Stimuli-responsive nanocarriers for intracellular delivery

The emergence of different nanoparticles (NPs) has made a significant revolution in the field of medicine. Different NPs in the form of metallic NPs, dendrimers, polymeric NPs, carbon quantum dots and liposomes have been functionalized and used as platforms for intracellular delivery of biomolecules, drugs, imaging agents and nucleic acids. These NPs are designed to improve the pharmacokinetic properties of the drug, improve their bioavailability and successfully surpass physiological or pathological obstacles in the biological system so that therapeutic efficacy is achieved. In this review I present some of the current approaches used in intracellular delivery systems, with a focus on various stimuli-responsive nanocarriers, including cell-penetrating peptides, to highlight their various biomedical applications.     

Tumor extracellular acidity-activated nanoparticles as drug delivery systems for enhanced cancer therapy

pH-responsive nanoparticles (NPs) are currently under intense development as drug delivery systems for cancer therapy. Among various pH-responsiveness, NPs that are designed to target slightly acidic extracellular pH environment (pH_e) of solid tumors provide a new paradigm of tumor targeted drug delivery. Compared to conventional specific surface targeting approaches, the pH_e-targeting strategy is considered to be more general due to the common occurrence of acidic microenvironment in solid tumors. This review mainly focuses on the design and applications of pH_e-activated NPs, with special emphasis on pH_e-activated surface charge reversal NPs, for drug and siRNA delivery to tumors. The novel development of NPs described here offers great potential for achieving better therapeutic effects in cancer treatment.     

Nanoparticulate drug delivery systems for cancer chemotherapy

Nanoparticles (NPs) are, in general, colloidal particles, less than 1000 nm, that can be used for better drug delivery and prepared either by encapsulating the drug within a vesicle and or by dispersing the drug molecules within a matrix. Nanoparticulate drug delivery systems have been extensively studied in recent years for spatial and temporal delivery, especially in tumour and brain targeting. NPs have great promise for better drug delivery as found in both pharmaceutical and clinical research. As a drug carrier, NPs have significant advantages like better bioavailability, systemic stability, high drug loading, long blood circulation time and selective distribution in the organs/tissues with longer half life. The selective targeting of NPs can be achieved by the enhanced permeability and retention effect (EPR-effect), attaching specific ligands, or by making selective distribution due to change of the physiological conditions of specific systems like nature, pH, temperature, etc. It has been observed that drug-loaded NPs can have selective distribution to organs/tissues using different types of and proportions of polymers. The current aim of researchers is to prepare NPs that are long-lived with and that demonstrate the appropriate selective distribution for better therapy and thus improved clinical outcomes. Nanoparticulate drug delivery systems have the potential to deliver a drug to the target site with specificity and to maintain the desired concentration at the site for the intended time without untoward effects. In this review article, the methods for the preparation of NPs, their characterization, biodistribution, and pharmacokinetic characteristics are discussed.     

Nanoparticulate drug delivery systems for cancer chemotherapy

Abstract

Nanoparticles (NPs) are, in general, colloidal particles, less than 1000 nm, that can be used for better drug delivery and prepared either by encapsulating the drug within a vesicle and or by dispersing the drug molecules within a matrix. Nanoparticulate drug delivery systems have been extensively studied in recent years for spatial and temporal delivery, especially in tumour and brain targeting. NPs have great promise for better drug delivery as found in both pharmaceutical and clinical research. As a drug carrier, NPs have significant advantages like better bioavailability, systemic stability, high drug loading, long blood circulation time and selective distribution in the organs/tissues with longer half life. The selective targeting of NPs can be achieved by the enhanced permeability and retention effect (EPR-effect), attaching specific ligands, or by making selective distribution due to change of the physiological conditions of specific systems like nature, pH, temperature, etc. It has been observed that drug-loaded NPs can have selective distribution to organs/tissues using different types of and proportions of polymers. The current aim of researchers is to prepare NPs that are long-lived with and that demonstrate the appropriate selective distribution for better therapy and thus improved clinical outcomes. Nanoparticulate drug delivery systems have the potential to deliver a drug to the target site with specificity and to maintain the desired concentration at the site for the intended time without untoward effects. In this review article, the methods for the preparation of NPs, their characterization, biodistribution, and pharmacokinetic characteristics are discussed.     

