The journey of a drug-carrier in the body: an anatomo-physiological perspective

Self-assembled polymeric vectors mixtures: characterization of the polymorphism and existence of synergistic effects in photodynamic therapy

The objective of this work was to assess the relation between the purity of polymeric self-assemblies vectors solution and their photodynamic therapeutic efficiency. For this, several amphiphilic block copolymers of poly(ethyleneoxide-b-ε-caprolactone) have been used to form self-assemblies with different morphologies (micelles, worm-like micelles or vesicles). In a first step, controlled mixtures of preformed micelles and vesicles have been characterized both by dynamic light scattering and asymmetrical flow field flow fractionation (AsFlFFF). For this, a custom-made program, STORMS, was developed to analyze DLS data in a thorough manner by providing a large set of fitting parameters. This showed that DLS only sensed the larger vesicles when the micelles/vesicles ratio was 80/20 w/w. On the other hand, AsFlFFF allowed clear detection of the presence of micelles when this same ratio was as low as 10/90. Subsequently, the photodynamic therapy efficiency of various controlled mixtures was assessed using multicellular spheroids when a photosensitizer, pheophorbide a, was encapsulated in the polymer self-assemblies. Some mixtures were shown to be as efficient as monomorphous systems. In some cases, mixtures were found to exhibit a higher PDT efficiency compared to the individual nano-objects, revealing a synergistic effect for the efficient delivery of the photosensitizer. Polymorphous vectors can therefore be superior in therapeutic applications.

Long-circulating Janus nanoparticles made by electrohydrodynamic co-jetting for systemic drug delivery applications

BACKGROUND

Nanoparticles with controlled physical properties have been widely used for controlled release applications. In addition to shape, the anisotropic nature of the particles can be an important design criterion to ensure selective surface modification or independent release of combinations of drugs.

PURPOSE

Electrohydrodynamic (EHD) co-jetting is used for the fabrication of uniform anisotropic nanoparticles with individual compartments and initial physicochemical and biological characterization is reported.

METHODS

EHD co-jetting is used to create nanoparticles, which are characterized at each stage with scanning electron microscopy (SEM), structured illumination microscopy (SIM), dynamic light scattering (DLS) and nanoparticle tracking analysis (NTA). Surface immobilization techniques are used to incorporate polyethylene glycol (PEG) and I(125) radiolabels into the nanoparticles. Particles are injected in mice and the particle distribution after 1, 4 and 24 hours is assessed.

RESULTS AND DISCUSSION

Nanoparticles with an average diameter of 105.7 nm are prepared by EHD co-jetting. The particles contain functional chemical groups for further surface modification and radiolabeling. The density of PEG molecules attached to the surface of nanoparticles is determined to range between 0.02 and 6.04 ligands per square nanometer. A significant fraction of the nanoparticles (1.2% injected dose per mass of organ) circulates in the blood after 24 h.

CONCLUSION

EHD co-jetting is a versatile method for the fabrication of nanoparticles for drug delivery. Circulation of the nanoparticles for 24 h is a pre-requisite for subsequent studies to explore defined targeting of the nanoparticles to a specific anatomic site.

Impact of surfactant treatment of paclitaxel nanocrystals on biodistribution and tumor accumulation in tumor-bearing mice

We have previously tested paclitaxel nanocrystals (PTX-NCs) in tumor murine models and learned that the nanocrystal formulation could achieve similar and superior anticancer efficacy to the conventional Taxol® formulation, but with significantly reduced side-effects. The nanocrystals were not coated with any surfactants and a majority of the injected dose was taken up by the liver (>40%), while a minimal amount was present in the blood circulation and quickly eliminated. The aim of this work was to treat the surface of PTX-NCs with PEG-based polymers and examine the impact by surface coating on biodistribution, pharmacokinetics, and tumor retention. Testing in tumor-bearing mice showed that PTX-NCs treated with Pluronic® F68 (PEG-PPG-PEG block polymer) significantly enhanced blood circulation of the drug and accumulation in tumor tissue. The absolute amount reaching the tumor, however, was still minimal relative to the dose.

Activatable Water-Soluble Probes Enhance Tumor Imaging by Responding to Dysregulated pH and Exhibiting High Tumor-to-Liver Fluorescence Emission Contrast

Dysregulated pH has been recognized as a universal tumor microenvironment signature that can delineate tumors from normal tissues. Existing fluorescent probes that activate in response to pH are hindered by either fast clearance (in the case of small molecules) or high liver background emission (in the case of large particles). There remains a need to design water-soluble, long circulating, pH-responsive nanoprobes with high tumor-to-liver contrast. Herein, we report a modular chemical strategy to create acidic pH-sensitive and water-soluble fluorescent probes for high in vivo tumor detection and minimal liver activation. A combination of a modified Knoevenagel reaction and PEGylation yielded a series of NIR BODIPY fluorophores with tunable pKas, high quantum yield, and optimal orbital energies to enable photoinduced electron transfer (PeT) activation in response to pH. After intravenous administration, Probe 5c localized to tumors and provided excellent tumor-to-liver contrast (apparent T/L = 3) because it minimally activates in the liver. This phenomenon was further confirmed by direct ex vivo imaging experiments on harvested organs. Because no targeting ligands were required, we believe that this report introduces a versatile strategy to directly synthesize soluble probes with broad potential utility including fluorescence-based image-guided surgery, cancer diagnosis, and theranostic nanomedicine.

