Design aspects of poly(alkylcyanoacrylate) nanoparticles for drug delivery

Effects of Different Molecular Weight Oxidized Dextran as Crosslinkers on Stability and Antioxidant Capacity of Curcumin-Loaded Nanoparticles

Curcumin is a polyphenolic compound that has been widely investigated for its health benefits. However, the clinical relevance of curcumin is limited due to its low water solubility and inefficient absorption. Therefore, curcumin is often encapsulated in nanocarriers to improve its delivery and function. In this study, composite nanoparticles composed of stearic acid-modified chitosan (SA-CS) and sodium caseinate (NaCas) were formed using sodium periodate-oxidized dextran with different molecular weights as a crosslinking agent. The effects of oxidized dextran (Odex) with different molecular weights on the composite nanoparticles were compared. The optimal SA-CS/NaCas/Odex composite nanoparticle (NPO) was obtained using an Odex (150 kDa)-to-SA-CS mass ratio of 2:1. Its size, polydispersity index (PDI), and zeta potential (ZP) were 130.2 nm, 0.149, and 25.4 mV, respectively. The particles were highly stable in simulated gastric fluid (SGF) in vitro, and their size and PDI were 172.3 nm and 0.263, respectively. The encapsulation rate of NPO loaded with curcumin (Cur-NPO) was 93% under optimal ultrasonic conditions. Compared with free curcumin, the sustained release of Cur-NPO significantly reduced to 17.9%, and free-radical-scavenging ability improved to 78.7%. In general, the optimal prepared NPO exhibited good GI stability and has potential applications in the formulation of orally bioactive hydrophobic drugs.

Quercetin and Its Nano-Formulations for Brain Tumor Therapy—Current Developments and Future Perspectives for Paediatric Studies

The development of efficient treatments for tumors affecting the central nervous system (CNS) remains an open challenge. Particularly, gliomas are the most malignant and lethal form of brain tumors in adults, causing death in patients just over 6 months after diagnosis without treatment. The current treatment protocol consists of surgery, followed using synthetic drugs and radiation. However, the efficacy of these protocols is associated with side effects, poor prognosis and with a median survival of fewer than two years. Recently, many studies were focused on applying plant-derived products to manage various diseases, including brain cancers. Quercetin is a bioactive compound derived from various fruits and vegetables (asparagus, apples, berries, cherries, onions and red leaf lettuce). Numerous in vivo and in vitro studies highlighted that quercetin through multitargeted molecular mechanisms (apoptosis, necrosis, anti-proliferative activity and suppression of tumor invasion and migration) effectively reduces the progression of tumor cells. This review aims to summarize current developments and recent advances of quercetin’s anticancer potential in brain tumors. Since all reported studies demonstrating the anti-cancer potential of quercetin were conducted using adult models, it is suggested to expand further research in the field of paediatrics. This could offer new perspectives on brain cancer treatment for paediatric patients.

Neuro-nanotechnology: diagnostic and therapeutic nano-based strategies in applied neuroscience

Artificial, de-novo manufactured materials (with controlled nano-sized characteristics) have been progressively used by neuroscientists during the last several decades. The introduction of novel implantable bioelectronics interfaces that are better suited to their biological targets is one example of an innovation that has emerged as a result of advanced nanostructures and implantable bioelectronics interfaces, which has increased the potential of prostheses and neural interfaces. The unique physical-chemical properties of nanoparticles have also facilitated the development of novel imaging instruments for advanced laboratory systems, as well as intelligently manufactured scaffolds and microelectrodes and other technologies designed to increase our understanding of neural tissue processes. The incorporation of nanotechnology into physiology and cell biology enables the tailoring of molecular interactions. This involves unique interactions with neurons and glial cells in neuroscience. Technology solutions intended to effectively interact with neuronal cells, improved molecular-based diagnostic techniques, biomaterials and hybridized compounds utilized for neural regeneration, neuroprotection, and targeted delivery of medicines as well as small chemicals across the blood-brain barrier are all purposes of the present article.

