Dextrin nanoparticles: Studies on the interaction with murine macrophages and blood clearance

Structure of the Active Nanocomplex of Antiviral and Anti-Infectious Iodine-Containing Drug FS-1

Chromatographic analysis shows that the ionic nanostructured complex of the FS-1 drug contains nanocomplexes of α-dextrin with a size of ~40–48 Å. Based on good agreement between the UV spectra of the model structures and the experimental spectrum of the FS-1 drug, the structure of the active FS-1 nanocomplex is proposed. The structure of the active centers of the drug in the dextrin ring was calculated using the quantum-chemical approach DFT/B3PW91. The active centers, i.e., a complex of molecular iodine with lithium halide (I), a binuclear complex of magnesium and lithium containing molecular iodine, triiodide (II), and triiodide (III), are located inside the dextrin helix. The polypeptide outside the dextrin helix forms a hydrogen bond with dextrin in Complex I and coordinates the molecular iodine in Complex II. It is revealed that the active centers of the FS-1drug can be segregated from the dextrin helix and form complexes with DNA nucleotide triplets. The active centers of the FS-1 drug are only segregated on specific sections of DNA. The formation of a complex between the DNA nucleotide and the active center of FS-1 is a key stage in the mechanisms of anti-HIV, anti-coronavirus (Complex I) and antibacterial action (Complex II).

Development of dextrin-amphotericin B formulations for the treatment of Leishmaniasis

The most effective medicines available for the treatment of leishmaniasis, a life-threatening disease, exhibit serious toxicological issues. To achieve better therapeutic efficiency while decreasing toxicity associated with amphotericin B (AmB), water-soluble dextrin-AmB (Dex-AmB) formulations were developed. Self-assembled nanocomplexes were formed by dissolving Dex and AmB in alkaline borate buffer, followed by dialysis and either freeze-drying (FD) or nano spray-drying (SD), yielding water dispersible particles with a diameter of 214 nm and 347 nm, respectively. The very simple production process allowed the formation of amorphous inclusion complexes containing 14% of AmB in the form of monomers and water-soluble aggregates. Nanocomplexes were effective against parasites in axenic culture (IC₅₀ of 0.056 and 0.096 μM for L. amazonensis and 0.030 and 0.044 μM for L. infantum, respectively for Dex-AmB FD and Dex-AmB SD) and in decreasing the intramacrophagic infection with L. infantum (IC₅₀ of 0.017 and 0.023 μM, respectively for Dex-AmB FD and Dex-AmB SD). Also, the formulations were able to significantly reduce the cytotoxicity of AmB. Overall, this study demonstrates the suitability of dextrin as an AmB carrier and the facile and inexpensive development of a delivery system for the treatment of leishmaniasis.

In vivo systemic toxicity assessment of an oxidized dextrin-based hydrogel and its effectiveness as a carrier and stabilizer of granular synthetic bone substitutes

The worldwide incidence of bone disorders is raising, mainly due to aging population. The lack of effective treatments is pushing the development of synthetic bone substitutes (SBSs). Most ceramic-based SBSs commercially available display limited handling properties. Attempting to solve these issues and achieve wider acceptance by the clinicians, granular ceramics have been associated with hydrogels (HGs) to produce injectable/moldable SBSs. Dextrin, a low-molecular-weight carbohydrate, was used to develop a fully resorbable and injectable HG. It was first oxidized with sodium periodate and then cross-linked with adipic acid dihydrazide. The in vivo biocompatibility and safety of the dextrin-based HG was assessed by subacute systemic toxicity and skin sensitization tests, using rodent models. The results showed that the HG did not induce any systemic toxic effect, skin reaction, or genotoxicity, neither impaired the bone repair/regeneration process. Then, the HG was successfully combined with granular bone substitute, registered as Bonelike (250-500 μm) to obtain a moldable/injectable SBS, which was implanted in tibial fractures in goats for 3 and 6 weeks. The obtained results showed that HG allowed the stabilization of the granules into the defect, ensuring effective handling, and molding properties of the formulation, as well as an efficient cohesion of the granules. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1678-1689, 2019.

