Polymeric protective agents for nanoparticles in drug delivery and targeting

Nano-enhanced immunotherapy: Targeting the immunosuppressive tumor microenvironment

The tumor microenvironment (TME), which is mostly composed of tumor cells, immune cells, signaling molecules, stromal tissue, and the vascular system, is an integrated system that is conducive to the formation of tumors. TME heterogeneity makes the response to immunotherapy different in different tumors, such as "immune-cold" and "immune-hot" tumors. Tumor-associated macrophages, myeloid-derived suppressor cells, and regulatory T cells are the major suppressive immune cells and their different phenotypes interact and influence cancer cells by secreting different signaling factors, thus playing a key role in the formation of the TME as well as in the initiation, growth, and metastasis of cancer cells. Nanotechnology development has facilitated overcoming the obstacles that limit the further development of conventional immunotherapy, such as toxic side effects and lack of targeting. In this review, we focus on the role of three major suppressive immune cells in the TME as well as in tumor development, clinical trials of different drugs targeting immune cells, and different attempts to combine drugs with nanomaterials. The aim is to reveal the relationship between immunotherapy, immunosuppressive TME and nanomedicine, thus laying the foundation for further development of immunotherapy.

Recent Advances in Targeted Nanocarriers for the Management of Triple Negative Breast Cancer

Triple-negative breast cancer (TNBC) is a life-threatening form of breast cancer which has been found to account for 15% of all the subtypes of breast cancer. Currently available treatments are significantly less effective in TNBC management because of several factors such as poor bioavailability, low specificity, multidrug resistance, poor cellular uptake, and unwanted side effects being the major ones. As a rapidly growing field, nano-therapeutics offers promising alternatives for breast cancer treatment. This platform provides a suitable pathway for crossing biological barriers and allowing sustained systemic circulation time and an improved pharmacokinetic profile of the drug. Apart from this, it also provides an optimized target-specific drug delivery system and improves drug accumulation in tumor cells. This review provides insights into the molecular mechanisms associated with the pathogenesis of TNBC, along with summarizing the conventional therapy and recent advances of different nano-carriers for the management of TNBC.

Black TiO2 nanoprobe-mediated mild phototherapy reduces intracellular lipid levels in atherosclerotic foam cells via cholesterol regulation pathways instead of apoptosis

Given that apoptosis increases the risk of plaque rupture, strategies that reduce intracellular lipid levels without killing foam cells are warranted for safe and effective treatment of atherosclerosis. In this study, a mild phototherapy strategy is carried out to achieve the hypothesis. Foam cell-targeted nanoprobes that allow photothermal therapy (PTT) and/or photodynamic therapy (PDT) were prepared by loading hyaluronan and porphine onto black TiO₂ nanoparticles. The results showed that when temperatures below 45 °C, PTT alone and PTT + PDT significantly reduced the intracellular lipid burden without inducing evidently apoptosis or necrosis. In contrast, the use of PDT alone resulted in only a slight reduction in lipid levels and induced massive apoptosis or necrosis. The protective effect against apoptosis or necrosis after mild-temperature PTT and PTT + PDT was correlated with the upregulation of heat shock protein 27. Further, mild-temperature PTT and PTT + PDT attenuated intracellular cholesterol biosynthesis and excess cholesterol uptake via the SREBP2/LDLR pathway, and also triggered ABCA1-mediated cholesterol efflux, ultimately inhibiting lipid accumulation in foam cells. Our results offer new insights into the mechanism of lipid regulation in foam cells and indicate that the black TiO₂ nanoprobes could allow safer and more effective phototherapy of atherosclerosis.

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Mild phototherapy reduced the intracellular lipid in foam cells without inducing obvious apoptosis or necrosis.

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HSP27 was upregulated in foam cells treated by mild phototherapy, which could protect cells against apoptosis or necrosis.

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Mild phototherapy attenuated intracellular cholesterol biosynthesis and excess uptake, also boosted cholesterol efflux.

