A comparative study of chitosan shielding effect on nano-carriers hydrophilicity and biodistribution

Magnetic and pH-responsive magnetite/chitosan (core/shell) nanoparticles for dual-targeted methotrexate delivery in cancer therapy

Methotrexate successful therapy encounters various challenges in chemotherapy, such as poor oral bioavailability, low specificity, side effects and the development of drug resistances. In this study, it is proposed a dual-targeted nanocarrier comprising magnetite/chitosan nanoparticles for an efficient Methotrexate delivery. The formation of the particles was confirmed through morphological analysis using electron microscopy and elemental mappings via energy dispersive X-ray spectroscopy. These nanoparticles exhibited a size of ≈ 270 nm, a zeta potential of ≈ 24 mV, and magnetic responsiveness, as demonstrated by hysteresis cycle analysis and visual observations under a magnetic field. In addition, these particles displayed high stability, as evidenced by size and surface electric charge measurements, during storage at both 4 ºC and 25 ºC for at least 30 days. Electrophoretic properties were examined in relation to pH and ionic strength, confirming these core/shell nanostructure. The nanoparticles demonstrated a pH-responsive drug release as observed by a sustained Methotrexate release over the next 90 h under pH ≈ 7.4, while complete release occurred within 3 h under acidic conditions (pH ≈ 5.5). In the biocompatibility assessment, the magnetite/chitosan particles showed excellent hemocompatibility ex vivo and no cytotoxic effects on normal MCF-10 A and cancer MCF-7 cells. Furthermore, the Methotrexate-loaded nanoparticles significantly enhanced the antitumor activity reducing the half-maximal inhibitory concentration by ≈ 2.7-fold less compared to the free chemotherapeutic.

Chitosan-coated PLA/poloxamer nanoparticles stimulate immunologic cancer cell death and synergistic chemo-immunotherapeutic efficacy

Cancer, a key factor in declining global life expectancy, has driven the integration of chemotherapy and immunotherapy to address multidrug resistance and influence the tumor microenvironment. We developed a novel vaccine delivery carrier, a chitosan-coated polylactic acid/poloxamer nanoparticle (CPP NP), designed to co-encapsulate an anticancer drug and antigen without any chemical conjugation process, enabling effective and synergistic cancer chemo-immunotherapy. The CPP NP achieved synergistic efficacy through paclitaxel (PTX), an immunogenic cell death-inducing chemotherapeutic agent; ovalbumin (OVA), which promotes dendritic cell maturation; and enhanced cellular uptake facilitated by chitosan. The PTX and OVA-loaded CPP NPs (PTX/OVA@CPP NPs) were stable in PBS for four weeks and resuspended well after lyophilization without any cryoprotectants. Moreover, PTX and OVA from the NPs exhibited a sustained release rate and pH-responsive release pattern within different cellular microenvironments. Importantly, PTX@CPP NPs exhibited much higher anticancer efficacy across various cancer cell lines, even multidrug-resistant cells, compared to free PTX and PTX@PP NPs without the chitosan coating. In antigen-presenting cells, OVA@CPP NPs led to higher IL-2 secretion and cellular uptake compared to free OVA and OVA@PP NPs. Furthermore, in a tumor-bearing mouse model, PTX/OVA@CPP NPs exhibited strong synergistic tumor suppression and triggered OVA antigen-specific responses, promoting an antitumor immune response. These findings demonstrate that PTX/OVA@CPP NPs show potential as new chemo-immunotherapeutic agents for effective cancer treatment.

Metastatic Melanoma: A Preclinical Model Standardization and Development of a Chitosan-Coated Nanoemulsion Containing Temozolomide to Treat Brain Metastasis

Melanoma is the most aggressive type of skin cancer. Brain metastasis is the worst scenario in metastatic melanoma and the treatment options for these patients are limited. Temozolomide (TMZ) is a chemotherapy agent used to treat primary central nervous system tumors. Our objective was to develop chitosan-coated nanoemulsion containing temozolomide (CNE-TMZ) for nasal route administration to melanoma brain metastasis treatment. A preclinical model of metastatic brain melanoma was standardized, and the efficiency of the developed formulation was further determined in vitro and in vivo. The nanoemulsion was done by spontaneous emulsification method and the formulation was characterized by size, pH, polydispersity index, and zeta potential. Culture assessments to determine cell viability were done in the A375 human melanoma cell line. To determine the safety of formulation, healthy C57/BL6 mice were treated with a nanoemulsion without TMZ. The model in vivo used B16-F10 cells implanted by stereotaxic surgery in C57/BL6 mice brains. The results demonstrate that the preclinical model used showed to be useful to analyze the efficiency of new candidate drugs to treat melanoma brain metastasis. The chitosan-coated nanoemulsions with TMZ showed the expected physicochemical characteristics and demonstrated safety and efficacy, reducing around 70% the tumor size compared to control mice, and presenting a tendency in mitotic index reduction, becoming an interesting approach to treat melanoma brain metastasis.