Potential of mannan or dextrin nanogels as vaccine carrier/adjuvant systems

Polymeric nanogels have been sophisticatedly designed promising a new generation of vaccine delivery/adjuvant systems capable of boosting immune response, a strategic priority in vaccine design. Here, nanogels made of mannan or dextrin were evaluated for their potential as carriers/adjuvants in vaccine formulations. Since lymph nodes are preferential target organs for vaccine delivery systems, nanogels were biotin-labeled, injected in the footpad of rats, and their presence in draining lymph nodes was assessed by immunofluorescence. Nanogels were detected in the popliteal and inguinal lymph nodes by 24 h upon subcutaneous administration, indicating entrapment in lymphatic organs. Moreover, the model antigen ovalbumin was physically encapsulated within nanogels and physicochemically characterized concerning size, zeta potential, ovalbumin loading, and entrapment efficiency. The immunogenicity of these formulations was assessed in mice intradermally immunized with ovalbumin–mannan or ovalbumin–dextrin by determining ovalbumin-specific antibody serum titers. Intradermal vaccination using ovalbumin–mannan elicited a humoral immune response in which ovalbumin-specific IgG1 levels were significantly higher than those obtained with ovalbumin alone, indicating a TH2-type response. In contrast, dextrin nanogel did not show adjuvant potential. Altogether, these results indicate that mannan nanogel is a material that should be explored as a future antigen delivery system.

Biocompatibility of a Self-Assembled Crosslinkable Hyaluronic Acid Nanogel

Hyaluronic acid nanogel (HyA-AT) is a redox sensitive crosslinkable nanogel, obtained through the conjugation of a thiolated hydrophobic molecule to the hyaluronic acid chain. Engineered nanogel was studied for its biocompatibility, including immunocompatibility and hemocompatability. The nanogel did not compromise the metabolic activity or cellular membrane integrity of 3T3, microvascular endothelial cells, and RAW 264.7 cell lines, as determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide and lactate dehydrogenase release assays. Also, we didn't observe any apoptotic effect on these cell lines through the Annexin V-FITC test. Furthermore, the nanogel cell internalization was analyzed using murine bone marrow derived macrophages, and the in vivo and ex vivo biodistribution of the Cy5.5 labeled nanogel was monitored using a non-invasive near-infrared fluorescence imaging system. The HyA-AT nanogel exhibits fairly a long half-live in the blood stream, thus showing potential for drug delivery applications.

Enhanced anti-tumor effect of pH-responsive dextrin nanogels delivering doxorubicin on colorectal cancer

Efficacy of doxorubicin (DOX) in colorectal cancer treatment is limited by undesirable side-effects, which are partially due to nonspecific delivery DOX to the tumor target site. This study aimed to develop pH-responsive dextrin nanogels (DNGs) as anticancer drug carriers with pH-controlled drug release. DNGs prepared with formaldehyde as a cross-linker (FDNGs) exhibited smaller size, compared to that using glyoxal (GDNGs). Both DNGs showed pH-dependent drug release properties; drug release was slow at neutral pH but increased significantly in acidic medium. The cytotoxicity of empty and DOX-loaded FDNGs was lower than free DOX and GDNGs, against two commonly used colorectal cancer cells. Intracellular uptake studies indicated that the DOX-loaded FDNGs could efficiently deliver DOX into the nuclei. In vivo, DOX-loaded FDNGs substantially enhanced anti-tumor efficacy, compared to free DOX, exhibiting much higher effects on inhibiting proliferation and inducing apoptosis, as confirmed by mice weight shifts, tumor weight, tumor volume and histological assessment. Therefore, FDNGs are promising as a potential drug delivery vehicle for colorectal cancer therapy.

Biocompatibility of a self-assembled glycol chitosan nanogel

The research of chitosan-based nanogel for biomedical applications has grown exponentially in the last years; however, its biocompatibility is still insufficiently reported. Hence, the present work provides a thorough study of the biocompatibility of a glycol chitosan (GC) nanogel. The obtained results showed that GC nanogel induced slight decrease on metabolic activity of RAW, 3T3 and HMEC cell cultures, although no effect on cell membrane integrity was verified. The nanogel does not promote cell death by apoptosis and/or necrosis, exception made for the HMEC cell line challenged with the higher GC nanogel concentration. Cell cycle arrest on G1 phase was observed only in the case of RAW cells. Remarkably, the nanogel is poorly internalized by bone marrow derived macrophages and does not trigger the activation of the complement system. GC nanogel blood compatibility was confirmed through haemolysis and whole blood clotting time assays. Overall, the results demonstrated the safety of the use of the GC nanogel as drug delivery system.

