Nanotechnology approaches for drug and small molecule delivery across the blood brain barrier

Nanomaterial Probes for Nuclear Imaging

Nuclear imaging is a powerful non-invasive imaging technique that is rapidly developing in medical theranostics. Nuclear imaging requires radiolabeling isotopes for non-invasive imaging through the radioactive decay emission of the radionuclide. Nuclear imaging probes, commonly known as radiotracers, are radioisotope-labeled small molecules. Nanomaterials have shown potential as nuclear imaging probes for theranostic applications. By modifying the surface of nanomaterials, multifunctional radio-labeled nanomaterials can be obtained for in vivo biodistribution and targeting in initial animal imaging studies. Various surface modification strategies have been developed, and targeting moieties have been attached to the nanomaterials to render biocompatibility and enable specific targeting. Through integration of complementary imaging probes to a single nanoparticulate, multimodal molecular imaging can be performed as images with high sensitivity, resolution, and specificity. In this review, nanomaterial nuclear imaging probes including inorganic nanomaterials such as quantum dots (QDs), organic nanomaterials such as liposomes, and exosomes are summarized. These new developments in nanomaterials are expected to introduce a paradigm shift in nuclear imaging, thereby creating new opportunities for theranostic medical imaging tools.

Graphene-Based Scaffolds for Regenerative Medicine

Leading-edge regenerative medicine can take advantage of improved knowledge of key roles played, both in stem cell fate determination and in cell growth/differentiation, by mechano-transduction and other physicochemical stimuli from the tissue environment. This prompted advanced nanomaterials research to provide tissue engineers with next-generation scaffolds consisting of smart nanocomposites and/or hydrogels with nanofillers, where balanced combinations of specific matrices and nanomaterials can mediate and finely tune such stimuli and cues. In this review, we focus on graphene-based nanomaterials as, in addition to modulating nanotopography, elastic modulus and viscoelastic features of the scaffold, they can also regulate its conductivity. This feature is crucial to the determination and differentiation of some cell lineages and is of special interest to neural regenerative medicine. Hereafter we depict relevant properties of such nanofillers, illustrate how problems related to their eventual cytotoxicity are solved via enhanced synthesis, purification and derivatization protocols, and finally provide examples of successful applications in regenerative medicine on a number of tissues.

A New Frontier: The Convergence of Nanotechnology, Brain Machine Interfaces, and Artificial Intelligence

A confluence of technological capabilities is creating an opportunity for machine learning and artificial intelligence (AI) to enable "smart" nanoengineered brain machine interfaces (BMI). This new generation of technologies will be able to communicate with the brain in ways that support contextual learning and adaptation to changing functional requirements. This applies to both invasive technologies aimed at restoring neurological function, as in the case of neural prosthesis, as well as non-invasive technologies enabled by signals such as electroencephalograph (EEG). Advances in computation, hardware, and algorithms that learn and adapt in a contextually dependent way will be able to leverage the capabilities that nanoengineering offers the design and functionality of BMI. We explore the enabling capabilities that these devices may exhibit, why they matter, and the state of the technologies necessary to build them. We also discuss a number of open technical challenges and problems that will need to be solved in order to achieve this.

Biosynthesis, Characterization, and Biological Activities of Iron Nanoparticles using Sesamum indicum Seeds Extract

Background:

Iron nanoparticles (FeNPs) have got many biomedical and health applications because of biocompatible and nontoxic nature to humans.

Objective:

To synthesize the FeNPs using natural sources.

Materials and Methods:

In this study, simple and economical procedure was adopted for FeNPs synthesis. Sesame seeds were processed to obtain seed extract as a biological material for FeNPs production. FeNPs were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopic.

Results:

The average diameter of these FeNPs was 99 nm. These nanoparticles showed significant anti-typhoid activity (30 mm zone of inhibition) as compared to ciprofloxacin (32 mm) as standard. Furthermore, in vitro alpha-amylase inhibitory assay also showed moderate antidiabetic activity with more than 50% inhibition.

Conclusion:

This study would be helpful in understanding of nanoparticles synthesis from natural sources and ultimately will be used as potential alternative therapeutic agents.

SUMMARY

Iron nanoparticles (FeNPs) were synthesized by Sesamum indicum seeds

FeNPs were characterized by scanning electron microscope with average diameter of 99 nm

These FeNPs are effective against Salmonella typhi, a causative agent of typhoid

These FeNPs can be used as antidiabetic agent.

Abbreviations used: FeNPs: Iron Nano Particles; SEM: Scanning Electron Microscopy; MIC: Minimum Inhibitory Concentration; S. indicum: Sesamum Indicum.