Controlling the Stealth Effect of Nanocarriers through Understanding the Protein Corona

The past decade has seen a significant increase in interest in the use of polymeric nanocarriers in medical applications. In particular, when used as drug vectors in targeted delivery, nanocarriers could overcome many obstacles for drug therapy. Nevertheless, their application is still impeded by the complex composition of the blood proteins covering the particle surface, termed the protein corona. The protein corona complicates any prediction of cell interactions, biodistribution, and toxicity. In particular, the unspecific uptake of nanocarriers is a major obstacle in clinical studies. This Minireview provides an overview of what we currently know about the characteristics of the protein corona of nanocarriers, with a focus on surface functionalization that reduces unspecific uptake (the stealth effect). The ongoing improvement of nanocarriers to allow them to meet all the requirements necessary for successful application, including targeted delivery and stealth, are further discussed.

In vivo biodistribution of stable spherical and filamentous micelles probed by high-sensitivity SPECT

Understanding how nanoparticle properties such as size, morphology and rigidity influence their circulation time and biodistribution is essential for the development of nanomedicine therapies. Herein we assess the influence of morphology on cellular internalization, in vivo biodistribution and circulation time of nanocarriers using polystyrene-b-poly(ethylene oxide) micelles of spherical or elongated morphology. The glassy nature of polystyrene guarantees the morphological stability of the carriers in vivo and by encapsulating Indium-111 in their core, an assessment of the longitudinal in vivo biodistribution of the particles in healthy mice is performed with single photon emission computed tomography imaging. Our results show prolonged blood circulation, longer than 24 hours, for all micelle morphologies studied. Dynamics of micelle accumulation in the liver and other organs of the reticuloendothelial system show a size-dependent nature and late stage liver clearance is observed for the elongated morphology. Apparent contradictions between recent similar studies can be resolved by considering the effects of flexibility and degradation of the elongated micelles on their circulation time and biodistribution.

Minor changes in the macrocyclic ligands but major consequences on the efficiency of gold nanoparticles designed for radiosensitization

Many studies have been devoted to adapting the design of gold nanoparticles to efficiently exploit their promising capability to enhance the effects of radiotherapy. In particular, the addition of magnetic resonance imaging modality constitutes an attractive strategy for enhancing the selectivity of radiotherapy since it allows the determination of the most suited delay between the injection of nanoparticles and irradiation. This requires the functionalization of the gold core by an organic shell composed of thiolated gadolinium chelates. The risk of nephrogenic systemic fibrosis induced by the release of gadolinium ions should encourage the use of macrocyclic chelators which form highly stable and inert complexes with gadolinium ions. In this context, three types of gold nanoparticles (Au@DTDOTA, Au@TADOTA and Au@TADOTAGA) combining MRI, nuclear imaging and radiosensitization have been developed with different macrocyclic ligands anchored onto the gold cores. Despite similarities in size and organic shell composition, the distribution of gadolinium chelate-coated gold nanoparticles (Au@TADOTA-Gd and Au@TADOTAGA-Gd) in the tumor zone is clearly different. As a result, the intravenous injection of Au@TADOTAGA-Gd prior to the irradiation of 9L gliosarcoma bearing rats leads to the highest increase in lifespan whereas the radiophysical effects of Au@TADOTAGA-Gd and Au@TADOTA-Gd are very similar.

Gulp1 is associated with the pharmacokinetics of PEGylated liposomal doxorubicin (PLD) in inbred mouse strains

Nanoparticles (NP) including liposomes are cleared by phagocytes of the mononuclear phagocyte system. High inter-patient variability in pharmacokinetics of PEGylated liposomal doxorubicin (PLD) has been reported. We hypothesized that genetic factors may be associated with the variable disposition of PLD. We evaluated plasma and tissue disposition of doxorubicin after administration of PLD at 6mg/kg IV ×1 via tail vein in 23 different male inbred mouse strains. An approximately 13-fold difference in plasma clearance of PLD was observed among inbred strains. We identified a correlation between strain-specific differences in PLD clearance and genetic variation within a genomic region encoding GULP1 (PTB domain containing engulfment adapter 1) protein using haplotype associated mapping and the efficient mixed-model association algorithms. Our results also show that Gulp1 expression in adipose tissue was associated with PLD disposition in plasma. Our findings suggest that genetic variants may be associated with inter-individual pharmacokinetic differences in NP clearance.

