Past and future evolution in colloidal drug delivery systems

Critical Review of Food Colloidal Delivery System for Bioactive Compounds: Physical Characterization and Application

Bioactive compounds (BACs) have attracted much attention due to their potential health benefits. However, such substances have problems such as difficulty dissolving in water, poor stability, and low intestinal absorption, leading to serious limitations in practical applications. Nowadays, food colloidal delivery carriers have become a highly promising solution due to their safety, controllability, and efficiency. The use of natural macromolecules to construct delivery carriers can not only regulate the solubility, stability, and intestinal absorption of BACs but also effectively enhance the nutritional added value of functional foods, improve sensory properties, and extend shelf life. Moreover, smart-responsive colloidal delivery carriers can control the release characteristics of BACs, thus improving their absorption rate in the human body. This review describes the characteristics of several typical food colloid delivery carriers, focuses on their physical properties from static structure to dynamic release, summarizes their applications in delivery systems, and provides an outlook on the future development of food colloid delivery carriers. The different compositions and structures of food colloids tend to affect their stability and release behaviors, and the different surface properties and rheological characteristics of the carriers predestine their different application scenarios. The control of in vivo release properties and the effect on food media should be emphasized in the future exploration of safer and more controllable carrier systems.

Simultaneous and independent topological control of identical microparticles in non-periodic energy landscapes

Topological protection ensures stability of information and particle transport against perturbations. We explore experimentally and computationally the topologically protected transport of magnetic colloids above spatially inhomogeneous magnetic patterns, revealing that transport complexity can be encoded in both the driving loop and the pattern. Complex patterns support intricate transport modes when the microparticles are subjected to simple time-periodic loops of a uniform magnetic field. We design a pattern featuring a topological defect that functions as an attractor or a repeller of microparticles, as well as a pattern that directs microparticles along a prescribed complex trajectory. Using simple patterns and complex loops, we simultaneously and independently control the motion of several identical microparticles differing only in their positions above the pattern. Combining complex patterns and complex loops we transport microparticles from unknown locations to predefined positions and then force them to follow arbitrarily complex trajectories concurrently. Our findings pave the way for new avenues in transport control and dynamic self-assembly in colloidal science.

Generation of multi-layered protein bodies in N. benthamiana for the encapsulation of vaccine antigens

The ability of plants to assemble particulate structures such as virus-like particles and protein storage organelles allows the direct bioencapsulation of recombinant proteins during the manufacturing process, which holds promise for the development of new drug delivery vehicles. Storage organelles found in plants such as protein bodies (PBs) have been successfully used as tools for accumulation and encapsulation of recombinant proteins. The fusion of sequences derived from 27-kDa-γ-zein, a major storage protein of maize, with a protein of interest leads to the incorporation of the chimeric protein into the stable and protected environment inside newly induced PBs. While this procedure has proven successful for several, but not all recombinant proteins, the aim of this study was to refine the technology by using a combination of PB-forming proteins, thereby generating multi-layered protein assemblies in N. benthamiana. We used fluorescent proteins to demonstrate that up to three proteinaceous components can be incorporated into different layers. In addition to 27-kDa-γ-zein, which is essential for PB initiation, 16-kDa-γ-zein was identified as a key element to promote the incorporation of a third zein-component into the core of the PBs. We show that a vaccine antigen could be incorporated into the matrix of multi-layered PBs, and the protein microparticles were characterized by confocal and electron microscopy as well as flow cytometry. In future, this approach will enable the generation of designer PBs that serve as drug carriers and integrate multiple components that can be functionalized in different ways.

Recent advances of polymer based nanosystems in cancer management

Cancer is still one of the leading causes of death worldwide. Nanotechnology, particularly nanoparticle-based platforms, is at the leading edge of current cancer management research. Polymer-based nanosystems have piqued the interest of researchers owing to their many benefits over other conventional drug delivery systems. Polymers derived from both natural and synthetic sources have various biomedical applications due to unique qualities like porosity, mechanical strength, biocompatibility, and biodegradability. Polymers such as poly(lactic-co-glycolic acid) (PLGA), polycaprolactone (PCL), and polyethylene glycol (PEG) have been approved by the USFDA and are being researched for drug delivery applications. They have been reported to be potential carriers for drug loading and are used in theranostic applications. In this review, we have primarily focused on the aforementioned polymers and their conjugates. In addition, the therapeutic and diagnostic implications of polymer-based nanosystems have been briefly reviewed. Furthermore, the safety of the developed polymeric formulations is crucial, and we have discussed their biocompatibility in detail. This article also discusses recent developments in block co-polymer-based nanosystems for cancer treatment. The review ends with the challenges of clinical translation of polymer-based nanosystems in drug delivery for cancer therapy.