Biopolymers and Osmolytes - A Focus towards the Prospects of Stability and Adjuvanticity of Vaccines

‘New-Gen Vaccines’ are grabbing the attention of scientists as they are much suitable for an immune-compromised group of individuals as well as infants. The major drawbacks of these vaccines are lower immunogenicity and instability. The need for a convenient and safe adjuvant is still under exploration. On the other hand, thermal instability leads to the inactivation of the vaccine and becomes detrimental in many cases. Thus, there is a need to incorporate new kinds of excipients into vaccine formulation to enhance the potency/immunogenicity of vaccine antigens and also act as stabilizers. A limited or single excipient in providing the required dual-activity is vital to break the stereotypical usage of the well-entrenched adverse ingredients. In the proposed review, the efficiency of naturally occurring biocompatible carbohydrate polymers and osmolytes and their ‘dual-role’ is briefed. In addition, the information on the possible mechanisms of action of carbohydrate polymers in vaccines as adjuvants and stabilizers are also discussed.

Advanced Optical Imaging-Guided Nanotheranostics towards Personalized Cancer Drug Delivery

Nanomedicine involves the use of nanotechnology for clinical applications and holds promise to improve treatments. Recent developments offer new hope for cancer detection, prevention and treatment; however, being a heterogenous disorder, cancer calls for a more targeted treatment approach. Personalized Medicine (PM) aims to revolutionize cancer therapy by matching the most effective treatment to individual patients. Nanotheranostics comprise a combination of therapy and diagnostic imaging incorporated in a nanosystem and are developed to fulfill the promise of PM by helping in the selection of treatments, the objective monitoring of response and the planning of follow-up therapy. Although well-established imaging techniques, such as Magnetic Resonance Imaging (MRI), Computed Tomography (CT), Positron Emission Tomography (PET) and Single-Photon Emission Computed Tomography (SPECT), are primarily used in the development of theranostics, Optical Imaging (OI) offers some advantages, such as high sensitivity, spatial and temporal resolution and less invasiveness. Additionally, it allows for multiplexing, using multi-color imaging and DNA barcoding, which further aids in the development of personalized treatments. Recent advances have also given rise to techniques permitting better penetration, opening new doors for OI-guided nanotheranostics. In this review, we describe in detail these recent advances that may be used to design and develop efficient and specific nanotheranostics for personalized cancer drug delivery.

Surface Coating-Modulated Phytotoxic Responses of Silver Nanoparticles in Plants and Freshwater Green Algae

Silver nanoparticles (AgNPs) have been implemented in a wide range of commercial products, resulting in their unregulated release into aquatic as well as terrestrial systems. This raises concerns over their impending environmental effects. Once released into the environment, they are prone to various transformation processes that modify their reactivity. In order to increase AgNP stability, different stabilizing coatings are applied during their synthesis. However, coating agents determine particle size and shape and influence their solubility, reactivity, and overall stability as well as their behavior and transformations in the biological medium. In this review, we attempt to give an overview on how the employment of different stabilizing coatings can modulate AgNP-induced phytotoxicity with respect to growth, physiology, and gene and protein expression in terrestrial and aquatic plants and freshwater algae.

Functionalized Nanoparticles Targeting Tumor-Associated Macrophages as Cancer Therapy

The tumor microenvironment (TME) plays a central role in regulating antitumor immune responses. As an important part of the TME, alternatively activated type 2 (M2) macrophages drive the development of primary and secondary tumors by promoting tumor cell proliferation, tumor angiogenesis, extracellular matrix remodeling and overall immunosuppression. Immunotherapy approaches targeting tumor-associated macrophages (TAMs) in order to reduce the immunosuppressive state in the TME have received great attention. Although these methods hold great potential for the treatment of several cancers, they also face some limitations, such as the fast degradation rate of drugs and drug-induced cytotoxicity of organs and tissues. Nanomedicine formulations that prevent TAM signaling and recruitment to the TME or deplete M2 TAMs to reduce tumor growth and metastasis represent encouraging novel strategies in cancer therapy. They allow the specific delivery of antitumor drugs to the tumor area, thereby reducing side effects associated with systemic application. In this review, we give an overview of TAM biology and the current state of nanomedicines that target M2 macrophages in the course of cancer immunotherapy, with a specific focus on nanoparticles (NPs). We summarize how different types of NPs target M2 TAMs, and how the physicochemical properties of NPs (size, shape, charge and targeting ligands) influence NP uptake by TAMs in vitro and in vivo in the TME. Furthermore, we provide a comparative analysis of passive and active NP-based TAM-targeting strategies and discuss their therapeutic potential.

