Micro/nanostructured polymeric systems for biomedical and pharmaceutical applications

Development, Characterization and Cell Viability Inhibition of PVA Spheres Loaded with Doxorubicin and 4'-Amino-1-Naphthyl-Chalcone (D14) for Osteosarcoma

Chalcones (1,3-diaryl-2-propen-1-ones) are naturally occurring polyphenols with known anticancer activity against a variety of tumor cell lines, including osteosarcoma (OS). In this paper, we present the preparation and characterization of spheres (~2 mm) from polyvinyl alcohol (PVA) containing a combination of 4′-Amino-1-Naphthyl-Chalcone (D14) and doxorubicin, to act as a new polymeric dual-drug anticancer delivery. D14 is a potent inhibitor of osteosarcoma progression and, when combined with doxorubicin, presents a synergetic effect; hence, physically crosslinked PVA spheres loaded with D14 and doxorubicin were prepared using liquid nitrogen and six freeze–thawing cycles. Physical-chemical characterization using a scanning electron microscope (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) presented that the drugs were incorporated into the spheres via weak interactions between the drugs and the polymeric chains, resulting in overall good drug stability. The cytotoxicity activity of the PVA spheres co-encapsulating both drugs was tested against the U2OS human osteosarcoma cell line by 3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide (MTT) assay, and compared to the spheres carrying either D14 or doxorubicin alone. The co-delivery showed a cytotoxic effect 2.6-fold greater than doxorubicin alone, revealing a significant synergistic effect with a coefficient of drug interaction (CDI) of 0.49. The obtained results suggest this developed PVA sphere as a potential dual-drug delivery system that could be used for the prominent synergistic anticancer activity of co-delivering D14 and doxorubicin, providing a new potential strategy for improved osteosarcoma treatment.

Nanoparticles Based on Quaternary Ammonium Chitosan-methyl-β-cyclodextrin Conjugate for the Neuropeptide Dalargin Delivery to the Central Nervous System: An In Vitro Study

Peptide oral administration is a hard goal to reach, especially if the brain is the target site. The purpose of the present study was to set up a vehicle apt to promote oral absorption of the neuropeptide dalargin (DAL), allowing it to cross the intestinal mucosal barrier, resist enzymatic degradation, and transport drugs to the brain after crossing the blood–brain barrier. Therefore, a chitosan quaternary ammonium derivative was synthesized and conjugated with methyl-β-cyclodextrin to prepare DAL-medicated nanoparticles (DAL-NP). DAL-NP particle size was 227.7 nm, zeta potential +8.60 mV, encapsulation efficiency 89%. DAL-NP protected DAL from degradation by chymotrypsin or pancreatin and tripled DAL degradation time compared to non-encapsulated DAL. Use of DAL-NP was safe for either Caco-2 or bEnd.3 cells, with the latter selected as a blood–brain barrier model. DAL-NP could also cross either the Caco-2 or bEnd.3 monolayer by the transepithelial route. The results suggest a potential DAL-NP ability to transport to the brain a DAL dose fraction administered orally, although in vivo experiments will be needed to confirm the present data obtained in vitro.

Nanomaterial based drug delivery systems for the treatment of neurodegenerative diseases

With an aging population that has been increasing in recent years, the need for the development of therapeutic approaches for treatment of neurodegenerative disorders (ND) has increased. ND, which are characterized by the progressive loss of the structure or function of neurons, are often associated with neuronal death. In spite of screening numerous drugs, currently there is no specific treatment that can cure these diseases or slow down their progression. Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia, Huntington's disease, and prion diseases belong to ND which affect enormous numbers of people globally. There are some main possible reasons for failure in the treatment of neurodegenerative diseases such as limitations introduced by the Blood-Brain Barrier (BBB), the Blood-Cerebrospinal Fluid Barrier (BCFB) and P-glycoproteins. Current advances in nanotechnology present opportunities to overcome the mentioned limitations by using nanotechnology and designing nanomaterials improving the delivery of active drug candidates. Some of the basic and developing strategies to overcome drug delivery impediments are the local delivery of drugs, receptor-mediated transcytosis, physicochemical disruption of the BBB, cell-penetrating peptides and magnetic disruption. Recently, the application of nanoparticles has been developed to improve the efficiency of drug delivery. Nanoengineered particles as nanodrugs possess the capacity to cross the BBB and also show decreased invasiveness. Examples include inorganic, magnetic, polymeric and carbonic nanoparticles that have been developed to improve drug delivery efficiency. Despite numerous papers published in this filed, there are some unsolved issues that need to be addressed for successful treatment of neurodegenerative diseases. These are discussed herein.

Biopolymer Substrates in Buccal Drug Delivery: Current Status and Future Trend

BACKGROUND

This paper provides a critical review of biopolymer-based substrates, especially the cellulose derivatives, for their application in buccal drug delivery. Drug delivery to the buccal mucous has the benefits of immobile muscle, abundant vascularization and rapid recovery, but not all the drugs can be administered through the buccal mucosa (e.g., macromolecular drugs), due to the low bioavailability caused by their large molecular size. This shortfall inspired the rapid development of drug-compounding technologies and the corresponding usage of biopolymer substrates.

