The potential advantages of nanoparticle drug delivery systems in chemotherapy of tuberculosis

Applications of nanotechnology to imaging and therapy of brain tumors

In the past decade, numerous advances in the understanding of brain tumor physiology, tumor imaging, and tumor therapy have been attained. In some cases, these advances have resulted from refinements of pre-existing technologies (eg, improvements of contrast-enhanced magnetic resonance imaging). In other instances, advances have resulted from development of novel technologies. The development of nanomedicine (ie, applications of nanotechnology to the field of medicine) is an example of the latter. In this review, the authors explain the principles that underlay nanoparticle design and function as well as the means by which nanoparticles can be used for imaging and therapy of brain tumors.

Water-soluble and biocompatible sono/photosensitizer nanoparticles for enhanced cancer therapy

Aims: Most sono/photosensitizers of cancer sonodynamic/photodynamic therapy (SDT/PDT), such as hypocrellin SL052, are water-insoluble, therefore restricting their clinical applications. In this article, we present a water-soluble nanocarrier to load the SDT/PDT sensitizer SL052 with improved pharmacokinetics and therapeutic efficacy. Materials & methods: Nanoclusters of polyvinylpyrrolidones with SL052 formed water-soluble nanoparticles (SL052-NPs) while retaining the chemical structure of SL052. Results: The experimental results show that SL052-NPs improve the drug’s physicochemical properties and significantly enhance the efficacy of SL052 in terms of pharmacokinetics and cancer killing. Water-soluble SL052-NPs can be used to deliver the drug to deep cancer tissues. A potential benefit of SL052-NPs is that polyvinylpyrrolidones can help SL052 evade the reticuloendothelial system, thereby increasing circulation half-life and improving drug biodistribution. Conclusion: SL052-NPs greatly improved the physicochemical properties of SL052 without modifying its chemical structure, allowing for deep-site cancer drug delivery, imaging for diagnosis, and ultrasound or photocontrolled localized cancer therapy.

Photosensitizer loaded HSA nanoparticles II: in vitro investigations

The photosensitizing efficiency of human serum albumin (HSA) nanoparticles loaded with the photosensitizers meta-tetra(hydroxy-phenyl)-chlorin (mTHPC) and meta-tetra(hydroxy-phenyl)-porphyrin (mTHPP) was investigated in vitro. The endocytotic intracellular uptake, and the time dependent drug release caused by nanoparticle decomposition of the PS loaded HSA nanoparticles were studied on Jurkat cells in suspension. The photoxicity as well as the intracellular singlet oxygen ((1)O(2)) generation were investigated in dependence on the incubation time. The obtained results show that HSA nanoparticles are promising carriers for the clinical used mTHPC (Foscan). After release the ((1)O(2)) generation as well as the phototoxicity are more efficient compared with mTHPC applied without the HSA nanoparticles.

Association of quantum dot nanoparticles with Pseudomonas aeruginosa biofilm

Quantum dots (QDs) of two different surface chemistries (carboxyl [COOH] and polyethylene glycol [PEG] modified) were utilized to determine the impact of surface functionality on QD mobility and distribution in Pseudomonas aeruginosa PAO1 biofilms. Confocal laser scanning microscopy was utilized to evaluate QD association with biofilm components (proteins, cells, and polysaccharides). Quantum dots did not preferentially associate with cell surfaces compared but did colocalize with extracellular proteins in the biofilm matrix. Neither PEG nor COOH QDs were found to be internalized by individual bacterial cells. Neither QD functionality nor flow rate of QD application (0.3 mL min(-1) or 3.0 mL min(-1)) resulted in a marked difference in QD association with P. aeruginosa biofilms. However, center of density determinations indicated COOH QDs could more easily penetrate the biofilm matrix by diffusion than PEG QDs. Biofilms with PEG QDs associated had rougher polysaccharide layers and rougher cell distribution than biofilms with COOH QDs. This work suggests natural biofilms may serve as deposition locations in natural and engineered environmental systems, and biofilm structural parameters may change based on exposure to nanomaterials of varied physical characteristics.

Cytotoxic Activities of Silver Nanoparticles and Silver Ions in Parent and Tamoxifen-Resistant T47D Human Breast Cancer Cells and Their Combination Effects with Tamoxifen against Resistant Cells

Studies on biomedical applications of nanoparticles are growing with a rapid pace. In medicine, nanoparticles may be the solution for multi-drug-resistance which is still a major drawback in chemotherapy of cancer. In the present study, we investigated the potential cytotoxic effect of silver nanoparticles (Ag NPs) and silver ions (Ag(+)) in both parent and tamoxifen-resistant T47D cells in presence and absence of tamoxifen. Ag NPs were synthesized (< 28 nm) and MTT assay was carried out. The associated IC(50) values were found to be: 6.31 µg/ml for Ag NPs/parent cells, 37.06 µg/ml for Ag NPs/tamoxifen-resistant cells, 33.06 µg/ml for Ag(+)/parent cells and 10.10 µg/ml for Ag(+)/resistant cells. As a separate experiment, the effect of subinhibitory concentrations of Ag NPs and Ag(+) on the proliferation of tamoxifen-resistant cells was evaluated at non-toxic concentrations of tamoxifen. Our results suggested that in non-cytotoxic concentrations of silver nanomaterials and tamoxifen, the combinations of Ag(+)-tamoxifen and Ag NPs-tamoxifen are still cytotoxic. This finding may be of great potential benefit in chemotherapy of breast cancer; since much lower doses of tamoxifen may be needed to produce the same cytotoxic effect and side effects will be reduced.