Physicochemical and Stability Evaluation of Topical Niosomal Encapsulating Fosinopril/γ-Cyclodextrin Complex for Ocular Delivery

This study aimed to develop a chemically stable niosomal eye drop containing fosinopril (FOS) for lowering intraocular pressure. The effects of cyclodextrin (CD), surfactant types and membrane stabilizer/charged inducers on physiochemical and chemical properties of niosome were evaluated. The pH value, average particle size, size distribution and zeta potentials were within the acceptable range. All niosomal formulations were shown to be slightly hypertonic with low viscosity. Span® 60/dicetyl phosphate niosomes in the presence and absence of γCD were selected as the optimum formulations according to their high %entrapment efficiency and negative zeta potential values as well as controlled release profile. According to ex vivo permeation study, the obtained lowest flux and apparent permeability coefficient values confirmed that FOS/γCD complex was encapsulated within the inner aqueous core of niosome and could be able to protect FOS from its hydrolytic degradation. The in vitro cytotoxicity revealed that niosome entrapped FOS or FOS/γCD formulations were moderate irritation to the eyes. Furthermore, FOS-loaded niosomal preparations exhibited good physical and chemical stabilities especially of those in the presence of γCD, for at least three months under the storage condition of 2–8 °C.

Therapeutic potential of nanoemulsions as feasible wagons for targeting Alzheimer's disease

Alzheimer's disease (AD) is an irreversible dementia state with characteristic clinical manifestations, including declining cognitive skills and loss of memory, which particularly affects the older population. Despite significant efforts in the field of nano-based drug delivery, there have been few successes achieved in the design of a rational drug therapy. Nanoemulsions (NEs) have potential for the delivery of AD therapeutics owing to their capability for brain drug delivery. Still, there is a long way to go before such therapeutics become a reality in the clinic. In this review, we highlight the preclinical assessment of NEs for AD and discuss the regulatory constraints to their clinical acceptance.

Colloidal nanosystems with mucoadhesive properties designed for ocular topical delivery

Over the last years, the scientific interest about topical ocular delivery targeting the posterior segment of the eye has been increasing. This is probably due to the fact that this is a non-invasive administration route, well tolerated by patients and with fewer local and systemic side effects. However, it is a challenging task due to the external ocular barriers, tear film clearance, blood flow in the conjunctiva and choriocapillaris and due to the blood-retinal barriers, amongst other features. An enhanced intraocular bioavailability of drugs can be achieved by either improving corneal permeability or by improving precorneal retention time. Regarding this last option, increasing residence time in the precorneal area can be achieved using mucoadhesive polymers such as xyloglucan, poly(acrylate), hyaluronic acid, chitosan, and carbomers. On the other hand, colloidal particles can interact with the ocular mucosa and enhance corneal and conjunctival permeability. These nanosystems are able to deliver a wide range of drugs, including macromolecules, providing stability and improving ocular bioavailability. New pharmaceutical approaches based on nanotechnology associated to bioadhesive compounds have emerged as strategies for a more efficient treatment of ocular diseases. Bearing this in mind, this review provides an overview of the current mucoadhesive colloidal nanosystems developed for ocular topical administration, focusing on their advantages and limitations.

