Current Pharmaceutical Design - Volume 23, Issue 35, 2017

Background: Micellization provides numerous merits for the delivery of water insoluble anti-cancer therapeutic agents including a nanosized ‘core–shell’ drug delivery system. Recently, hydrophobically-modified polysaccharides and proteins are attracting much attention as micelle forming polymers to entrap poorly soluble anti-cancer drugs. Method: By virtue of their small size, the self-assembled micelles can passively target tumor tissues via enhanced permeation and retention effect (EPR). Moreover, the amphiphilic micelles can be exploited for active-targeted drug delivery by attaching specific targeting ligands to the outer micellar hydrophilic surface. Results: Here, we review the conjugation techniques, drug loading methods, physicochemical characteristics of the most important amphiphilic polysaccharides and proteins used as anti-cancer drug delivery systems. Attention focuses on the mechanisms of tumor-targeting and enhanced anti-tumor efficacy of the encapsulated drugs. This review will highlight the remarkable advances of hydrophobized polysaccharide and protein micelles and their potential applications as anti-cancer drug delivery nanosystems. Conclusion: Micellar nanocarriers fabricated from amphiphilic natural polymers hold great promise as vehicles for anti-cancer drugs.

Micelles are nanoparticles formed by the self-assembly of amphiphilic block copolymers in certain solvents above concentrations called critical micelle concentration (CMC). Micelles are used in different fields like food, cosmetics, medicine, etc. These nanosized delivery systems are under spotlight in the recent years with new achievements in terms of their in vivo stability, ability to protect entrapped drug, release kinetics, ease of cellular penetration and thereby increased therapeutic efficacy. Drug loaded micelles can be prepared by dialysis, oil-in-water method, solid dispersion, freezing, spray drying, etc. The aim of this review is to give an overview of the research on micelles (in vitro, in vivo and clinical) as delivery system for cancer treatment. Passive targeting is one route for accumulation of nanosized micellar drug formulations. Many research groups from both academia and industry focus on developing new strategies for improving the therapeutic efficacy of micellar systems (active targeting to the tumor site, designing multidrug delivery systems for overcoming multidrug resistance or micelles formed by prodrug conjugates, etc). There is only one micellar drug formulation in South Korea that has reached clinical practice. However, there are many untargeted anticancer drug loaded micellar formulations in clinical trials, which have potential for use in clinics. Many more products are expected to be on the market in the near future.

Polymer micellar nanogels are a group of core-shell polymeric micelles with swelling properties in aqueous media. Nanogel systems have proven their potential in controlled, sustained and targetable drug delivery area with no immunological responses. This review includes a comprehensive wide range of self-assembly of polymeric nanogels as delivery systems for anticancer drugs. Nanogels are nanoparticulate drug delivery systems which are specially designed for enhanced target oriented and cellular uptake of drugs with emphasis on chemotherapeutic agents studied in this review. Self-assembling nanogels are based on natural substances or synthetic polymers including: hyaluronic acid, heparin, alginate, cyclodextrins, chondroeitin sulfate, starch, mannan, chitosan, pullulan, poly(N-isopropylacrylamide), polyvynil alcohol, Pluronic F127, polyacrylic acid, poly(hydroxylethyl methacrylate), poly[2- (dimethylamino)ethyl methacrylate and polylactide-co-glycolide-polyethylen glycol amphiphilic di or tri block copolymer used to deliver anticancer drugs are introduced and discussed.

Protein nanocarriers possess unique merits including minimal cytotoxicity, numerous renewable sources, and high drug-binding capability. In opposition to delivery carriers utilizing hydrophilic animal proteins, hydrophobic plant proteins (e.g, zein) have great tendency in fabricating controlled-release particulate carriers without additional chemical modification to stiffen them, which in turn evades the use of toxic chemical crosslinkers. Moreover, zein is related to a class of alcohol-soluble prolamins and generally recognized as safe (GRAS) carrier for drug delivery. Various techniques have been adopted to fabricate zein-based nanoparticulate systems including phase separation coacervation, spray-drying, supercritical anti-solvent approach, electrospinning and self-assembly. This manuscript reviews the recent advances in the zein-based colloidal nano-carrier systems such as nanospheres, nanocapsules, micelles and nanofibers with a special focus on their physicochemical characteristics and drug delivery applications.