Photophysical evaluation of mTHPC-loaded HSA nanoparticles as novel PDT delivery systems

Controlled drug release is one of the main goals of recent developments in drug carrier systems. In this work human serum albumin (HSA) nanoparticles as carriers for 5-, 10-, 15-, 20-Tetrakis (3-hydroxyphenyl)-chlorin (mTHPC) were investigated. The photophysical properties of mTHPC-HSA nanoparticles in dependence of loading ratio and level of HSA cross-linking were determined. Further the drug release after uptake by Jurkat cells and in vitro singlet oxygen kinetics were examined. The loading ratio of the mTHPC-HSA nanoparticles turned out to be of major importance for the PDT relevant electronic parameters in solution. Therefore, only HSA nanoparticles with low mTHPC-loading ratio generate singlet oxygen in D(2)O. However, after cellular uptake all mTHPC-HSA samples generate singlet oxygen in Jurkat cells, but the decomposition rate depends on the level of HSA cross-linking.

Towards nanomedicines: design protocols to assemble, visualize and test carbon nanotube probes for multi-modality biomedical imaging

Nanomedicine is an interdisciplinary field, still in its infancy, where an accurate scientific assessment of potential risks and benefits is urgently needed, as is the engagement of end users and the public in this facet of the nanotechnology debate. There is increasing interest in improving our understanding of the interactions between nanomaterials and living systems, with regard to both the underlying chemistry and the physics of effects on the nanoscale. Ultimately, such knowledge promises new vistas for designing the 'smart' medicines of the future, of which targeted personalized drugs are the holy grail. Imaging and therapeutic components, including metallic radioisotopes, semiconductor quantum dots and magnetic materials, may be used to construct 'nanocarriers' (by encapsulation or conjugation) by rapid and simple (covalent and supramolecular) chemistry. The biomedical functions of the resulting materials are as yet largely unexplored. Encapsulation in nanocarriers could achieve delivery of the reagents (imaging and therapeutic drugs) to the sites of action in the body, while minimizing systemic toxicity and enzymatic degradation. These functional systems have the potential to become a general solution in drug delivery. Here we review recent developments concerning the applications of nanoparticles, including carbon nanotubes, as synthetic scaffolds for designing nanomedicines. This article will also focus on how understanding and design at the molecular level could help interdisciplinary teams develop research towards new diagnostics and therapeutics both in the short and the long term.

Targeting of survivin by nanoliposomal ceramide induces complete remission in a rat model of NK-LGL leukemia

The natural killer (NK) type of aggressive large granular lymphocytic (LGL) leukemia is a fatal illness that pursues a rapid clinical course. There are no effective therapies for this illness, and pathogenetic mechanisms remain undefined. Here we report that the survivin was highly expressed in both aggressive and chronic leukemic NK cells but not in normal NK cells. In vitro treatment of human and rat NK-LGL leukemia cells with cell-permeable, short-chain C₆-ceramide (C₆) in nanoliposomal formulation led to caspase-dependent apoptosis and diminished survivin protein expression, in a time- and dose-dependent manner. Importantly, systemic intravenous delivery of nanoliposomal ceramide induced complete remission in the syngeneic Fischer F344 rat model of aggressive NK-LGL leukemia. Therapeutic efficacy was associated with decreased expression of survivin in vivo. These data suggest that in vivo targeting of survivin through delivery of nanoliposomal C₆-ceramide may be a promising therapeutic approach for a fatal leukemia.

Current development and future prospects in chemotherapy of tuberculosis

Although treatment of drug-susceptible tuberculosis (TB) under ideal conditions may be successful in >or=95% of cases, cure rates in the field are often significantly lower due to the logistical challenges of administering and properly supervising the intake of combination chemotherapy for 6-9 months. Success rates are far worse for multidrug-resistant and extensively drug-resistant TB cases. There is general agreement that new anti-TB drugs are needed to shorten or otherwise simplify treatment for drug-susceptible and multidrug-resistant/extensively drug-resistant-TB, including TB associated with HIV infection. For the first time in over 40 years, a nascent pipeline of new anti-TB drug candidates has been assembled. Eleven candidates from seven classes are currently being evaluated in clinical trials. They include novel chemical entities belonging to entirely new classes of antibacterials, agents approved for use against infections other than TB, and an agent already approved for limited use against TB. In this article, we review the current state of TB treatment and its limitations and provide updates on the status of new drugs in clinical trials. In the conclusion, we briefly highlight ongoing efforts to discover new compounds and recent advances in alternative drug delivery systems.