Biodegradable Polymeric Nanoparticles for Drug Delivery to Solid Tumors

Advances in nanotechnology have favored the development of novel colloidal formulations able to modulate the pharmacological and biopharmaceutical properties of drugs. The peculiar physico-chemical and technological properties of nanomaterial-based therapeutics have allowed for several successful applications in the treatment of cancer. The size, shape, charge and patterning of nanoscale therapeutic molecules are parameters that need to be investigated and modulated in order to promote and optimize cell and tissue interaction. In this review, the use of polymeric nanoparticles as drug delivery systems of anticancer compounds, their physico-chemical properties and their ability to be efficiently localized in specific tumor tissues have been described. The nanoencapsulation of antitumor active compounds in polymeric systems is a promising approach to improve the efficacy of various tumor treatments.

Engineering exosome polymer hybrids by atom transfer radical polymerization

Exosomes are emerging as ideal drug delivery vehicles due to their biological origin and ability to transfer cargo between cells. However, rapid clearance of exogenous exosomes from the circulation as well as aggregation of exosomes and shedding of surface proteins during storage limit their clinical translation. Here, we demonstrate highly controlled and reversible functionalization of exosome surfaces with well-defined polymers that modulate the exosome's physiochemical and pharmacokinetic properties. Using cholesterol-modified DNA tethers and complementary DNA block copolymers, exosome surfaces were engineered with different biocompatible polymers. Additionally, polymers were directly grafted from the exosome surface using biocompatible photo-mediated atom transfer radical polymerization (ATRP). These exosome polymer hybrids (EPHs) exhibited enhanced stability under various storage conditions and in the presence of proteolytic enzymes. Tuning of the polymer length and surface loading allowed precise control over exosome surface interactions, cellular uptake, and preserved bioactivity. EPHs show fourfold higher blood circulation time without altering tissue distribution profiles. Our results highlight the potential of precise nanoengineering of exosomes toward developing advanced drug and therapeutic delivery systems using modern ATRP methods.

Current advances in the development of novel polymeric nanoparticles for the treatment of neurodegenerative diseases

Effective intervention is essential to combat the coming epidemic of neurodegenerative (ND) diseases. Nanomedicine can overcome restrictions of CNS delivery imposed by the blood-brain barrier, and thus be instrumental in preclinical discovery and therapeutic intervention of ND diseases. Polymeric nanoparticles (PNPs) have shown great potential and versatility to encapsulate several compounds simultaneously in controlled drug-delivery systems and target them to the deepest brain regions. Here, we critically review recent advances in the development of drugs incorporated into PNPs and summarize the molecular changes and functional effects achieved in preclinical models of the most common ND disorders. We also briefly discuss the many challenges remaining to translate these findings and technological advances successfully to current clinical settings.

The preparation of pH and GSH dual responsive thiolated heparin/DOX complex and its application as drug carrier

The complicated preparation procedure and carrier's suspicious biocompatibility are two major limitations for traditional drug carrier. In this manuscript, a novel polyion complex (PIC) was prepared by simply mixing two biocompatible components, thiolated heparin and doxorubicin (DOX), and subsequently crosslinking under atmosphere, so that it can overcome the above limitations. The PIC's particle size kept stable for one week storage in PBS, and the particles wouldn't decomposed by the dilution, indicating excellent storage and anti-dilution stability resulting from the crosslinking. The PIC can release the larger amount of DOX in acidic environment than psychological environment, and largest amount in acidic and glutathione (GSH) environment, showing the pH and GSH dual sensitive drug release behavior. Furthermore, the PIC exhibited obvious tumor inhibition effect in vivo as well as long circulation ability and low heart toxicity by anti-tumor tests on tumor-bearing mice. Consequently, as-prepared PIC shows promising potential in drug carrier application.