Albumin polymeric Nanoparticles (NPs) have opened a great expectancy as for controlled drug delivery due to their therapeutic potency. Concomitantly biodegradable NPs technologies with target linked structures to pave the way of personalised medicine are becoming increasingly important in sight of a therapeutically effective research technology. This is particularly attractive for nanoparticle-based cancer delivery systems, based on the known limitations and efforts to overcome. This new group of gamma irradiated-NPs inherited both the protein delivery properties and robustness of polymer forming structures, and gamma irradiation techniques that leave clean, innocuous and biodegradable NPs. These protein NPs made of serum albumin are referred to SA NPs that possesses several characteristics making them especially attractive to be considered as a drug delivery system. This review focused on methodologies actually being used in the synthesis and characterisation of albumin NPs and different author's opinions on strategic ways to treat cancerous cell-lines with NPs. Utterly, challenges being overthrown by researchers are brought up to anneal an effective, all in one targeted albumin NPs to passed through in vitro and preclinical trials.

Significant research efforts have been concerned over the past few years to design carrier systems that could specifically deliver active agents to the tumor sites, with the purposes of maximizing the therapeutic benefits and minimizing the toxic side-effects. Hyaluronic acid is a type of polysaccharide that has been extensively studied as a selective targeting ligand to cancerous cells that overexpress its specific receptor CD44. The aim of this review is to highlight the role of HA in cancer, focusing on the recent advances of HA-functionalized lipid nanoparticles towards cancer therapy and imaging.

Cellulose is an important environmentally-friendly renewable polymer on the earth. Cellulose has been widely used as feedstocks for the synthesis of biomaterials, biofuels and biochemicals. Recently, cellulose and cellulose derivatives have received intense attention in biomedical applications, such as tissue engineering, scaffold, artificial blood vessel, skin grafts, artificial skin, drug carrier, and chronic skin diseases, many of which are somehow related to cancer therapy. In this mini-review, we focus on the up-to-date development of cellulosebased nanocarriers used for cancer therapy. Various cellulose-based nanocarriers such as bacterial cellulose (BC), cellulose acetate, microcrystalline cellulose, carboxymethyl cellulose, cellulose nanocrystals, cellulose nanofibrills, etc, are reviewed in terms of being used in drug delivery systems for cancer treatment. Different strategies for the synthesis of cellulose-based nanocarriers are summarized. Special attention is paid on the structure and properties of cellulose-based drug carriers for cancer therapy via some representative examples. Finally, the problems and future developments of these promising polymeric nanocarriers are raised and proposed.

Melanoma shows a high possibility of mortality after it metastasizes because of its aggressive nature. Although there are several options for anti-melanoma therapy, this skin malignancy is resistant to some therapies. Chemotherapy, biochemotherapy, immunotherapy, and adoptive cell therapy have failed to exhibit a significant amelioration in overall survival. Nanomedicine provides an opportunity to improve the efficiency of the antimelanoma regimen. Nanoparticles for treating melanoma provide the advantages over conventional therapies such as drug solubility increment, drug stability enhancement, epithelium permeability and bioavailability amelioration, half-life prolonging, tumor targeting, and side effect minimization. Polymeric nanocarriers are the most extensively studied platforms for the treatment of a variety of cancers. The polymers' sophisticated material engineering tailors the controllable physicochemical properties of the nanoparticles for melanoma penetration via passive and active delivery. The present study highlights the recent progress on the development of polymeric nanoparticles for melanoma treatment. We describe the concepts and improvement mechanisms of the nanomedical techniques for melanoma treatment. Passive targeting by modifying the structure and physicochemical characters of polymeric nanocarriers is a strategy for efficient drug delivery to the melanoma and its metastasis. On the other hand, active targeting such as peptide or antibody conjugation is another approach delivering the drugs or genes to the nidus site by the nanocarriers. This review offers an overview of the benefits of polymeric nanosystems for treating melanoma.

Background: Delivery of chemotherapeutic drugs for the diagnosis and treatment of cancer is becoming advanced day by day. However, the challenge of the effective delivery system still does exist. In various types of cancers, breast cancer is the most commonly diagnosed cancer among women. Breast cancer is a combination of different diseases. It cannot be considered as only one entity because there are many specific patient factors, which are involved in the development of this disease. Nanotechnology has opened a new area in the effective treatment of breast cancer due to the several benefits offered by this technology. Methods: Polymeric nanocarriers are among one of the effective delivery systems, which has given promising results in the treatment of breast cancers. Nanocarriers does exert their anticancer effect either through active or passive targeting mode. Results: The use of nanocarriers has been resolute about the adverse effects of chemotherapeutic drugs such as poor solubility and less penetrability in tumor cells. Conclusion: The present review is focused on recent developments regarding polymeric nanocarriers, such as polymeric micelles, polymeric nanoparticles, dendrimers, liposomes, nanoshells, fullerenes, carbon nanotubes (CNT) and quantum dots, etc. for their recent advancements in breast cancer therapy.