METHODS

Cellulose derivatives have been extensively developed for drug manufacturing to facilitate its delivery. We engaged in structured research of cellulose-based drug compounding technologies. We summarized the characteristic cellulose derivatives which have been used as the biocompatible substrates in buccal delivery systems. The discussion of potential use of the rapidly-developed nanocellulose (NC) is also notable in this paper.

RESULTS

Seventy-eight papers were referenced in this perspective paper with the majority (sixty-five) published later than 2010. Forty-seven papers defined the buccal drug delivery systems and their substrates. Fifteen papers outlined the properties and applications of cellulose derivatives. Nanocellulose was introduced as a leading edge of nanomaterial with sixteen papers highlighted its adaptability in drug compounding for buccal delivery.

CONCLUSION

The findings of this perspective paper proposed the potential use of cellulose derivatives, the typical kind of biopolymers, in the buccal drug delivery system for promoting the bioavailability of macromolecular drugs. Nanocellulose (NC) in particular was proposed as an innovative bio-binder/carrier for the controlled-release of drugs in buccal system.

Multifunctional Polymeric Nanoplatforms for Brain Diseases Diagnosis, Therapy and Theranostics

The blood-brain barrier (BBB) acts as a barrier to prevent the central nervous system (CNS) from damage by substances that originate from the blood circulation. The BBB limits drug penetration into the brain and is one of the major clinical obstacles to the treatment of CNS diseases. Nanotechnology-based delivery systems have been tested for overcoming this barrier and releasing related drugs into the brain matrix. In this review, nanoparticles (NPs) from simple to developed delivery systems are discussed for the delivery of a drug to the brain. This review particularly focuses on polymeric nanomaterials that have been used for CNS treatment. Polymeric NPs such as polylactide (PLA), poly (D, L-lactide-co-glycolide) (PLGA), poly (ε-caprolactone) (PCL), poly (alkyl cyanoacrylate) (PACA), human serum albumin (HSA), gelatin, and chitosan are discussed in detail.

Poloxamer 407 (Pluronic(®) F127)-based polymeric micelles for amphotericin B: In vitro biological activity, toxicity and in vivo therapeutic efficacy against murine tegumentary leishmaniasis

In the present study, a Poloxamer 407-based amphotericin B (AmpB)-containing polymeric micelles system (AmpB/M) was employed in the treatment of Leishmania amazonensis-infected BALB/c mice. Initially, the in vitro antileishmanial activity (IC50 value) of AmpB/M and B-AmpB/M (empty micelles) against stationary promastigotes and amastigotes-like forms of the parasites was determined, and results were of 1.83 ± 0.4 and 22.1 ± 0.7 μM, respectively, for the promastigotes, and of 2.27 ± 0.5 and 33.98 ± 2.6 μM, respectively, for the amastigotes-like. The cytotoxic concentration (CC50) values of these products were also evaluated, and we found the results of 119.5 ± 9.6 and 134.7 ± 10.3 μM, respectively. With these values, the selectivity index (SI) was calculated and results were of 65.3 and 5.4, respectively, for the promastigotes, and of 59.3 and 3.96, respectively, for the amastigotes-like of the parasites. Free AmpB showed IC50 values of 1.2 ± 0.3 and 2.5 ± 0.5 μM for the promastigotes and amastigotes-like, respectively, whereas the CC50 value was of 9.5 ± 0.4 μM. The SI values of this drug were of 7.9 and 3.8, respectively, for the promastigote and amastigote-like stages of the parasites. After, animals were infected and received saline or were treated subcutaneously with free AmpB, AmpB/M or B-AmpB/M. In the results, free AmpB-treated and infected mice showed reductions in their body weight, which were associated with hepatic and renal damage; however, no organic alteration was observed in the AmpB/M-treated animals. In addition, these animals showed significant reductions in their lesion average size and in the parasite burden in all evaluated infected tissue and organs, when compared to the other groups; as well as significantly higher levels of antileishmanial IFN-γ, IL-12, GM-CSF and nitrite, which were associated with low production of IL-4, IL-10 and IgG1 isotype antibodies. In conclusion, this AmpB/M system could be considered as an alternative for future studies in the treatment of tegumentary leishmaniasis.

Treatment of murine visceral leishmaniasis using an 8-hydroxyquinoline-containing polymeric micelle system

New therapeutics are urgently needed to treat visceral leishmaniasis (VL). Due to the fact that drug discovery is a long and expensive process, the development of delivery systems to carry old and toxic drugs could be considered, as well as the evaluation of new molecules that have already shown to present biological activity. In this context, the present study evaluated the in vitro and in vivo antileishmanial activity of an 8-hydroxyquinoline (8-HQN)-containing polymeric micelle (8-HQN/M) system against Leishmania infantum, the main causative agent of VL in the Americas. The experimental strategy used was based on the evaluation of the parasite load by a limiting-dilution technique in the spleen, liver, bone marrow and draining lymph nodes of the infected and treated animals, as well as by a quantitative PCR (qPCR) technique to also assess the splenic parasite load. The immune response developed was evaluated by the production of IFN-γ, IL-4, IL-10, IL-12 and GM-CSF cytokines, as well as by antileishmanial nitrite dosage and antibodies production. Hepatic and renal enzymes were also investigated to verify cellular injury as a result of treatments toxicity. In the results, 8-HQN/M-treated mice, when compared to the other groups: saline, free amphotericin B (AmpB, as a drug control), 8-HQN and B-8-HQN/M (as a micelle control) showed more significant reductions in their parasite burden in all evaluated organs. These animals also showed an antileishmanial Th1 immunity, which was represented by high levels of IFN-γ, IL-12, GM-CSF and nitrite, associated with a low production of IL-4 and IL-10 and anti-Leishmania IgG1 isotype antibodies. In addition, any hepatic or renal damage was found in these treated animals. In conclusion, 8-HQN/M was effective in treating L. infantum-infected BALB/c mice, and can be considered alone, or combined with other drugs, as an alternative treatment for VL.