Identification of novel cyanoacrylate monomers for use in nanoparticle drug delivery systems prepared by miniemulsion polymerisation - A multistep screening approach

Poly (alkyl cyanoacrylate) (PACA) polymeric nanoparticles (NPs) are promising drug carriers in drug delivery. However, the selection of commercially available alkyl cyanoacrylate (ACA) monomers is limited, because most monomers were designed for use in medical and industrial glues and later repurposed for drug encapsulation. This study therefore aimed to seek out novel ACA materials for use in NP systems using a toxicity led screening approach. A multistep strategy, including cytotoxicity screening of alcohols as degradation products of PACA (44 alcohols), NPs (14 polymers), and a final in vivo study (2 polymers) gave poly (2-ethylhexyl cyanoacrylate) PEHCA as a promising novel PACA candidate. For the first time, this work presents cytotoxicity data on several novel ACAs, PEHCA in vivo toxicity data, and miniemulsion polymerisation-based encapsulation of the cabazitaxel and NR688 in novel PACA candidates. Furthermore, several of the ACA candidates were compatible with a wider selection of lipophilic active pharmaceutical ingredients (APIs) versus commercially available controls. Combined, this work demonstrates the potential benefits of expanding the array of available ACA materials in drug delivery. Novel ACAs have the potential to encapsulate a wider range of APIs in miniemulsion polymerisation processes and may also broaden PACA applicability in other fields.

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Screening of novel poly(alkylcyanoacrylate) (PACA) materials to broaden PACA nanomedicine potential.

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A comprehensive screening process evaluated the toxicity of novel poly(alkylcyanoacrylate) (PACA) materials.

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Novel poly(2-ethylhexyl cyanoacrylate) nanoparticles has a promising safety profile.

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Novel ACA materials show potential to enable encapsulation of a wider range of APIs.

Alginate Microsphere Encapsulation of Drug-Loaded Nanoparticles: A Novel Strategy for Intraperitoneal Drug Delivery

Alginate hydrogels have been broadly investigated for use in medical applications due to their biocompatibility and the possibility to encapsulate cells, proteins, and drugs. In the treatment of peritoneal metastasis, rapid drug clearance from the peritoneal cavity is a major challenge. Aiming to delay drug absorption and reduce toxic side effects, cabazitaxel (CAB)-loaded poly(alkyl cyanoacrylate) (PACA) nanoparticles were encapsulated in alginate microspheres. The PACAlg alginate microspheres were synthesized by electrostatic droplet generation and the physicochemical properties, stability, drug release kinetics, and mesothelial cytotoxicity were analyzed before biodistribution and therapeutic efficacy were studied in mice. The 450 µm microspheres were stable at in vivo conditions for at least 21 days after intraperitoneal implantation in mice, and distributed evenly throughout the peritoneal cavity without aggregation or adhesion. The nanoparticles were stably retained in the alginate microspheres, and nanoparticle toxicity to mesothelial cells was reduced, while the therapeutic efficacy of free CAB was maintained or improved in vivo. Altogether, this work presents the alginate encapsulation of drug-loaded nanoparticles as a promising novel strategy for the treatment of peritoneal metastasis that can improve the therapeutic ratio between toxicity and therapeutic efficacy.

Biomedical Applications of Metal-Organic Frameworks for Disease Diagnosis and Drug Delivery: A Review

Metal-organic frameworks (MOFs) are a novel class of porous hybrid organic-inorganic materials that have attracted increasing attention over the past decade. MOFs can be used in chemical engineering, materials science, and chemistry applications. Recently, these structures have been thoroughly studied as promising platforms for biomedical applications. Due to their unique physical and chemical properties, they are regarded as promising candidates for disease diagnosis and drug delivery. Their well-defined structure, high porosity, tunable frameworks, wide range of pore shapes, ultrahigh surface area, relatively low toxicity, and easy chemical functionalization have made them the focus of extensive research. This review highlights the up-to-date progress of MOFs as potential platforms for disease diagnosis and drug delivery for a wide range of diseases such as cancer, diabetes, neurological disorders, and ocular diseases. A brief description of the synthesis methods of MOFs is first presented. Various examples of MOF-based sensors and DDSs are introduced for the different diseases. Finally, the challenges and perspectives are discussed to provide context for the future development of MOFs as efficient platforms for disease diagnosis and drug delivery systems.

Effect of oxidized dextran on the stability of gallic acid-modified chitosan-sodium caseinate nanoparticles

We incorporated oxidized dextran (Odex) into nanoparticles composed of gallic acid-modified chitosan (GA-CS) and sodium caseinate (NaCas). The mass ratio of GA-CS to NaCas and the pH of the reaction solution were optimized to obtain nanoparticles with excellent performance and stability. The interactions among various nanomaterials were confirmed by Fourier-transform infrared spectroscopy (FT-IR) and fluorescence spectrometer. The optimized complex nanoparticles had a diameter of approximately 131.2 nm with a polydispersity index (PDI) of 0.14, and a zeta potential of 26.2 mV. Our results showed that Odex enhanced the stability and function of GA-CS/NaCas nanoparticles (NP). At a curcumin loading of 10%, the encapsulation efficiency of Odex-crosslinked GA-CS/NaCas (NP (Odex)) was 96.2%, whereas that for uncrosslinked nanoparticles was 66.9%. Compared to the burst release profile of free curcumin in simulated GI fluids, the sustained release profile of encapsulated curcumin was observed. Radical-scavenging assays confirmed that the nanoparticles had excellent antioxidant activity themselves due to the grafting of phenolic acid on chitosan backbone. Overall, NP (Odex) with good GI stability and antioxidant activity hold promising for the oral delivery of hydrophobic bioactives.