Recent advances in long-acting drug delivery systems for anticancer drug

The use of systemic anticancer chemotherapy is intrinsically limited by its toxicity. Whether dealing with small molecules or biopharmaceuticals, after systemic administration, small doses fail to reach effective intratumoral concentrations, while high doses with significant tumor inhibition effects may also drive the death of healthy cells, endangering the patients. Therefore, strategies based on drug delivery systems (DDSs) for avoiding the systemic toxicity have been designed. Due to their ability to protect drugs from early elimination and control drug release, DDSs can foster tumor exposure to anticancer therapeutics by extending their circulation time or steadily releasing drugs into the tumor sites. However, approval of tailored DDSs systems for clinical use is minimal as the safety and the in vivo activity still need to be ameliorated by manipulating their physicochemical characteristics. During the last few years, several strategies have been described to improve their safety, stability, and fine-tune pharmaceuticals release kinetics. Herein, we reviewed the main DDSs, namely polymeric conjugates, nano or microparticles, hydrogels, and microneedles, explored for long-acting anticancer treatments, highlighting recently proposed modifications and their potential advantages for different anticancer therapies. Additionally, important limitations of long-acting anticancer therapies and future technology directions were also covered.

PEGylated and functionalized polylactide-based nanocapsules: An overview

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

PLGA's Plight and the Role of Stealth Surface Modification Strategies in Its Use for Intravenous Particulate Drug Delivery

Numerous human disorders can benefit from targeted, intravenous (IV) drug delivery. Polymeric nanoparticles have been designed to undergo systemic circulation and deliver their therapeutic cargo to target sites in a controlled manner. Poly(lactic-co-glycolic) acid (PLGA) is a particularly promising biomaterial for designing intravenous drug carriers due to its biocompatibility, biodegradability, and history of clinical success across other routes of administration. Despite these merits, PLGA remains markedly absent in clinically approved IV drug delivery formulations. A prominent factor in PLGA particles' inability to succeed intravenously may lie in the hydrophobic character of the polyester, leading to the adsorption of serum proteins (i.e., opsonization) and a cascade of events that end in their premature clearance from the bloodstream. PEGylation, or surface-attached polyethylene glycol chains, is a common strategy for shielding particles from opsonization. Polyethylene glycol (PEG) continues to be regarded as the ultimate "stealth" solution despite the lack of clinical progress of PEGylated PLGA carriers. This review reflects on some of the reasons for the clinical failure of PLGA, particularly the drawbacks of PEGylation, and highlights alternative surface coatings on PLGA particles. Ultimately, a new approach will be needed to harness the potential of PLGA nanoparticles and allow their widespread clinical adoption.

A Tri-Stimuli Responsive (Maghemite/PLGA)/Chitosan Nanostructure with Promising Applications in Lung Cancer

A (core/shell)/shell nanostructure (production performance ≈ 50%, mean diameter ≈ 330 nm) was built using maghemite, PLGA, and chitosan. An extensive characterization proved the complete inclusion of the maghemite nuclei into the PLGA matrix (by nanoprecipitation solvent evaporation) and the disposition of the chitosan shell onto the nanocomposite (by coacervation). Short-term stability and the adequate magnetism of the nanocomposites were demonstrated by size and electrokinetic determinations, and by defining the first magnetization curve and the responsiveness of the colloid to a permanent magnet, respectively. Safety of the nanoparticles was postulated when considering the results from blood compatibility studies, and toxicity assays against human colonic CCD-18 fibroblasts and colon carcinoma T-84 cells. Cisplatin incorporation to the PLGA matrix generated appropriate loading values (≈15%), and a dual pH- and heat (hyperthermia)-responsive drug release behaviour (≈4.7-fold faster release at pH 5.0 and 45 °C compared to pH 7.4 and 37 °C). The half maximal inhibitory concentration of the cisplatin-loaded nanoparticles against human lung adenocarcinoma A-549 cells was ≈1.6-fold less than that of the free chemotherapeutic. Such a biocompatible and tri-stimuli responsive (maghemite/PLGA)/chitosan nanostructure may found a promising use for the effective treatment of lung cancer.