Nasal and Olfactory Deposition with Normal and Bidirectional Intranasal Delivery Techniques: In Vitro Tests and Numerical Simulations

BACKGROUND

Intranasal delivery protocols that can effectively deposit drugs to the olfactory region are severely lacking. Furthermore, it is still challenging to quantify nasal deposition on a regional or local basis, which is crucial in assessing the performance of targeted olfactory drug delivery.

OBJECTIVES

To visually and quantitatively compare drug depositions in the nose and olfactory region with normal and bidirectional breathing patterns with vibrating mesh and jet nebulizers.

METHODS

A sectional nose cast was developed based on an anatomically accurate nasal airway model to visualize deposition patterns and quantify regional doses. Sar-Gel was used to visualize the deposition pattern inside the nose and the delivered doses were measured using a high precision scale. Numerical modeling was performed to understand the underlying mechanisms in both the normal and bidirectional deliveries.

RESULTS

Results show that the bidirectional technique yielded higher deposition in both the nasal cavity and the olfactory region for both nebulizers. However, the vibrating mesh nebulizer was found to be more responsive to the bidirectional breathing and elicited more increase in the olfactory delivery than the PARI Sinus. The deposition patterns under the bidirectional breathing are highly different between the two nasal passages, with more dispersed distributions in the nasal passage with exiting flows. For both nebulizers, reducing the inhalation flow rates increased the nasal dose, but decreased the olfactory dose, which was consistent between in vitro measurements and numerical simulations.

CONCLUSIONS

The bi directional technique with a vibrating mesh nebulizer is recommended for both nasal systematic and olfactory drug deliveries. The Sar-Gel based method in combination with sectional nasal casts appears to be a practical approach to visualize local depositions.

The effect of safranal loaded mucoadhesive nanoemulsion on oxidative stress markers in cerebral ischemia

Antioxidants, with reported neuroprotective activity, encounter free radical induced neural damage leading to reduced risk of cerebral ischemia-reperfusion (IR) injury. Safranal, an antioxidant drug with potential role in the amelioration of cerebral ischemia, endures low solubility and poor absorption property thus resulting a low serum and tissue bioavailability. This research aims to prepare nanoemulsion with the concept; to increase the bioavailability in order to reduce oxidative stress-induced brain injury as well as to evaluate the brain-drug targeting following non-invasive nasal route administration in middle cerebral artery occlusion (MCAO) animal model. Titration method was used to prepare safranal mucoadhesive nanoemulsion (SMNE) followed by further characterization, i.e. entrapment efficiency, particles size, and zeta potential study. Optimized SMNE showed; mean globule size of 89.64 nm (±9.12), zeta potential -11.39 mV (±1.32), drug content 98.47% (±1.01), and viscosity of 124 cp (±14). Rats were subjected to 2 h of MCAO, successively followed by a 22 h reperfusion, after which the grip strength, locomotor activity, and biochemical studies, i.e. glutathione reductase (GR), glutathione peroxidase, lipid peroxidation, catalase, and superoxide dismutase were studied as assessment tool for effective treatment in brain. SMNE administered i.n. (intranasal) in MCAO induced cerebral ischemia rats exhibited significant improvement in neurobehavioral (locomotor and grip strength) and antioxidant activity as well as histopathological studies. The toxicity studies performed at the end revealed safe nature of developed SMNE.

Rutin-encapsulated chitosan nanoparticles targeted to the brain in the treatment of Cerebral Ischemia

OBJECTIVE

Rutin, a potent antioxidant, has been reported to reduce the risk of ischemic disease. Our study aims to prepare rutin-encapsulated-chitosan nanoparticles (RUT-CS-NPs) via ionic gelation method and determine its results, based on different parameters i.e. surface morphology characterization, in-vitro or ex-vivo release, dynamic light scattering and differential scanning calorimetry (DSC), for treating cerebral ischemia.

METHODS

UPLC-ESI-Q-TOF-MS/MS was used to evaluate the optimized RT-CS-NPs1 for brain-drug uptake as well as to follow-up the pharmacokinetics, bio-distrbution, brain-targeting efficiency and potential after intranasal administration (i.n.).

KEY FINDINGS

A particle size of <100nm for the formulation, significantly affected by drug:CS ratio, and entrapment efficiency and loading capacity of 84.98%±4.18% and 39.48%±3.16%, respectively were observed for RUT. Pharmacokinetics, bio-distribution, brain-targeting efficiency (1443.48±39.39%) and brain drug-targeting potential (93.00±5.69%) showed enhanced bioavailability for RUT in brain as compared to intravenous administration. In addition; improved neurobehavioral activity, histopathology and reduced infarction volume effects were observed in middle cerebral artery occlusion (MCAO) induced cerebral ischemic rats model after i.n. administration of RUT-CS-NPs.