Inspired by nonenveloped viruses escaping from endo-lysosomes: a pH-sensitive polyurethane micelle for effective intracellular trafficking

A multifunctional drug delivery system (DDS) for cancer therapy still faces great challenges due to multiple physiological barriers encountered in vivo. To increase the efficacy of current cancer treatment a new anticancer DDS mimicking the response of nonenveloped viruses, triggered by acidic pH to escape endo-lysosomes, is developed. Such a smart DDS is self-assembled from biodegradable pH-sensitive polyurethane containing hydrazone bonds in the backbone, named pHPM. The pHPM exhibits excellent micellization characteristics and high loading capacity for hydrophobic chemotherapeutic drugs. The responses of the pHPM in acidic media, undergoing charge conversion and hydrophobic core exposure, resulting from the detachment of the hydrophilic polyethylene glycol (PEG) shell, are similar to the behavior of a nonenveloped virus when trapped in acidic endo-lysosomes. Moreover, the degradation mechanism was verified by gel permeation chromatography (GPC). The endo-lysosomal membrane rupture induced by these transformed micelles is clearly observed by transmission electron microscopy. Consequently, excellent antitumor activity is confirmed both in vitro and in vivo. The results verify that the pHPM could be a promising new drug delivery tool for the treatment of cancer and other diseases.

Protein adsorption is required for stealth effect of poly(ethylene glycol)- and poly(phosphoester)-coated nanocarriers

The current gold standard to reduce non-specific cellular uptake of drug delivery vehicles is by covalent attachment of poly(ethylene glycol) (PEG). It is thought that PEG can reduce protein adsorption and thereby confer a stealth effect. Here, we show that polystyrene nanocarriers that have been modified with PEG or poly(ethyl ethylene phosphate) (PEEP) and exposed to plasma proteins exhibit a low cellular uptake, whereas those not exposed to plasma proteins show high non-specific uptake. Mass spectrometric analysis revealed that exposed nanocarriers formed a protein corona that contains an abundance of clusterin proteins (also known as apolipoprotein J). When the polymer-modified nanocarriers were incubated with clusterin, non-specific cellular uptake could be reduced. Our results show that in addition to reducing protein adsorption, PEG, and now PEEPs, can affect the composition of the protein corona that forms around nanocarriers, and the presence of distinct proteins is necessary to prevent non-specific cellular uptake.

pH-Responsive Polymer Conjugate of Pirarubicin With Styrene Maleic Acid Copolymer as a Potential Therapeutic for Ovarian Cancer

Previous studies indicated the potential of styrene maleic acid copolymer (SMA)-conjugated pirarubicin (4'-O-tetrahydropyranyldoxorubicin [THP]) for targeted anticancer therapy based on the enhanced permeability and retention effect. In this study, to achieve further improved therapeutic efficacy, a pH-responsive SMA-conjugated THP-containing hydrazone bond (SMA-hyd-THP) was synthesized and evaluated in vitro and ex vivo using human ovarian cancer cells and tissues. SMA-hyd-THP showed good water solubility, forming micelles with a mean particle size of 48.0 nm, which is applicable for enhanced permeability and retention-based tumor accumulation. The THP loading in this preparation was 15% (wt/wt), and release rate of free THP from SMA-hyd-THP at physiological pH (7.4) was approximately 10% in 72 h. However, it increased rapidly at pH 6.5 (42%) and 5.5 (83%), which indicates that tumor environment of weak acidic condition (pH 6.5-6.9) is favorable for release of THP. This notion was partly proved by incubating SMA-hyd-THP with tumor tissues from ovarian cancer patients. In addition, release of THP was not affected by serum, suggesting that SMA-hyd-THP is relatively stable in circulation. Finally, SMA-hyd-THP showed much increased cytotoxicity against various ovarian cancer cells at acidic tumor pH (6.5). These findings may provide an option for targeted therapy against ovarian cancer.

NANOMEDICINE: will it offer possibilities to overcome multiple drug resistance in cancer?

This review is written with the purpose to review the current nanomedicine literature and provide an outlook on the developments in utilizing nanoscale drug constructs in treatment of solid cancers as well as in the potential treatment of multi-drug resistant cancers. No specific design principles for this review have been utilized apart from our active choice to avoid results only based on in vitro studies. Few drugs based on nanotechnology have progressed to clinical trials, since most are based only on in vitro experiments which do not give the necessary data for the research to progress towards pre-clinical studies. The area of nanomedicine has indeed spark much attention and holds promise for improved future therapeutics in the treatment of solid cancers. However, despite much investment few targeted therapeutics have successfully progressed to early clinical trials, indicating yet again that the human body is complicated and that much more understanding of the fundamentals of receptor interactions, physics of nanomedical constructs and their circulation in the body is indeed needed. We believe that nanomedical therapeutics can allow for more efficient treatments of resistant cancers, and may well be a cornerstone for RNA based therapeutics in the future given their general need for shielding from the harsh environment in the blood stream.

Enhancing dendritic cell activation and HIV vaccine effectiveness through nanoparticle vaccination

Novel vaccination approaches are needed to prevent and control human immunodeficiency virus (HIV) infection. A growing body of literature demonstrates the potential of nanotechnology to modulate the human immune system and generate targeted, controlled immune responses. In this Review, we summarize important advances in how 'nanovaccinology' can be used to develop safe and effective vaccines for HIV. We highlight the central role of dendritic cells in the immune response to vaccination and describe how nanotechnology can be used to enhance delivery to and activation of these important antigen-presenting cells. Strategies employed to improve biodistribution are discussed, including improved lymph node delivery and mucosal penetration concepts, before detailing methods to enhance the humoral and/or cellular immune response to vaccines. We conclude with a commentary on the current state of nanovaccinology.