Lyophilization of Nanocapsules: Instability Sources, Formulation and Process Parameters

Polymeric nanocapsules have gained more and more interest in the medical sciences. Their core-shell structure offers numerous advantages, especially regarding their use as drug delivery systems. This review begins by presenting the different intrinsic sources of the instability of nanocapsules. The physical and chemical potential instabilities of nanocapsules reduce their shelf-life and constitute a barrier to their clinical use and to their commercialization. To overcome these issues, lyophilization is often used as a process of choice in the pharmaceutical industry especially when labile compounds are used. The state of the art of lyophilization nanocapsules is reviewed. The formulation properties and the process parameters are discussed for a complete understanding of their impact on the stability and storage of the final dried product. To assess the quality of the dried product, various characterization methods are also discussed.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

Nano drug delivery systems in upper gastrointestinal cancer therapy

Upper gastrointestinal (GI) carcinomas are characterized as one of the deadliest cancer types with the highest recurrence rates. Their treatment is challenging due to late diagnosis, early metastasis formation, resistance to systemic therapy and complicated surgeries performed in poorly accessible locations. Current cancer medication face deficiencies such as high toxicity and systemic side-effects due to the non-specific distribution of the drug agent. Nanomedicine has the potential to offer sophisticated therapeutic possibilities through adjusted delivery systems. This review aims to provide an overview of novel approaches and perspectives on nanoparticle (NP) drug delivery systems for gastrointestinal carcinomas. Present regimen for the treatment of upper GI carcinomas are described prior to detailing various NP drug delivery formulations and their current and potential role in GI cancer theranostics with a specific emphasis on targeted nanodelivery systems. To date, only a handful of NP systems have met the standard of care requirements for GI carcinoma patients. However, an increasing number of studies provide evidence supporting NP-based diagnostic and therapeutic tools. Future development and strategic use of NP-based drug formulations will be a hallmark in the treatment of various cancers. This article seeks to highlight the exciting potential of novel NPs for targeted cancer therapy in GI carcinomas and thus provide motivation for further research in this field.

Advantages of the combined use of cyclodextrins and nanocarriers in drug delivery: A review

Complexation with cyclodextrins (CDs) has been widely and successfully used in pharmaceutical field, mainly for enhancing solubility, stability and bioavailability of a variety of drugs. However, some important drawbacks, including rapid removal from the bloodstream after in vivo administration, or possible replacement, in biological media, of the entrapped drug moieties by other molecules with higher affinity for the CD cavity, can limit the CDs effectiveness as drug carriers. This review is focused on combined strategies simultaneously exploiting CD complexation, and loading of the complexed drug into various colloidal carriers (liposomes, niosomes, polymeric nanoparticles, lipid nanoparticles, nanoemulsions, micelles) which have been investigated as a possible means for circumventing the problems associated with both such carriers, when used separately, and join their relative benefits in a unique delivery system. Several examples of applications have been reported, to illustrate the possible advantages achievable by such a dual strategy, depending on the CD-nanocarrier combination, and mainly resulting in enhanced performance of the delivery system and improved biopharmaceutical properties and therapeutic efficacy of drugs. The major problems and/or drawbacks found in the development of such systems, as well as the (rare) case of failures in achieving the expected improvements have also been highlighted.

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.

A journey through the emergence of nanomedicines with poly(alkylcyanoacrylate) based nanoparticles

Starting in the late 1970s, the pioneering work of Patrick Couvreur gave birth to the first biodegradable nanoparticles composed of a biodegradable synthetic polymer. These nanoparticles, made of poly(alkylcyanoacrylate) (PACA), were the first synthetic polymer-based nanoparticulate drug carriers undergoing a phase III clinical trial so far. Analyzing the journey from the birth of PACA nanoparticles to their clinical evaluation, this paper highlights their remarkable adaptability to bypass various drug delivery challenges found on the way. At present, PACA nanoparticles include a wide range of nanoparticles that can associate drugs of different chemical nature and can be administered in vivo by different routes. The most recent technologies giving the nanoparticles customised functions could also be implemented on this family of nanoparticles. Through different examples, this paper discusses the seminal role of the PACA nanoparticles' family in the development of nanomedicines.