Functional silica nanoparticle-mediated neuronal membrane sealing following traumatic spinal cord injury

The mechanical damage to neurons and their processes induced by spinal cord injury (SCI) causes a progressive cascade of pathophysiological events beginning with the derangement of ionic equilibrium and collapse of membrane permeability. This leads to a cumulative deterioration of neurons, axons, and the tissue architecture of the cord. We have previously shown that the application of the hydrophilic polymer polyethylene glycol (PEG) following spinal cord or brain injury can rapidly restore membrane integrity, reduce oxidative stress, restore impaired axonal conductivity, and mediate functional recovery in rats, guinea pigs, and dogs. However there are limits to both the concentration and the molecular weight of the application that do not permit the broadest recovery across an injured animal population. In this study, PEG-decorated silica nanoparticles (PSiNPs) sealed cells, as shown by the significantly reduced leakage of lactate dehydrogenase from damaged cells compared with uncoated particles or PEG alone. Further in vivo tests showed that PSiNPs also significantly reduced the formation of reactive oxygen species and the process of lipid peroxidation of the membrane. Fabrication of PSiNPs containing embedded dyes also revealed targeting of the particles to damaged, but not undamaged, spinal cord tissues. In an in vivo crush/contusion model of guinea pig SCI, every animal but one injected with PSiNPs recovered conduction through the cord lesion, whereas none of the control animals did. These findings suggest that the use of multifunctional nanoparticles may offer a novel treatment approach for spinal cord injury, traumatic brain injury, and possibly neurodegenerative disorders.

Isoxyl aerosols for tuberculosis treatment: preparation and characterization of particles

Isoxyl is a potent antituberculosis drug effective in treating various multidrug-resistant strains in the absence of known side effects. Isoxyl has been used exclusively, but infrequently, via the oral route and has exhibited very poor and highly variable bioavailability due to its sparing solubility in water. These properties resulted in failure of some clinical trials and, consequently, isoxyl's use has been limited. Delivery of isoxyl to the lungs, a major site of Mycobacterium tuberculosis infection, is an attractive alternative route of administration that may rescue this abandoned drug for a disease that urgently requires new therapies. Particles for pulmonary delivery were prepared by antisolvent precipitation. Nanofibers with a width of 200 nm were obtained by injecting isoxyl solution in ethanol to water at a volume ratio of solvent to antisolvent of 1:5. Based on this preliminary result, a well-controlled method, involving nozzle mixing, was employed to prepare isoxyl particles. All the particles were 200 to 400 nm in width but had different lengths depending on properties of the solvents. However, generating these nanoparticles by simultaneous spray drying produced isoxyl microparticles (Feret's diameter, 1.19-1.77 microm) with no discernible nanoparticle substructure. The bulking agent, mannitol, helped to prevent these nanoparticles from agglomeration during process and resulted in nanoparticle aggregates in micron-sized superstructures. Future studies will focus on understanding difference of these isoxyl microparticles and nanoparticles/nanoparticle aggregates in terms of in vivo disposition and efficacy.

ZnO nanoparticles enhanced antibacterial activity of ciprofloxacin against Staphylococcus aureus and Escherichia coli

Nanoparticle metal oxides offer a wide variety of potential applications in medicine due to the unprecedented advances in nanobiotechnology research. In this work, the effect of zinc oxide (ZnO) nanoparticles prepared by mechano-chemical method on the antibacterial activity of different antibiotics was evaluated using disk diffusion method against Staphylococcus aureus and Escherichia coli. The average size of ZnO nanoparticles was between 20 nm and 45 nm. Although ZnO nanoparticles (500 microg/disk) decreased the antibacterial activity of amoxicillin, penicillin G, and nitrofurantoin in S. aureus, the antibacterial activity of ciprofloxacin increased in the presence of ZnO nanoparticles in both test strains. A total of 27% and 22% increase in inhibition zone areas was observed for ciprofloxacin in the presence of ZnO nanoparticles in S. aureus and E. coli, respectively. The enhancing effect of this nanomaterial on the antibacterial activity of ciprofloxacin was further investigated at three different contents (500, 1000, and 2000 microg/disk) against various clinical isolates of S. aureus and E. coli The enhancing effect of ZnO nanoparticles on the antibacterial activity of ciprofloxacin was concentration-dependent against all test strains. The most enhancing activities were observed in the contents of the 2000 microg/disk.

Toxicology and drug delivery by cucurbit[n]uril type molecular containers

BACKGROUND

Many drug delivery systems are based on the ability of certain macrocyclic compounds - such as cyclodextrins (CDs) - to act as molecular containers for pharmaceutical agents in water. Indeed beta-CD and its derivatives have been widely used in the formulation of hydrophobic pharmaceuticals despite their poor abilities to act as a molecular container (e.g., weak binding (K(a)<10(4) M(-1)) and their challenges toward chemical functionalization. Cucurbit[n]urils (CB[n]) are a class of molecular containers that bind to a variety of cationic and neutral species with high affinity (K(a)>10(4) M(-1)) and therefore show great promise as a drug delivery system.