CONCLUSION

A significant role of mucoadhesive-RT-CS-NPs1 as observed after high targeting potential and efficiency of the formulation prove; RUT-CS-NPs are more effectively accessed and target easily the brain.

Gelsolin Amyloidogenesis Is Effectively Modulated by Curcumin and Emetine Conjugated PLGA Nanoparticles

Small molecule based therapeutic intervention of amyloids has been limited by their low solubility and poor pharmacokinetic characteristics. We report here, the use of water soluble poly lactic-co-glycolic acid (PLGA)-encapsulated curcumin and emetine nanoparticles (Cm-NPs and Em-NPs, respectively), as potential modulators of gelsolin amyloidogenesis. Using the amyloid-specific dye Thioflavin T (ThT) as an indicator along with electron microscopic imaging we show that the presence of Cm-NPs augmented amyloid formation in gelsolin by skipping the pre-fibrillar assemblies, while Em-NPs induced non-fibrillar aggregates. These two types of aggregates differed in their morphologies, surface hydrophobicity and secondary structural signatures, confirming that they followed distinct pathways. In spite of differences, both these aggregates displayed reduced toxicity against SH-SY5Y human neuroblastoma cells as compared to control gelsolin amyloids. We conclude that the cytotoxicity of gelsolin amyloids can be reduced by either stalling or accelerating its fibrillation process. In addition, Cm-NPs increased the fibrillar bulk while Em-NPs defibrillated the pre-formed gelsolin amyloids. Moreover, amyloid modulation happened at a much lower concentration and at a faster rate by the PLGA encapsulated compounds as compared to their free forms. Thus, besides improving pharmacokinetic and biocompatible properties of curcumin and emetine, PLGA conjugation elevates the therapeutic potential of both small molecules against amyloid fibrillation and toxicity.

Inorganic nanovectors for nucleic acid delivery

Nucleic acids show immense potential to treat cancer, acquired immune deficiency syndrome, neurological diseases and other incurable human diseases. Upon systemic administration, they encounter a series of barriers and hence barely reach the site of action, the cell. Intracellular delivery of nucleic acids is facilitated by nanovectors, both viral and non-viral. A major advantage of non-viral vectors over viral vectors is safety. Nanovectors evaluated specifically for nucleic acid delivery include polyplexes, lipoplexes and other cationic carrier-based vectors. However, more recently there is an increased interest in inorganic nanovectors for nucleic acid delivery. Nevertheless, there is no comprehensive review on the subject. The present review would cover in detail specific properties and types of inorganic nanovectors, their preparation techniques and various biomedical applications as therapeutics, diagnostics and theranostics. Future prospects are also suggested.

"Extremely minimally invasive": recent advances in nanotechnology research and future applications in neurosurgery

The term "nanotechnology" refers to the development of materials and devices that have been designed with specific properties at the nanometer scale (10(-9) m), usually being less than 100 nm in size. Recent advances in nanotechnology have promised to enable visualization and intervention at the subcellular level, and its incorporation to future medical therapeutics is expected to bring new avenues for molecular imaging, targeted drug delivery, and personalized interventions. Although the central nervous system presents unique challenges to the implementation of new therapeutic strategies involving nanotechnology (such as the heterogeneous molecular environment of different CNS regions, the existence of multiple processing centers with different cytoarchitecture, and the presence of the blood-brain barrier), numerous studies have demonstrated that the incorporation of nanotechnology resources into the armamentarium of neurosurgery may lead to breakthrough advances in the near future. In this article, the authors present a critical review on the current 'state-of-the-art' of basic research in nanotechnology with special attention to those issues which present the greatest potential to generate major therapeutic progresses in the neurosurgical field, including nanoelectromechanical systems, nano-scaffolds for neural regeneration, sutureless anastomosis, molecular imaging, targeted drug delivery, and theranostic strategies.

Targeted brain derived neurotropic factors (BDNF) delivery across the blood-brain barrier for neuro-protection using magnetic nano carriers: an in-vitro study