Nanomedicine for drug delivery in South Africa: a protocol for systematic review

BACKGROUND

The emergence of nanomedicine in the past decade has changed the landscape of disease diagnosis and treatment. Nanomedicine makes use of nanostructures for applications in different fields of medicine, including drug delivery, biosensors, neuro-electronic interfaces, in vivo imaging, and cell-specific molecular interactions. Despite its relative infancy, nanomedicine has generated a significant body of research as evidenced by peer reviewed literature and several patents. This proposed systematic review will focus specifically on drug delivery systems in which nanoparticles are used to enhance the pharmacological and therapeutic properties of drugs. The strength of nanoparticulate drug delivery systems is their ability to alter the pharmacokinetics and bio-distribution of drugs. Globally, the discourse on nanomedicine is dominated by research being done in the developed countries of Europe and in the United States of America. Less attention has been given to the applications of nanomedicine in developing countries, particularly Africa. There is dearth of information on the applications of nanomedicine in terms of drug delivery with particular reference to which diseases are being targeted generally in Africa. The review will describe the specific diseases that are being targeted and the progress being made in South Africa, with a view to determining whether the applications of nanomedicine are being appropriated to address the context-specific challenges in this country or if they mimic what is being done globally.

METHODS

Keywords related to nanomedicine and drug delivery will be combined to build a search strategy for each of the following databases: PubMed, Cochrane Library (including Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Database of Systematic Reviews, Cochrane Methodology Register), Google Scholar, NHS Health Technology Assessment Database and Web of Science. We will also check reference lists of included studies for other eligible reports and search unpublished data. To ensure that the search is comprehensive, grey literature will be searched extensively. Literature to be included will have nanomedicine in drug delivery as the primary application and report on the specific diseases that are targeted in South Africa. Two authors will independently screen the search output, select studies and extract data; discrepancies will be resolved by consensus and discussion. When no consensus is reached, the third author will be consulted DISCUSSION: The systematic review will inform the government, policy-makers, investors, health professionals, scientists, and engineers about the applications of nanomedicine in drug delivery. In particular, it will identify the diseases targeted by the application of nanomedicine for drug delivery and the progress being made in South Africa as the disease burden of this country differs from that of developed countries where nanomedicine has been widely used for drug delivery.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42017057388.

Ultrasound Improves the Delivery and Therapeutic Effect of Nanoparticle-Stabilized Microbubbles in Breast Cancer Xenografts

Compared with conventional chemotherapy, encapsulation of drugs in nanoparticles can improve efficacy and reduce toxicity. However, delivery of nanoparticles is often insufficient and heterogeneous because of various biological barriers and uneven tumor perfusion. We investigated a unique multifunctional drug delivery system consisting of microbubbles stabilized by polymeric nanoparticles (NPMBs), enabling ultrasound-mediated drug delivery. The aim was to examine mechanisms of ultrasound-mediated delivery and to determine if increased tumor uptake had a therapeutic benefit. Cellular uptake and toxicity, circulation and biodistribution were characterized. After intravenous injection of NPMBs into mice, tumors were treated with ultrasound of various pressures and pulse lengths, and distribution of nanoparticles was imaged on tumor sections. No effects of low pressures were observed, whereas complete bubble destruction at higher pressures improved tumor uptake 2.3 times, without tissue damage. An enhanced therapeutic effect was illustrated in a promising proof-of-concept study, in which all tumors exhibited regression into complete remission.

Recent advances in the use of nanoparticles for allergen-specific immunotherapy

The number of patients suffering from allergic asthma and rhinoconjunctivitis has increased dramatically within the last decades. Allergen-specific immunotherapy (AIT) is the only available cause-oriented therapy so far. AIT reduces symptoms, but has also a disease-modifying effect. Disadvantages are a long-lasting procedure, and in a few cases potential systemic adverse reactions. Encapsulation of allergens or DNA vaccines into nanostructures may provide advantages compared to the conventional AIT with noncapsulated allergen extracts: The protein/DNA molecule can be protected from degradation, higher local concentrations and targeted delivery to the site of action appear possible, and most importantly, recognition of encapsulated allergen by the immune system, especially by IgE antibodies, is prevented. AIT with nanoparticles (NPs) may offer a safer and potentially more efficient way of treatment for allergic diseases. In this review, we summarize the use of biodegradable NPs consisting of synthetic or natural polymers, liposomes, and virus-like particles as well as nonbiodegradable NPs like dendrimers, and carbon- or metal-based NPs for AIT. More or less successful applications of these NPs in prophylactic as well as therapeutic vaccination approaches in rodents or other animals as well as first human clinical trials are discussed in detail.