METHODOLOGY

In this study we investigated the toxicology, uptake, and bioactivity of two cucurbit[n]urils (CB[5] and CB[7]) and three CB[n]-type containers (Pentamer 1, methyl hexamer 2, and phenyl hexamer 3). All five containers demonstrated high cell tolerance at concentrations of up to 1 mM in cell lines originating from kidney, liver or blood tissue using assays for metabolic activity and cytotoxicity. Furthermore, the CB[7] molecular container was efficiently internalized by macrophages indicating their potential for the intracellular delivery of drugs. Bioactivity assays showed that the first-line tuberculosis drug, ethambutol, was as efficient in treating mycobacteria infected macrophages when loaded into CB[7] as when given in the unbound form. This result suggests that CB[7]-bound drug molecules can be released from the container to find their intracellular target.

CONCLUSION

Our study reveals very low toxicity of five members of the cucurbit[n]uril family of nanocontainers. It demonstrates the uptake of containers by cells and intracellular release of container-loaded drugs. These results provide initial proof-of-concept towards the use of CB[n] molecular containers as an advanced drug delivery system.

Inhibition of Mycobacterium tuberculosis tyrosine phosphatase PtpA by synthetic chalcones: kinetics, molecular modeling, toxicity and effect on growth

Tuberculosis (TB) is a major cause of morbidity and mortality throughout the world, and it is estimated that one-third of the world's population is infected with Mycobacterium tuberculosis. Among a series of tested compounds, we have recently identified five synthetic chalcones which inhibit the activity of M. tuberculosis protein tyrosine phosphatase A (PtpA), an enzyme associated with M. tuberculosis infectivity. Kinetic studies demonstrated that these compounds are reversible competitive inhibitors. In this work we also carried out the analysis of the molecular recognition of these inhibitors on their macromolecular target, PtpA, through molecular modeling. We observed that the predominant determinants responsible for the inhibitory activity of the chalcones are the positions of the two methoxyl groups at the A-ring, that establish hydrogen bonds with the amino acid residues Arg17, His49, and Thr12 in the active site of PtpA, and the substitution of the phenyl ring for a 2-naphthyl group as B-ring, that undergoes pi stacking hydrophobic interaction with the Trp48 residue from PtpA. Interestingly, reduction of mycobacterial survival in human macrophages upon inhibitor treatment suggests their potential use as novel therapeutics. The biological activity, synthetic versatility, and low cost are clear advantages of this new class of potential tuberculostatic agents.

Mannosylated nanoparticulate carriers of rifabutin for alveolar targeting

The objective of the present study was to evaluate the prospective of engineered nanoparticles for selective delivery of an antituberculosis drug, rifabutin, to alveolar tissues. Drug-loaded solid lipid nanoparticles (SLNs) were synthesized and efficiently mannosylated. The formation of uncoated and coated SLNs was characterized by FTIR spectroscopy and SEM studies. A variety of physicochemical parameters such as drug loading, particle size, polydispersity index, zeta potential, and in vitro drug release were determined. The toxicity and targeting potential of the prepared formulation were assessed with alveolar macrophage uptake, hematological studies, and in vivo studies of uncoated and coated SLNs. Ex vivo cellular uptake studies of SLNs formulations in alveolar macrophages depicted almost six times enhanced uptake due to mannose coating. The hematological studies proved mannose-conjugated system to be less immunogenic and suitable for sustained delivery as evaluated against uncoated formulation. Further, the serum level and organ distribution studies demonstrated efficiency of the system for prolonged circulation and spatial delivery of rifabutin to alveolar tissues. Finally, it was concluded that mannose-conjugated SLNs can be exploited for effective and targeted delivery of rifabutin compared to its uncoated formulation and ultimately increasing the therapeutic margin of safety while reducing the side effects.

New old challenges in tuberculosis: potentially effective nanotechnologies in drug delivery

Tuberculosis (TB) is the second most deadly infectious disease. Despite potentially curative pharmacotherapies being available for over 50 years, the length of the treatment and the pill burden can hamper patient lifestyle. Thus, low compliance and adherence to administration schedules remain the main reasons for therapeutic failure and contribute to the development of multi-drug-resistant (MDR) strains. Pediatric patients constitute a high risk population. Most of the first-line drugs are not commercially available in pediatric form. The design of novel antibiotics attempts to overcome drug resistance, to shorten the treatment course and to reduce drug interactions with antiretroviral therapies. On the other hand, the existing anti-TB drugs are still effective. Overcoming technological drawbacks of these therapeutic agents as well as improving the effectiveness of the drug by targeting the infection reservoirs remains the central aims of Pharmaceutical Technology. In this framework, nanotechnologies appear as one of the most promising approaches for the development of more effective and compliant medicines. The present review thoroughly overviews the state-of-the-art in the development of nano-based drug delivery systems for encapsulation and release of anti-TB drugs and discusses the challenges that are faced in the development of a more effective, compliant and also affordable TB pharmacotherapy.