Parenteral use of drugs; such as opiates exert immunomodulatory effects and serve as a cofactor in the progression of HIV-1 infection, thereby potentiating HIV related neurotoxicity ultimately leading to progression of NeuroAIDS. Morphine exposure is known to induce apoptosis, down regulate cAMP response element-binding (CREB) expression and decrease in dendritic branching and spine density in cultured cells. Use of neuroprotective agent; brain derived neurotropic factor (BDNF), which protects neurons against these effects, could be of therapeutic benefit in the treatment of opiate addiction. Previous studies have shown that BDNF was not transported through the blood brain barrier (BBB) in-vivo.; and hence it is not effective in-vivo. Therefore development of a drug delivery system that can cross BBB may have significant therapeutic advantage. In the present study, we hypothesized that magnetically guided nanocarrier may provide a viable approach for targeting BDNF across the BBB. We developed a magnetic nanoparticle (MNP) based carrier bound to BDNF and evaluated its efficacy and ability to transmigrate across the BBB using an in-vitro BBB model. The end point determinations of BDNF that crossed BBB were apoptosis, CREB expression and dendritic spine density measurement. We found that transmigrated BDNF was effective in suppressing the morphine induced apoptosis, inducing CREB expression and restoring the spine density. Our results suggest that the developed nanocarrier will provide a potential therapeutic approach to treat opiate addiction, protect neurotoxicity and synaptic density degeneration.

Modeling of release position and ventilation effects on olfactory aerosol drug delivery

Direct nose-to-brain drug delivery has multiple advantages over conventional intravenous deliveries. However, demonstration of its clinical feasibility is still in adolescence due to the lack of devices that effectively deliver medications to olfactory epitheliums. The objective of this study is to numerically evaluate two olfactory delivery protocols in a MRI-based nasal airway model: (1) pointed drug release in the vestibule (i.e., vestibular intubation), and (2) deep intubation with mediation released close to the olfactory mucosa. Influences of breathing maneuvers on olfactory delivery were also studied. It was observed that the front vestibular release gave higher olfactory dosage than the posterior vestibular release, and deep intubations yielded better outcomes than vestibular intubations. Specifically, the optimal olfactory dosage was achieved with deep intubation during inhalation. Breath-holding or exhalation, which was initially considered advantageous, resulted in unfocused depositions throughout the nasal turbinate region. Results of this study have implications for developing new olfactory delivery devices and for optimizing delivery protocols specific to patients' ventilations.

Development and evaluation of thymoquinone-encapsulated chitosan nanoparticles for nose-to-brain targeting: a pharmacoscintigraphic study

Chitosan (CS) nanoparticles of thymoquinone (TQ) were prepared by the ionic gelation method and are characterized on the basis of surface morphology, in vitro or ex vivo release, dynamic light scattering, and X-ray diffractometry (XRD) studies. Dynamic laser light scattering and transmission electron microscopy confirmed the particle diameter was between 150 to 200 nm. The results showed that the particle size of the formulation was significantly affected by the drug:CS ratio, whereas it was least significantly affected by the tripolyphosphate:CS ratio. The entrapment efficiency and loading capacity of TQ was found to be 63.3% ± 3.5% and 31.23% ± 3.14%, respectively. The drug-entrapment efficiency and drug-loading capacity of the nanoparticles appears to be inversely proportional to the drug:CS ratio. An XRD study proves that TQ dispersed in the nanoparticles changes its form from crystalline to amorphous. This was further confirmed by differential scanning calorimetry thermography. The flat thermogram of the nanoparticle data indicated that TQ formed a molecular dispersion within the nanoparticles. Optimized nanoparticles were evaluated further with the help of scintigraphy imaging, which ascertains the uptake of drug into the brain. Based on maximum concentration, time-to-maximum concentration, area-under-curve over 24 hours, and elimination rate constant, intranasal TQ-loaded nanoparticles (TQ-NP1) proved more effective in brain targeting compared to intravenous and intranasal TQ solution. The high drug-targeting potential and efficiency demonstrates the significant role of the mucoadhesive properties of TQ-NP1.

Nanoparticle-mediated targeted delivery of antiretrovirals to the brain

Nanotechnology offers a new platform for therapeutic delivery of antiretrovirals to the central nervous system (CNS) where human immunodeficiency virus (HIV-1) is sequestered in patients with HIV-1-associated neurological disorders (HAND). HAND is a spectrum of neurocognitive disorders that continue to persist in HIV-1-infected patients in spite of successful highly active antiretroviral therapy (HAART). Nanoformulated antiretroviral drugs offer multifunctionality, that is, the ability to package multiple diagnostic and therapeutic agents within the same nanocomposite, along with the added provisions of site-directed delivery, delivery across the blood-brain barrier (BBB), and controlled release of therapeutics. We have stably incorporated the antiretroviral drug, Amprenavir, within a transferrin (Tf)-conjugated quantum dot (QD), and evaluated the transversing ability of this Tf-QD-Amprenavir nanoplex across an in vitro BBB model and analyzed its antiviral efficacy in HIV-1-infected monocytes. We describe methods for synthesis of the Tf-QD-Amprenavir nanoplex and approaches to evaluate both its BBB transversing capability and antiviral efficacy.