Design and evaluation of lipoprotein resembling curcumin-encapsulated protein-free nanostructured lipid carrier for brain targeting

Many nanoparticle matrixes have been demonstrated to be efficient in brain targeting, but there are still certain limitations for them. To overcome the shortcomings of the existing nanoparticulate systems for brain-targeted delivery, a lipoprotein resembling protein-free nanostructured lipid carrier (PS80-NLC) loaded with curcumin was constructed and assessed for in vitro and in vivo performance. Firstly, single factor at a time approach was employed to investigate the effects of various formulation factors. Mean particle sizes of ≤100nm, high entrapment efficiency (EE, about 95%) and drug loading (DL, >3%) were obtained for the optimized formulations. In vitro release studies in the presence of plasma indicated stability of the formulation under physiological condition. Compared with NLC, PS80-NLC showed noticeably higher affinity for bEnd.3 cells (1.56 folds greater than NLC) but with lower uptake in macrophages. The brain coronal sections showed strong and widely distributed fluorescence intensity of PS80-NLC than that of NLC in the cortex. Ex vivo imaging studies further confirmed that PS80-NLC could effectively permeate BBB and preferentially accumulate in the brain (2.38 times greater than NLC). The considerable in vitro and in vivo performance of the safe and biocompatible PS80-NLC makes it a suitable option for further investigations in brain targeted drug delivery.

Design attributes of long-circulating polymeric drug delivery vehicles

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

Epirubicin loading in poly(butyl cyanoacrylate) nanoparticles manifests via altered intracellular localization and cellular response in cervical carcinoma (HeLa) cells

OBJECTIVE

Drug loading into nanocarriers is used to facilitate drug delivery to target cells and organs. We have previously reported a change in cellular localization of epirubicin after loading to poly(butyl cyanoacrylate) (PBCA) nanoparticles. We aimed to further investigate the altered cellular localization and cellular responses to the described drug formulation.

MATERIALS AND METHODS

HeLa cells were treated with epirubicin-loaded PBCA nanoparticles prepared by the pre-polymerization method. A systematic study was performed to evaluate the formulation cytotoxicity. Cellular localization and uptake of the formulation as well as cellular response to the treatment were evaluated.

RESULTS

Our studies revealed decreased cytotoxicity of the nanoparticle-formulated epirubicin compared to the free drug as well as a noticeable change in the drug's intracellular localization. Epirubicin-loaded nanoparticles were internalized via endocytosis, accumulated inside endosomal vesicles and induced a two-fold stronger pro-apoptotic signal when compared to the free drug. The level of the tumor suppressor protein p53 in HeLa cells increased significantly upon treatment with free epirubicin, but remained relatively unchanged when cells were treated with equivalent dose of nanoparticle-loaded drug, suggesting a possible shift from p53-dependent DNA/RNA intercalation-based induction of cytotoxicity by free epirubicin to a caspase 3-induced cell death by the epirubicin-loaded PBCA formulation.

Infectious Diseases: Need for Targeted Drug Delivery

Infectious diseases are a leading cause of death worldwide, with the constant fear of global epidemics. It is indeed an irony that the reticuloendothelial system (RES), the body’s major defence system, is the primary site for intracellular infections which are more difficult to treat. Pro-inflammatory M1 macrophages play an important role in defence. However, ingenious pathogen survival mechanisms including phagolysosome destruction enable their persistence. Microbial biofilms present additional challenges. Low intracellular drug concentrations, drug efflux by efflux pumps and/or enzymatic degradation, emergence of multi-drug resistance (MDR), are serious limitations of conventional therapy. Targeted delivery using nanocarriers, and passive and active targeting strategies could provide quantum increase in intracellular drug concentration. Receptor mediated endocytosis using appropriate ligands is a viable approach. Liposomes and polymeric/lipidic nanoparticles, dendrimers micelles and micro/nanoemulsions could all be relied upon. Specialised targeting approaches are demonstrated for important diseases like tuberculosis, HIV and Malaria. Application of targeted delivery in the treatment of veterinary infections is exemplified and future possibilities indicated. The chapter thus provides an overview on important aspects of infectious diseases and the challenges therein, while stressing on the promise of targeted drug delivery in augmenting therapy of infectious diseases.

Dynamic light scattering and X-ray photoelectron spectroscopy characterization of PEGylated polymer nanocarriers: internal structure and surface properties

In this work, nanospheres and nanocapsules are precipitated in confined impinging jet mixers through solvent displacement and characterized. Acetone and water are used as the solvent and antisolvent, respectively, together with polymethoxypolyethylene glycol cyanoacrylate-co-hexadecylcyanoacrylate and Miglyol as the copolymer and oil, respectively. Characterization is performed with dynamic light scattering, with electrophoretic measurements, and for the first time with X-ray photoelectron spectroscopy. Results show that the presence of polyethylene glycol chains seems to be more pronounced on the surface of nanospheres than on that of nanocapsules. The thickness of the copolymer layer in nanocapsules ranges from 1 to 10 nm, depending on the value of the oil:copolymer mass ratio. Fast dilution is confirmed to have a positive effect in suppressing aggregation but can induce further copolymer precipitation.