Nanotechnology solutions for mucosal immunization

The current prevalence of infectious diseases in many developing regions of the world is a serious burden, impacting both the general health as well as economic growth of these communities. Additionally, treatment with conventional medication becomes increasingly challenging due to emergence of new and drug resistant strains jeopardizing the progress made in recent years towards control and elimination of certain types of infectious diseases. Thus, from a public health perspective, prevention such as through immunization by vaccination, which has proven to be most effective, might be the best alternative to prevent and combat infectious diseases in these regions. To achieve this, development of wide-scale immunization programs become necessary including vaccines that can easily and widely be distributed, stored and administered. Mucosal vaccines offer great potential since they can be administered via oral or intranasal delivery route which does not require trained personnel, avoids the use of needles and improves overall patient compliance and acceptance. However, it necessitates the implementation of specific immunization strategies to improve their efficacy. Application of nanotechnology to design and create particle mediated delivery systems that can efficiently encapsulate vaccine components for protection of the sensitive payload, target the mucosal immune system and incorporate mucosal adjuvants maximizing immune response is key strategy to improve the effectiveness of mucosal vaccines.

Impact of hydrogel nanoparticle size and functionalization on in vivo behavior for lung imaging and therapeutics

Polymer chemistry offers the possibility of synthesizing multifunctional nanoparticles which incorporate moieties that enhance diagnostic and therapeutic targeting of cargo delivery to the lung. However, since rules for predicting particle behavior following modification are not well-defined, it is essential that probes for tracking fate in vivo are also included. Accordingly, we designed polyacrylamide-based hydrogel particles of differing sizes, functionalized with a nona-arginine cell-penetrating peptide (Arg(9)), and labeled with imaging components to assess lung retention and cellular uptake after intratracheal administration. Radiolabeled microparticles (1-5 microm diameter) and nanoparticles (20-40 nm diameter) without and with Arg(9) showed diffuse airspace distribution by positron emission tomography imaging. Biodistribution studies revealed that particle clearance and extrapulmonary distribution was, in part, size dependent. Microparticles were rapidly cleared by mucociliary routes but, unexpectedly, also through the circulation. In contrast, nanoparticles had prolonged lung retention enhanced by Arg(9) and were significantly restricted to the lung. For all particle types, uptake was predominant in alveolar macrophages and, to a lesser extent, lung epithelial cells. In general, particles did not induce local inflammatory responses, with the exception of microparticles bearing Arg(9). Whereas microparticles may be advantageous for short-term applications, nanosized particles constitute an efficient high-retention and non-inflammatory vehicle for the delivery of diagnostic imaging agents and therapeutics to lung airspaces and alveolar macrophages that can be enhanced by Arg(9). Importantly, our results show that minor particle modifications may significantly impact in vivo behavior within the complex environments of the lung, underscoring the need for animal modeling.

Cell-specific targeting in the mouse inner ear using nanoparticles conjugated with a neurotrophin-derived peptide ligand: potential tool for drug delivery

Cell specific targeting is an emerging field in nanomedicine. Homing of the multifunctional nanoparticles (MFNPs) is achieved by the conjugation of targeting moieties on the nanoparticle surface. The inner ear is an attractive target for new drug delivery strategies as it is hard to access and hearing loss is a significant worldwide problem. In this work we investigated the utility of a Nerve Growth Factor-derived peptide (hNgf_EE) functionalized nanoparticles (NPs) to target cells of the inner ear. These functionalized NPs were introduced to organotypic explant cultures of the mouse inner ear and to PC-12 rat pheochromocytoma cells. The NPs did not show any signs of toxicity. Specific targeting and higher binding affinity to spiral ganglion neurons, Schwann cells and nerve fibers of the explant cultures were achieved through ligand mediated multivalent binding to tyrosine kinase receptors and to p75 neurotrophin receptors. Unspecific uptake of NPs was investigated using NPs conjugated with scrambled hNgf_EE peptide. Our results indicate a selective cochlear cell targeting by MFNPs, which may be a potential tool for cell specific drug and gene delivery to the inner ear.

Preparation and evaluation of gelatin/sodium carboxymethyl cellulose polyelectrolyte complex microparticles for controlled delivery of isoniazid

The ratio of gelatin to sodium carboxymethyl cellulose (SCMC) at which maximum yield was obtained was optimized. This optimized ratio of gelatin to SCMC along with other parameters was used to prepare microparticles of different sizes. Vegetable oil was used as emulsion medium. Effect of various factors like amount of surfactant, concentration of polymer on the formation, and size of the microparticles was investigated. These microparticles were used as carrier for isoniazid. Among different cross-linkers, glutaraldehyde was found to be the most effective cross-linker at the temperature and pH at which the reaction was carried out. The loading efficiency and release behavior of loaded microparticles were found to be dependent on the amount of cross-linker used, concentration of drug, and time of immersion. Maximum drug loading efficiency was observed at higher immersion time. The release rate of isoniazid was more at higher pH compared to that of at lower pH. The sizes of the microparticles were investigated by scanning electron microscope. In all the cases, the microparticles formed were found spherical in shape except to those at low stirring speed where they were agglomerated. Fourier transform infrared study indicated the successful incorporation of isoniazid into the microparticles. Differential scanning calorimetry study showed a molecular level dispersion of isoniazid in the microparticles. X-ray diffraction study revealed the development of some crystallinity due to the encapsulation of isoniazid.