In vivo efficacy of meglumine antimoniate-loaded nanoparticles for cutaneous leishmaniasis: a systematic review

Background: Nanotechnology is a promising strategy to improve existing antileishmanial agents. Objective: To explore the evidence of encapsulated meglumine antimoniate for cutaneous leishmaniasis treatment in animal models. Materials & methods: The studies were recovered from PubMed, Scopus, EMBASE, LILACS, WoS and Google according to eligibility criteria following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and the Population, Intervention, Comparison, Outcomes and Study design (PICOS) strategy. Study appraisal was assessed using the Animal Research Reporting of In Vivo Experiments, SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE) and Grading of Recommendations Assessment, Development and Evaluation (GRADE) recommendations. Results: Five studies were included. Liposomes, metallic and polymeric nanoparticles were tested in BALB/c mice against Leishmania major, L. tropica or L. amazonensis. Limitations: Few studies were found to meet the eligibility criteria. Conclusion: All formulations had a significant efficacy, similar to the meglumine antimoniate reference treatment concerning the lesion size and parasite burden. The studies had a high and moderate risk of bias, and the confidence in cumulative evidence was considered low. Therefore, we encourage the development of high-quality preclinical studies. Registration: PROSPERO register CRD42020170191.

Microparticles and Nanoparticles from Plants-The Benefits of Bioencapsulation

The efficacy of drugs and vaccines depends on their stability and ability to interact with their targets in vivo. Many drugs benefit from encapsulation, which protects them from harsh conditions and allows targeted delivery and controlled release. Although many encapsulation methods are inexpensive, such as the formulation of tablets for oral delivery, others require complex procedures that add significantly to production costs and require low-temperature transport and storage, making them inaccessible in developing countries. In this review we consider the benefits of encapsulation technologies based on plants. Plant-derived biopolymers such as starch and the maize storage protein zein are already used as protective coatings, but plant cells used as production host provide natural in vivo bioencapsulation that survives passage through the stomach and releases drugs in the intestine, due to the presence of microbes that can digest the cell wall. Proteins can also be encapsulated in subcellular compartments such as protein bodies, which ensure stability and activity while often conferring additional immunomodulatory effects. Finally, we consider the incorporation of drugs and vaccines into plant-derived nanoparticles assembled from the components of viruses. These are extremely versatile, allowing the display of epitopes and targeting peptides as well as carrying cargoes of drugs and imaging molecules.

Improvement of the multi-performance biocharacteristics of cordycepin using BiloNiosome-core/chitosan-shell hybrid nanocarriers

Cordycepin, a derivative of the nucleotide adenosine, has displayed several pharmacological activities including enhanced apoptosis and cancer cells inhibition. However, oral administration of cordycepin has limited practical use due to its poor bioavailability in the intestine. Herein, we developed and demonstrated a hybrid nanocarrier system in the form of biloniosome-core/chitosan-shell hybrid nanocarriers (HNCs) in order to improve the bio-characteristics of cordycepin. In this study, HNCs were prepared by using a solvent (ethanol) injection method involving cordycepin as the biloniosome core and mucoadhesive chitosan biopolymer as a coating shell. Our results showed that the cordycepin-loaded HNCs were positively charged with enhanced mucoadhesive characteristics and highly stable in gastric fluid. The increased permeability of cordycepin-loaded HNCs compared with standard cordycepin was confirmed by in vitro intestinal permeation study across the human intestinal barrier. In addition, we demonstrated that the cordycepin-loaded HNCs are able to release their components in an active form resulting in enhanced anti-cancer activity in two-dimensional (2D) cell cultures as well as in three-dimensional (3D) multi-cellular spheroids of colon cancer cells. Further, quantitative real time PCR analysis of apoptotic gene expression revealed that cordycepin HNCs can induce apoptosis in cancer cells by negatively regulating the expression of B-cell lymphoma-extra large (BCL-XL). I Overall our results showed that the hybrid nanocarrier systems represent a promising strategy for improving the bio-characteristics of cordycepin which can be considered as a potential anti-cancer agent for colorectal cancer chemotherapy.

Ratite oils for local transdermal therapy of 4-OH tamoxifen: development, characterization, and ex vivo evaluation