Engineered nanoparticles. How brain friendly is this new guest?

In the last 30 years, the use of engineered nanoparticles (NPs) has progressively increased in many industrial and medical applications. In therapy, NPs may allow more effective cellular and subcellular targeting of drugs. In diagnostic applications, quantum dots are exploited for their optical characteristics, while superparamagnetic iron oxides NPs are used in magnetic resonance imaging. NPs are used in semiconductors, packaging, textiles, solar cells, batteries and plastic materials. Despite the great progress in nanotechnologies, comparatively little is known to date on the effects that exposure to NPs may have on the human body, in general and specifically on the brain. NPs can enter the human body through skin, digestive tract, airways and blood and they may cross the blood-brain barrier to reach the central nervous system. In addition to the paucity of studies describing NP effects on brain function, some of them also suffer of insufficient NPs characterization, inadequate standardization of conditions and lack of contaminant evaluation, so that results from different studies can hardly be compared. It has been shown in vitro and in vivo in rodents that NPs can impair dopaminergic and serotoninergic systems. Changes of neuronal morphology and neuronal death were reported in mice treated with NPs. NPs can also affect the respiratory chain of mitochondria and Bax protein levels, thereby causing apoptosis. Changes in expression of genes involved in redox pathways in mouse brain regions were described. NPs can induce autophagy, and accumulate in lysosomes impairing their degradation capacity. Cytoskeleton and vesicle trafficking may also be affected. NPs treated animals showed neuroinflammation with microglia activation, which could induce neurodegeneration. Considering the available data, it is important to design adequate models and experimental systems to evaluate in a reliable and controlled fashion the effects of NPs on the brain, and generate data representative of effects on the human brain, thereby useful for developing robust and valid nanosafety standards.

Development of a dual nanocarrier system as a potential stratagem against amyloid-induced toxicity

OBJECTIVE

Therapeutic formulation to reduce amyloid beta (Aβ) insult in neuronal cells remains an important focus in the treatment of Alzheimer's disease. To combat the multifactorial threats that arise during amyloid plaque formation, multi-dimensional approach is required.

METHODS

Peptide sequence KLVFF derived from the core recognition motif of Aβ1 - 42 can bind to the plaques and help to reduce further accumulation. In our previous work, we have reported various self-assembling structures of KLVFF along with its surface tension lowering ability to overcome the cytotoxicity caused by Aβ1 - 42. In the present work, we have developed a novel combination of peptide-curcumin-loaded liposomal formulation and characterized for its morphology, protein adsorption and colloidal stability. The therapeutic efficacy of the formulation was tested using a cholinergic neuronal cell line pre-treated with Aβ1 - 42.

RESULTS

The physiochemical characterization and in vitro efficacy of peptide-curcumin-loaded liposomal formulation were found to outperform well in bringing down the amyloid toxicity.

CONCLUSION

This cumulative evidence indicates that the nanocarrier-based alternative treatment stratagem is an effective way to treat Alzheimer's disease.

Polybutylcyanoacrylate nanoparticles and drugs of the platinum family: last status

Cisplatinum and carboplatinum drugs from platinum-containing family are anti-cancer drugs. Using these drugs causes side effects. Targeted and selective prescription decreases side effects of the drugs. This can be achieved using nanotechnology. In this study, cisplatinum and carboplatinum drugs were loaded on polybutylcyanoacrylate nanoparticles using emulsion polymerization method. To determine amount of loaded drug onto nanoparticle, spectrophotometry method was used. Evaluation of cytotoxicity of such nanoparticles was performed on MCF-7 cell line using MTT assay. Loading percentage of cisplatinum and carboplatinum drugs on nanoparticles were estimated 4 and 6 %, respectively. Cytotoxicity survival rate for cisplatinum and nanoparticle containing cisplatinum at the lowest concentration (p < 0.01) (20 μM) were estimated 64 ± 1 and 67 ± 0.5 %, respectively. These values at the highest concentration (p < 0.01) (160 μM) were measured 28 ± 0.7 and 31 ± 0.4 %. Additionally for carboplatinum and nanoparticles containing carboplatinum at the concentration (p < 0.01) (20 μM) amounts were estimated to be 80 ± 0.6 and 84 ± 0.6 %, while at the concentration (p < 0.01) (160 μM) were identified to be 44 ± 0.5 and 51 ± 0.2 %, respectively. Probably, due to low level of loading, cytotoxicity of both drugs at nano particle status was decreased in comparison with their standard form.