Ocular implant containing bevacizumab-loaded chitosan nanoparticles intended for choroidal neovascularization treatment

Choroidal neovascularization (CNV) is among the leading causes of blindness worldwide. Bevacizumab has demonstrated promising effects on CNV treatment; however, frequent intravitreal injection is its major drawback. Current study aimed to address this issue by developing a sustained release formulation through nanoparticles of bevacizumab imbedded in an ocular implant. Bevacizumab-loaded chitosan nanoparticles were prepared by ionic gelation method and inserted in the matrix of hyaluronic acid and zinc sulfate. Despite the common approaches in using ultraviolet (UV)-spectrophotometry, microprotein-Bradford, and bicinchoninic acid (BCA), assay for protein assessment, our results revealed a remarkable UV-Vis absorption overlap of protein and chitosan during these analysis and thus enzyme-linked immunosorbent assay was employed for the antibody concentration assay. The size of optimized nanoparticles obtained through statistical analysis based on design of experiments was 78.5 ± 1.9 nm with polydispersity index of 0.13 ± 0.05 and the entrapment-efficiency and loading-efficiency were 67.6 ± 6.7 and 15.7 ± 5.7%, respectively. The scanning electron microscopy and confocal microscopy images revealed a homogenous distribution of nanoparticles in the implant matrix and the release test results indicated an appropriate extended release of bevacizumab from the carrier over two months. In conclusion, the prepared system provided a sustained release bevacizumab delivery formulation which can introduce a promising ocular drug delivery system intended for posterior segment disease. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2261-2271, 2018.

The preparation and morphology control of heparin-based pH sensitive polyion complexes and their application as drug carriers

Heparin as negative polysaccharide is a universal building block to form polyion complex with different cationic counterparts. In this paper, three different cations, including chitosan, benzyldodecyldimethyl ammonium bromide and doxorubicin hydrochloride, were used to prepare heparin-based polyion complexes (HPICs). Their morphologies could be tuned by heparin content in HPIC, and they also showed pH-sensitive decomposition. Doxorubicin was further encapsulated into micelle and vesicle carrier made from heparin-benzyldodecyl dimethyl ammonium bromide PIC, whereas heparin-doxorubicin PIC could be directly used as drug carrier. In vitro drug release proved the drug carriers exhibit obvious pH sensitive release behaviour. Cytotoxicity indicated the drug carrier possessed significant cytotoxicity to tumor cells. The cell uptake observed by CLSM showed the carrier was able to deliver antitumor drug into tumor cell's nucleus. Consequently, these results showed the promising potential of HPIC in drug carrier application.

A synergistic approach for management of lung carcinoma through folic acid functionalized co-therapy of capsaicin and gefitinib nanoparticles: Enhanced apoptosis and metalloproteinase-9 down-regulation

BACKGROUND

Lung cancer is one of the most lethal cancers and lacks effective treatment strategy. Therapeutic efficacy can be improved through active targeting approach utilizing surface engineered nanoparticles (NPs) for cancer therapy.

PURPOSE

The present study envisioned development of Folic acid (FA) functionalized NPs for co-administration of gefitinib (Gnb) and capsaicin (Cap) respectively to enhance the therapeutic outcome by disabling the barriers related to tumors extracellular matrix.

RESEARCH METHODS AND PROCEDURE

The FA conjugated Gnb/Cap polymeric (PLGA-PEG) NPs were prepared using oil in water emulsion technique and methodically developed using Quality by Design (QbD) concept employing central composite design. The developed formulations were subjected to various in vitro (A549 cell lines) and in vivo evaluations in urethane-induced lung cancer.

RESULTS

The modified NPs displayed particle sizes of 217.0 ± 3.2 nm and 213.0 ± 5.2 nm and drug release of 85.65 ± 3.21% and 81.43 ± 4.32% for Gnb and Cap respectively. Higher cellular uptake and lower cell viability in A549 cell line was displayed by functionalized NPs compared to free drug. Co administration of Gnb and Cap NPs displayed significant targeting potential, reduction in tumor volume while restoring the biochemical parameters viz., SOD, catalase, TBARS and protein carbonyl, towards normal levels when compared with toxic group. Significant down regulation was observed for anti-apoptotic proteins (MMP-9) and up regulation of pro-apoptotic proteins (caspase-3, caspase-9 and MMP-9) with co-therapy of Gnb and Cap NPs, when compared with individual therapy through Gnb/Cap.

CONCLUSION

Potentiation of the action of Gnb when co administered with Cap NPs can be a promising breakthrough for developing safe, effective and targeted delivery for lung carcinoma therapy.