The anti-inflammatory property of ratite oils as well as its ability to act as a penetration enhancer makes it an ideal agent to be used in transdermal formulations. The present study aims to develop an effective transfersomal delivery of 4-hydroxytamoxifen (4-OHT), an anti-cancer drug, using ratite oil as a carrier agent for the treatment of breast cancer (BC). The 4-OHT transfersomes were prepared with and without ratite oils using soy phosphatidylcholine and three different edge activators (EAs) in five different molar ratios using the rotary evaporation-ultrasonication method. Optimal transfersome formulations were selected using physical-chemical characterization and ex vivo studies. Results from physical-chemical characterization of the developed formulations found sodium taurocholate to be the most suitable EA, which recorded highest entrapment efficiency of 95.1 ± 2.70% with 85:15, (w/w) and lowest vesicle size of 82.3 ± 0.02 nm with 75:25, (w/w) molar ratios. TEM and DSC studies showed that the vesicles were readily identified and present in a nearly perfect spherical shape. In addition, formulations with emu oil had better stability than formulations with ostrich oil. Physical stability studies at 4 °C showed that ratite oil transfersomes were stable up to 4 weeks, while transfersomes without ratite oils were stable for 8 weeks. Ex vivo permeability studies using porcine skin concluded that 4-OHT transfersomal formulations with (85:15, w/w) without emu oil have the potential to be used in transdermal delivery approach to enhance permeation of 4-OHT, which may be beneficial in the treatment of BC.

Dendrimers as Pharmaceutical Excipients: Synthesis, Properties, Toxicity and Biomedical Applications

The European Medicines Agency (EMA) and the Current Good Manufacturing Practices (cGMP) in the United States of America, define excipient as the constituents of the pharmaceutical form other than the active ingredient, i.e., any component that is intended to furnish pharmacological activity. Although dendrimers do not have a pharmacopoeia monograph and, therefore, cannot be recognized as a pharmaceutical excipient, these nanostructures have received enormous attention from researchers. Due to their unique properties, like the nanoscale uniform size, a high degree of branching, polyvalency, aqueous solubility, internal cavities, and biocompatibility, dendrimers are ideal as active excipients, enhancing the solubility of poorly water-soluble drugs. The fact that the dendrimer's properties are controllable during their synthesis render them promising agents for drug-delivery applications in several pharmaceutical formulations. Additionally, dendrimers can be used for reducing the drug toxicity and for the enhancement of the drug efficacy. This review aims to discuss the properties that turn dendrimers into pharmaceutical excipients and their potential applications in the pharmaceutical and biomedical fields.

In Vitro Evaluation of Eudragit Matrices for Oral Delivery of BCG Vaccine to Animals

Bacillus Calmette–Guérin (BCG) vaccine is the only licensed vaccine against tuberculosis (TB) in humans and animals. It is most commonly administered parenterally, but oral delivery is highly advantageous for the immunisation of cattle and wildlife hosts of TB in particular. Since BCG is susceptible to inactivation in the gut, vaccine formulations were prepared from suspensions of Eudragit L100 copolymer powder and BCG in phosphate-buffered saline (PBS), containing Tween^® 80, with and without the addition of mannitol or trehalose. Samples were frozen at −20 °C, freeze-dried and the lyophilised powders were compressed to produce BCG–Eudragit matrices. Production of the dried powders resulted in a reduction in BCG viability. Substantial losses in viability occurred at the initial formulation stage and at the stage of powder compaction. Data indicated that the Eudragit matrix protected BCG against simulated gastric fluid (SGF). The matrices remained intact in SGF and dissolved completely in simulated intestinal fluid (SIF) within three hours. The inclusion of mannitol or trehalose in the matrix provided additional protection to BCG during freeze-drying. Control needs to be exercised over BCG aggregation, freeze-drying and powder compaction conditions to minimise physical damage of the bacterial cell wall and maximise the viability of oral BCG vaccines prepared by dry powder compaction.

Basic principles of drug delivery systems - the case of paclitaxel

Cancer is the second cause of death worldwide, exceeded only by cardiovascular diseases. The prevalent treatment currently used against metastatic cancer is chemotherapy. Among the most studied drugs that inhibit neoplastic cells from acquiring unlimited replicative ability (a hallmark of cancer) are the taxanes. They operate via a unique molecular mechanism affecting mitosis. In this review, we show this mechanism for one of them, paclitaxel, and for other (non-taxanes) anti-mitotic drugs. However, the use of paclitaxel is seriously limited (its bioavailability is <10%) due to several long-standing challenges: its poor water solubility (0.3 μg/mL), its being a substrate for the efflux multidrug transporter P-gp, and, in the case of oral delivery, its first-pass metabolism by certain enzymes. Adequate delivery methods are therefore required to enhance the anti-tumor activity of paclitaxel. Thus, we have also reviewed drug delivery strategies in light of the various physical, chemical, and enzymatic obstacles facing the (especially oral) delivery of drugs in general and paclitaxel in particular. Among the powerful and versatile platforms that have been developed and achieved unprecedented opportunities as drug carriers, microemulsions might have great potential for this aim. This is due to properties such as thermodynamic stability (leading to long shelf-life), increased drug solubilization, and ease of preparation and administration. In this review, we define microemulsions and nanoemulsions, analyze their pertinent properties, and review the results of several drug delivery carriers based on these systems.