Enhanced bioavailability of orally administered flurbiprofen by combined use of hydroxypropyl-cyclodextrin and poly(alkyl-cyanoacrylate) nanoparticles

Flurbiprofen was formulated into nanoparticle suspension to improve its oral bioavailability. Hydroxypropyl-β-cyclodextrin inclusion-flurbiprofen complex (HP-β-CD-FP) was prepared, then incorporating this complex into poly(alkyl-cyanoacrylate) (PACA) nanoparticles. HP-β-CD-FP-PACA nanoparticle was prepared by the emulsion solvent polymerization method. The zeta potential was -26.8 mV, the mean volume particle diameter was 134 nm, drug encapsulation efficiency was 53.3 ± 3.6 % and concentration was 1.5 mg/mL. The bioavailability of flurbiprofen from optimized nanoparticles was assessed in male Wistar rats at a dose of 15 mg/kg. As compared to the flurbiprofen suspension, 211.6 % relative bioavailability was observed for flurbiprofen nanoparticles. The reduced particle size and increased surface area may contribute to improve oral bioavailability of flurbiprofen.

Spray-dried chitosan microparticles for cellular delivery of an antigenic protein: physico-chemical properties and cellular uptake by dendritic cells and macrophages

PURPOSE

Spray-dried chitosan microparticles for cellular delivery of antigen to dendritic cells (DC) and macrophages (Mϕ) were investigated.

METHODS

Chitosan microparticles were prepared by spray drying. For comparison, poly(lactic-co-glycolic acid) (PLGA) and poly(α-butyl cyanoacrylate) (BCA) micro-/nanoparticles were generated. Bovine serum albumin (BSA) was used as a model antigen. The particles were characterized in terms of size, morphology, surface charge, surface composition, protein content, entrapment efficiency, in vitro release, and protein integrity. Additionally, they were subject to cell viability and cellular uptake study with DC and Mϕ.

RESULTS

Size of chitosan, PLGA, and BCA micro-/nanoparticles ranged between 3.11-7.18, 0.94-6.26, and 0.30-6.34 μm, respectively. Particle morphology and in vitro protein release varied, depending on polymer type, particle composition and preparation process parameters. Chitosan microparticles were cationic, while PLGA microparticles were neutral. BCA micro-/nanoparticles were either anionic or cationic, according to polymerization pH. Protein content and entrapment efficiency of chitosan and PLGA microparticles were relatively consistent. Only integrity and conformational structure of protein encapsulated in chitosan microparticles were completely retained. Chitosan and PLGA microparticles were non-toxic to DC and Mϕ, but the former were internalized more efficiently.

CONCLUSIONS

Spray-dried chitosan microparticles delivered the antigen efficiently to DC and Mϕ.

Nanocarriers for tracking and treating diseases

Site directed drug delivery with high efficacy is the biggest challenge in the area of current pharmaceuticals. Biodegradable polymer-based controlled release nanoparticle platforms could be beneficial for targeted delivery of therapeutics and contrast agents for a myriad of important human diseases. Biodegradable nanoparticles, which can be engineered to load multiple drugs with varied physicochemical properties, contrast agents, and cellular or intracellular component targeting moieties, have emerged as potential alternatives for tracking and treating human diseases. In this review, we will highlight the current advances in the design and execution of such platforms for their potential application in the diagnosis and treatment of variety of diseases ranging from cancer to Alzheimer's and we will provide a critical analysis of the associated challenges for their possible clinical translation.

Magnetic targeting of nanoparticles across the intact blood-brain barrier

Delivery of therapeutic or diagnostic agents across an intact blood-brain barrier (BBB) remains a major challenge. Here we demonstrate in a mouse model that magnetic nanoparticles (MNPs) can cross the normal BBB when subjected to an external magnetic field. Following a systemic administration, an applied external magnetic field mediates the ability of MNPs to permeate the BBB and accumulate in a perivascular zone of the brain parenchyma. Direct tracking and localization inside endothelial cells and in the perivascular extracellular matrix in vivo was established using fluorescent MNPs. These MNPs were inert and associated with low toxicity, using a non-invasive reporter for astrogliosis, biochemical and histological studies. Atomic force microscopy demonstrated that MNPs were internalized by endothelial cells, suggesting that trans-cellular trafficking may be a mechanism for the MNP crossing of the BBB observed. The silica-coated magnetic nanocapsules (SiMNCs) allow on-demand drug release via remote radio frequency (RF) magnetic field. Together, these results establish an effective strategy for regulating the biodistribution of MNPs in the brain through the application of an external magnetic field.