Polymer and nano-technology applications for repair and reconstruction of the central nervous system

The hydrophilic polymer PEG and its related derivatives, have served as therapeutic agents to reconstruct the phospholipid bilayers of damaged cell membranes by erasing defects in the plasmalemma. The special attributes of hydrophilic polymers when in contact with cell membranes have been used for several decades since these well-known properties have been exploited in the manufacture of monoclonal antibodies. However, while traditional therapeutic efforts to combat traumatic injuries of the central nervous system (CNS) have not been successful, nanotechnology-based drug delivery has become a new emerging strategy with the additional promise of targeted membrane repair. As such, this potential use of nanotechnology provides new avenues for nanomedicine that uses nanoparticles themselves as the therapeutic agent in addition to their other functionalities. Here we will specifically address new advances in experimental treatment of Spinal Cord and Traumatic Brain injury (SCI and TBI respectively). We focus on the concept of repair of the neurolemma and axolemma in the acute stage of injury, with less emphasis on the worthwhile, and voluminous, issues concerning regenerative medicine/nanomedicine. It is not that the two are mutually exclusive - they are not. However, the survival of the neuron and the tissues of white matter are critical to any further success in what will likely be a multi-component therapy for TBI and SCI. This review includes a brief explanation of the characteristics of traumatic spinal cord injury SCI, the biological basis of the injuries, and the treatment opportunities of current polymer-based therapies. In particular, we update our own progress in such applications for CNS injuries with various suggestions and discussion, primarily nanocarrier-based drug delivery systems. The application of nanoparticles as drug-delivery vehicles to the CNS may likely be advantageous over existing molecular-based therapies. As a "proof-of-concept", we will discuss the recent investigations that have preferentially facilitated repair and functional recovery from breaches in neural membranes via rapid sealing and reassembly of the compromised site with silica or chitosan nanoparticles.

Nanoscale materials for tackling brain cancer: recent progress and outlook

This article reports on recent progress in the development of advanced nanoscale photoreactive, magnetic and multifunctional materials applicable to brain cancer diagnostics, imaging, and therapy, with an emphasis on the latest contributions and the novelty of the approach, along with the most promising emergent trends.

Nanotoxicology and nanoparticle safety in biomedical designs

Nanotechnology has wide applications in many fields, especially in the biological sciences and medicine. Nanomaterials are applied as coating materials or in treatment and diagnosis. Nanoparticles such as titania, zirconia, silver, diamonds, iron oxides, carbon nanotubes, and biodegradable polymers have been studied in diagnosis and treatment. Many of these nanoparticles may have toxic effects on cells. Many factors such as size, inherent properties, and surface chemistry may cause nanoparticle toxicity. There are methods for improving the performance and reducing toxicity of nanoparticles in medical design, such as biocompatible coating materials or biodegradable/biocompatible nanoparticles. Most metal oxide nanoparticles show toxic effects, but no toxic effects have been observed with biocompatible coatings. Biodegradable nanoparticles are also used in the efficient design of medical materials, which will be reviewed in this article.

Advances in novel drug delivery strategies for breast cancer therapy

Breast cancer remains one of the world's most devastating diseases. However, better understanding of tumor biology and improved diagnostic devices could lead to improved therapeutic outcomes. Nanotechnology has the potential to revolutionize cancer diagnosis and therapy. Various nanocarriers have been introduced to improve the therapeutic efficacy of anticancer drugs, including liposomes, polymeric micelles, quantum dots, nanoparticles, and dendrimers. Recently, targeted drug delivery systems for anti-tumor drugs have demonstrated great potential to lower cytotoxicity and increase therapeutic effects. Various ligands/approaches have been explored for targeting breast cancer. This paper provides an overview of breast cancer, conventional therapy, potential of nanotechnology in management of breast cancer, and rational approaches for targeting breast cancer.

Bacterial Magnetosome: A Novel Biogenetic Magnetic Targeted Drug Carrier with Potential Multifunctions

Bacterial magnetosomes (BMs) synthesized by magnetotactic bacteria have recently drawn great interest due to their unique features. BMs are used experimentally as carriers for antibodies, enzymes, ligands, nucleic acids, and chemotherapeutic drugs. In addition to the common attractive properties of magnetic carriers, BMs also show superiority as targeting nanoscale drug carriers, which is hardly matched by artificial magnetic particles. We are presenting the potential applications of BMs as drug carriers by introducing the drug-loading methods and strategies and the recent research progress of BMs which has contributed to the application of BMs as drug carriers.

Nanoplatforms for constructing new approaches to cancer treatment, imaging, and drug delivery: what should be the policy?