SPECT/CT Imaging of Pluronic Nanocarriers with Varying Poly(ethylene oxide) Block Length and Aggregation State

Optimal biodistribution and prolonged circulation of nanocarriers improve diagnostic and therapeutic effects of enhanced permeability and retention-based nanomedicines. Despite extensive use of Pluronics in polymer-based pharmaceuticals, the influence of different poly(ethylene oxide) (PEO) block length and aggregation state on the biodistribution of the carriers is rather unexplored. In this work, we studied these effects by evaluating the biodistribution of Pluronic unimers and cross-linked micelles with different PEO block size. In vivo biodistribution of (111)In-radiolabeled Pluronic nanocarriers was investigated in healthy mice using single photon emission computed tomography. All carriers show fast uptake in the organs from the reticuloendothelial system followed by a steady elimination through the hepatobiliary tract and renal filtration. The PEO block length affects the initial renal clearance of the compounds and the overall liver uptake. The aggregation state influences the long-term accumulation of the nanocarriers in the liver. We showed that the circulation time and elimination pathways can be tuned by varying the physicochemical properties of Pluronic copolymers. Our results can be beneficial for the design of future Pluronic-based nanomedicines.

Recent advances in mesoporous silica nanoparticles for antitumor therapy: our contribution

Since 2001, when our research group proposed for the first time MCM-41 as a drug release system, the scientific community has demonstrated a growing interest in mesoporous silica nanoparticles (MSNs) for their revolutionary potential in nanomedicine. Among the diverse pathologies that can be treated with MSNs, cancer has received increasing attention. MSNs can be loaded with large amounts of therapeutic cargoes and once intravenously administrated preferentially accumulate in solid tumours via the enhanced permeation and retention (EPR) effect. Herein we report the recent developments achieved by our research group as a pioneer in this field, highlighting: the design of sophisticated MSNs as stimuli-responsive drug delivery systems to release the entrapped cargo upon exposure to a given stimulus while preventing the premature release of highly cytotoxic drugs before reaching the target; transporting non-toxic prodrugs and the enzyme responsible for its conversion into cytotoxic agents into the same MSNs; improving the selectivity and cellular uptake by cancer cells by active targeting of MSNs; increasing the penetration of MSNs within the tumour mass, which is one of the major challenges in the use of NPs to treat solid tumours.

Comparison of methods for the fabrication and the characterization of polymer self-assemblies: what are the important parameters?

The ability to self-assemble was evaluated for a large variety of amphiphilic block copolymers, including poly(ethyleneoxide-b-ε-caprolactone), poly(ethyleneoxide-b-d,l-lactide), poly(ethyleneoxide-b-styrene), poly(ethyleneoxide-b-butadiene) and poly(ethyleneoxide-b-methylmethacrylate). Different methods of formation are discussed, such as cosolvent addition, film hydration or electroformation. The influence of experimental parameters and macromolecular structures on the size and morphology of the final self-assembled structures is investigated and critically compared with the literature. The same process is carried out regarding the characterization of these structures. This analysis demonstrates the great care that should be taken when dealing with such polymeric assemblies. If the morphology of such assemblies can be predicted to some extent by macromolecular parameters like the hydrophilic/hydrophobic balance, those parameters cannot be considered as universal. In addition, external experimental parameters (methods of preparation, use of co-solvent, …) appeared as critical key parameters to obtain a good control over the final structure of such objects, which are very often not at thermodynamic equilibrium but kinetically frozen. A principal component analysis is also proposed, in order to examine the important parameters for forming the self-assemblies. Here again, the hydrophilic/hydrophobic fraction is identified as an important parameter.

Synergistic combination of antioxidants, silver nanoparticles and chitosan in a nanoparticle based formulation: Characterization and cytotoxic effect on MCF-7 breast cancer cell lines

HYPOTHESIS

Chitosan (Cs) is a biocompatible, biodegradable cationic polymer having the ability of targeted drug delivery. Vitamin E and C are not synthesized in our body thus, when encapsulated within a carrier system these vitamins in combination with/alone can be utilized for their anti-cancer potentials.

EXPERIMENT

The present investigation was conducted to develop a stable nanoparticle based formulation encapsulating antioxidants (Vitamin E, catechol) and silver nanoparticles synthesized from Hibiscus rosa-sinensis (HRS) petal extracts within a chitosan matrix. The prepared nanoformulations were characterized using Field emission scanning electron microscopy (Fe-SEM), X-ray diffraction (XRD) and Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR). They were further tested for their antioxidant potentials using DPPH assay, hydrogen peroxide scavenging assay, nitric oxide scavenging assay and ferrous antioxidant reducing potential assay.