Control of silk microsphere formation using polyethylene glycol (PEG)

A one step, rapid method to prepare silk microspheres was developed, with particle size controlled by the addition of polyethylene glycol (PEG). PEG molecular weight (4.0K-20.0KDa) and concentration (20-50wt%), as well as silk concentration (5-20wt%), were key factors that determined particle sizes varying in a range of 1-100μm. Addition of methanol to the PEG-silk combinations increased the content of crystalline β-sheet in the silk microspheres. To track the distribution and degradation of silk microspheres in vivo, 3-mercaptopropionic acid (MPA)-coated CdTe quantum dots (QDs) were physically entrapped in the silk microspheres. QDs tightly bound to the β-sheet domains of silk via hydrophobic interactions, with over 96% of the loaded QDs remaining in the silk microspheres after exhaustive extraction. The fluorescence of QDs-incorporated silk microspheres less stable in cell culture medium than in phosphate buffer solution (PBS) and water. After subcutaneous injection in mice, microspheres prepared from 20% silk (approx. 30μm diameter particles) still fluoresced at 24h, while those prepared from 8% silk (approx. 4μm diameter particles) and free QDs were not detectable, reflecting the QDs quenching and particle size effect on microsphere clearance in vivo. The larger microspheres were more resistant to cell internalization and degradation. Since PEG is an FDA-approved polymer, and silk is FDA approved for some medical devices, the methods developed in the present study will be useful in a variety of biomedical applications where simple, rapid and scalable preparation of silk microspheres is required.

STATEMENT OF SIGNIFICANCE

The work is of significance to the biomaterial and controlled release society because it provides a new option for fabricating silk microspheres in one simple step of mixing silk and polyethylene glycol (PEG), with the size and properties of microspheres controllable by PEG molecular weight as well as PEG and silk concentrations. Although fabrication of silk microspheres have been reported previously using spray-drying, liposome-templating, polyvinyl alcohol (PVA) emulsification, etc., applications were hindered due to harsh conditions (temperature, solvents, etc.) and complicated procedures used as well as low yield and less controllable particle size (usually <10μm). Since PEG is an FDA-approved polymer, and silk is FDA approved for some medical devices, the methods developed in the present study will be useful in a variety of biomedical applications where simple, rapid and scalable preparation of silk microspheres is required.

An 8-hydroxyquinoline-containing polymeric micelle system is effective for the treatment of murine tegumentary leishmaniasis

The current treatment of leishmaniasis has been hampered due to the high toxicity of the available drugs and long duration protocols, which often lead to its abandonment. In the present study, a poloxamer 407-based delivery system was developed, and a molecule, 8-hydroxyquinoline (8-HQN), was incorporated with it, leading to an 8-HQN/micelle (8-HQN/M) composition. Assays were performed to evaluate the in vitro antileishmanial activity of 8-HQN/M against Leishmania amazonensis stationary promastigotes. The cytotoxicity in murine macrophages and in human red cells, as well as the efficacy of the treatment in macrophages infected by parasites, was also assessed. This product was also evaluated for the treatment of murine tegumentary leishmaniasis, using L. amazonensis-infected BALB/c mice. To evaluate the in vivo efficacy of the treatment, the average lesion diameter (area) in the infected tissue, as well as the parasite load at the site of infection (skin), spleen, liver and draining lymph nodes were examined. Non-incorporated micelle (B-8-HQN/M) and the free molecule (8-HQN) were used as controls, besides animals that received only saline. The parasite burden was evaluated by limiting dilution and quantitative real-time PCR (qPCR) techniques, and immunological parameters associated with the treatments were also investigated. In the results, the 8-HQN/M group, when compared to the others, presented more significant reductions in the average lesion diameter and in the parasite burden in the skin and all evaluated organs. These animals also showed significantly higher levels of parasite-specific IFN-γ, IL-12, and GM-CSF, associated with low levels of IL-4 and IL-10, when compared to the saline, 8-HQN/M, and B-8-HQN groups. A predominant IL-12-driven IFN-γ production, against parasite proteins, mainly produced by CD4⁺ T cells, was observed in the treated animals, post-infection. In conclusion, 8-HQN/M was highly effective in treating L. amazonensis-infected BALB/c mice and can be considered alone, or combined with other drugs, as an alternative treatment for tegumentary leishmaniasis. Graphical Abstract Therapeutic scheme and immunological and parasitological parameters developed in the present study.

