/pDNA complexes in hMSCs was enhanced by light irradiation even under conditions that inhibited endocytosis. The hemolytic activity of PS with irradiation (0.9 J/cm(2)) significantly increased to 55%. Thus, PS with light irradiation facilitated both the internalization and endosomal escape of gene complexes. For osteogenic induction, the Runt-related transcription factor 2 (Runx2) gene was transferred to hMSCs via PS-induced transfection. Von Kossa staining indicated that Runx2 overexpression significantly enhanced the osteogenesis of hMSCs. Therefore, this PS-induced gene delivery method has potential value for stem cell therapy via gene delivery.

Photo-mediated internalization of nanocomplex for effective gene delivery to adipose tissue-derived stem cells

To deliver efficiently osteogenic, chondrogenic or adipogenic induction genes, such as Runx2, SOX9 and C/EBP-α, to adipose tissue-derived stem cells (ADSCs), a photo-mediated nanocomplex internalization gene delivery system was designed using chlorin e6 as a photosensitizer (PS) and polyethyleneimine (PEI) as a gene delivery carrier. In this system, gene delivery efficacy was significantly increased in ADSCs by photo irradiation. The gene transfection efficiency of Runx2, SOX9 and C/EBP-α was increased by 8.6-, 6.7- and 9.3-fold, respectively, by applying 0.7J/cm(2) of irradiation. Osteogenic, chondrogenic and adipogenic differentiation was confirmed by differentiation-related markers and histological analysis. ADSCs transfected with Runx2, SOX9 and C/EBP-α genes via photo irradiation indicated enhanced differentiation in comparison to the non-irradiated cells. These findings demonstrate that photo-mediated internalization is a promising system for efficient gene delivery and differentiation in ADSCs.

Acidic Tumor pH-Responsive Nanophotomedicine for Targeted Photodynamic Cancer Therapy

An acidic tumor pH-responsive nanophotomedicine pH-NanoPM for targeted photodynamic therapy PDT was demonstrated herein. The pH-NanoPM was prepared with a size of ~110 nm by self-assembly of a pH-responsive polymeric photosensitizer pH-PPS consisting of pH-cleavable methoxypolyethylene glycol pH-C-mPEG. Because the pH-C-mPEG can be detached from the nanoparticles by hydrolysis of the benzoic-imine group at the pH of an acidic tumor ~6.5, the particle size and surface charge of the pH-NanoPM were changed along with the environmental pH condition. After detachment of the pH-C-mPEG, the pH-NanoPM particles became positively charged +18.67±1.95 mV due to exposure of primary amine groups and decreased to a size of ~40 nm. From in vitro cellular experiments with HeLa human cervical cancer cells, the pH-NanoPM exhibited enhanced cellular internalization at acidic tumor pH compared to normal pH, which led to a significant cancer cell killing effect. These results suggest that this system has the potential to be used as a new class of nanophotomedicine for targeted photodynamic cancer therapy.