FINDINGS

The nanoformulations were found to be highly hemocompatible and showed high encapsulation efficiency up to 76%. They also showed higher antioxidant activity than their base materials. Further, their anti-cancer efficacy was observed against MCF-7 breast cancer cells having IC50 values of 53.36±0.36μg/mL (chitosan-ascorbic acid-glucose), 55.28±0.85μg/mL (chitosan-Vitamin E), 63.72±0.27μg/mL (Chitosan-catechol) and 58.53±0.55μg/mL (chitosan-silver nanoparticles). Thus, the prepared formulations can be therapeutically applied for effective and targeted delivery in breast cancer treatment.

Nanoparticle-liver interactions: Cellular uptake and hepatobiliary elimination

30-99% of administered nanoparticles will accumulate and sequester in the liver after administration into the body. This results in reduced delivery to the targeted diseased tissue and potentially leads to increased toxicity at the hepatic cellular level. This review article focuses on the inter- and intra-cellular interaction between nanoparticles and hepatic cells, the elimination mechanism of nanoparticles through the hepatobiliary system, and current strategies to manipulate liver sequestration. The ability to solve the "nanoparticle-liver" interaction is critical to the clinical translation of nanotechnology for diagnosing and treating cancer, diabetes, cardiovascular disorders, and other diseases.

Current applications of nanoparticles in infectious diseases

For decades infections have been treated easily with drugs. However, in the 21st century, they may become lethal again owing to the development of antimicrobial resistance. Pathogens can become resistant by means of different mechanisms, such as increasing the time they spend in the intracellular environment, where drugs are unable to reach therapeutic levels. Moreover, drugs are also subject to certain problems that decrease their efficacy. This requires the use of high doses, and frequent administrations must be implemented, causing adverse side effects or toxicity. The use of nanoparticle systems can help to overcome such problems and increase drug efficacy. Accordingly, there is considerable current interest in their use as antimicrobial agents against different pathogens like bacteria, virus, fungi or parasites, multidrug-resistant strains and biofilms; as targeting vectors towards specific tissues; as vaccines and as theranostic systems. This review begins with an overview of the different types and characteristics of nanoparticles used to deliver drugs to the target, followed by a review of current research and clinical trials addressing the use of nanoparticles within the field of infectious diseases.

Aptamer-modified polymer nanoparticles for targeted drug delivery

The purpose of this study was to develop a model system for targeted drug delivery. This system should enable targeted drug release at a certain tissue in the body. In conventional drug delivery systems, drugs are often delivered unspecifically resulting in unwarranted adverse effects. To circumvent this problem, there is an increasing demand for the development of intelligent drug delivery systems allowing a tissue-specific mode of delivery. Within this study, nanoparticles consisting of two biocompatible polymers are used. Because of their small size, nanoparticles are well-suited for effective drug delivery. The small size affects their movement through cell and tissue barriers. Their cellular uptake is easier when compared to larger drug delivery systems. Paclitaxel was encapsulated into the nanoparticles as a model drug, and to achieve specific targeting an aptamer directed against lung cancer cells was coupled to the nanoparticles surface. Nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), and nanotracking analysis (NTA). Also their surface charge was characterized from ζ-potential measurements. Their preparation was optimized and subsequently specificity of drug-loaded and aptamer-functionalized nanoparticles was investigated using lung cancer cells.

Polymeric Nanoparticles for Cancer Photodynamic Therapy

In chemotherapy a fine balance between therapeutic and toxic effects needs to be found for each patient, adapting standard combination protocols each time. Nanotherapeutics has been introduced into clinical practice for treating tumors with the aim of improving the therapeutic outcome of conventional therapies and of alleviating their toxicity and overcoming multidrug resistance. Photodynamic therapy (PDT) is a clinically approved, minimally invasive procedure emerging in cancer treatment. It involves the administration of a photosensitizer (PS) which, under light irradiation and in the presence of molecular oxygen, produces cytotoxic species. Unfortunately, most PSs lack specificity for tumor cells and are poorly soluble in aqueous media, where they can form aggregates with low photoactivity. Nanotechnological approaches in PDT (nanoPDT) can offer a valid option to deliver PSs in the body and to solve at least some of these issues. Currently, polymeric nanoparticles (NPs) are emerging as nanoPDT system because their features (size, surface properties, and release rate) can be readily manipulated by selecting appropriate materials in a vast range of possible candidates commercially available and by synthesizing novel tailor-made materials. Delivery of PSs through NPs offers a great opportunity to overcome PDT drawbacks based on the concept that a nanocarrier can drive therapeutic concentrations of PS to the tumor cells without generating any harmful effect in non-target tissues. Furthermore, carriers for nanoPDT can surmount solubility issues and the tendency of PS to aggregate, which can severely affect photophysical, chemical, and biological properties. Finally, multimodal NPs carrying different drugs/bioactive species with complementary mechanisms of cancer cell killing and incorporating an imaging agent can be developed. In the following, we describe the principles of PDT use in cancer and the pillars of rational design of nanoPDT carriers dictated by tumor and PS features. Then we illustrate the main nanoPDT systems demonstrating potential in preclinical models together with emerging concepts for their advanced design.

In Situ formation of pH-/thermo-sensitive nanohybrids via friendly-assembly of poly(N-vinylpyrrolidone) onto LAPONITE®

Decoration of silicate nanodisks with a pH-sensitive polymer allows for the effective delivery of an anticancer drug in cancer cells with high efficacy.