Novel pH-responsive dextrin nanogels for doxorubicin delivery to cancer cells with reduced cytotoxicity to cardiomyocytes and stem cells

The aim of this study was to develop pH-responsive dextrin nanogels (DNGs) capable of triggered intracellular DOX release at the lower pH of cancer cells. DNGs were prepared by an emulsion cross-linking method using glyoxal as cross-linker to create an acid-labile bond. A higher molecular weight of dextrin with increasing mole ratio of dextrin to glyoxal decreased the average diameter of DNGs. DNGs showed slightly negative surface charge and pH-responsive behavior. The in vitro drug release was slow at pH 7.4 and increased with decreasing pH (pH 5>6.8). The cytotoxicity of DOX-loaded DNGs in mesenchymal stem cells and cardiomyocytes was lower than that of free DOX. Moreover, DOX-loaded DNGs were efficiently internalized by tumor cells with rapid release of DOX into the nucleus. Thus, DOX-loaded DNGs were successful for intracellular targeted anti-tumor drug delivery and reducing side-effects to non-tumor cells such as cardiomyocytes and stem cells.

Upconverting and NIR emitting rare earth based nanostructures for NIR-bioimaging

In recent years, significant progress was achieved in the field of nanomedicine and bioimaging, but the development of new biomarkers for reliable detection of diseases at an early stage, molecular imaging, targeting and therapy remains crucial. The disadvantages of commonly used organic dyes include photobleaching, autofluorescence, phototoxicity and scattering when UV (ultraviolet) or visible light is used for excitation. The limited penetration depth of the excitation light and the visible emission into and from the biological tissue is a further drawback with regard to in vivo bioimaging. Lanthanide containing inorganic nanostructures emitting in the near-infrared (NIR) range under NIR excitation may overcome those problems. Due to the outstanding optical and magnetic properties of lanthanide ions (Ln(3+)), nanoscopic host materials doped with Ln(3+), e.g. Y2O3:Er(3+),Yb(3+), are promising candidates for NIR-NIR bioimaging. Ln(3+)-doped gadolinium-based inorganic nanostructures, such as Gd2O3:Er(3+),Yb(3+), have a high potential as opto-magnetic markers allowing the combination of time-resolved optical imaging and magnetic resonance imaging (MRI) of high spatial resolution. Recent progress in our research on over-1000 nm NIR fluorescent nanoprobes for in vivo NIR-NIR bioimaging will be discussed in this review.

Engineering antiphagocytic biomimetic drug carriers

Drug-delivery carriers have the potential to not only treat but also diagnose many diseases; however, they still lack the complexity of natural-particulate systems. Cell-based therapies using tumor-targeting T cells and tumor-homing mesenchymal stem cells have given researchers a means to exploit the characteristics exhibited by innate-biological entities. Similarly, immune evasion by pathogens has inspired the development of natural polymers to cloak drug carriers. The 'marker-of-self' CD47 protein, which is found ubiquitously on mammalian cell surfaces, has been used for evading phagocyte clearance of drug carriers. This review will focus on the recent progress of drug carriers co-opting the tricks that cells in nature use to hide safely under the radar of the body's innate immune system.

Cytotoxic aspects of gadolinium oxide nanostructures for up-conversion and NIR bioimaging

Bioimaging is an important diagnostic tool in the investigation and visualization of biological phenomena in cells and in medicine. In this context, up-converting Gd(2)O(3):Er(3+),Yb(3+) nanostructures (nanoparticles, nanorods) have been synthesized by precipitation methods and hydrothermal synthesis. Independent of size and morphology, Gd(2)O(3):Er(3+),Yb(3+) powders show up-conversion (550 nm, 670 nm) and near-infrared emission (1.5 μm) upon 980 nm excitation, which makes these structures interesting for application as biomarkers. With regard to their potential application in bioimaging, cytotoxicity is an important aspect and is strongly affected by the physico-chemical properties of the investigated nanostructures. Therefore, the cytotoxic effect of bare and poly(ethylene glycol)-b-poly(acrylic acid) block co-polymer-modified nanostructures on non-phagocytic and phagocytic cells (B-cell hybridoma cells and macrophages) was investigated. The observed cytotoxic behavior in the case of macrophages incubated with bare nanostructures was assigned to the poor chemical durability of gadolinium oxide, but could be overcome by surface modification.