One-step electrohydrodynamic production of drug-loaded micro- and nanoparticles

The objective of this work was to produce drug-loaded nanometre- and micrometre-scale particles using a single-step process that provides control over particle size and size distribution. Co-axial electrohydrodynamic processing was used, at ambient temperature and pressure, with poly(lactic-co-glycolic acid) as the polymeric coating material and oestradiol as the encapsulated drug. The particle diameter was varied from less than 120 nm to a few micrometres, by simple methodical adjustments in the processing parameters (polymer concentration and applied voltage). In vitro studies were performed to determine the drug release profile from the particles during unassisted and ultrasound-stimulated degradation in simulated body fluid. An encapsulation efficiency of approximately 70% was achieved and release of the drug was sustained for a period of over 20 days. Exposing the particles to ultrasound (22.5 kHz) increased the rate of release by approximately 8 per cent. This processing method offers several advantages over conventional emulsification techniques for the preparation of drug-loaded particles. Most significantly, process efficiency and the drug's functionality are preserved, as complex multistep processing involving harsh solvents, other additives and elevated temperatures or pressures are avoided. Production rates of 10(12) particles min(-1) can be achieved with a single pair of co-axial needles and the process is amenable to being scaled up by using multiple sets.

Gelatin nanocarriers as potential vectors for effective management of tuberculosis

The aim of the research work was to develop and characterize rifampicin (RIF) loaded gelatin nanoparticulate delivery system for the effective management of tuberculosis. Gelatin nanoparticles (GPs) containing RIF were prepared using two-step desolvation method. Formulations were characterized through transmission electron microscopy (TEM), atomic force microscopy (AFM), size and size distribution analysis, polydispersity index (PDI), zeta potential, percent drug entrapment, percent nanoparticulate yield and in vitro drug release. Formulations were further characterized for in vitro cytotoxicity, in vivo biodistribution, and antitubercular activity. The nanoparticles were found to be spherical in shape. The size of nanoparticles was found to be 264+/-11.2 nm with low PDI suggesting the narrow particle size distribution. The drug release showed the biphasic pattern of release i.e. initial burst followed by a sustained release pattern. The cytotoxicity studies revealed that nanoparticles are safe, non toxic as compared to free drug. In vivo biodistribution study showed higher localization of RIF loaded GPs in various organs, as compared to plain RIF solution in PBS (pH 7.4). In contrast to free drug, the nanoparticles not only sustained the plasma level but also enhanced the AUC and mean residence time (MRT) of the drug, suggesting improved pharmacokinetics of drug. RIF GPs additionally resulted in significant reduction in bacterial counts in the lungs and spleen of TB-infected mice. Hence, GPs hold promising potential for increasing drug targetability vis a vis reducing dosing frequency with the interception of minimal side effects, for efficient management of tuberculosis.

Therapeutic application of peptides and proteins: parenteral forever?

Varied therapeutic peptides and proteins represent a rapidly growing part of marketed drugs and have an undisputed place alongside other established therapies. Nevertheless, such biodrugs have several drawbacks that hinder their therapeutic application. These are undesirable physicochemical properties, such as variable solubility, low bioavailability and limited stability. These issues can be overcome by addition of stabilizing agents and directed injectable administration, which can however result in low patient compliance. Hence, there is a drive in the biotechnology industry to produce needle-free and more user-friendly drugs, and this has led to the growth of nano-enabled drug delivery systems in the last decade. As discussed here, nanobiotechnology is becoming a commercially feasible and promising opportunity for oral, pulmonary and transdermal administration routes.

Nanodiamond-insulin complexes as pH-dependent protein delivery vehicles

Enhanced specificity in drug delivery aims to improve upon systemic elution methods by locally concentrating therapeutic agents and reducing negative side effects. Due to their robust physical properties, biocompatibility and drug loading capabilities, nanodiamonds serve as drug delivery platforms that can be applied towards the elution of a broad range of therapeutically-active compounds. In this work, bovine insulin was non-covalently bound to detonated nanodiamonds via physical adsorption in an aqueous solution and demonstrated pH-dependent desorption in alkaline environments of sodium hydroxide. Insulin adsorption to NDs was confirmed by FT-IR spectroscopy and zeta potential measurements, while both adsorption and desorption were visualized with TEM imaging, quantified using protein detection assays and protein function demonstrated by MTT and RT-PCR. NDs combined with insulin at a 4:1 ratio showed 79.8+/-4.3% adsorption and 31.3+/-1.6% desorption in pH-neutral and alkaline solutions, respectively. Additionally, a 5-day desorption assay in NaOH (pH 10.5) and neutral solution resulted in 45.8+/-3.8% and 2.2+/-1.2% desorption, respectively. MTT viability assays and quantitative RT-PCR (expression of Ins1 and Csf3/G-csf genes) reveal bound insulin remains inactive until alkaline-mediated desorption. For applications in sustained drug delivery and therapy we have developed a therapeutic protein-ND complex with demonstrated tunable release and preserved activity.