Toxicity studies of poly(anhydride) nanoparticles as carriers for oral drug delivery

PURPOSE

To evaluate the acute and subacute toxicity of poly(anhydride) nanoparticles as carriers for oral drug/antigen delivery.

METHODS

Three types of poly(anhydride) nanoparticles were assayed: conventional (NP), nanoparticles containing 2-hydroxypropyl-β-cyclodextrin (NP-HPCD) and nanoparticles coated with poly(ethylene glycol) 6000 (PEG-NP). Nanoparticles were prepared by a desolvation method and characterized in terms of size, zeta potential and morphology. For in vivo oral studies, acute and sub-acute toxicity studies were performed in rats in accordance to the OECD 425 and 407 guidelines respectively. Finally, biodistribution studies were carried out after radiolabelling nanoparticles with (99m)technetium.

RESULTS

Nanoparticle formulations displayed a homogeneous size of about 180 nm and a negative zeta potential. The LD(50) for all the nanoparticles tested was established to be higher than 2000 mg/kg bw. In the sub-chronic oral toxicity studies at two different doses (30 and 300 mg/kg bw), no evident signs of toxicity were found. Lastly, biodistribution studies demonstrated that these carriers remained in the gut with no evidences of particle translocation or distribution to other organs.

CONCLUSIONS

Poly(anhydride) nanoparticles (either conventional or modified with HPCD or PEG6000) showed no toxic effects, indicating that these carriers might be a safe strategy for oral delivery of therapeutics.

Conformation of surface-decorating dextran chains affects the pharmacokinetics and biodistribution of doxorubicin-loaded nanoparticles

Recent reports showed that subtle modifications of nanoparticle surface properties induced dramatic changes of interactions with serum proteins. The present work was aimed to investigate the effect of the conformation of dextran chains decorating the surface of poly(alkylcyanoacrylate) (PACA) nanoparticles on the pharmacokinetic and biodistribution of a model drug associated with the nanoparticles. Doxorubicin was associated with PACA nanoparticles prepared by anionic emulsion polymerization (AEP) (Dox-AEP) and redox radical emulsion polymerization (RREP) (Dox-RREP). Nanoparticles and the free drug (f-Dox) were injected intravenously to rats to determine the pharmacokinetic and biodistribution of doxorubicin. Curves of the pharmacokinetics showed a rapid phase of distribution followed by a slower elimination phase. Pharmacokinetic parameters of the distribution phase determined for the Dox-RREP were significantly different from those of f-Dox and Dox-AEP, while no difference was observed in the elimination phase of the three formulations. Rats treated with Dox-RREP showed lower Dox concentrations in liver but higher concentrations in heart, lungs, and kidneys compared to those treated with the other formulations. Dox-RREP exhibited a new type of stealth behavior characterized by a short circulation time and a rapid distribution in highly vascularized organs bypassing the MPS. The difference in pharmacokinetic and biodistribution observed between the drugs formulated with the two types of nanoparticles was attributed to the difference in the conformation of the dextran chains stranded on the nanoparticle surface.

Nanomedicine: towards development of patient-friendly drug-delivery systems for oncological applications

The focus on nanotechnology in cancer treatment and diagnosis has intensified due to the serious side effects caused by anticancer agents as a result of their cytotoxic actions on normal cells. This nonspecific action of chemotherapy has awakened a need for formulations capable of definitive targeting with enhanced tumor-killing. Nanooncology, the application of nanobiotechnology to the management of cancer, is currently the most important area of nanomedicine. Currently several nanomaterial-based drug-delivery systems are in vogue and several others are in various stages of development. Tumor-targeted drug-delivery systems are envisioned as magic bullets for cancer therapy and several groups are working globally for development of robust systems.

Toxicity of nanomaterials

Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan's Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity (286 references).

Miniemulsion polymerizations of n-butyl cyanoacrylate via two routes: towards a control of particle degradation

This study aimed at determining the influence of the mechanism of polymerization on the molar mass and degradation of poly(n-butyl cyanoacrylate) (PBCA) nanoparticles obtained by miniemulsion polymerization. Therefore, nanoparticles of poly(n-butyl cyanoacrylate) were synthesized via radical and/or anionic miniemulsion polymerization stabilized by Brij®78, a POE based surfactant. Polymerization conditions had little influence on the final diameter while it severely affected the final molar masses of PBCA. An increase of the temperature and of the pH of the continuous phase led to higher molar masses. A further increase was observed when a radical initiator was added in the monomer. The evolution of the molar mass of the synthesized poly(n-butyl cyanoacrylate) was followed as a function of time at pH 7.4 by Size Exclusion Chromatography. As expected, the degradation kinetics strongly depended on the polymerization mechanism (anionic or radical).