In the last decades, gene therapy has become a novel therapeutic strategy for cancer treatment, including immunologic and molecular approaches. Among molecular avenue, the design of efficient and effective gene delivery systems, like cationic liposomes and niosomes, has been widely investigated and proposed as the most promising research area. The advantages of cationic vesicles rely on their natural ability to form complexes with anionic genetic molecules and deliver them into the cells via the endosomal pathway. Obviously, cationic vesicles- mediated gene delivery is affected by numerous factors, in particular composition, that strongly affects vesicle physical-chemistry characteristics and transfection effectiveness. This review will analyse the potential of cationic nanocarriers in cancer gene therapy, focusing on the role of liposomes and niosomes as vesicular devices and giving an exhaustive collection of the most representative investigations.

Non-specific distribution of chemotherapeutic agents in the body where they affect both cancer as well as normal cells resulting in serious side effects is the major reason for the high mortality rate of cancer. Thus, there is a need for developing targeted delivery strategies specially employing nanoplatform-based cancer therapies that provide specific targeting to tumor cells. In this regard, biopolymeric nanoplatforms such as liposomes, protein- and polysaccharide- based nanoparticles have gained more attention due to their biocompatibility, biodegradability and less toxicity. In terms of targeting, monoclonal antibodies (mAbs), folic acid (FA) and transferrin (Tf) can be considered as the moieties to be attached to the nanoplatforms to deliver their payload to its site of action. This review article focuses on the recent progress in the field of targeted drug and gene delivery systems with emphasizes on liposomes, protein (specially human and bovine serum albumin)-based nanoparticles and polysaccharide (specially chitosan and dextran)-based nanoparticles as the biopolymeric nanoplatforms, which are decorated with mAbs, FA and Tf as the targeting ligands.

Targeting drugs or pharmaceutical compounds to tumor site increases cancer treatment efficiency and therapeutic outcome. Nanoparticles are unique delivery systems for site-targeting within an organism. Many novel technologies have been established in drug research and development area. Nanotechnology now offers nanometer size polymeric nanoparticles and these particles direct drugs to their targets, protect drugs against degradation, and release the drug in a controlled manner. Modification of nanoparticle surface by molecules leads to prolonged retention and accumulation in the target area of the organism. Current efforts of designing polymeric nanoparticles include drug activation in the target area, controlled drug release at the site upon stimulation, and increased drug loading capacity of drug polymer conjugates. Recent progress in molecular mechanism elucidation of cancer cell and rising research in nanoparticle designs may provide efficient cancer treatment modality and innovative nanoparticle designs in the near future. Recent years have seen many developments in the field of innovative peptide based drug nanoparticles. Although none of them approved to be used in clinics yet, peptides are promising structures due to their simple and nonantigenic nature. Biodegradable materials are also preferred materials in drug delivery. Polysaccharide-based micelle systems improve hydrophobic drug and protein delivery. Ease of saccharide structure modification improves pharmacokinetic and pharmacodynamic properties of drug molecules as well as their delivery to a specific site in a controlled manner and sustained rate. Small molecules, especially drugs, conjugated to nanoparticles and several nanoparticles of this type are in the clinical trials and at the market. This review provides recent developments of polymeric nanoparticles conjugated with peptides, saccharides, and small molecules in cancer theraphy.

Background: The ‘tumor microenvironment’ comprised of tumor cells, non-malignant stromal tissues, signaling molecules and the extracellular matrix. Tumor microenvironment has unique physical and physiological characteristics including vascular abnormalities, hypoxia, acidic pH, specific enzymes and growth factors upregulation and high reducing potential. It is these endogenous properties of the tumor environment that can be used to trigger the release of cancer therapeutics both locally and as a function of disease state. Biopolymers such as proteins, polypeptides and polysaccharides are actively being designed to be bioresponsive nanocarriers for drug delivery due to their relative biocompatibility, biodegradability and low immunogenicity. Objective: This review focuses on the use of physicochemical attributes of the endogenous tumor microenvironment to provide the impetus for on-demand release of therapeutics from biopolymer-based nanocarriers that are sensitive to pH, enzymes, redox conditions and combinations thereof. Conclusion: The development of multifunctional nanocarriers based upon a rational approach for targeting and delivering therapeutics to tumors is an area of active research. Despite the huge amount of work done in this area, especially using pH as a means of eliciting drug release at tumor sites, there is a dearth of work whereby different stages during tumor development are targeted for treatment. Although nanocarriers that are able to react to multiple components of the tumor microenvironment are starting to become common-place, it seems that the ability to release various factors at specific times crucial to therapy has not been studied to a large extent as a means of regaining tissue homeostasis.