Dual release of a hydrophilic and a hydrophobic osteogenic factor from a single liposome

Dual release of growth/differentiation factors from liposomes induced osteogenic differentiation of mesenchymal stem cells.

Theranostic hollow/mesoporous organosilica nanospheres enhance the therapeutic efficacy of anticancer drugs in metastatic hormone-resistant prostate cancer

Hollow mesoporous silica materials have received intensive interest in the field of cancer treatment owing to their large drug loading capacity, controlled release property and excellent biocompatibility.

Methods for production of uniform small-sized polymersome with rigid membrane

We report a facile methodology for the formation of uniform small-sized poly(ethylene glycol)-block-polystyrene (PEG-b-PS) polymersomes, via extrusion and sonication methods by using organic solvent as plasticizing agent.

Recapitulation of complex transport and action of drugs at the tumor microenvironment using tumor-microenvironment-on-chip

Targeted delivery aims to selectively distribute drugs to targeted tumor tissues but not to healthy tissues. This can address many clinical challenges by maximizing the efficacy but minimizing the toxicity of anti-cancer drugs. However, a complex tumor microenvironment poses various barriers hindering the transport of drugs and drug delivery systems. New tumor models that allow for the systematic study of these complex environments are highly desired to provide reliable test beds to develop drug delivery systems for targeted delivery. Recently, research efforts have yielded new in vitro tumor models, the so called tumor-microenvironment-on-chip, that recapitulate certain characteristics of the tumor microenvironment. These new models show benefits over other conventional tumor models, and have the potential to accelerate drug discovery and enable precision medicine. However, further research is warranted to overcome their limitations and to properly interpret the data obtained from these models. In this article, key features of the in vivo tumor microenvironment that are relevant to drug transport processes for targeted delivery were discussed, and the current status and challenges for developing in vitro transport model systems were reviewed.

Increasing the density of nanomedicines improves their ultrasound-mediated delivery to tumours

Nanomedicines have provided fresh impetus in the fight against cancer due to their selectivity and power. However, these agents are limited when delivered intravenously due to their rapid clearance from the bloodstream and poor passage from the bloodstream into target tumours. Here we describe a novel stealthing strategy which addresses both these limitations and thereby demonstrate that both the passive and mechanically-mediated tumour accumulation of the model nanomedicine adenovirus (Ad) can be substantially enhanced. In our strategy gold nanoparticles were thoroughly modified with 2kDa polyethyleneglycol (PEG) and then linked to Ad via a single reduction-cleavable 5kDa PEG. The resulting Ad-gold-PEG construct was compared to non-modified Ad or conventionally stealthed Ad-poly[N-(2-hydroxypropyl)methacrylamide] (Ad-PHPMA). Notably, although Ad-gold-PEG was of similar size and surface charge to Ad-PHPMA the increase in density, resulting from the inclusion of the gold nanoparticles, provided a substantial enhancement of ultrasound-mediated transport. In an in vitro tumour mimicking phantom, the level and distance of Ad-gold-PEG transport was shown to be substantially greater than achieved with Ad-PHPMA. In in vivo studies 0.1% of an unmodified Ad dose was shown to accumulate in tumours, whereas over 12% of the injected dose was recovered from the tumours of mice treated with Ad-gold-PEG and ultrasound. Ultimately, a significant increase in anti-tumour efficacy resulted from this strategy. This stealthing and density-increasing technology could ultimately enhance clinical utility of intravenously delivered nanoscale medicines including viruses, liposomes and antibodies.

Crystalline Oligo(ethylene sulfide) Domains Define Highly Stable Supramolecular Block Copolymer Assemblies

With proper control over copolymer design and solvation conditions, self-assembled materials display impressive morphological variety that encompasses nanoscale colloids as well as bulk three-dimensional architectures. Here we take advantage of both hydrophobicity and crystallinity to mediate supramolecular self-assembly of spherical micellar, linear fibrillar, or hydrogel structures by a family of highly asymmetric poly(ethylene glycol)-b-oligo(ethylene sulfide) (PEG-OES) copolymers. Assembly structural polymorphism was achieved with modification of PEG-OES topology (linear versus multiarm) and with precise, monomer-by-monomer control of OES length. Notably, all three morphologies were accessed utilizing OES oligomers with degrees of polymerization as short as three. These exceptionally small assembly forming blocks represent the first application of ethylene sulfide oligomers in supramolecular materials. While the assemblies demonstrated robust aqueous stability over time, oxidation by hydrogen peroxide progressively converted ethylene sulfide residues to increasingly hydrophilic and amorphous sulfoxides and sulfones, causing morphological changes and permanent disassembly. We utilized complementary microscopic and spectroscopic techniques to confirm this chemical stimulus-responsive behavior in self-assembled PEG-OES colloidal dispersions and physical gels. In addition to inherent stimulus-responsive behavior, fibrillar assemblies demonstrated biologically relevant molecular delivery, as confirmed by the dose-dependent activation of murine bone marrow-derived dendritic cells following fibril-mediated delivery of the immunological adjuvant monophosphoryl lipid A. In physical gels composed of either linear or multiarm PEG-OES precursors, rheologic analysis also identified mechanical stimulus-responsive shear thinning behavior. Thanks to the facile preparation, user-defined morphology, aqueous stability, carrier functionality, and stimuli-responsive behaviors of PEG-OES supramolecular assemblies, our findings support a future role for these materials as injectable or implantable biomaterials.