Perspectives on polymeric nanostructures for the therapeutic application of antimicrobial peptides

Antimicrobial peptides (AMPs) are a class of promising anti-infective molecules but their therapeutic application is opposed by their poor bioavailability, susceptibility to protease degradation and potential toxicity. The advancement of nanoformulation technologies offers encouraging perspectives for the development of novel therapeutic strategies based on AMPs to treat antibiotic resistant microbial infections. Additionally, the use of polymers endowed per-se with antibacterial properties, stands out as an innovative approach for the development of a new generation of drug delivery systems in which an enhanced antimicrobial action could be obtained by the synergic combination of bioactive polymer matrices and drugs. Herein, the latest AMPs drug delivery research is discussed.

Nanofibers used for delivery of antimicrobial agents

Nanotechnology has gained an increased interest in several different areas of biotechnology including the drug delivery via nanofibers. Self-assembly, phase separation and electrospinning can all be used to successfully generate nanofibers with sizes well within the range of those of the fibers present in the native extracellular matrix (50-500 nm). In this article, the authors introduced the most popular applications of nanofibers related to the delivery of antimicrobial agents for infectious diseases. To date, only a few in-vivo studies are available at present to demonstrate its clinical potential; most of the studies are of exploratory nature and rely mostly on in-vitro experiments. Therefore, further advancement in the production and clinical performance of drug-loaded nanofibrous matrices seems necessary.

Sulfated Seaweed Polysaccharides as Multifunctional Materials in Drug Delivery Applications

In the last decades, the discovery of metabolites from marine resources showing biological activity has increased significantly. Among marine resources, seaweed is a valuable source of structurally diverse bioactive compounds. The cell walls of marine algae are rich in sulfated polysaccharides, including carrageenan in red algae, ulvan in green algae and fucoidan in brown algae. Sulfated polysaccharides have been increasingly studied over the years in the pharmaceutical field, given their potential usefulness in applications such as the design of drug delivery systems. The purpose of this review is to discuss potential applications of these polymers in drug delivery systems, with a focus on carrageenan, ulvan and fucoidan. General information regarding structure, extraction process and physicochemical properties is presented, along with a brief reference to reported biological activities. For each material, specific applications under the scope of drug delivery are described, addressing in privileged manner particulate carriers, as well as hydrogels and beads. A final section approaches the application of sulfated polysaccharides in targeted drug delivery, focusing with particular interest the capacity for macrophage targeting.

Nanotechnology for protein delivery: Overview and perspectives

Protein-based therapeutics have made a significant impact in the treatment of a variety of important human diseases. However, given their intrinsically vulnerable structure and susceptibility to enzymatic degradation, many therapeutic proteins such as enzymes, growth factors, hormones, and cytokines suffer from poor physicochemical/biological stability and immunogenicity that may limit their potential benefits, and in some cases limit their utility. Furthermore, when protein therapeutics are developed for intracellular targets, their internalization and biological activity may be limited by inefficient membrane permeability and/or endosomal escape. Development of effective protein delivery strategies is therefore essential to further enhance therapeutic outcomes to enable widespread medical applications. This review discusses the advantages and limitations of marketed and developmental-stage protein delivery strategies, and provides a focused overview of recent advances in nanotechnology platforms for the systemic delivery of therapeutic proteins. In addition, we also highlight nanoparticle-mediated non-invasive administration approaches (e.g., oral, nasal, pulmonary, and transdermal routes) for protein delivery.

Developing cutaneous applications of paromomycin entrapped in stimuli-sensitive block copolymer nanogel dispersions

AIM

A new paromomycin micellar nanogel based on poloxamer 407 was developed.

MATERIALS & METHODS

 In vitro release and ex vivo permeation/retention studies were conducted. In vivo tolerance was assayed by transepidermal water loss. Ex vivo cytotoxicity on RAW and VERO cells and antileishmanial activity on Leishmania promastigotes was tested.

RESULTS

The particle size was 9.19 nm (99% loading efficiency) exhibiting Newtonian behavior at 4°C and was pseudoplastic at 25 and 40°C. Drug release followed a Weibull model and the drug remaining in the skin was 31.652 µg/g/cm(2). In vivo tolerance achieved excellent results with negligible cellular toxicity and the best antileishmanial efficiency.

CONCLUSION

The nanogel provided controlled, effective and safe delivery of paromomycin for the treatment of cutaneous leishmaniasis.

Development of Biocompatible and Functional Polymeric Nanoparticles for Site-Specific Delivery of Radionuclides

Introduction

Encapsulation of biologically active molecules into nanoparticles (NPs), for site-specific delivery, is a fast growing area. These NPs must be biocompatible, non-toxic, and able to release their load in a controlled way. We have developed a series of NPs based on (bio)degradable and biocompatible poly(malic acid) derivatives, poly(benzyl malate) (PMLABe), with its PEG-grafted stealth analog and target-specific biotin-PEG-b-PMLABe one. A lipophilic radiotracer has then been encapsulated into these NPs.