Active Gating, Molecular Pumping, and Turnover Determination in Biomimetic Lipidic Cubic Mesophases with Reconstituted Membrane Proteins

Understanding the mechanisms controlling molecular transport in bioinspired materials is a central topic in many branches of nanotechnology. In this work, we show that biomolecules of fundamental importance in biological processes, such as glucose, can be transported in an active, controlled, and selective manner across macroscopic lipidic cubic mesophases, by correctly reconstituting within them their corresponding membrane protein transporters, such as Staphylococcus epidermidis (GlcP_Se). Importantly, by duly exploiting the symporter properties of GlcP_Se of coupled glucose/H⁺ transport, the diffusion of glucose can further be tuned by independent physiological stimuli, such as parallel or antiparallel pH gradients, offering an important model to study molecular exchange processes in cellular machinery. We finally show that by measuring the transport properties of the lipidic mesophases with and without the GlcP_Se membrane protein reconstituted within, it becomes possible to determine its intrinsic conductance. We generalize these findings to other membrane proteins from the antiporters family, such as the bacterial ClC exchanger from Escherichia coli (EcClC), providing a robust method for evaluating the turnover rate of the membrane proteins in general.

Multifunctionalized iron oxide nanoparticles for selective targeting of pancreatic cancer cells

Nanomedicine nowadays offers novel solutions in cancer therapy by introducing multimodal treatments in one single formulation. In addition, nanoparticles act as nanocarriers changing the solubility, biodistribution and efficiency of the therapeutic molecules, thus generating more efficient treatments and reducing their side effects. To apply these novel therapeutic approaches, efforts are focused on the multi-functionalization of the nanoparticles and will open up new avenues to advanced combinational therapies. Pancreatic ductal adenocarcinoma (PDAC) is a cancer with unmet medical needs. Abundant expression of the anti-phagocytosis signal CD47 has also been observed on pancreatic cancer cells, in particular a subset of cancer stem cells (CSCs) responsible for resistance to standard therapy and metastatic potential. CD47 receptor is found on pancreatic cancer and highly expressed on CSCs, but not on normal pancreas. Inhibiting CD47 using monoclonal antibodies has been shown as an effective strategy to treat PDAC in vivo. However, CD47 inhibition effectively slowed tumor growth only in combination with Gemcitabine or Abraxane. In this work, we present the generation of multifunctionalized iron oxide magnetic nanoparticles (MNPs) that include the anti-CD47 antibody and the chemotherapeutic drug Gemcitabine in a single formulation. We demonstrate the in vitro efficacy of the formulation against CD47-positive pancreatic cancer cells. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader.

"Application of Box-Behnken design for optimization and development of quetiapine fumarate loaded chitosan nanoparticles for brain delivery via intranasal route* "

The objective of the present investigation was to optimize and develop quetiapine fumarate (QF) loaded chitosan nanoparticles (QF-NP) by ionic gelation method using Box-Behnken design. Three independent variables viz., X1-Concentration of chitosan, X2-Concentration of sodium tripolyphosphate and X3-Volume of sodium tripolyphosphate were taken to investigate their effect on dependent variables (Y1-Size, Y2-PDI and Y3-%EE). Optimized formula of QF-NP was selected from the design space which was further evaluated for physicochemical, morphological, solid state characterization, nasal diffusion and in-vivo distribution for brain targeting following non-invasive intranasal administration. The average particle size, PDI, %EE and nasal diffusion were found to be 131.08±7.45nm, 0.252±0.064, 89.93±3.85% and 65.24±5.26% respectively. Neither toxicity nor structural damage on nasal mucosa was observed upon histopathological examination. Significantly higher brain/blood ratio and 2 folds higher nasal bioavailability in brain with QF-NP in comparison to drug solution following intranasal administration revealed preferential nose to brain transport bypassing blood-brain barrier and prolonged retention of QF at site of action suggesting superiority of chitosan as permeability enhancer. Overall, the above finding shows promising results in the area of developing non-invasive intranasal route as an alternative to oral route for brain delivery.