Synthesis,Characterization and In Vitro Study of Biocompatible Cinnamaldehyde Functionalized Magnetite Nanoparticles (CPGF Nps) For Hyperthermia and Drug Delivery Applications in Breast Cancer

Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anti-cancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe₃O₄ nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of ∼20 nm. TGA data revealed the drug payload of ∼18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PR positive/Her2 negative (MCF7) and ER/PR negative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6°C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.     

Cancer theranostics: the rise of targeted magnetic nanoparticles

Interest in utilizing magnetic nanoparticles (MNP) for biomedical applications has increased considerably over the past two decades. This excitement has been driven in large part by the success of MNPs as contrast agents in magnetic resonance imaging. The recent investigative trend with respect to cancer has continued down a diagnostic path, but has also turned toward concurrent therapy, giving rise to the distinction of MNPs as potential "theranostics". Here we review both the key technical principles of MNPs and ongoing advancement toward a cancer theranostic MNP. Recent progress in diagnostics, hyperthermia treatments, and drug delivery are all considered. We conclude by identifying current barriers to clinical translation of MNPs and offer considerations for their future development.     

Promising approaches in using magnetic nanoparticles in oncology

The development of new and effective drug delivery systems for cancer treatment represents one of the significant challenges facing biomedical technology in the last decade. Among the different methods of drug delivery, magnetic drug targeting, by enabling specific delivery of chemotherapeutic agents through the use of magnetic nanoparticles and magnetic field gradient, could be a promising approach. Recently, magnetic nanoparticles have attracted additional attention because of their potential as contrast agents for magnetic resonance imaging and heat mediators for cancer therapy. This review summarizes these approaches in the use of magnetic nanoparticles in biomedical applications and novel methods for their optimization.     

A health concern regarding the protein corona,aggregation and disaggregation

Nanoparticle (NP)–protein complexes exhibit the “correct identity” of NP in biological media. Therefore, protein–NP interactions should be closely explored to understand and modulate the nature of NPs in medical implementations. This review focuses mainly on the physicochemical parameters such as dimension, surface chemistry, morphology of NPs, and influence of pH on the formation of protein corona and conformational changes of adsorbed proteins by different kinds of techniques. Also, the impact of protein corona on the colloidal stability of NPs is discussed. Uncontrolled protein attachment on NPs may bring unwanted impacts such as protein denaturation and aggregation. In contrast, controlled protein adsorption by optimal concentration, size, pH, and surface modification of NPs may result in potential implementation of NPs as therapeutic agents especially for disaggregation of amyloid fibrils. Also, the effect of NPs-protein corona on reducing the cytotoxicity and clinical implications such as drug delivery, cancer therapy, imaging and diagnosis will be discussed. Validated correlative physicochemical parameters for NP–protein corona formation frequently derived from protein corona fingerprints of NPs which are more valid than the parameters obtained only on the base of NP features. This review may provide useful information regarding the potency as well as the adverse effects of NPs to predict their behavior in vivo.     