Methods

Monomers were synthesized from dl-aspartic acid. PEG₄₂-b-PMLABe₇₃ and Biot-PEG₆₆-b-PMLABe₇₃ block copolymers were obtained by anionic ring-opening polymerization of benzyl malolactonate in presence of α-methoxy-ω-carboxy-PEG₄₂ and α-biotin-ω-carboxy-PEG₆₆ as initiators. NPs were prepared by nanoprecipitation. Size, polydispersity, and zeta potential were measured by dynamic light scattering (DLS) and zetametry. ^99mTc-SSS was prepared as previously described. Encapsulation efficacy was assessed by varying different parameters, such as encapsulation with preformed NPs or during their formation, influence of the solvent, and of the method to prepare the NPs. After decay, ^99mTc-loaded NPs were also analyzed by DLS and zetametry. NPs’ morphology was assessed by transmission electron microscopy.

Results

^99mTc-SSS was added during nanoprecipitation, using two different methods, to ensure good encapsulation. Radiolabeled NPs present increased diameters, with identical low polydispersity indexes and negative zeta potentials in comparison to non-radiolabeled NPs.

Conclusion

A radiotracer was successfully encapsulated, but some further optimization is still needed. The next step will be to modify these radiolabeled NPs with a hepatotrope peptide, and to replace ^99mTc with ¹⁸⁸Re for therapy. Our team is also working on drugs’ encapsulation and grafting of a fluorescent probe. Combining these modalities is of interest for combined chemo-/radiotherapy, bimodal imaging, and/or theranostic approach.

Biocompatibility and Stability of Polysaccharide Polyelectrolyte Complexes Aimed at Respiratory Delivery

Chitosan (CS) and chondroitin sulfate (CHS) are natural polymers with demonstrated applicability in drug delivery, while nanoparticles are one of the most explored carriers for transmucosal delivery of biopharmaceuticals. In this work we have prepared CS/CHS nanoparticles and associated for the first time the therapeutic protein insulin. Fluorescein isothiocyanate bovine serum albumin (FITC-BSA) was also used to enable comparison of behaviors regarding differences in molecular weight (5.7 kDa versus 67 kDa). Nanoparticles of approximately 200 nm and positive zeta potential around +20 mV were obtained. These parameters remained stable for up to 1 month at 4 °C. Proteins were associated with efficiencies of more than 50%. The release of FITC-BSA in PBS pH 7.4 was more sustained (50% in 24 h) than that of insulin (85% in 24 h). The biocompatibility of nanoparticles was tested in Calu-3 and A549 cells by means of three different assays. The metabolic assay MTT, the determination of lactate dehydrogenase release, and the quantification of the inflammatory response generated by cell exposure to nanoparticles have indicated an absence of overt toxicity. Overall, the results suggest good indications on the application of CS/CHS nanoparticles in respiratory transmucosal protein delivery, but the set of assays should be widened to clarify obtained results.

Natural and synthetic poly(malic acid)-based derivates: a family of versatile biopolymers for the design of drug nanocarriers

The field of specific drug delivery is an expanding research domain. Besides the use of liposomes formed from various lipids, natural and synthetic polymers have been developed to prepare more efficient drug delivery systems either under macromolecular prodrugs or under particulate nanovectors. To ameliorate the biocompatibility of such nanocarriers, degradable natural or synthetic polymers have attracted the interest of many researchers. In this context, poly(malic acid) (PMLA) extracted from microorganisms or synthesized from malic or aspartic acid was used to prepare water-soluble drug carriers or nanoparticles. Within this review, both the preparation and the applications of PMLA derivatives are described emphasizing the in vitro and in vivo assays. The results obtained by several groups highlight the interest of such polyesters in the field of drug delivery.

Polysaccharide nanoparticles for protein and Peptide delivery: exploring less-known materials

Finding adequate carriers for protein and peptide delivery has become an urgent need, owing to the growing number of macromolecules identified as having therapeutic potential. Nanoparticles have emerged in the field as very promising vehicles and much work has been directed to testing the capacity of different materials to compose the matrix of these carriers. Natural materials and, specifically, polysaccharides have been taking the forefront of the challenge, because of several favoring properties that include the higher propensity to exhibit biodegradability and biocompatibility, and also the high structural flexibility. The majority of works found in the literature regarding polysaccharide nanoparticles uses very popular materials like chitosan or hyaluronic acid. This review is aimed at describing and exploring the potential of polysaccharides that are not so well known or that are less explored. For those, the main properties will be described, together with an overview of the reported applications as nanoparticle matrix materials.

New potential therapeutic approach for the treatment of B-Cell malignancies using chlorambucil/hydroxychloroquine-loaded anti-CD20 nanoparticles

Current B-cell disorder treatments take advantage of dose-intensive chemotherapy regimens and immunotherapy via use of monoclonal antibodies. Unfortunately, they may lead to insufficient tumor distribution of therapeutic agents, and often cause adverse effects on patients. In this contribution, we propose a novel therapeutic approach in which relatively high doses of Hydroxychloroquine and Chlorambucil were loaded into biodegradable nanoparticles coated with an anti-CD20 antibody. We demonstrate their ability to effectively target and internalize in tumor B-cells. Moreover, these nanoparticles were able to kill not only p53 mutated/deleted lymphoma cell lines expressing a low amount of CD20, but also circulating primary cells purified from chronic lymphocitic leukemia patients. Their safety was demonstrated in healthy mice, and their therapeutic effects in a new model of Burkitt's lymphoma. The latter serves as a prototype of an aggressive lympho-proliferative disease. In vitro and in vivo data showed the ability of anti-CD20 nanoparticles loaded with Hydroxychloroquine and Chlorambucil to increase tumor cell killing in comparison to free cytotoxic agents or Rituximab. These results shed light on the potential of anti-CD20 nanoparticles carrying Hydroxychloroquine and Chlorambucil for controlling a disseminated model of aggressive lymphoma, and lend credence to the idea of adopting this therapeutic approach for the treatment of B-cell disorders.

