Copolymer technology for advanced nanomedicine

Nanotechnology for multimodality treatment of cancer

Nanotechnology is the latest evolving field and its applications in medicine in recent decades has shown great potential. It has also given a new face to the therapeutics against cancer in recent years. The electronic databases of MEDLINE, EMBASE and PubMed were searched for recent studies, reporting the importance of nanomedicine. The concluding remarks of the above papers mostly confirmed the growing potential of nanomedicine, particularly in the field of cancer. Furthermore, nanomedicine has been observed to promote the therapeutic effect of agents by formulating them into nanocarriers. Delivery of the therapeutic agents via nanodelivery systems is dedicated to solving problems in traditional anticancer agents, including formulation in the physiological environment, their accumulation in tumor, and their adverse side effect in normal organs. The present review focused on the latest updates on nanotechnology in cancer. In conclusion, the future of any therapeutic option lies in the specific delivery of the particular drug. Additionally, this specific delivery may be achieved efficiently by nanodelivery systems and more studies should be conducted in this direction for the establishment of nanodelivery systems as gold standard delivery modules in clinical setting.

Nanomedicine strategies for sustained, controlled and targeted treatment of cancer stem cells

Cancer stem cells (CSCs) are original cancer cells that are of characteristics associated with normal stem cells. CSCs are toughest against various treatments and thus responsible for cancer metastasis and recurrence. Therefore, development of specific and effective treatment of CSCs plays a key role in improving survival and life quality of cancer patients, especially those in the metastatic stage. Nanomedicine strategies, which include prodrugs, micelles, liposomes and nanoparticles of biodegradable polymers, could substantially improve the therapeutic index of conventional therapeutics due to its manner of sustained, controlled and targeted delivery of high transportation efficiency across the cell membrane and low elimination by intracellular autophagy, and thus provide a practical solution to solve the problem encountered in CSCs treatment. This review gives briefly the latest information to summarize the concept, strategies, mechanisms and current status as well as future promises of nanomedicine strategies for treatment of CSCs.

Radiosensitization of TPGS-emulsified docetaxel-loaded poly(lactic-co-glycolic acid) nanoparticles in CNE-1 and A549 cells

Docetaxel is among the most effective radiosensitizers. It is widely used as radiosensitizer in many tumors, including head and neck carcinoma. Nevertheless, poor solubility and severe hypersensitivity limit its clinical use and its therapeutic effect remains to be improved. In this study, docetaxel-loaded polymeric nanoparticles were prepared by nanoprecipitation method to be new radiosensitizer with lower side effects and higher efficacy. The physiochemical characteristics of the nanoparticles were studied. Two human tumor cell lines which are resistant to radiotherapy were used in this research. We have compared the radioenhancement efficacy of docetaxel-loaded nanoparticles with docetaxel in A549 and CNE-1 cells. Compared with docetaxel, radiosensitization of docetaxel-loaded nanoparticles was improved significantly (sensitization enhancement ratio in A549 increased 1.24-fold to 1.68-fold when the radiation was applied 2 h after the drug, p < 0.01, sensitization enhancement ratio in CNE-1 increased 1.32-fold to 1.61-fold, p < 0.05). We explored the mechanisms for the radiosensitization efficiency and the difference between docetaxel and docetaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles. The improved radiosensitization efficacy was associated with enhanced G2/M arrest, promoted apoptosis and the role of D-alpha-tocopheryl polyethylene glycol 1000 succinate which will enhance the cell uptake and inhibit the multiple drug resistance. Moreover, the radiosensitization efficacy of docetaxel-loaded nanoparticles was more prominent than docetaxel. In conclusion, tocopheryl polyethylene glycol 1000 succinate-emulsified docetaxel-loaded PLGA nanoparticles were more efficacious and fewer adverse effects were observed than with the commercial docetaxel formulation. Thus, PLGA nanoparticles hold promise as a radiosensitizing agent.

Multimodality treatment of cancer with herceptin conjugated, thermomagnetic iron oxides and docetaxel loaded nanoparticles of biodegradable polymers

We developed a system of nanoparticles of poly(lactide)-d-α-tocopheryl polyethylene glycol succinate (PLA-TPGS) and carboxyl group-terminated TPGS (TPGS-COOH) copolymer blend for multimodality treatment of cancer, which formulated docetaxel for chemotherapy, herceptin for biotherapy and targeting, and iron oxides (IOs) for hyperthermia therapy, which are denoted as MMNPs. It is demonstrated that the MMNPs achieved a significantly higher therapeutic effects than the various combination of the corresponding individual modality treatment NPs and the dual modality treatment NPs due to the synergistic effects among the chemo, bio, and thermo therapies. We further developed a method by employing the concept of NPs IC50, the concentration of the agent-, or agents-loaded nanoparticles that is needed to kill 50% of the cancer cells, to quantitatively access the synergistic effects of the multimodality treatment. It is shown by employing the SK-BR-3 cell line as an in vitro model of the HER2-positive breast cancer that the NPs IC50 is 0.42 mg/mL DCL-NPs plus 1.33 mg/mL Her-NPs plus 0.59 mg/mL IOs-NPs, a total NPs concentration of 2.34 mg/mL for the treatment of a physical mixture of the DCL-NPs, Her-NPs and IOs-NPs at the 1:2:7 weight ratio, while it is only 0.0011 mg/mL for the MMNPs for 24 h, which is 2130 fold more efficient than the physical mixture of the corresponding single modality treatments.

Quantitative control of targeting effect of anticancer drugs formulated by ligand-conjugated nanoparticles of biodegradable copolymer blend

There have been two strategies developed in the recent literature for quantitative control of the targeting effects for drug delivery by ligand-conjugated nanoparticles of biodegradable copolymer blend such as PLGA/PLGA-PEG, i.e. the pre-conjugation strategy and the post-conjugation strategy, in which the ligand conjugation was made before and after the nanoparticle formulation respectively. This research developed another drug delivery system of the PLA-TPGS/TPGS-COOH copolymer blend and further improved the post-conjugation strategy to precisely control the targeting effects by two ways: one is to adjust the PLA-TPGS:TPGS-COOH copolymer blend ratio in the nanoparticle formulation process, which provides a way for coarse control, and another is to control the feeding concentration of the ligand in the herceptin conjugation process, which further provides a fine control. Herceptin conjugation was visualized by the FETEM with immumogold labeling and further quantified by the two techniques, i.e. the Bradford assay and the flow cytometry to confirm each other. The positive correlation between the surface density of the ligand and the cellular internalization as well as the cytotoxicity of the nanoparticle formulations was assessed, which demonstrated that the strategy developed in this research is simple and feasible, which can precisely control the targeting effects of the nanoparticles of biodegradable polymers as well as other nanocarriers such as micelles and liposomes.