AS1411 aptamer tagged PLGA-lecithin-PEG nanoparticles for tumor cell targeting and drug delivery

Liposomes and polymers are widely used drug carriers for controlled release since they offer many advantages like increased treatment effectiveness, reduced toxicity and are of biodegradable nature. In this work, anticancer drug‐loaded PLGA‐lecithin‐PEG nanoparticles (NPs) were synthesized and were functionalized with AS1411 anti‐nucleolin aptamers for site‐specific targeting against tumor cells which over expresses nucleolin receptors. The particles were characterized by transmission electron microscope (TEM) and X‐ray photoelectron spectroscopy (XPS). The drug‐loading efficiency, encapsulation efficiency and in vitro drug release studies were conducted using UV spectroscopy. Cytotoxicity studies were carried out in two different cancer cell lines, MCF‐7 and GI‐1 cells and two different normal cells, L929 cells and HMEC cells. Confocal microscopy and flowcytometry confirmed the cellular uptake of particles and targeted drug delivery. The morphology analysis of the NPs proved that the particles were smooth and spherical in shape with a size ranging from 60 to 110 nm. Drug‐loading studies indicated that under the same drug loading, the aptamer‐targeted NPs show enhanced cancer killing effect compared to the corresponding non‐targeted NPs. In addition, the PLGA‐lecithin‐PEG NPs exhibited high encapsulation efficiency and superior sustained drug release than the drug loaded in plain PLGA NPs. The results confirmed that AS1411 aptamer‐PLGA‐lecithin‐PEG NPs are potential carrier candidates for differential targeted drug delivery. Biotechnol. Bioeng. 2012; 109: 2920–2931. © 2012 Wiley Periodicals, Inc.     

Gefitinib loaded PLGA and chitosan coated PLGA nanoparticles with magnified cytotoxicity against A549 lung cancer cell lines

In the current study, gefitinib loaded PLGA nanoparticles (GFT-PLGA-NPs) and chitosan coated PLGA nanoparticles (GFT-CS-PLGA-NPs) were synthesized to investigate the role of surface charge of NPs for developing drug delivery system for non-small-cell lung cancer (NSCLC). The developed NPs were evaluated for their size, PDI, zeta potential (ZP), drug entrapment, drug loading, DSC, FTIR, XRD, in vitro release profile, and morphology. The anti-cancer activity of GFT loaded PLGA NPs and GFT loaded CS-PLGA-NPs were examined in human A549 lung cancer cell lines. In vitro release studies of GFT-CS-PLGA-NPs showed more sustained release in comparison to GFT-PLGA-NPs due surface charge attraction of chitosan. In addition, viability of A549 cells decreases significantly with the increasing concentration of GFT-PLGA NPs and GFT-CS-PLGA-NPs when compared to that of pure GFT and blank PLGA NPs. In addition, the microscopic analysis and counting of viable cells also validate the cytotoxicity of the developed NPs. This investigation proved that the developed NPs would be efficient carriers to deliver GFT with improved efficacy against NSCLC.     

Nanoparticle-mediated targeted drug delivery for breast cancer treatment

Breast cancer (BC) is the most common malignancy in women worldwide, and one of the deadliest after lung cancer. Currently, standard methods for cancer therapy including BC are surgery followed by chemotherapy or radiotherapy. However, both chemotherapy and radiotherapy often fail to treat BC due to the side effects that these therapies incur in normal tissues and organs. In recent years, various nanoparticles (NPs) have been discovered and synthesized to be able to selectively target tumor cells without causing any harm to the healthy cells or organs. Therefore, NPs-mediated targeted drug delivery systems (DDS) have become a promising technique to treat BC. In addition to their selectivity to target tumor cells and reduce side effects, NPs have other unique properties which make them desirable for cancer treatment such as low toxicity, good compatibility, ease of preparation, high photoluminescence (PL) for bioimaging in vivo, and high loadability of drugs due to their tunable surface functionalities. In this study, we summarize with a critical analysis of the most recent therapeutic studies involving various NPs-mediated DDS as alternatives for the traditional treatment approaches for BC. It will shed light on the significance of NPs-mediated DDS and serve as a guide to seeking for the ideal methodology for future targeted drug delivery for an efficient BC treatment.     