Functionalization density dependent toxicity of oxidized multiwalled carbon nanotubes in a murine macrophage cell line

The present study investigates the effect of functionalization density on the toxicity and cellular uptake of oxidized multiwalled carbon nanotubes (f-MWCNTs) in vitro. The toxicity of f-MWCNTs at varying degrees of carboxylation was assessed in a murine macrophage RAW 264.7 cell line, a model for liver Kupffer cells. In vitro cytotoxicity of oxidized MWCNTs was directly proportional to their functionalization density. The increased cytotoxicity was associated with a concurrent increase in the number of apoptotic cells and production of reactive nitrogen species (RNS). In contrast, reactive oxygen species (ROS) generation was the highest in the case of pristine MWCNTs and decreased with increased functionalization density. Quantitative cellular uptake studies indicated that endogenous ROS production was independent of the concentration of CNTs internalized by a specific cell population and was directly proportional to their surface hydrophobicity. Mechanistic studies suggested that cellular uptake of CNTs was critically charge-dependent and mediated through scavenger receptors, albeit the involvement of nonscavenger receptor mechanisms at low CNT concentrations and their saturation at the experimental concentration cannot be ruled out. A mathematical model was established to correlate between the cellular uptake of CNTs with their length and zeta potential. In an attempt to correlate the results of in vitro toxicity experiments with those of the in vivo toxicity in the mouse model, we found that the toxicity trends in vitro and in vivo are rather opposing. The apparent anomaly was explained on the basis of different experimental conditions and doses associated with cells under in vivo and in vitro culture conditions.

Antiproliferative activity of fucan nanogel

Sulfated fucans comprise families of polydisperse natural polysaccharides based on sulfated L-fucose. Our aim was to investigate whether fucan nanogel induces cell-specific responses. To that end, a non toxic fucan extracted from Spatoglossum schröederi was chemically modified by grafting hexadecylamine to the polymer hydrophilic backbone. The resulting modified material (SNFuc) formed nanosized particles. The degree of substitution with hydrophobic chains was close to 100%, as estimated by elemental analysis. SNFfuc in aqueous media had a mean diameter of 123 nm and zeta potential of -38.3 ± 0.74 mV, as measured by dynamic light scattering. Nanoparticles conserved their size for up to 70 days. SNFuc cytotoxicity was determined using the MTT assay after culturing different cell lines for 24 h. Tumor-cell (HepG2, 786, H-S5) proliferation was inhibited by 2.0%-43.7% at nanogel concentrations of 0.05-0.5 mg/mL and rabbit aorta endothelial cells (RAEC) non-tumor cell line proliferation displayed inhibition of 8.0%-22.0%. On the other hand, nanogel improved Chinese hamster ovary (CHO) and monocyte macrophage cell (RAW) non-tumor cell line proliferation in the same concentration range. The antiproliferative effect against tumor cells was also confirmed using the BrdU test. Flow cytometric analysis revealed that the fucan nanogel inhibited 786 cell proliferation through caspase and caspase-independent mechanisms. In addition, SNFuc blocks 786 cell passages in the S and G2-M phases of the cell cycle.

Supramolecular assembled nanogel made of mannan

The supramolecular assembly of amphiphilic mannan, synthesized by the Michael addition of hydrophobic 1-hexadecanethiol to vinyl methacrylated mannan, originates in aqueous medium the formation of a nanogel, stabilized by hydrophobic interactions among alkyl chains. The critical aggregation concentration, calculated by fluorescence spectroscopy ranged between 0.002 and 0.01 mg/mL, depending on the polymer degree of substitution. The cryo-field emission scanning electron microscopy showed spherical macromolecular micelles with diameters between 100 and 500 nm. The dynamic light scattering analysis revealed a polydisperse colloidal system, with mean hydrodynamic diameter between 50 and 140 nm, depending on the polymer degree of substitution. The nanogel is negatively charged, stable over a 6 months storage period, and stable at pH 3-8, salt or urea solutions. Bovine serum albumin and curcumin were spontaneously incorporated in the nanogel, being stabilized by the hydrophobic domains, opening the possibility for future applications as potential delivery systems for therapeutic molecules. In vitro assays were carried out to characterize the biocompatibility of the nanogel. A toxic effect of mannan-C(16) was observed, specific to mouse macrophage-like cell line J774, not affecting mouse embryo fibroblast cell line 3T3 viability.