Nioplexes encapsulated in supramolecular hybrid biohydrogels as versatile delivery platforms for nucleic acids

Supramolecular hydrogels based on N-protected phenylalanine (Fmoc–Phe–OH) were used to encapsulate non-ionic surfactant vesicles (niosomes).

Cellular Response to Linear and Branched Poly(acrylic acid)

Poly(acrylic acid-co-sodium acrylate) (PNaA) is a pH-responsive polymer with potential in anticancer drug delivery. The cytotoxicity and intracellular effects of 3-arm star, hyperbranched and linear PNaA were investigated with L1210 progenitor leukemia cells and L6 myoblast cells. Free solution capillary electrophoresis demonstrated interactions of PNaA with serum proteins. In a 72 h MTT assay most PNaAs exhibited a IC50 between 7 and 14 mmol L(-1), showing that precipitation may be a sufficient purification for PNaA dilute solutions. Dialyzed 3-arm star and hyperbranched PNaA caused an increase in L6 cell viability, challenging the suitability of MTT as cytotoxicity assay for PNaA. Fluorescent confocal microscopy revealed merging of cellular lipids after exposure to PNaA, likely caused by serum starvation.

Doxorubicin loaded polymeric gold nanoparticles targeted to human folate receptor upon laser photothermal therapy potentiates chemotherapy in breast cancer cell lines

The current research focuses on the application of folate conjugated and doxorubicin loaded polymeric gold nanoparticles (GNPs) for the targeted treatment of folate receptor overexpressing breast cancers, augmented by adjunctive laser photothermal therapy. Herein, GNPs surface modified with folate, drug doxorubicin and polyethylene glycol were engineered and were used as vehicles for folate receptor targeted delivery of doxorubicin into cancer cells. Subsequently, the GNPs were photo-excited using laser light for mediating hyperthermia in the cancer cells. In vitro studies were performed to validate the efficacy of the combined modality of folate conjugated and doxorubicin loaded polymeric GNP mediated chemotherapy followed by photothermal therapy in comparison to treatment with free drug; and the combination modality showed better therapeutic efficacy than that of plain doxorubicin treatment in MDA-MB-231 breast cancer cells that express increased levels of surface folate receptors when compared to MCF-7 breast cancer cells that express low levels of folate receptor. The mechanism of cell death was investigated using fluorescent microscopy. Immunoassays showed the up-regulation of the pro-apoptotic protein p53 and down-regulation of the anti-apoptotic protein Bcl-2. Collectively, these results suggest that the folate tagged doxorubicin loaded GNPs are an attractive platform for targeted delivery of doxorubicin and are agents suitable for photothermal cancer therapy.

Summary report of PQRI Workshop on Nanomaterial in Drug Products: current experience and management of potential risks

At the Product Quality Research Institute (PQRI) Workshop held last January 14-15, 2014, participants from academia, industry, and governmental agencies involved in the development and regulation of nanomedicines discussed the current state of characterization, formulation development, manufacturing, and nonclinical safety evaluation of nanomaterial-containing drug products for human use. The workshop discussions identified areas where additional understanding of material attributes, absorption, biodistribution, cellular and tissue uptake, and disposition of nanosized particles would continue to inform their safe use in drug products. Analytical techniques and methods used for in vitro characterization and stability testing of formulations containing nanomaterials were discussed, along with their advantages and limitations. Areas where additional regulatory guidance and material characterization standards would help in the development and approval of nanomedicines were explored. Representatives from the US Food and Drug Administration (USFDA), Health Canada, and European Medicines Agency (EMA) presented information about the diversity of nanomaterials in approved and newly developed drug products. USFDA, Health Canada, and EMA regulators discussed the applicability of current regulatory policies in presentations and open discussion. Information contained in several of the recent EMA reflection papers was discussed in detail, along with their scope and intent to enhance scientific understanding about disposition, efficacy, and safety of nanomaterials introduced in vivo and regulatory requirements for testing and market authorization. Opportunities for interaction with regulatory agencies during the lifecycle of nanomedicines were also addressed at the meeting. This is a summary of the workshop presentations and discussions, including considerations for future regulatory guidance on drug products containing nanomaterials.