Antibody conjugates and therapeutic strategies

Immunotherapeutics represent the largest group of molecules currently in development as new drug entities. These versatile molecules are being investigated for the treatment of a range of pathological conditions including cancer, infectious and inflammatory diseases. Antibodies can be used to exert biological effects themselves or as delivery agents of conjugated drug molecules. Site-specific delivery of therapeutic agents has been an ultimate goal of the pharmaceutical industry in order to maximize drug action and minimize side effects. Antibodies have the potential to realize this objective and in this review we will examine some of the main strategies currently being employed for the development of these diverse therapeutic molecules.     

Effect of the surface charge density of nanoparticles on their translocation across pulmonary surfactant monolayer: a molecular dynamics simulation

Interaction between nanoparticles (NPs) and pulmonary surfactant monolayer plays a very significant role in nanoparticle-based pulmonary drug delivery system. Previous researches have indicated that different properties of nanoparticles can affect their translocation across pulmonary surfactant monolayer. Here we performed coarse-grained molecular dynamics simulation aimed at nanoparticles’ surface charge density effect on their penetration behaviours. Several hydrophilic nanoparticles with different surface charge densities were modelled in the simulations. The results show that NPs’ surface charge density affects their translocation capability: the higher the surface charge densities of NPs are, the worse their translocation capability is. It will cause the structural changes of pulmonary surfactant monolayer, and inhibit the normal phase transition of the monolayer during the compression process. Besides, charged NPs can be adsorbed on the surface of the monolayer after translocation as a stable state, and the adsorption capability of NPs increases generally with the increase of surface charge densities. Our simulation results suggest that the study of nanoparticle-based pulmonary drug delivery system should consider the nanoparticles’ surface charge density effect in order to avoid biological toxicity and improve efficacy.     

Use of herbal medicines and natural products: An alternative approach to overcoming the apoptotic resistance of pancreatic cancer

Pancreatic cancer has a poor prognosis with a 5-year survival rate of <5%. It does not respond well to either chemotherapy or radiotherapy, due partly to apoptotic resistance (AR) of the cancer cells. AR has been attributed to certain genetic abnormalities or defects in apoptotic signaling pathways. In pancreatic cancer, significant mutations of K-ras and p53, constitutive activation of NFκB, over-expression of heat shock proteins (Hsp90, Hsp70), histone deacetylase (HDACs) and the activities of other proteins (COX-2, Nrf2 and bcl-2 family members) are closely linked with resistance to apoptosis and invasion. AR has also been associated with aberrant signaling of MAPK, PI3K–AKT, JAK/STAT, SHH, Notch, and Wnt/β-catenin pathways. Strategies targeting these signaling molecules and pathways provide an alternative for overcoming AR in pancreatic cancer. The use of herbal medicines or natural products (HM/NPs) alone or in combination with conventional anti-cancer agents has been shown to produce beneficial effects through actions upon multiple molecular pathways involved in AR. The current standard first-line chemotherapeutic agents for pancreatic cancer are gemcitabine (Gem) or Gem-containing combinations; however, the efficacy is dissatisfied and this limitation is largely attributed to AR. Meanwhile, emerging data have pointed to a combination of HM/NPs that may augment the sensitivity of pancreatic cancer cells to Gem. Greater understanding of how these compounds affect the molecular mechanisms of apoptosis may propel development of HM/NPs as anti-cancer agents and/or adjuvant therapies forward.In this review, we give a critical appraisal of the use of HM/NPs alone and in combination with anti-cancer drugs. We also discuss the potential regulatory mechanisms whereby AR is involved in these protective pathways.     

Raloxifene-encapsulated hyaluronic acid-decorated chitosan nanoparticles selectively induce apoptosis in lung cancer cells