Redox-responsive polymer inhibits macrophages uptake for effective intracellular gene delivery and enhanced cancer therapy

The development of advanced gene delivery carriers with stimuli-responsive release manner for tumor therapeutics is desirable, since they can exclusively release the therapeutic gene via their structural changes in response to the specific stimuli of the target site. Moreover, interactions between macrophages and drug delivery systems (DDSs) seriously impair the treatment efficiency of DDSs, thus macrophages uptake inhibition would to some extent improve the intracellular uptake of DDSs in tumor cells. Herein, a PEGylated redox-responsive gene delivery system was developed for effective cancer therapy. PEG modified glycolipid-like polymer (P-CSSO) was electrostatic interacted with p53 to form P-CSSO/p53 complexes, which exhibited an enhanced redox sensitivity in that the disulfide bond was degraded and the rate the plasmid released from P-CSSO was 2.29-fold that of nonresponsive platform (P-CSO-SA) in 10 mM levels of glutathione (GSH). PEGylation could significantly weaken macrophages uptake, while enhance the accumulation of P-CSSO in tumor cells both in vitro and in vivo. Compared with nonresponsive complexes (P-CSO-SA/p53) (59.2%) and Lipofectamine™ 2000/p53 complexes (52.0%), the tumor inhibition rate of P-CSSO/p53 complexes (77.1%) significantly increased, which was higher than CSSO/p53 complexes (69.9%). The present study indicates that tumor microenvironment sensitive and macrophages uptake suppressive P-CSSO/p53 is a powerful in vivo gene delivery system for enhanced anticancer therapy.

Bioconversion of Chitin to Bioactive Chitooligosaccharides: Amelioration and Coastal Pollution Reduction by Microbial Resources

Chitin-metabolizing products are of high industrial relevance in current scenario due to their wide biological applications, relatively lower cost, greater abundance, and sustainable supply. Chitooligosaccharides have remarkably wide spectrum of applications in therapeutics such as antitumor agents, immunomodulators, drug delivery, gene therapy, wound dressings, as chitinase inhibitors to prevent malaria. Hypocholesterolemic and antimicrobial activities of chitooligosaccharides make them a molecule of choice for food industry, and their functional profile depends on the physicochemical characteristics. Recently, chitin-based nanomaterials are also gaining tremendous importance in biomedical and agricultural applications. Crystallinity and insolubility of chitin imposes a major hurdle in the way of polymer utilization. Chemical production processes are known to produce chitooligosaccharides with variable degree of polymerization and properties along with ecological concerns. Biological production routes mainly involve chitinases, chitosanases, and chitin-binding proteins. Development of bio-catalytic production routes for chitin will not only enhance the production of commercially viable chitooligosaccharides with defined molecular properties but will also provide a means to combat marine pollution with value addition.

Cyclodextrin-grafted poly(anhydride) nanoparticles for oral glibenclamide administration. In vivo evaluation using C. elegans

The aim of this work was to prepare and evaluate cyclodextrins-modified poly(anhydride) nanoparticles to enhance the oral administration of glibenclamide. A conjugate polymer was synthesized by incorporating hydroxypropyl-β-cyclodextrin to the backbone of poly(methylvinyl ether-co-maleic anhydride) via Steglich reaction. The degree of substitution of anhydride rings by cyclodextrins molecules was calculated to be 4.9% using H-NMR spectroscopy. A central composite design of experiments was used to optimize the preparative process. Under the optimal conditions, nanoparticles displayed a size of about 170 nm, a surface charge of -47 mV and a drug loading of 69 µg GB/mg. X-ray diffraction studies confirmed the loss of the crystalline structure of GB due to its dispersion into the nanoparticles, either included into cyclodextrin cavities or entrapped in the polymer chains. Glibenclamide was mainly release by Fickian-diffusion in simulated intestinal fluid. GB-loaded nanoparticles produced a hypolipidemic effect over C. elegans N2 wild-type and daf-2 mutant. The action mechanism included daf-2 and daf-28 genes, both implicated in the insulin signaling pathway of C. elegans. In summary, the covalent linkage of cyclodextrin to the poly(anhydride) backbone could be an interesting strategy to prepare nanoparticles for the oral administration of glibenclamide.