Bile salts-containing vesicles: promising pharmaceutical carriers for oral delivery of poorly water-soluble drugs and peptide/protein-based therapeutics or vaccines

Most of the new drugs, biological therapeutics (proteins/peptides) and vaccines have poor performance after oral administration due to poor solubility or degradation in the gastrointestinal tract (GIT). Though, vesicular carriers exemplified by liposomes or niosomes can protect the entrapped agent to a certain extent from degradation. Nevertheless, the harsh GIT environment exemplified by low pH, presence of bile salts and enzymes limits their capabilities by destabilizing them. In response to that, more resistant bile salts-containing vesicles (BS-vesicles) were developed by inclusion of bile salts into lipid bilayers constructs. The effectiveness of orally administrated BS-vesicles in improving the performance of vesicles has been demonstrated in researches. Yet, these attempts did not gain considerable attention. This is the first review that provides a comprehensive overview of utilizing BS-vesicles as a promising pharmaceutical carrier with a special focus on their successful applications in oral delivery of therapeutic macromolecules and vaccines. Insights on the possible mechanisms by which BS-vesicles improve the oral bioavailability of the encapsulated drug or immunological response of entrapped vaccine are explained. In addition, methods adopted to prepare and characterize BS-vesicles are described. Finally, the gap in the scientific researches tackling BS-vesicles that needs to be addressed is highlighted.

Solid state synthesis of carbon-encapsulated iron carbide nanoparticles and their interaction with living cells

Superparamagnetic carbon-encapsulated iron carbide nanoparticles have been synthesized and tested for cytotoxicity.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

Cholesterol--a biological compound as a building block in bionanotechnology

Cholesterol is a molecule with many tasks in nature but also a long history in science. This feature article highlights the contribution of this small compound to bionanotechnology. We discuss relevant chemical aspects in this context followed by an overview of its self-assembly capabilities both as a free molecule and when conjugated to a polymer. Further, cholesterol in the context of liposomes is reviewed and its impact ranging from biosensing to drug delivery is outlined. Cholesterol is and will be an indispensable player in bionanotechnology, contributing to the progress of this potent field of research.

High-throughput production and structural characterization of libraries of self-assembly lipidic cubic phase materials

A protocol is presented for the high-throughput (HT) production of lyotropic liquid crystalline phases from libraries of lipids and lipid mixtures using standard liquid dispensing robotics, implementing methods that circumvent the problems traditionally associated with handling the highly viscous cubic phase. In addition, the ability to structurally characterize lipidic phases and assess functionality for membrane proteins contained within cubic phases, in a HT manner, is demonstrated. The techniques are combined and exemplified using the application of membrane protein crystallization within lipidic cubic phases.

Co-delivery of antigen and a lipophilic anti-inflammatory drug to cells via a tailorable nanocarrier emulsion

Nanotechnology promises new drug carriers that can be tailored to specific applications. Here we report a new approach to drug delivery based on tailorable nanocarrier emulsions (TNEs), motivated by a need to co-deliver a protein antigen and a lipophilic drug for specific inhibition of nuclear factor kappa B (NF-κB) in antigen presenting cells (APCs). Co-delivery for NF-κB inhibition holds promise as a strategy for the treatment of rheumatoid arthritis. We used a highly surface-active peptide (SAP) to prepare a nanosized emulsion having defined surface properties predictable from the SAP sequence. Incorporating the lipophilic drug into the oil phase at the time of emulsion formation enabled its facile packaging. The SAP is depleted from bulk during emulsification, allowing simple subsequent addition of the drug-loaded oil-in-water emulsion to a solution of protein antigen. Decoration of emulsion surface with antigen was achieved via electrostatic deposition. In vitro data showed that the TNE prepared this way was internalized and well-tolerated by model APCs, and that good suppression of NF-κB expression was achieved. This work reports a new type of nanotechnology-based carrier, a TNE, which can potentially be tailored for co-delivery of multiple therapeutic components, and can be made using simple methods using only biocompatible materials.