Engineering of stealth (maghemite/PLGA)/chitosan (core/shell)/shell nanocomposites with potential applications for combined MRI and hyperthermia against cancer

(Maghemite/poly(d,l-lactide-co-glycolide))/chitosan (core/shell)/shell nanoparticles have been prepared reproducibly by nanoprecipitation solvent evaporation plus coacervation (production performance ≈ 45%, average size ≈ 325 nm). Transmission electron microscopy, energy dispersive X-ray spectroscopy, electrophoretic determinations, and X-ray diffraction patterns demonstrated the satisfactory embedment of iron oxide nanocores within the solid polymer matrix and the formation of an external shell of chitosan in the nanostructure. The adequate magnetic responsiveness of the nanocomposites was characterized in vitro by hysteresis cycle determinations and by visualization of the nanosystem under the influence of a 0.4 T permanent magnet. Safety and biocompatibility of the (core/shell)/shell particles were based on in vitro haemocompatibility studies and cytotoxicity tests against HFF-1 human foreskin fibroblasts and on ex vivo toxicity assessments on tissue samples from Balb/c mice. Transversal relaxivities, determined in vitro at a low magnetic field of 1.44 T, demonstrated their capability as T2 contrast agents for magnetic resonance imaging, being comparable to that of some iron oxide-based contrast agents. Heating properties were evaluated in a high frequency alternating electromagnetic gradient: a constant maximum temperature of ≈46 °C was generated within ≈50 min, while antitumour hyperthermia tests on T-84 colonic adenocarcinoma cells proved the relevant decrease in cell viability (to ≈ 39%) when treated with the nanosystem under the influence of that electromagnetic field. Finally, in vivo magnetic resonance imaging studies and ex vivo histology determinations of iron deposits postulated the efficacy of chitosan to provide long-circulating capabilities to the nanocomposites, retarding nanoparticle recognition by the mononuclear phagocyte system. To our knowledge, this is the first study describing such a type of biocompatible and long-circulating nanoplatform with promising theranostic applications (biomedical imaging and hyperthermia) against cancer.

Development of a New Polymeric Nanocarrier Dedicated to Controlled Clozapine Delivery at the Dopamine D2-Serotonin 5-HT1A Heteromers

Clozapine, the second generation antipsychotic drug, is one of the prominent compounds used for treatment of schizophrenia. Unfortunately, use of this drug is still limited due to serious side effects connected to its unspecific and non-selective action. Nevertheless, clozapine still remains the first-choice drug for the situation of drug-resistance schizophrenia. Development of the new strategy of clozapine delivery into well-defined parts of the brain has been a great challenge for modern science. In the present paper we focus on the presentation of a new nanocarrier for clozapine and its use for targeted transport, enabling its interaction with the dopamine D₂ and serotonin 5-HT_1A heteromers (D₂-5-HT_1A) in the brain tissue. Clozapine polymeric nanocapsules (CLO-NCs) were prepared using anionic surfactant AOT (sodium docusate) as an emulsifier, and bio-compatible polyelectrolytes such as: poly-l-glutamic acid (PGA) and poly-l-lysine (PLL). Outer layer of the carrier was grafted by polyethylene glycol (PEG). Several variants of nanocarriers containing the antipsychotic varying in physicochemical parameters were tested. This kind of approach may enable the availability and safety of the drug, improve the selectivity of its action, and finally increase effectiveness of schizophrenia therapy. Moreover, the purpose of the manuscript is to cover a wide scope of the issues, which should be considered while designing a novel means for drug delivery. It is important to determine the interactions of a new nanocarrier with many cell components on various cellular levels in order to be sure that the new nanocarrier will be safe and won’t cause undesired effects for a patient.

A pH-sensitive nanoagent self-assembled from a highly negatively-charged phthalocyanine with excellent biosafety for photothermal therapy

Photothermal therapy (PTT) is a promising strategy for cancer treatment. However, the development of highly efficient photothermal agents with excellent biosafety, particularly with low liver retention, is very meaningful for clinical applications, but it is also challenging. We herein prepared a pH-sensitive nanoagent (NanoPc3) by the self-assembly of a zinc(ii) phthalocyanine substituted with hexadeca-sulphonates linked by hydrazone bonds for photoacoustic imaging and PTT. Due to the highly negative surface potential (-30.80 mV in water), NanoPc3 could effectively escape the phagocytosis of the reticuloendothelial system and be rapidly cleared from normal tissues, leading to little accumulation in the liver and excellent biosafety. The highly negatively-charged NanoPc3 changed into nearly neutral nanoparticles (NanoPc3H) under slightly acidic conditions, resulting in enhanced cellular uptake and retention time in tumor tissues. Moreover, the tumor of H22 tumor-bearing mice treated with NanoPc3 almost disappeared, suggesting an outstanding photothermal antitumor effect. NanoPc3 also hardly showed skin phototoxicity under irradiation. Its excellent antitumor effect and biosafety make NanoPc3 highly promising in clinical applications. This work will provide a new strategy for the design of tumor-targeted photothermal nanoagents with high biosafety.