Non-small cell lung cancer (NSCLC) and hepatocellular carcinoma (HCC) are leading causes of cancer mortality and morbidity around the world. Despite the recent advances in their diagnosis and therapy, their prognosis remains poor owing to the development of drug resistance and metastasis. Raloxifene (RX), a drug first used in the treatment of osteoporosis, was recently approved for NSCLC and HCC prevention. Unfortunately, many of the therapies that use RX are likely to become ineffective due to drug resistance. Herein, we developed a novel delivery strategy by utilizing hyaluronic acid (HA) and chitosan (CS) complexation to increase the half-life and activity of RX. Consequently, we explored the pro-apoptotic and cytotoxic effects of RX-HA-CS nanoparticles (NPs) against NSCLC (A549) and HCC (HepG2 and Huh-7) cell lines. The highest entrapment efficiency (EE%) was noted in RX-HA-CS NPs (92%) compared to RX-HA NPs (87.5%) and RX-CS NPs (68%). In addition, RX-HA-CS NPs induced the highest cytotoxicity against A549 cells compared to other platforms. The significant suppression of A549 cell viability was achieved via glucose uptake reduction resulting in diminished bioenergetics of cancer cells and activation of apoptosis via nitric oxide level elevation. This study is the first to assess the efficacy of RX in its HA-CS nano-formulation against lung and liver cancer cells and demonstrated its selective cytotoxic and apoptotic potential against human lung A549 cancer cell line. These findings demonstrate a promising drug delivery system to help mitigate drug resistance in lung cancer.     

Sulfonates-PMMA nanoparticles conjugates: A versatile system for multimodal application

We report herein the viability of a novel nanoparticles (NPs) conjugated system, namely the attachment, based on ionic and hydrophobic interactions, of different sulfonated organic salts to positively charged poly(methylmethacrylate) (PMMA)-based core-shell nanoparticles (EA0) having an high density of ammonium groups on their shells. In this context three different applications of the sulfonates@EA0 systems have been described. In detail, their ability as cytotoxic drugs and pro-drugs carriers was evaluated in vitro on NCI-H460 cell line and in vivo against human ovarian carcinoma IGROV-1 cells. Besides, 8-hydroxypyrene-1,3,6-trisulfonic acid, trisodium salt (HPTS) was chosen for NPs loading, and its internalization as bioimaging probe was evaluated on Hep G2 cells. Overall, the available data support the interest for these PMMA NPs@sulfonates systems as a promising formulation for theranostic applications. In vivo biological data strongly support the potential value of these core-shell NPs as delivery system for negatively charged drugs or biologically active molecules. Additionally, we have demonstrated the ability of these PMMA core-shell nanoparticles to act as efficient carriers of fluorophores. In principle, thanks to the high PMMA NPs external charge density, sequential and very easy post-loading of different sulfonates is achievable, thus allowing the preparation of nanocarriers either with bi-modal drug delivery behaviour or as theranostic systems.     

Plant protein-based hydrophobic fine and ultrafine carrier particles in drug delivery systems

For thousands of years, plants and their products have been used as the mainstay of medicinal therapy. In recent years, besides attempts to isolate the active ingredients of medicinal plants, other new applications of plant products, such as their use to prepare drug delivery vehicles, have been discovered. Nanobiotechnology is a branch of pharmacology that can provide new approaches for drug delivery by the preparation of biocompatible carrier nanoparticles (NPs). In this article, we review recent studies with four important plant proteins that have been used as carriers for targeted delivery of drugs and genes. Zein is a water-insoluble protein from maize; Gliadin is a 70% alcohol-soluble protein from wheat and corn; legumin is a casein-like protein from leguminous seeds such as peas; lectins are glycoproteins naturally occurring in many plants that recognize specific carbohydrate residues. NPs formed from these proteins show good biocompatibility, possess the ability to enhance solubility, and provide sustained release of drugs and reduce their toxicity and side effects. The effects of preparation methods on the size and loading capacity of these NPs are also described in this review.     