Molecular engineering solutions for therapeutic peptide delivery

Proteins and their interactions in and out of cells must be well-orchestrated for the healthy functioning and regulation of the body. Even the slightest disharmony can cause diseases. Therapeutic peptides are short amino acid sequences (generally considered <50 amino acids) that can naturally mimic the binding interfaces between proteins and thus, influence protein-protein interactions. Because of their fidelity of binding, peptides are a promising next generation of personalized medicines to reinstate biological harmony. Peptides as a group are highly selective, relatively safe, and biocompatible. However, they are also vulnerable to many in vivo pharmacologic barriers limiting their clinical translation. Current advances in molecular, chemical, and nanoparticle engineering are helping to overcome these previously insurmountable obstacles and improve the future of peptides as active and highly selective therapeutics. In this review, we focus on self-assembled vehicles as nanoparticles to carry and protect therapeutic peptides through this journey, and deliver them to the desired tissue.

Comparative Study of Ex Vivo Transmucosal Permeation of Pioglitazone Nanoparticles for the Treatment of Alzheimer's Disease

Pioglitazone has been reported in the literature to have a substantial role in the improvement of overall cognition in a mouse model. With this in mind, the aim of this study was to determine the most efficacious route for the administration of Pioglitazone nanoparticles (PGZ-NPs) in order to promote drug delivery to the brain for the treatment of Alzheimer's disease. PGZ-loaded NPs were developed by the solvent displacement method. Parameters such as mean size, polydispersity index, zeta potential, encapsulation efficacy, rheological behavior, and short-term stability were evaluated. Ex vivo permeation studies were then carried out using buccal, sublingual, nasal, and intestinal mucosa. PGZ-NPs with a size around of 160 nm showed high permeability in all mucosae. However, the permeation and prediction parameters revealed that lag-time and vehicle/tissue partition coefficient of nasal mucosa were significantly lower than other studied mucosae, while the diffusion coefficient and theoretical steady-state plasma concentration of the drug were higher, providing biopharmaceutical results that reveal more favorable PGZ permeation through the nasal mucosa. The results suggest that nasal mucosa represents an attractive and non-invasive pathway for PGZ-NPs administration to the brain since the drug permeation was demonstrated to be more favorable in this tissue.

Coating Matters: Review on Colloidal Stability of Nanoparticles with Biocompatible Coatings in Biological Media, Living Cells and Organisms

Within the last two decades, the field of nanomedicine has not developed as successfully as has widely been hoped for. The main reason for this is the immense complexity of the biological systems, including the physico-chemical properties of the biological fluids as well as the biochemistry and the physiology of living systems. The nanoparticles' physicochemical properties are also highly important. These differ profoundly from those of freshly synthesized particles when applied in biological/living systems as recent research in this field reveals. The physico-chemical properties of nanoparticles are predefined by their structural and functional design (core and coating material) and are highly affected by their interaction with the environment (temperature, pH, salt, proteins, cells). Since the coating material is the first part of the particle to come in contact with the environment, it does not only provide biocompatibility, but also defines the behavior (e.g. colloidal stability) and the fate (degradation, excretion, accumulation) of nanoparticles in the living systems. Hence, the coating matters, particularly for a nanoparticle system for biomedical applications, which has to fulfill its task in the complex environment of biological fluids, cells and organisms. In this review, we evaluate the performance of different coating materials for nanoparticles concerning their ability to provide colloidal stability in biological media and living systems.

Stealth Biocompatible Si-Based Nanoparticles for Biomedical Applications

A challenge regarding the design of nanocarriers for drug delivery is to prevent their recognition by the immune system. To improve the blood residence time and prevent their capture by organs, nanoparticles can be designed with stealth properties using polymeric coating. In this study, we focused on the influence of surface modification with polyethylene glycol and/or mannose on the stealth behavior of porous silicon nanoparticles (pSiNP, ~200 nm). In vivo biodistribution of pSiNPs formulations were evaluated in mice 5 h after intravenous injection. Results indicated that the distribution in the organs was surface functionalization-dependent. Pristine pSiNPs and PEGylated pSiNPs were distributed mainly in the liver and spleen, while mannose-functionalized pSiNPs escaped capture by the spleen, and had higher blood retention. The most efficient stealth behavior was observed with PEGylated pSiNPs anchored with mannose that were the most excreted in urine at 5 h. The biodegradation kinetics evaluated in vitro were in agreement with these in vivo observations. The biocompatibility of the pristine and functionalized pSiNPs was confirmed in vitro on human cell lines and in vivo by cytotoxic and systemic inflammation investigations, respectively. With their biocompatibility, biodegradability, and stealth properties, the pSiNPs functionalized with mannose and PEG show promising potential for biomedical applications.