Nanotechnology is the design and assembly of submicroscopic devices called nanoparticles, which are 1-100 nm in diameter. Nanomedicine is the application of nanotechnology for the diagnosis and treatment of human disease. Disease-specific receptors on the surface of cells provide useful targets for nanoparticles. Because nanoparticles can be engineered from components that (1) recognize disease at the cellular level, (2) are visible on imaging studies, and (3) deliver therapeutic compounds, nanotechnology is well suited for the diagnosis and treatment of a variety of diseases. Nanotechnology will enable earlier detection and treatment of diseases that are best treated in their initial stages, such as cancer. Advances in nanotechnology will also spur the discovery of new methods for delivery of therapeutic compounds, including genes and proteins, to diseased tissue. A myriad of nanostructured drugs with effective site-targeting can be developed by combining a diverse selection of targeting, diagnostic, and therapeutic components. Incorporating immune target specificity with nanostructures introduces a new type of treatment modality, nano-immunochemotherapy, for patients with cancer. In this review, we will discuss the development and potential applications of nanoscale platforms in medical diagnosis and treatment. To impact the care of patients with neurological diseases, advances in nanotechnology will require accelerated translation to the fields of brain mapping, CNS imaging, and nanoneurosurgery. Advances in nanoplatform, nano-imaging, and nano-drug delivery will drive the future development of nanomedicine, personalized medicine, and targeted therapy. We believe that the formation of a science, technology, medicine law-healthcare policy (STML) hub/center, which encourages collaboration among universities, medical centers, US government, industry, patient advocacy groups, charitable foundations, and philanthropists, could significantly facilitate such advancements and contribute to the translation of nanotechnology across medical disciplines.

Nanoparticulate systems for drug delivery and targeting to the central nervous system

Brain delivery is one of the major challenges for the neuropharmaceutical industry since an alarming increase in brain disease incidence is going on. Despite major advances in neuroscience, many potential therapeutic agents are denied access to the central nervous system (CNS) because of the existence of a physiological low permeable barrier, the blood-brain barrier (BBB). To obtain an improvement of drug CNS performance, sophisticated approaches such as nanoparticulate systems are rapidly developing. Many recent data demonstrate that drugs could be transported successfully into the brain using colloidal systems after i.v. injection by several mechanisms such as endocytosis or P-glycoprotein inhibition. This review summarizes the main brain targeted nanoparticulate carriers such as liposomes, lipid nanoparticles, polymeric nanoparticles, and micelles with great potential in drug delivery into the CNS.

Recent advances in nanotechnology based drug delivery to the brain

Drug delivery into the brain was difficult due to the existence of blood brain barrier, which only permits some molecules to pass through freely. In past decades, nanotechnology has enabled many technical advances including drug delivery into the brain with high efficiency and accuracy. In the present paper, we summarize recent important advances in employing nanotechnology for drug delivery to the brain as well as controlled drug release.

Nanotechnology applications and approaches for neuroregeneration and drug delivery to the central nervous system

Nanotechnology is the science and engineering concerned with the design, synthesis, and characterization of materials and devices that have a functional organization in at least one dimension on the nanometer (i.e., one billionth of a meter) scale. The potential impact of bottom up self-assembling nanotechnology, custom made molecules that self-assemble or self-organize into higher ordered structures in response to a defined chemical or physical cue, and top down lithographic type technologies where detail is engineered at smaller scales starting from bulk materials, stems from the fact that these nanoengineered materials and devices exhibit emergent mesocale and macroscale chemical and physical properties that are often different than their constituent nanoscale building block molecules or materials. As such, applications of nanotechnology to medicine and biology allow the interaction and integration of cells and tissues with nanoengineered substrates at a molecular (i.e., subcellular) level with a very high degree of functional specificity and control. This review considers applications of nanotechnology aimed at the neuroprotection and functional regeneration of the central nervous system (CNS) following traumatic or degenerative insults, and nanotechnology approaches for delivering drugs and other small molecules across the blood-brain barrier. It also discusses developing platform technologies that may prove to have broad applications to medicine and physiology, including some being developed for rescuing or replacing anatomical and/or functional CNS structures.

Biomedical Nanomagnetics: A Spin Through Possibilities in Imaging, Diagnostics, and Therapy