Uses of nanoparticles for central nervous system imaging and therapy

SUMMARY

Applications of nanotechnology to medicine are leading to novel means of imaging living systems and of delivering therapy. Much nanotechnology research is focused on methods for imaging central nervous system functions and disease states. In this review, the principles of nanoparticle design and function are discussed with specific emphasis on applications to neuroradiology. In addition to innovative forms of imaging, this review describes therapeutic uses of nanoparticles, such as drug delivery systems, neuroprotection devices, and methods for tissue regeneration.

Nanofountain-probe-based high-resolution patterning and single-cell injection of functionalized nanodiamonds

Nanodiamonds are rapidly emerging as promising carriers for next-generation therapeutics and drug delivery. However, developing future nanoscale devices and arrays that harness these nanoparticles will require unrealized spatial control. Furthermore, single-cell in vitro transfection methods lack an instrument that simultaneously offers the advantages of having nanoscale dimensions and control and continuous delivery via microfluidic components. To address this, two modes of controlled delivery of functionalized diamond nanoparticles are demonstrated using a broadly applicable nanofountain probe, a tool for direct-write nanopatterning with sub-100-nm resolution and direct in vitro single-cell injection. This study demonstrates the versatility of the nanofountain probe as a tool for high-fidelity delivery of functionalized nanodiamonds and other agents in nanomanufacturing and single-cell biological studies. These initial demonstrations of controlled delivery open the door to future studies examining the nanofountain probe's potential in delivering specific doses of DNA, viruses, and other therapeutically relevant biomolecules.

PAMAM nanoparticles promote acute lung injury by inducing autophagic cell death through the Akt-TSC2-mTOR signaling pathway

Nanotechnology is an important and emerging industry with a projected annual market of around one trillion US dollars by 2011-2015. Concerns about the toxicity of nanomaterials in humans, however, have recently been raised. Although studies of nanoparticle toxicity have focused on lung disease the molecular link between nanoparticle exposure and lung injury remained unclear. In this report, we show that cationic Starburst polyamidoamine dendrimer (PAMAM), a class of nanomaterials that are being widely developed for clinical applications can induce acute lung injury in vivo. PAMAM triggers autophagic cell death by deregulating the Akt-TSC2-mTOR signaling pathway. The autophagy inhibitor 3-methyladenine rescued PAMAM dendrimer-induced cell death and ameliorated acute lung injury caused by PAMAM in mice. Our data provide a molecular explanation for nanoparticle-induced lung injury, and suggest potential remedies to address the growing concerns of nanotechnology safety.

Nanotechnology: the coming revolution and its implications for consumers, clinicians, and informatics

Nanotechnology promises to revolutionize manufactured materials as we know them, creating a vast array of new products, drug delivery devices, and monitoring mechanisms. The promise of these products and devices is tremendous. Likewise, the implications of this technology are immense, ranging across consumers, clinicians, and the practice of informatics. Specific implications include opportunities for education of health care consumers and clinicians about the safe and ethical use of nanomaterials, a requirement for new policies and regulations, potential radical role changes for both consumers and clinicians, and new demands in the practice of informatics. The most pressing concern for health applications is the safe use of nanomaterials. Given the promise of nanomaterials and the implications across at least these 3 areas, nurses need to understand the capabilities and limitations of nanomaterials, proceed with reasoned caution, and plan now for its wide-ranging impacts.

Toxicity of CdSe Nanoparticles in Caco-2 Cell Cultures

Background

Potential routes of nanomaterial exposure include inhalation, dermal contact, and ingestion. Toxicology of inhalation of ultra-fine particles has been extensively studied; however, risks of nanomaterial exposure via ingestion are currently almost unknown. Using enterocyte-like Caco-2 cells as a small intestine epithelial model, the possible toxicity of CdSe quantum dot (QD) exposure via ingestion was investigated. Effect of simulated gastric fluid treatment on CdSe QD cytotoxicity was also studied.

Results

Commercially available CdSe QDs, which have a ZnS shell and poly-ethylene glycol (PEG) coating, and in-house prepared surfactant coated CdSe QDs were dosed to Caco-2 cells. Cell viability and attachment were studied after 24 hours of incubation. It was found that cytotoxicity of CdSe QDs was modulated by surface coating, as PEG coated CdSe QDs had less of an effect on Caco-2 cell viability and attachment. Acid treatment increased the toxicity of PEG coated QDs, most likely due to damage or removal of the surface coating and exposure of CdSe core material. Incubation with un-dialyzed in-house prepared CdSe QD preparations, which contained an excess amount of free Cd²⁺, resulted in dramatically reduced cell viability.