Fibrin-based scaffold incorporating VEGF- and bFGF-loaded nanoparticles stimulates wound healing in diabetic mice

Diabetic skin ulcers are difficult to heal spontaneously due to the reduced levels and activity of endogenous growth factors. Recombinant human vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are known to stimulate cell proliferation and accelerate wound healing. Direct delivery of VEGF and bFGF at the wound site in a sustained and controllable way without loss of bioactivity would enhance their biological effects. The aim of this study was to develop a poly(ether)urethane-polydimethylsiloxane/fibrin-based scaffold containing poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with VEGF and bFGF (scaffold/GF-loaded NPs) and to evaluate its wound healing properties in genetically diabetic mice (db/db). The scaffold application on full-thickness dorsal skin wounds significantly accelerated wound closure at day 15 compared to scaffolds without growth factors (control scaffold) or containing unloaded PLGA nanoparticles (scaffold/unloaded NPs). However, the closure rate was similar to that observed in mice treated with scaffolds containing free VEGF and bFGF (scaffold/GFs). Both scaffolds containing growth factors induced complete re-epithelialization, with enhanced granulation tissue formation/maturity and collagen deposition compared to the other groups, as revealed by histological analysis. The ability of the scaffold/GF-loaded NPs to promote wound healing in a diabetic mouse model suggests its potential use as a dressing in patients with diabetic foot ulcers.

Pullulan-based nanoparticles as carriers for transmucosal protein delivery

Polymeric nanoparticles have revealed very effective in transmucosal delivery of proteins. Polysaccharides are among the most used materials for the production of these carriers, owing to their structural flexibility and propensity to evidence biocompatibility and biodegradability. In parallel, there is a preference for the use of mild methods for their production, in order to prevent protein degradation, ensure lower costs and easier procedures that enable scaling up. In this work we propose the production of pullulan-based nanoparticles by a mild method of polyelectrolyte complexation. As pullulan is a neutral polysaccharide, sulfated and aminated derivatives of the polymer were synthesized to provide pullulan with a charge. These derivatives were then complexed with chitosan and carrageenan, respectively, to produce the nanocarriers. Positively charged nanoparticles of 180-270 nm were obtained, evidencing ability to associate bovine serum albumin, which was selected as model protein. In PBS pH 7.4, pullulan-based nanoparticles were found to have a burst release of 30% of the protein, which maintained up to 24h. Nanoparticle size and zeta potential were preserved upon freeze-drying in the presence of appropriate cryoprotectants. A factorial design was approached to assess the cytotoxicity of raw materials and nanoparticles by the metabolic test MTT. Nanoparticles demonstrated to not cause overt toxicity in a respiratory cell model (Calu-3). Pullulan has, thus, demonstrated to hold potential for the production of nanoparticles with an application in protein delivery.

Micro and nanoparticle-based delivery systems for vaccine immunotherapy: an immunological and materials perspective

The development and widespread application of vaccines has been one of the most significant achievements of modern medicine. Vaccines have not only been instrumental in controlling and even eliminating life-threatening diseases like polio, measles, diphtheria, etc., but have also been immensely powerful in enhancing the worldwide outlook of public health over the past century. Despite these successes, there are still many complex disorders (e.g., cancer, HIV, and other emerging infectious diseases) for which effective preventative or therapeutic vaccines have been difficult to develop. This failure can be attributed primarily to our inability to precisely control and modulate the highly complex immune memory response, specifically the cellular response. Dominated by B and T cell maturation and function, the cellular response is primarily initiated by potent immunostimulators and antigens. Efficient and targeted delivery of these immunomodulatory and immunostimulatory molecules to appropriate cells is key to successful development of next generation vaccine formulations. Over the past decade, particulate carriers have emerged as an attractive means for enhancing the delivery efficacy and potency of vaccines and associated immunomodulatory molecules. Specifically, polymer-based micro and nanoparticles are being extensively studied for a wide variety of applications. In this review, we discuss the immunological fundamentals for developing effective vaccines and how materials and material properties can be exploited to improve these therapies. Particular emphasis is given to polymer-based particles and how the route of administration of particulate systems affects the phenotype and robustness of an immune response. Comparison of various strategies and recent advancements in the field are discussed along with insights into current limitations and future directions.