Biomedical nanomagnetics is a multidisciplinary area of research in science, engineering and medicine with broad applications in imaging, diagnostics and therapy. Recent developments offer exciting possibilities in personalized medicine provided a truly integrated approach, combining chemistry, materials science, physics, engineering, biology and medicine, is implemented. Emphasizing this perspective, here we address important issues for the rapid development of the field, i.e., magnetic behavior at the nanoscale with emphasis on the relaxation dynamics, synthesis and surface functionalization of nanoparticles and core-shell structures, biocompatibility and toxicity studies, biological constraints and opportunities, and in vivo and in vitro applications. Specifically, we discuss targeted drug delivery and triggered release, novel contrast agents for magnetic resonance imaging, cancer therapy using magnetic fluid hyperthermia, in vitro diagnostics and the emerging magnetic particle imaging technique, that is quantitative and sensitive enough to compete with established imaging methods. In addition, the physics of self-assembly, which is fundamental to both biology and the future development of nanoscience, is illustrated with magnetic nanoparticles. It is shown that various competing energies associated with self-assembly converge on the nanometer length scale and different assemblies can be tailored by varying particle size and size distribution. Throughout this paper, while we discuss our recent research in the broad context of the multidisciplinary literature, we hope to bridge the gap between related work in physics/chemistry/engineering and biology/medicine and, at the same time, present the essential concepts in the individual disciplines. This approach is essential as biomedical nanomagnetics moves into the next phase of innovative translational research with emphasis on development of quantitative in vivo imaging, targeted and triggered drug release, and image guided therapy including validation of delivery and therapy response.

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.

Magnetic nanoformulation of azidothymidine 5'-triphosphate for targeted delivery across the blood-brain barrier

Despite significant advances in highly active antiretroviral therapy (HAART), the prevalence of neuroAIDS remains high. This is mainly attributed to inability of antiretroviral therapy (ART) to cross the blood–brain barrier (BBB), thus resulting in insufficient drug concentration within the brain. Therefore, development of an active drug targeting system is an attractive strategy to increase the efficacy and delivery of ART to the brain. We report herein development of magnetic azidothymidine 5′-triphosphate (AZTTP) liposomal nanoformulation and its ability to transmigrate across an in vitro BBB model by application of an external magnetic field. We hypothesize that this magnetically guided nanoformulation can transverse the BBB by direct transport or via monocyte-mediated transport. Magnetic AZTTP liposomes were prepared using a mixture of phosphatidyl choline and cholesterol. The average size of prepared liposomes was about 150 nm with maximum drug and magnetite loading efficiency of 54.5% and 45.3%, respectively. Further, magnetic AZTTP liposomes were checked for transmigration across an in vitro BBB model using direct or monocyte-mediated transport by application of an external magnetic field. The results show that apparent permeability of magnetic AZTTP liposomes was 3-fold higher than free AZTTP. Also, the magnetic AZTTP liposomes were efficiently taken up by monocytes and these magnetic monocytes showed enhanced transendothelial migration compared to normal/non-magnetic monocytes in presence of an external magnetic field. Thus, we anticipate that the developed magnetic nanoformulation can be used for targeting active nucleotide analog reverse transcriptase inhibitors to the brain by application of an external magnetic force and thereby eliminate the brain HIV reservoir and help to treat neuroAIDS.

Potential Risks of Nanofood to Consumers

The field of nanotechnologies is rapidly developing and applications can be found throughout the entire food production chain. This is expected to lead to many new products with new and exciting features that are not feasible using conventional production processes. Although the obvious beneficial effects of the application of nanotechnologies are well recognized, the potential human and environmental impacts of engineered nanomaterials have so far received little attention. As nanotechnologies are likely to be used in food production more and more in the future, this raises the question of consumer exposure to nanofood. This chapter presents a review of scientific issues that need to be addressed in order to perform a robust safety assessment of the use of nanotechnologies in food production. One of the main issues to be addressed includes development of validated analytical tools for characterisation of nanomaterials in food. This is essentially needed to enable assessment of consumer exposure. Furthermore, fundamental knowledge on the biokinetics and interaction of nanomaterials at both organism and cellular levels needs to be generated. Only with this knowledge can a reliable assessment of the potential hazards be made. Integrating this knowledge in the established risk analysis paradigm is a prerequisite for the sustainable development of nano foods, which will also need consumer acceptance of the new applications in food production.

Chapter 2 - Quantum dot nanotechnologies for neuroimaging

Functionalized quantum dot nanocrystals provide an opportunity for high signal-to-noise ratio specific labeling of cells with micron-scale spatial resolution, and extend the cellular imaging toolbox available to the cellular neurobiologist. In this review we discuss previous work from our group aimed at optimizing quantum dot labeling protocols specific to neurons and neural glial cells, labeling and imaging of intact neural retinal tissue sections in a rat model of retinal degeneration focused on the formation of the glial scar following focal reactive gliosis, and on the characterization and estimation of the number of functionally available antibodies for biological binding conjugated to quantum dots following two popular conjugation schemes.