Nanomedicine as a potent strategy in melanoma tumor microenvironment

Melanoma originated from melanocytes is the most aggressive type of skin cancer. Despite considerable progresses in clinical treatment with the discovery of BRAF or MEK inhibitors and monoclonal antibodies, the durability of response to treatment is often limited to the development of acquired resistance and systemic toxicity. The limited success of conventional treatment highlights the importance of understanding the role of melanoma tumor microenvironment in tumor developement and drug resistance. Nanoparticles represent a promising strategy for the development of new cancer treatments able to improve the bioavailability of drugs and increase their penetration by targeting specifically tumors cells and/or tumor environment. In this review, we will discuss the main influence of tumor microenvironment in melanoma growth and treatment outcome. Furthermore, third generation loaded nanotechnologies represent an exciting tool for detection, treatment, and escape from possible mechanism of resistance mediated by tumor microenvironment, and will be highlighted in this review.

Doxorubicin and siRNA Codelivery via Chitosan-Coated pH-Responsive Mixed Micellar Polyplexes for Enhanced Cancer Therapy in Multidrug-Resistant Tumors

This study investigated the potential of chitosan-coated mixed micellar nanocarriers (polyplexes) for codelivery of siRNA and doxorubicin (DOX). DOX-loaded mixed micelles (serving as cores) were prepared by thin film hydration method and coated with chitosan (CS, serving as outer shell), and complexed with multidrug resistance (MDR) inhibiting siRNA. Selective targeting was achieved by folic acid conjugation. The polyplexes showed pH-responsive enhanced DOX release in acidic tumor pH, resulting in higher intracellular accumulation, which was further augmented by downregulation of mdr-1 gene after treatment with siRNA-complexed polyplexes. In vitro cytotoxicity assay demonstrated an enhanced cytotoxicity in native 4T1 and multidrug-resistant 4T1-mdr cell lines, compared to free DOX. Furthermore, in vivo, polyplexes codelivery resulted in highest DOX accumulation and significantly reduced the tumor volume in mice with 4T1 and 4T1-mdr tumors as compared to the free DOX groups, leading to improved survival times in mice. In conclusion, codelivery of siRNA and DOX via polyplexes has excellent potential as targeted drug nanocarriers for treatment of MDR cancers.

Low molecular weight chitosan-coated polymeric nanoparticles for sustained and pH-sensitive delivery of paclitaxel

Low molecular weight chitosan (LMWC) is a promising polymer for surface modification of nanoparticles (NPs), which can impart both stealth effect and electrostatic interaction with cells at mildly acidic pH of tumors. We previously produced LMWC-coated NPs via covalent conjugation to poly(lactic-co-glycolic) acid (PLGA-LMWC NPs). However, this method had several weaknesses including inefficiency and complexity of the production as well as increased hydrophilicity of the polymer matrix, which led to poor drug release control. Here, we used the dopamine polymerization method to produce LMWC-coated NPs (PLGA-pD-LMWC NPs), where the core NPs were prepared with PLGA that served best to load and retain drugs and then functionalized with LMWC via polydopamine layer. The PLGA-pD-LMWC NPs overcame the limitations of PLGA-LMWC NPs while maintaining their advantages. First of all, PLGA-pD-LMWC NPs attenuated the release of paclitaxel to a greater extent than PLGA-LMWC NPs. Moreover, PLGA-pD-LMWC NPs had a pH-dependent surface charge profile and cellular interactions similar to PLGA-LMWC NPs, enabling acid-specific NP-cell interaction and enhanced drug delivery to cells in weakly acidic environment. Although the LMWC layer did not completely prevent protein binding in serum solution, PLGA-pD-LMWC NPs showed less phagocytic uptake than bare PLGA NPs.