Biocompatibility of chitosan carriers with application in drug delivery

Chitosan is one of the most used polysaccharides in the design of drug delivery strategies for administration of either biomacromolecules or low molecular weight drugs. For these purposes, it is frequently used as matrix forming material in both nano and micron-sized particles. In addition to its interesting physicochemical and biopharmaceutical properties, which include high mucoadhesion and a great capacity to produce drug delivery systems, ensuring the biocompatibility of the drug delivery vehicles is a highly relevant issue. Nevertheless, this subject is not addressed as frequently as desired and even though the application of chitosan carriers has been widely explored, the demonstration of systems biocompatibility is still in its infancy. In this review, addressing the biocompatibility of chitosan carriers with application in drug delivery is discussed and the methods used in vitro and in vivo, exploring the effect of different variables, are described. We further provide a discussion on the pros and cons of used methodologies, as well as on the difficulties arising from the absence of standardization of procedures.

Nanostructuring molecular materials as particles and vesicles for drug delivery, using compressed and supercritical fluids

The structuring of synthetic and biological therapeutic actives as micro- and nano-particulate materials is a widely accepted formulation strategy to improve efficacy and reduce the toxicity of drugs. However, the development of efficient production platforms that enable the formulation of these nanomedicines at an industrial scale and with the quality requirements imposed by regulatory agencies remains a challenge. In this framework, compressed fluid-based methods are promising technologies for the controlled and reproducible preparation of uniform micro- and nano-particulate nanomedicines at a large scale. This review provides an overall but practical knowledge about what has been achieved so far in the field of compressed fluids applied to the preparation of solid micro- and nanoparticles and vesicles as drug delivery systems. In addition, recent examples of application of these technologies to the production of polymeric nanostructured microparticles highly loaded with gentamicin and to the preparation of uniform cholesterol-rich vesicular systems are explained.

Recombinant elastin-mimetic biomaterials: Emerging applications in medicine

Biomaterials derived from protein-based block copolymers are increasingly investigated for potential application in medicine. In particular, recombinant elastin block copolymers provide significant opportunities to modulate material microstructure and can be processed in various forms, including particles, films, gels, and fiber networks. As a consequence, biological and mechanical responses of elastin-based biomaterials are tunable through precise control of block size and amino acid sequence. In this review, the synthesis of a set of elastin-mimetic triblock copolymers and their diverse processing methods for generating material platforms currently applied in medicine will be discussed.

Multifunctional nanoparticles of biodegradable copolymer blend for cancer diagnosis and treatment

AIMS

A multifunctional nanoparticle (NP) system is developed to provide a sustained, controlled and targeted co-delivery of quantum dots (QDs) as a model imaging agent and docetaxel as a model anticancer drug. The NPs are made of a polymeric blend of poly(lactic-co-glycolic acid), which forms a biodegradable NP matrix, and the novel copolymer D-alpha-tocopheryl polyethylene glycol 1000 succinate-COOH, which facilitates ligand conjugation on the NP surface.

MATERIALS & METHODS

The NPs were prepared by nanoprecipitation and characterized for their size and size distribution, surface morphology, surface charge, QD/drug encapsulation and loading efficiency, and in vitro drug release profile. The targeting effects of such NPs were evaluated both quantitatively and qualitatively through the cellular uptake of the QDs as well as the cytotoxicity of the drug using MCF-7 cells, which overexpress folate receptors and NIH 3T3 cells, which have no folate receptors overexpression.

RESULTS & CONCLUSIONS

NPs with folate conjugated on their surface achieved much higher cellular uptake than those with no folate conjugation in MCF-7 cells while no significant targeting effect could be observed for NIH 3T3 cells. The drug formulated in the folate-conjugated NPs were more efficious compared with NPs with no folate conjugation as well as the current clinical formulation Taxotere.

Glyconanoparticles: multifunctional nanomaterials for biomedical applications

Metal-based glyconanoparticles (GNPs) are biofunctional nanomaterials that combine the unique physical, chemical and optical properties of the metallic nucleus with the characteristics of the carbohydrate coating. The latter characteristics comprise a series of advantages that range from ensuring water solubility, biocompatibility and stability to targeting properties. The selection of suitable carbohydrates for specifically targeting biomarkers opens up the possibility to employ metallic GNPs in diagnostics and/or therapy. Within the vast nanoscience field, this review intends to focus on the advances of multifunctional and multimodal GNPs, which make use of the ‘glycocode’ to specifically address pathogens or pathological-related biomedical problems. Examples of their potential application in antiadhesion therapy and diagnosis are highlighted. From the ex vivo diagnostic perspective, it can be predicted that GNPs will soon be used clinically. However, the in vivo application of metallic GNPs in humans will probably need more time. In particular, major concerns regarding nanotoxicity need to be exhaustively addressed. However, it is expected that the sugar shell of GNPs will lower the intrinsic toxicity of metal nanoclusters better than other non-natural coatings.

Targeted Delivery of Protein Drugs by Nanocarriers

Recent advances in biotechnology demonstrate that peptides and proteins are the basis of a new generation of drugs. However, the transportation of protein drugs in the body is limited by their high molecular weight, which prevents the crossing of tissue barriers, and by their short lifetime due to immuno response and enzymatic degradation. Moreover, the ability to selectively deliver drugs to target organs, tissues or cells is a major challenge in the treatment of several human diseases, including cancer. Indeed, targeted delivery can be much more efficient than systemic application, while improving bioavailability and limiting undesirable side effects. This review describes how the use of targeted nanocarriers such as nanoparticles and liposomes can improve the pharmacokinetic properties of protein drugs, thus increasing their safety and maximizing the therapeutic effect.