Conclusion

Exposure to CdSe QDs resulted in cultured intestinal cell detachment and death; cytotoxicity depended largely, however, on the QD coating and treatment (e.g. acid treatment, dialysis). Experimental results generally indicated that Caco-2 cell viability correlated with concentration of free Cd²⁺ ions present in cell culture medium. Exposure to low (gastric) pH affected cytotoxicity of CdSe QDs, indicating that route of exposure may be an important factor in QD cytotoxicity.

The release characteristics of a model protein from self-assembled succinimide-terminated poly(lactide-co-glycolide ethylene oxide fumarate) nanoparticles

Lactide-co-glycolide-based functionalized nanoparticles (NPs), because of their high surface areas for conjugation and biodegradability, are attractive as carriers for stabilization and sustained delivery of therapeutic agents and protein drugs. The objective of this work was to compare the release characteristics of model molecules encapsulated in NPs produced from poly(lactide-co-glycolide fumarate) (PLGF) macromer with those of model molecules conjugated to NPs produced from succinimide (NHS)-terminated PLGF-NHS macromer. Poly(lactide fumarate) (PLAF), PLGF and poly(lactide-co-ethylene oxide fumarate) (PLEOF) macromers were synthesized by condensation polymerization. The hydroxyl end-groups of PLAF and PLGF macromers were reacted with N,N(')-disuccinimidyl carbonate (DSC) to produce succinimide-terminated PLAF-NHS and PLGF-NHS macromers. The macromers were self-assembled by dialysis to form NPs. The amphiphilic PLEOF macromer was used as the surfactant to stabilize the NPs in the process of self-assembly. 1-(2-pyridylazo)-2-naphthol (PAN) was used as a model small molecule for encapsulation in PLAF or PLGF NPs and bovine serum albumin (BSA) was used as a model protein for conjugation to PLAF-NHS and PLGF-NHS NPs. The profile of release of the encapsulated PAN from PLAF and PLGF NPs was non-linear and consisted of a burst release followed by a period of sustained release. The release profile for BSA, conjugated to PLAF-NHS and PLGF-NHS NPs, was linear up to complete degradation of the NPs. PLGF and PLAF NPs degraded in 15 and 28 days, respectively, while PLGF-NHS and PLAF-NHS NPs degraded in 25 and 38 days, which demonstrated that the release was dominated by erosion of the matrix. PLAF-NHS and PLGF-NHS NPs are potentially useful as carriers for sustained in situ release of protein drugs.

Targeted delivery of nanoparticles for the treatment of lung diseases

Targeted delivery of drug molecules to organs or special sites is one of the most challenging research areas in pharmaceutical sciences. By developing colloidal delivery systems such as liposomes, micelles and nanoparticles a new frontier was opened for improving drug delivery. Nanoparticles with their special characteristics such as small particle size, large surface area and the capability of changing their surface properties have numerous advantages compared with other delivery systems. Targeted nanoparticle delivery to the lungs is an emerging area of interest. This article reviews research performed over the last decades on the application of nanoparticles administered via different routes of administration for treatment or diagnostic purposes. Nanotoxicological aspects of pulmonary delivery are also discussed.

Management of multidrug-resistant tuberculosis: Update 2007

Multidrug-resistant tuberculosis (MDR-TB) with bacillary resistance to at least isoniazid and rifampicin in vitro is a worldwide phenomenon. Hot spots of the disease are found scattered in different continents. Prevention of its development through good tuberculosis control programmes operating under the directly observed therapy, short-course (DOTS) strategy is of paramount importance. However, with established MDR-TB, treatment with alternative and specific chemotherapy is necessary to achieve a beneficial outcome. Such an approach on a programme basis is currently known as the 'DOTS-Plus' strategy. Second-line (reserve) drugs utilized in the treatment of MDR-TB are generally less potent and more toxic, perhaps with the notable exceptions of some fluoroquinolones and injectable agents. Surgery has a distinct adjunctive role for the management of MDR-TB in selected patients. The emergence of extensively drug-resistant tuberculosis (XDR-TB), that is, MDR-TB with additional bacillary resistance to the fluoroquinolones and injectables, has provided a very alarming challenge to global health, as the disease currently has a low cure rate and high mortality. In order to combat XDR-TB, strengthening of DOTS and DOTS-Plus programmes is mandatory, especially in the face of surging HIV infection. Furthermore, more attention needs to be focused on developing new drugs with potent bactericidal and sterilizing activities and low side-effects, and above all, drugs that are affordable for communities worldwide.

Inhaled nanoparticles--a current review

The field of nanotechnology may hold the promise of significant improvements in the health and well being of patients, as well as in manufacturing technologies. The knowledge of this impact of nanomaterials on public health is limited so far. This paper briefly reviews the unique size-controlled properties of nanomaterials, their disposition in the body after inhalation, and the factors influencing the fate of inhaled nanomaterials. The physiology of the lung makes it an ideal target organ for non-invasive local and systemic drug delivery, especially for protein and poorly water-soluble drugs that have low oral bioavailability via oral administration. The potential application of pulmonary drug delivery of nanoparticles to the lungs, specifically in context of published results reported on nanomaterials in environmental epidemiology and toxicology is reviewed in this paper.