A surface modification of clozapine-loaded nanocapsules improves their efficacy: A study of formulation development and biological assessment

This work aimed to develop nanocapsules (NC) coated with polysorbate 80 (P80), cationic chitosan (CS) or polyethylene glycol (PEG) using clozapine (CZP) as the drug model. The zeta potential, pH and encapsulation efficiency were directly affected by the CS coating. Using the bag dialysis method, the in vitro CZP release from CS-coated nanocapsules was similar to the PEG-coated at pH 7.4. Nanocapsules coated with PEG and CS exhibited an increased action duration compared to the P80-coated nanocapsules in pseudo-psychosis induced by d,l-amphetamine in rats. When comparing both groups, the group administered CS-coated nanocapsules showed better activity than the PEG-coated nanocapsules at 6, 10 and 12h after d,l-amphetamine administration. The pharmacokinetic assessment in rats demonstrated that the observed half-lives were free CZP<P80-coated<PEG-coated ̴ CS-coated nanocapsules. Both the P80- and PEG-coated nanocapsules showed a statistically significant increase in their volume of distribution compared to free CZP. On the other hand, the cationic nanocapsules showed a decrease in total clearance. Together, these results indicate that the PEG and CS coatings are a promising delivery system for CZP in the treatment of schizophrenia.

Hydrophilic mesoporous carbon nanospheres with high drug-loading efficiency for doxorubicin delivery and cancer therapy

In this study, a highly effective transmembrane delivery vehicle based on PEGylated oxidized mesoporous carbon nanosphere (oMCN@PEG) was successfully fabricated in a facile strategy. oMCN@PEG exhibited a narrow size distribution of 90 nm, excellent hydrophilicity, good biocompatibility, and a very high loading efficiency for doxorubicin (DOX). The drug system (oMCN@DOX@PEG) exhibited excellent stability under neutral pH conditions, but with dramatic releases of DOX at reduced pH conditions. Pharmacokinetics study revealed that oMCN@DOX@PEG could prolong the circulation of DOX in the blood stream. The endocytosis, cytotoxicity, and anticancer effect in vitro and in vivo of the drug-loaded nanoparticles were also evaluated. Our results showed that the nanoparticles efficiently penetrated the membrane of tumor cells, subsequently released drugs, and efficiently inhibited the growth of cancer cells both in vitro and in vivo. Especially, oMCN@DOX@PEG also exhibited significant antimetastasis effect in advanced stage of malignant cancer, improving the survival time of tumor-bearing mice. The results suggested that oMCN@PEG might be a promising anticancer drug delivery vehicle for cancer therapy.

An In Vitro Thrombolysis Study Using a Mixture of Fast-Acting and Slower Release Microspheres

PURPOSE

To test the hypothesis that a mixture combining fast and slower release rate microspheres can restore blood flow rapidly and prevent formation of another blockage in thrombolysis.

METHODS

We used polyethylene glycol (PEG) microspheres which provide the release of the encapsulated streptokinase (SK) on the scale of minutes, and Eudragit FS30D (Eud), a polymethacrylate polymer, for development of delayed release microspheres which were desirable to prevent a putative second thrombus. Eud microspheres were coated with chitosan (CS) to further extend half-life. Experiments included the development, characterization of Eud/SK and CS-Eud/SK microspheres, and in vitro thrombolytic studies of the mixtures of PEG/SK and Eud /SK microspheres and of PEG/SK and CS-Eud/SK microspheres.

RESULTS

CS-Eud/SK microspheres have slightly lower encapsulation efficiency, reduced activity of SK, and a much slower release of SK when compared with microspheres of Eud/SK microspheres. Counter-intuitively, slower release leads to faster thrombolysis after reocclusion as a result of greater retention of agent and the mechanism of distributed intraclot thrombolysis.

CONCLUSIONS

A mixture of PEG/SK and CS-Eud/SK microspheres could break up the blood clot rapidly while providing clot-lytic efficacy in prevention of a second blockage up to 4 h.

PEG/heparin-decorated lipid–polymer hybrid nanoparticles for long-circulating drug delivery

Surface modification of lipid–polymer hybrid nanoparticles with the combined PEG and heparin was developed to achieve a significant prolongation in blood circulation.

Guiding principles in the design of ligand-targeted nanomedicines

Medicines for the treatment of most human pathologies are encumbered by unwanted side effects that arise from the deposition of an effective drug into the wrong tissues. The logical remedy for these undesirable properties involves selective targeting of the therapeutic agent to pathologic cells, thereby avoiding collateral toxicity to healthy cells. Since significant advantages can also accrue by incorporating a therapeutic or imaging agent into a nanoparticle, many laboratories are now combining both benefits into a single formulation. This review will focus on the major guiding principles in the design of ligand-targeted nanoparticles, including optimization of their chemical and physical properties, selection of the ideal targeting ligand, engineering of the appropriate surface passivation and linker strategies to achieve selective delivery of the entrapped cargo to the desired diseased cell.