Cellular Uptake and Antitumor Activity of DOX-hyd-PEG-FA Nanoparticles

A PEG-based, folate mediated, active tumor targeting drug delivery system using DOX-hyd-PEG-FA nanoparticles (NPs) were prepared. DOX-hyd-PEG-FA NPs showed a significantly faster DOX release in pH 5.0 medium than in pH 7.4 medium. Compared with DOX-hyd-PEG NPs, DOX-hyd-PEG-FA NPs increased the intracellular accumulation of DOX and showed a DOX translocation from lysosomes to nucleus. The cytotoxicity of DOX-hyd-PEG-FA NPs on KB cells was much higher than that of free DOX, DOX-ami-PEG-FA NPs and DOX-hyd-PEG NPs. The cytotoxicity of DOX-hyd-PEG-FA NPs on KB cells was attenuated in the presence of exogenous folic acid. The IC₅₀ of DOX-hyd-PEG-FA NPs and DOX-hyd-PEG NPs on A549 cells showed no significant difference. After DOX-hyd-PEG-FA NPs were intravenously administered, the amount of DOX distributed in tumor tissue was significantly increased, while the amount of DOX distributed in heart was greatly decreased as compared with free DOX. Compared with free DOX, NPs yielded improved survival rate, prolonged life span, delayed tumor growth and reduced the cardiotoxicity in tumor bearing mice model. These results indicated that the acid sensitivity, passive and active tumor targeting abilities were likely to act synergistically to enhance the drug delivery efficiency of DOX-hyd-PEG-FA NPs. Therefore, DOX-hyd-PEG-FA NPs are a promising drug delivery system for targeted cancer therapy.     

Innovative nano-carriers in anticancer drug delivery-a comprehensive review

In the scientific field, nanotechnology has offered multipurpose and designated functional nanoparticles (NPs) for the development of applications in nano-medicine. This present review focuses on cutting edge of nanotechnology in biomedical applications as drug carries in cancer treatment. The nanotechnology overcomes several limitations of drug delivery systems used in distinct therapeutic approaches of cancer treatment. The serious effect of conventional chemotherapeutics by nonspecific targeting, the lack of solubility, and the inability of chemotherapeutics entry to cancer cells which, offers a great opportunity for nanotechnology to play significant roles in cancer biology. The selective delivery of nano-drugs to the targeted cancer cells by the programmed way and avoiding nonspecific interactions to the healthy cells. The present review focuses on the methods of improving the size, shape and characteristics of nanomaterials which can be exploited for cancer therapy. The successful designing of nanocarriers can be tailored for cancer treatment for upcoming future as nano-medicines.     

Effects of transport inhibitors on the cellular uptake of carboxylated polystyrene nanoparticles in different cell lines

Nanotechnology is expected to play a vital role in the rapidly developing field of nanomedicine, creating innovative solutions and therapies for currently untreatable diseases, and providing new tools for various biomedical applications, such as drug delivery and gene therapy. In order to optimize the efficacy of nanoparticle (NP) delivery to cells, it is necessary to understand the mechanisms by which NPs are internalized by cells, as this will likely determine their ultimate sub-cellular fate and localisation. Here we have used pharmacological inhibitors of some of the major endocytic pathways to investigate nanoparticle uptake mechanisms in a range of representative human cell lines, including HeLa (cervical cancer), A549 (lung carcinoma) and 1321N1 (brain astrocytoma). Chlorpromazine and genistein were used to inhibit clathrin and caveolin mediated endocytosis, respectively. Cytochalasin A and nocodazole were used to inhibit, respectively, the polymerisation of actin and microtubule cytoskeleton. Uptake experiments were performed systematically across the different cell lines, using carboxylated polystyrene NPs of 40 nm and 200 nm diameters, as model NPs of sizes comparable to typical endocytic cargoes. The results clearly indicated that, in all cases and cell types, NPs entered cells via active energy dependent processes. NP uptake in HeLa and 1321N1 cells was strongly affected by actin depolymerisation, while A549 cells showed a stronger inhibition of NP uptake (in comparison to the other cell types) after microtubule disruption and treatment with genistein. A strong reduction of NP uptake was observed after chlorpromazine treatment only in the case of 1321N1 cells. These outcomes suggested that the same NP might exploit different uptake mechanisms to enter different cell types.