Recent developments in nanomedicine for melanoma treatment

Melanoma is a most aggressive skin cancer with limited therapeutic options and its incidence is increasing rapidly in recent years. The discovery and application of new targeted therapy agents have shown significant benefits. However, adverse side-effects and resistance to chemotherapy remain formidable challenges in the clinical treatment of malignant melanoma. Nanotherapeutics offers an important prospect of overcoming these drawbacks. The anti-tumoral applications of nanomedicine are varied, including those in chemotherapy, RNA interference, photothermal therapy, and photodynamic therapy. Furthermore, nanomedicine allows delivery of the effector structures into the tumor site via passive or active targeting, thereby allowing increased therapeutic specificity and reduced side effects. In this review, we summarize the latest developments in the application of nanocarrier-mediated targeted drug delivery to melanoma and nanomedicine-related clinical trials in melanoma treatment. We also discuss existing problems and opportunities for future developments, providing direction and new thoughts for further studies.

Hardly water-soluble drug-loaded gelatin nanoparticles sustaining a slow release: preparation by novel single-step O/W/O emulsion accompanying solvent diffusion

Paclitaxel (PTX)-loaded gelatin nanoparticles (NPs) were prepared, for the first time, by novel O/W/O emulsion with a single-step emulsion process accompanying solvent diffusion, in contrast to the conventional double-step emulsion processes. Linoleic acid was chosen among the natural fatty acids as the exterior medium for the single-step emulsion process accompanying solvent diffusion. The size mean and zeta potential of the PTX-loaded gelatin NPs in their suspension were 164.95 nm (±6.43 nm) distributed with a polydispersity of 0.074 (±0.046) and -23.85 mV (±12.66 mV), respectively. The size of the PTX-loaded gelatin NPs prepared in this study was the smallest among the reported sizes of PTX-loaded gelatin NPs, which would contribute to the enhanced permeability and retention (EPR). In addition, TEM showed that the loaded PTX was located mostly inside the gelatin NPs unlike previous investigations. Accordingly, the conceptual model of the designed PTX-loaded gelatin nanoparticle was introduced. Sustaining a slow PTX release on a day-time scale without an initial burst release into a release medium was observed along with a delay of more than 2 days (i.e., 50 h) before a bursting PTX release from 50 to 70 h despite the addition of a protein degrading enzyme. The observed PTX-loading efficiency was 54.5%. This loading efficiency was greater than that of previous study using gelatin of bloom 75-100 of Lu et al. to prepare PTX-loaded gelatin NPs using a desolvation method.

Applying nanotherapeutics to improve chemoradiotherapy treatment for cancer

Chemoradiotherapy (CRT) plays a key role in the curative treatment of many human cancers. The full utility of this paradigm is often restricted by limitations of conventional drug delivery. Nanotherapeutics have demonstrated great potential to overcome many of these issues. The potential benefits of nanotherapeutics in CRT include improved therapeutic efficacy, decreased toxicity, enhanced real-time in vivo tumor imaging, and the translation of novel small molecule drugs or nucleic acid therapies. Additionally, nanomedicines and radiation therapy exert distinct and complementary effects on the tumor microenvironment which can further enhance therapeutic efficacy compared with either modality alone. In this review, we highlight specific clinical and preclinical examples which demonstrate the potential benefits of nanotherapeutics in CRT.

Confined Pool-Buried Water-Soluble Nanoparticles from Reverse Micelles

With the special nature of confined water pools, reverse micelles (RMs) have shown potential for a wide range of applications. However, the inherent water insolubility of RMs hinders their further application prospect especially for applications related to biology. We present herein the first successful transformation of water-insoluble RMs into water-soluble nanoparticles without changing the confined aqueous interiors by hydrolysis/aminolysis of arm-cleavable interfacial cross-linked reverse micelles formed from diester surfactant 1. The unique properties exhibited by the aqueous interiors of the resulting pool-buried water-soluble nanoparticles (PWNPs) were demonstrated both by the template synthesis of gold nanoparticles in the absence of external reductants and by the fluorescence enhancement of encapsulated thioflavin T (ThT). Importantly, the unique potential for PWNPs in biological applications was exemplified by the use of ThT@PWNPs and "cell targeted" ThT@PWNPs as effective optical imaging agents of living cells. This work conceptually overcomes the application bottleneck of RMs and opens an entry to a new class of functional materials.