Biologically optimized nanosized molecules and particles: more than just size

The expanded biological and medical applications of nanomaterials place a premium on better understanding of the chemical and physical determinants of in vivo particles. Nanotechnology allows us to design a vast array of molecules with distinct chemical and biological characteristics, each with a specific size, charge, hydrophilicity, shape, and flexibility. To date, much research has focused on the role of particle size as a determinant of biodistribution and clearance. Additionally, much of what we know about the relationship between nanoparticle traits and pharmacokinetics has involved research limited to the gross average hydrodynamic size. Yet, other features such as particle shape and flexibility affect in vivo behavior and become increasingly important for designing and synthesizing nanosized molecules. Herein, we discuss determinants of in vivo behavior of nanosized molecules used as imaging agents with a focus on dendrimer-based contrast agents. We aim to discuss often overlooked or, yet to be considered, factors that affect in vivo behavior of synthetic nanosized molecules, as well as aim to highlight important gaps in current understanding.

Self-assembled dextrin nanogel as protein carrier: controlled release and biological activity of IL-10

Interleukin-10 (IL-10) is an anti-inflammatory cytokine, which active form is a non-covalent homodimer. Given the potential of IL-10 for application in various medical conditions, it is essential to develop systems for its effective delivery. In previous work, it has been shown that a dextrin nanogel effectively incorporated and stabilized rIL-10, enabling its release over time. In this work, the delivery system based on dextrin nanogels was further analyzed. The biocompatibility of the nanogel was comprehensively analyzed, through cytotoxicity (lactate dehydrogenase (LDH) release, MTS, Live, and Dead) and genotoxicity (comet) assays. The release profile of rIL-10 and its biological activity were evaluated in vivo, using C57BL/6 mice. Although able to maintain a stable concentration of IL-10 for at least 4 h in mice serum, the amount of protein released was rather low. Despite this, the amount of rIL-10 released from the complex was biologically active inhibiting TNF-α production, in vivo, by LPS-challenged mice. In spite of the significant stabilization achieved using the nanogel, rIL-10 still denatures rather quickly. An additional effort is thus necessary to develop an effective delivery system for this cytokine, able to release active protein over longer periods of time. Nevertheless, the good biocompatibility, the protein stabilization effect and the ability to perform as a carrier with controlled release suggest that self-assembled dextrin nanogels may be useful protein delivery systems.

Nanoparticles and modulation of immune responses

The exact role of engineered nanomaterials in immune system modulation remains unclear. The aim of this concise review is to give a comprehensive insight into recent published scientific data concerning the modulation of innate and adaptive immune responses by engineered nanoparticles, and to provide a basis for future experimental work related to designing safer, and more efficient biomaterials.

Studies on the biodistribution of dextrin nanoparticles

The characterization of biodistribution is a central requirement in the development of biomedical applications based on the use of nanoparticles, in particular for controlled drug delivery. The blood circulation time, organ biodistribution and rate of excretion must be well characterized in the process of product development. In this work, the biodistribution of recently developed self-assembled dextrin nanoparticles is addressed. Functionalization of the dextrin nanoparticles with a DOTA-monoamide-type metal chelator, via click chemistry, is described. The metal chelator functionalized nanoparticles were labelled with a gamma-emitting (153)Sm(3+) radioisotope and the blood clearance rate and organ biodistribution of the nanoparticles were obtained. The effect of PEG surface coating on the blood clearance rate and organ biodistribution of the nanoparticles was also studied.

Self-Assembled Hydrogel Nanoparticles for Drug Delivery Applications

Hydrogel nanoparticles—also referred to as polymeric nanogels or macromolecular micelles—are emerging as promising drug carriers for therapeutic applications. These nanostructures hold versatility and properties suitable for the delivery of bioactive molecules, namely of biopharmaceuticals. This article reviews the latest developments in the use of self-assembled polymeric nanogels for drug delivery applications, including small molecular weight drugs, proteins, peptides, oligosaccharides, vaccines and nucleic acids. The materials and techniques used in the development of self-assembling nanogels are also described.