Improved antitumor effect of paclitaxel administered in vivo as pH and glutathione-sensitive nanohydrogels

Most antitumor drugs usually affect not only rapidly dividing cells, such as those in tumors, but also highly proliferative cells in normal tissues. This nonspecific drawback could be successfully solved by using nanocarriers as controlled drug delivery systems. In this work, pH and redox-responsive nanohydrogels (NG) based on N-isopropylacrilamide (NIPA), N-hydroxyethyl acrylamide (HEEA) 2-acrylamidoethyl carbamate (2AAECM) and N,N'-cystaminebisacrylamide (CBA) as crosslinker were evaluated as bioreducible paclitaxel (PTX) nanocarriers for improving the accumulation of the drug within the tumor tissue and avoiding its conventional side effects. A single dose of PTX solution, unloaded-NHA 80/15/5CBA NG and PTX-loaded NHA 80/15/5-CBA NG (30 mg/kg PTX equivalent) were subcutaneously injected in female athymic nude mice bearing HeLa human tumor xenografts. PTX-loaded nanohydrogels showed higher antitumor activity than free PTX, as tumor evolution and Ki67 detection demonstrated. Histological tumor images revealed a higher content of defective mitotic figures and apoptotic bodies in PTX- treated tumors than in control or unloaded NG treated tumor samples. Nanohydrogels injection did not change any biochemical blood parameters, which means no liver or kidney damage after NG injection. However, differences in antioxidant defenses in MPS systems (liver, kidney and spleen) were observed among treatments, which may indicate an oxidative stress response after PTX injection.

Development of nanotoxicology: implications for drug delivery and medical devices

Current nanotoxicology research suffers from suboptimal in vitro models, lack of in vitro–in vivo correlations, variability within in vitro protocols, deficits in both material purity and physicochemical characterization. Reliable nanomaterial toxicity and mechanistic insights are required for health and toxicity risk assessments. Much in vitro toxicological data is inconclusive in designating whether nanomaterials for drug delivery and medical device implants are truly safe. A critique is presented to analyze the interface between toxicology and nanopharmaceuticals. Deficiencies of existing practices in toxicology are reviewed and useful emerging techniques (e.g., lab-on-a-chip, tissue engineering, atomic force microscopy, high-content analysis) are highlighted. Cross-fertilization between disciplines will aid development of biocompatible delivery and implant platforms while improvements are being suggested for better translation of nanotoxicology.

Nanotechnology in the war against cancer: new arms against an old enemy – a clinical view

ABSTRACT 

Clinical oncology is facing a paradigm shift. A new treatment philosophy is emerging and new targets are appearing that require new active agents. The medical use of nanotechnology – nanomedicine – holds several promising possibilities in the war against cancer. Some of these include: new formats for old drugs, that is, increasing efficacy while diminishing side effects; and new administration routes – that is, dermal, oral and pulmonary. In this overview, we describe some nanoparticles and their medical uses as well as highlight advantages of nanoparticles compared with conventional pharmaceuticals. We also point to some of the many technical challenges and potential risks with using nanotechnology for oncological applications.

Effect of the Polymer Architecture on the Structural and Biophysical Properties of PEG-PLA Nanoparticles

Polymers made of poly(ethylene glycol) chains grafted to poly(lactic acid) chains (PEG-g-PLA) were used to produce stealth drug nanocarriers. A library of comblike PEG-g-PLA polymers with different PEG grafting densities was prepared in order to obtain nanocarriers with dense PEG brushes at their surface, stability in suspension, and resistance to protein adsorption. The structural properties of nanoparticles (NPs) produced from these polymers by a surfactant-free method were assessed by dynamic light scattering, ζ potential, and transmission electron microscopy and found to be controlled by the amount of PEG present in the polymers. A critical transition from a solid NP structure to a soft particle with either a "micellelike" or a "polymer nanoaggregate" structure was observed when the PEG content was between 15 and 25% w/w. This structural transition was found to have a profound impact on the size of the NPs, their surface charge, their stability in suspension in the presence of salts, and the binding of proteins to the surface of the NPs. The arrangement of the PEG-g-PLA chains at the surface of the NPs was investigated by (1)H NMR and X-ray photoelectron spectroscopy (XPS). NMR results confirmed that the PEG chains were mostly segregated at the NP surface. Moreover, XPS and quantitative NMR allowed quantification of the PEG chain coverage density at the surface of the solid NPs. Concordance of the results between the two methods was found to be remarkable. Physical-chemical properties of the NPs such as resistance to aggregation in a saline environment as well as antifouling efficacy were related to the PEG surface density and ultimately to the polymer architecture. Resistance to protein adsorption was assessed by isothermal titration calorimetry using lysozyme. The results indicate a correlation between the PEG surface coverage and level of protein interactions. The results obtained lead us to propose such PEG-g-PLA polymers for nanomedicine development as an alternative to the predominant polyester-PEG diblock polymers.