Standardization of models and methods used to assess nanoparticles in cardiovascular applications

Nanotechnology has the potential to revolutionize the management and treatment of cardiovascular disease. Controlled drug delivery and nanoparticle-based molecular imaging agents have advanced cardiovascular disease therapy and diagnosis. However, the delivery vehicles (dendrimers, nanocrystals, nanotubes, nanoparticles, nanoshells, etc.), as well as the model systems that are used to mimic human cardiac disease, should be questioned in relation to their suitability. This review focuses on the variations of the biological assays and preclinical models that are currently being used to study the biocompatibility and suitability of nanomaterials in cardiovascular applications. There is a need to standardize appropriate models and methods that will promote the development of novel nanomaterial-based cardiovascular therapies.

Self-nanoemulsifying drug delivery systems: formulation insights, applications and advances

There has been a resurgence of interest in nanoemulsions for various pharmaceutical applications since low-energy emulsification methods, such as spontaneous or self-nanoemulsification, have been described. Self-nanoemulsifying drug delivery systems (SNEDDS) are anhydrous homogenous liquid mixtures consisting of oil, surfactant, drug and coemulsifier or solubilizer, which spontaneously form oil-in-water nanoemulsion of approximately 200 nm or less in size upon dilution with water under gentle stirring. The physicochemical properties, drug solubilization capacity and physiological fate considerably govern the selection of the SNEDDS components. The composition of the SNEDDS can be optimized with the help of phase diagrams, whereas statistical experimental design can be used to further optimize SNEDDS. SNEDDS can improve oral bioavailability of hydrophobic drugs by several mechanisms. The conversion of liquid SNEDDS to solid oral dosage forms or solid SNEDDS has also been achieved by researchers. Solid SNEDDS can offer better patient compliance and minimize problems associated with capsules filled with liquid SNEDDS.

Design and fabrication of magnetic nanoparticles for targeted drug delivery and imaging

Magnetic nanoparticles (MNPs) represent a class of non-invasive imaging agents that have been developed for magnetic resonance (MR) imaging. These MNPs have traditionally been used for disease imaging via passive targeting, but recent advances have opened the door to cellular-specific targeting, drug delivery, and multi-modal imaging by these nanoparticles. As more elaborate MNPs are envisioned, adherence to proper design criteria (e.g. size, coating, molecular functionalization) becomes even more essential. This review summarizes the design parameters that affect MNP performance in vivo, including the physicochemical properties and nanoparticle surface modifications, such as MNP coating and targeting ligand functionalizations that can enhance MNP management of biological barriers. A careful review of the chemistries used to modify the surfaces of MNPs is also given, with attention paid to optimizing the activity of bound ligands while maintaining favorable physicochemical properties.

Novel nanomedicine-based MRI contrast agents for gynecological malignancies

Gynecological cancers result in significant morbidity and mortality in women despite advances in treatment and diagnosis. This is due to detection of the disease in the late stages following metastatic spread in which treatment options become limited and may not result in positive outcomes. In addition, traditional contrast agents are not very effective in detecting primary metastatic tumors and cells due to a lack of specificity and sensitivity of the diagnostic tools, which limits their effectiveness. Recently, the field of nanomedicine-based contrast agents offers a great opportunity to develop highly sophisticated devices that can overcome many traditional hurdles of contrast agents including solubility, cell-specific targeting, toxicities, and immunological responses. These nanomedicine-based contrast agents including liposomes, micelles, dendrimers, multifunctional magnetic polymeric nanohybrids, fullerenes, and nanotubes represent improvements over their traditional counterparts, which can significantly advance the field of molecular imaging.

Silica xerogels as pharmaceutical drug carriers

This review focuses on silica xerogels obtained by the sol-gel method and their application as drug delivery systems. SiO(2) xerogels are potential biomaterials to be used as matrix materials for the extended and controlled release of different kinds of biologically active agents administered by various routes. The article includes some representative examples that describe the encapsulation of bioactive molecules and model compounds inside a silica matrix produced by the conventional sol-gel method or by ultrasound hydrolysis. The drug release rate from xerogels could be modified by adjusting several parameters, such as the type of precursor, the concentration of the catalyst and drying temperature. In vitro and in vivo studies have shown the efficacy and biodegradability of these composites. The potential application of silica xerogels as drug carrier systems is critically analyzed and discussed.