Supercritical fluid extraction: Recent advances and applications

Among the different extraction techniques used at analytical and preparative scale, supercritical fluid extraction (SFE) is one of the most used. This review covers the most recent developments of SFE in different fields, such as food science, natural products, by-product recovery, pharmaceutical and environmental sciences, during the period 2007-2009. The revision is focused on the most recent advances and applications in the different areas; among them, it is remarkable the strong impact of SFE to extract high value compounds from food and natural products but also its increasing importance in areas such as heavy metals recovery, enantiomeric resolution or drug delivery systems.

Silk nanospheres and microspheres from silk/pva blend films for drug delivery

Silk fibroin protein-based micro- and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtained from the blend in a three step process: (1) air-drying the blend solution into a film, (2) film dissolution in water and (3) removal of residual PVA by subsequent centrifugation. In both cases, the spheres had approximately 30% beta-sheet content and less than 5% residual PVA. Spindle-shaped silk particles, as opposed to the spherical particles formed above, were obtained by stretching the blend films before dissolving in water. Compared to the 1/1 ratio sample, the silk spheres prepared from the 1/4 ratio sample showed a more homogeneous size distribution ranging from 300 nm up to 20 microm. Further studies showed that sphere size and polydispersity could be controlled either by changing the concentration of silk and PVA or by applying ultrasonication on the blend solution. Drug loading was achieved by mixing model drugs in the original silk solution. The distribution and loading efficiency of the drug molecules in silk spheres depended on their hydrophobicity and charge, resulting in different drug release profiles. The entire fabrication procedure could be completed within one day. The only chemical used in the preparation except water was PVA, an FDA-approved ingredient in drug formulations. Silk micro- and nanospheres reported have potential as drug delivery carriers in a variety of biomedical applications.

Sustained antibacterial activity of doxycycline-loaded poly(D,L-lactide-co-glycolide) and poly(epsilon-caprolactone) nanoparticles

AIM

To increase the entrapment efficiency of doxycycline (DXY)-loaded poly(D,L-lactide-co-glycolide) (PLGA):poly(epsilon-caprolactone) (PCL) nanoparticles by up to 70% by varying the different formulation parameters such as polymer ratio, amount of drug loading (w/w), solvent selection, electrolyte addition and pH in the formulation.

METHOD

Biodegradable polymers PLGA and PCL are used in various ratios for nanoparticle preparation using the water-in-oil-in-water double emulsion technique for water-soluble DXY. The physicochemical characterization of nanoparticles included size and surface charge measurement, study of surface morphology using scanning-electron microscopy, Fourier transform infrared spectroscopy study, differential scanning calorimetry analysis and in vitro release kinetics study.

RESULTS

The mean particle size ranged from 230 to 360 nm, as measured by dynamic laser light scattering, and scanning-electron microscopy confirmed the spherical nature and smooth surface of the nanoparticles. Fourier transform infrared spectroscopy analysis of void nanoparticles, drug-loaded nanoparticles and native DXY indicated no interaction between the drug and polymer in the nanoparticle. Differential scanning calorimetry analysis of drug-loaded nanoparticles indicated a molecular level dispersion of DXY in the formulation. The antibacterial activity of native DXY and DXY-loaded nanoparticles were tested using a strain of Escherichia coli (DH5alpha) through growth inhibition and colony-counting method. The results indicated that DXY-loaded nanoparticles are more effective than native DXY due to the sustained release of DXY from nanoparticles in the E. coli strain.

Electrostatic binding of nanoparticles to mesenchymal stem cells via high molecular weight polyelectrolyte chains

Combining stem cell transplantation with nanoparticle-mediated delivery of drugs and pharmaceuticals is envisioned to be one of the next major developmental steps in regenerative medicine. However, a major challenge would be to keep nanoparticles co-localized with stem cells upon transplantation or transfusion in situ. Since nanoparticles are physically much smaller in size than cells and would not specifically bind to extracellular matrix, it is easier for them to disperse from the transplantation site via the blood circulation. Conjugating nanoparticles directly to the cell membrane can potentially interfere with cellular function by physically obstructing cell surface receptors from interacting with the extracellular matrix, various growth factors and cytokines and other cells. Moreover, drug-loaded nanoparticles may be internalized into the cytoplasm via endocytosis or phagocytosis, which may wreak damage on the cellular machinery, leading to impaired physiological function or cell death. A novel solution may be to utilize high molecular weight polyelectrolyte chains to electrostatically bind nanoparticles to cells. For this purpose, hyaluronan, poly-L-lysine and chitosan are of special interest, because these molecules are generally recognized to be biocompatible for application in various pharmaceutical and surgical products. This study investigated the use of these molecules to bind nanoparticles to mesenchymal stem cells (MSCs), and a novel technique of conjugating half the cell surface with nanoparticles through the use of polyelectrolyte chains was also developed. This would avoid blocking MSC interaction with cytokines, growth factors, extracellular matrix and other cells within the recipient tissue/organ upon delivery in situ.