The janus facet of nanomaterials

Application of nanoscale materials (NMs) displays a rapidly increasing trend in electronics, optics, chemical catalysis, biotechnology, and medicine due to versatile nature of NMs and easily adjustable physical, physicochemical, and chemical properties. However, the increasing abundance of NMs also poses significant new and emerging health and environmental risks. Despite growing efforts, understanding toxicity of NMs does not seem to cope with the demand, because NMs usually act entirely different from those of conventional small molecule drugs. Currently, large-scale application of available safety assessment protocols, as well as their furthering through case-by-case practice, is advisable. We define a standard work-scheme for nanotoxicity evaluation of NMs, comprising thorough characterization of structural, physical, physicochemical, and chemical traits, followed by measuring biodistribution in live tissue and blood combined with investigation of organ-specific effects especially regarding the function of the brain and the liver. We propose a range of biochemical, cellular, and immunological processes to be explored in order to provide information on the early effects of NMs on some basic physiological functions and chemical defense mechanisms. Together, these contributions give an overview with important implications for the understanding of many aspects of nanotoxicity.

Controlled drug release and hydrolysis mechanism of polymer-magnetic nanoparticle composite

Uniform and multifunctional poly(lactic acid) (PLA)-nanoparticle composite has enormous potential for applications in biomedical and materials science. A detailed understanding of the surface and interface chemistry of these composites is essential to design such materials with optimized function. Herein, we designed and investigated a simple PLA-magnetic nanoparticle composite system to elucidate the impact of nanoparticles on the degradation of polymer-nanoparticle composites. In order to have an in-depth understanding of the mechanisms of hydrolysis in PLA-nanoparticle composites, degradation processes were monitored by several surface sensitive techniques, including scanning electron microscopy, contact angle goniometry, atomic force microscopy, and sum frequency generation spectroscopy. As a second-order nonlinear optical technique, SFG spectroscopy was introduced to directly probe in situ chemical nature at the PLA-magnetic nanoparticle composite/aqueous interface, which allowed for the delineation of molecular mechanisms of various hydrolysis processes for degradation at the molecular level. The best PLA-NP material, with a concentration of 20% MNP in the composite, was found to enhance the drug release rate greater than 200 times while maintaining excellent controlled drug release characteristics. It was also found that during hydrolysis, various crystalline-like PLA domains on the surfaces of PLA-nanoparticle composites influenced various hydrolysis behaviors of PLA. Results from this study provide new insight into the design of nanomaterials with controlled degradation and drug release properties, and the underlined molecular mechanisms. The methodology developed in this study to characterize the polymer-nanoparticle composites is general and widely applicable.

Synergistic activity of combination therapy with PEGylated pemetrexed and gemcitabine for an effective cancer treatment

Combination therapy in cancer is now opted as a potential therapeutic strategy for cancer treatment. However, effective delivery of drugs in combination at the tumor site is marred by low bioavailability and systemic toxicity of individual drugs. Polymer therapeutics is indeed an upcoming approach for the combinational drug delivery in favor of better cancer management. Hence, the objective of our investigation was to develop a dual drug PEGylated system that carries two chemotherapeutic drugs simultaneously for effective treatment of cancer. In this regard, we have synthesized Pem-PEG-Gem, wherein pemetrexed (Pem) and gemcitabine (Gem) are conjugated to a heterobifunctional polyethylene glycol (PEG) polymer for the effective treatment of Non-Small Cell Lung Cancer (NSCLC). Our results demonstrate enhanced bioavailability of the individual drugs in Pem-PEG-Gem in comparison with the drugs in their native form. The developed Pem-PEG-Gem showed enhanced cell death with respect to their native counterparts when treated singly or in combination against NSCLC cells. This might be attributed to better cellular internalization through the process of macropinocytosis and synergistic cytotoxic action of Pem-PEG-Gem in NSCLC cells. Hence, we propose the above dual drug based polymer therapeutic approach suitable for better clinical application in the treatment of NSCLC.

Design attributes of long-circulating polymeric drug delivery vehicles

Following systemic administration polymeric drug delivery vehicles allow for a controlled and targeted release of the encapsulated medication at the desired site of action. For an elevated and organ specific accumulation of their cargo, nanocarriers need to avoid opsonization, activation of the complement system and uptake by macrophages of the mononuclear phagocyte system. In this respect, camouflaged vehicles revealed a delayed elimination from systemic circulation and an improved target organ deposition. For instance, a steric shielding of the carrier surface by poly(ethylene glycol) substantially decreased interactions with the biological environment. However, recent studies disclosed possible deficits of this approach, where most notably, poly(ethylene glycol)-modified drug delivery vehicles caused significant immune responses. At present, identification of novel potential carrier coating strategies facilitating negligible immune reactions is an emerging field of interest in drug delivery research. Moreover, physical carrier properties including geometry and elasticity seem to be very promising design attributes to surpass numerous biological barriers, in order to improve the efficacy of the delivered medication.