Over the last years, magnetic nanoparticles have received a great attention in cancer therapy and diagnosis. Magnetic drug targeting, is a particularly promising application in this area as the nanoparticles can be directed to the tumor by external magnetic field and concentrated the drug in this tumor tissue. In addition to this magnetic targeting, their inherent magnetic properties provide sensitive contrast enhancement in magnetic resonance imaging (MRI) and can, therefore, be visualized and used for theranostic purposes. Another important pillar of cancer therapy in which magnetic nanoparticles can be successfully employed is the hyperthermia induced either magnetically or by infrared irradiation. In addition, recent works have suggested that magnetic nanoparticles can be used for mechanical stimulation of cells affecting their viability. Most of these applications require modification of the physiochemical and surface properties of the magnetic nanoparticles to control their biodistribution, toxicity and pharmacokinetics. In relation to this, polymer coatings are probably the preference alternative to cover the magnetic nanoparticles for cancer treatment applications. In this review, we attempt to provide an overview of the recent advances in the development and applications of polymeric magnetic nanoparticles in cancer treatment and diagnosis including MRI, drug delivery, magnetic hyperthermia, photothermia and magnetolysis

Ultrasound contrast agents (UCA) represented by gas-filled microbubble, can provide simultaneous and co-localized enhancement on image contrast to help disease diagnosis by highlighting tissue borders. Nowadays, Some UCAs (e.g. Levovist®, Optison®, Definity®, and Sonovue®) are commercially available, and have been clinically utilized for enhanced ultrasonography in the US, Canada, Europe, Asia and so on. However, their large diameters (1~10 μm) mainly hinder more precise and deeper applications in the imaging of capillaryabundant organs or tissues (e.g. tumor), and undersized nanoscale UCAs also lack enough backscattering echo intensity to distinguish abnormal distribution of vessels. So novel shapes, structures and materials of nano-sized UCAs are constantly emerging for cancer ultrasonic imaging. Particularly, the cavitation effect of diagnostic ultrasound can accelerate effusion of loaded contents from UCAs, following cellular uptake. This will inevitably contribute to develop other potential applications of nano-sized UCAs towards cancer therapy and theranostics.

Cancer is becoming a leading cause of death in the last years. Although we have seen great advances, most human cancers remain incurable because many patients either do not respond or relapse to treatment. Several lines of research are disclosing new therapeutic targets which lead to new active drugs. However, there are still unsolved problems related to stabilization of the pharmaceutical ingredient in aqueous and biological media, pharmacokinetic and pharmacodynamic profiles and cellular uptake to name just a few. In this context, nanotechnology with the emerging tools of nanoengineering offers many possibilities to guide the design of new products with improved safety and efficacy. The presence of several reacting groups and the sensitivity of their properties to small changes in composition make nanocarriers tunable not only to modify their stability in a particular environment but also to respond to changes in biological situations in the right place and time frame. This review summarizes the main preparation methods and formulation strategies of nano and microcarriers designed for drug delivery applications for cancer treatment and will attempt to give a glimpse on how their structure, shape, physico-chemical properties and chemical composition may affect their overall stability and interactions with biological systems. We will also cover aspects of nanoengineering that are opening new opportunities for the development of more effective nanomedicines, emphasizing on the challenges that have to be kept in mind when dealing with biological activities of nanocarriers that depend not only on their chemical composition but also on those of the structures formed by them and by their interactions with biological systems. From this, a very important issue that emerges is that nanocarriers frequently display an intrinsic bioactivity (i.e.: immunomodulatory). Therefore, it should be stressed that nanocarriers cannot be considered as inert, biocompatible excipients. Furthermore, their biological activity will mostly depend on the physical and chemical properties of the structures of the nanoparticles that are presented to living systems. As an approach to the rational design of new pharmaceutical products, nanoengineering is providing new tools for the precise control of the properties of nanocarriers for cancer treatment.