Docetaxel-Loaded Nanoparticles Assembled from β-Cyclodextrin/Calixarene Giant Surfactants: Physicochemical Properties and Cytotoxic Effect in Prostate Cancer and Glioblastoma Cells

Giant amphiphiles encompassing a hydrophilic β-cyclodextrin (βCD) component and a hydrophobic calix[4]arene (CA₄) module undergo self-assembly in aqueous media to afford core-shell nanospheres or nanocapsules, depending on the nanoprecipitation protocol, with high docetaxel (DTX) loading capacity. The blank and loaded nanoparticles have been fully characterized by dynamic light scattering (DLS), ζ-potential measurements and cryo-transmission electron microscopy (cryo-TEM). The data are compatible with the distribution of the drug between the nanoparticle core and the shell, where it is probably anchored by inclusion of the DTX aromatic moieties in βCD cavities. Indeed, the release kinetics profiles evidenced an initial fast release of the drug, which likely accounts for the fraction hosted on the surface, followed by a slow and sustained release rate, corresponding to diffusion of DTX in the core, which can be finely tuned by modification of the giant amphiphile chemical structure. The ability of the docetaxel-loaded nanoparticles to induce cellular death in different prostate (human LnCap and PC3) and glioblastoma (human U87 and rat C6) cells was also explored. Giant amphiphile-based DTX formulations surpassing or matching the antitumoral activity of the free DTX formulation were identified in all cases with no need to employ any organic co-solvent, thus overcoming the DTX water solubility problems. Moreover, the presence of the βCD shell at the surface of the assemblies is intended to impart stealth properties against serum proteins while permitting nanoparticle surface decoration by supramolecular approaches, paving the way for a new generation of molecularly well-defined antitumoral drug delivery systems with improved specificity and efficiency. Altogether, the results provide a proof of concept of the suitability of the approach based on βCD-CA₄ giant amphiphiles to access DTX carriers with tunable properties.

Penetration of CdSe/ZnS quantum dots into differentiated vs undifferentiated Caco-2 cells

Background

Quantum dots (QDs) have great potential as fluorescent labels but cytotoxicity relating to extra- and intracellular degradation in biological systems has to be addressed prior to biomedical applications. In this study, human intestinal cells (Caco-2) grown on transwell membranes were used to study penetration depth, intracellular localization, translocation and cytotoxicity of CdSe/ZnS QDs with amino and carboxyl surface modifications. The focus of this study was to compare the penetration depth of QDs in differentiated vs undifferentiated cells using confocal microscopy and image processing.

Results

Caco-2 cells were exposed to QDs with amino (NH₂) and carboxyl (COOH) surface groups for 3 days using a concentration of 45 µg cadmium ml⁻¹. Image analysis of confocal/multiphoton microscopy z-stacks revealed no penetration of QDs into the cell lumen of differentiated Caco-2 cells. Interestingly, translocation of cadmium ions onto the basolateral side of differentiated monolayers was observed using high resolution inductively coupled plasma mass spectrometry (ICP-MS). Membrane damage was neither detected after short nor long term incubation in Caco-2 cells. On the other hand, intracellular localization of QDs after exposure to undifferentiated cells was observed and QDs were partially located within lysosomes.

Conclusions

In differentiated Caco-2 monolayers, representing a model for small intestinal enterocytes, no penetration of amino and carboxyl functionalized CdSe/ZnS QDs into the cell lumen was detected using microscopy analysis and image processing. In contrast, translocation of cadmium ions onto the basolateral side could be detected using ICP-MS. However, even after long term incubation, the integrity of the cell monolayer was not impaired and no cytotoxic effects could be detected. In undifferentiated Caco-2 cells, both QD modifications could be found in the cell lumen. Only to some extend, QDs were localized in endosomes or lysosomes in these cells. The results indicate that the differentiation status of Caco-2 cells is an important factor in internalization and localization studies using Caco-2 cells. Furthermore, a combination of microscopy analysis and sensitive detection techniques like ICP-MS are necessary for studying the interaction of cadmium containing QDs with cells.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-016-0222-9) contains supplementary material, which is available to authorized users.