Specific targeting of brain tumors with an optical/magnetic resonance imaging nanoprobe across the blood-brain barrier

Nanoparticle-based platforms have drawn considerable attention for their potential effect on oncology and other biomedical fields. However, their in vivo application is challenged by insufficient accumulation and retention within tumors due to limited specificity to the target, and an inability to traverse biological barriers. Here, we present a nanoprobe that shows an ability to cross the blood-brain barrier and specifically target brain tumors in a genetically engineered mouse model, as established through in vivo magnetic resonance and biophotonic imaging, and histologic and biodistribution analyses. The nanoprobe is comprised of an iron oxide nanoparticle coated with biocompatible polyethylene glycol-grafted chitosan copolymer, to which a tumor-targeting agent, chlorotoxin, and a near-IR fluorophore are conjugated. The nanoprobe shows an innocuous toxicity profile and sustained retention in tumors. With the versatile affinity of the targeting ligand and the flexible conjugation chemistry for alternative diagnostic and therapeutic agents, this nanoparticle platform can be potentially used for the diagnosis and treatment of a variety of tumor types.

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.

Substance P and beta-endorphin mediate electro-acupuncture induced analgesia in mouse cancer pain model

BACKGROUND

Opioid analgesics are generally used to combat the pain associated with cancerous conditions. These agents not only inhibit respiratory function and cause constipation, but also induce other significant side effects such as addiction and tolerance, all of which further contribute to a reduced quality of life for cancer patients. Thus, in the present study, the effects of electro-acupuncture treatment (EA) on mechanical allodynia were examined in a cancer pain mouse model.

METHODS

In order to produce a neuropathic cancer pain model, S-180 sarcoma cells were inoculated around the sciatic nerve of left legs of Balb/c mice. Magnetic Resonance Imaging (MRI) scanning confirmed the mass of S-180 cancer cells embedded around the sciatic nerve. Mechanical allodynia was most consistently induced in the mouse sarcoma cell line S-180 (2 x 10(6)sarcoma cells)-treated group compared to all the other groups studied. EA stimulation (2 Hz) was administered daily to ST36 (Zusanli) of S-180 bearing mice for 30 min for 9 days after S-180 inoculation.

RESULTS

EA treatment significantly prolonged paw withdrawal latency from 5 days after inoculation. It also shortened the cumulative lifting duration from 7 days after inoculation, compared to the tumor control. Also, the overexpression of pain peptide substance P in the dorsal horn of the spinal cord was significantly decreased in the EA-treated group compared to the tumor control on Day 9 post inoculation. Furthermore, EA treatment effectively increased the concentration of beta-endorphin in blood and brain samples of the mice to a greater extent than that of the tumor control as well as the normal group. The concentration of beta-endorphin for EA treatment group increased by 51.457% in the blood and 12.6% in the brain respectively, compared to the tumor control group.

CONCLUSION

The findings of this study suggest that a S-180 cancer pain model is useful as a consistent and short time animal model. It also indicated that EA treatment could be used as an alternative therapeutic method for cancer pain due to a consequent decrease in substance P and increase in beta-endorphin levels.

Translational nanomedicine: status assessment and opportunities

Nano-enabled technologies hold great promise for medicine and health. The rapid progress by the physical sciences/engineering communities in synthesizing nanostructures and characterizing their properties must be rapidly exploited in medicine and health toward reducing mortality rate, morbidity an illness imposes on a patient, disease prevalence, and general societal burden. A National Science Foundation-funded workshop, "Re-Engineering Basic and Clinical Research to Catalyze Translational Nanoscience," was held 16-19 March 2008 at the University of Southern California. Based on that workshop and literature review, this article briefly explores scientific, economic, and societal drivers for nanomedicine initiatives; examines the science, engineering, and medical research needs; succinctly reviews the US federal investment directly germane to medicine and health, with brief mention of the European Union (EU) effort; and presents recommendations to accelerate the translation of nano-enabled technologies from laboratory discovery into clinical practice.

FROM THE CLINICAL EDITOR

An excellent review paper based on the NSF funded workshop "Re-Engineering Basic and Clinical Research to Catalyze Translational Nanoscience" (16-19 March 2008) and extensive literature search, this paper briefly explores the current state and future perspectives of nanomedicine.

CNS disorders--current treatment options and the prospects for advanced therapies

The development of new pharmaceutical products has successfully addressed a multitude of disease states; however, new product development for treating disorders of the central nervous system (CNS) has lagged behind other therapeutic areas. This is due to several factors including the complexity of the diseases and the lack of technologies for delivery through the blood-brain barrier (BBB). This article examines the current state of six major CNS disease states: depression, epilepsy, multiple sclerosis (MS), neurodegenerative diseases (specifically Alzheimer's disease [AD]), neuropathic pain, and schizophrenia. Discussion topics include analysis of the biological mechanisms underlying each disease, currently approved products, and available animal models for development of new therapeutic agents. Analysis of currently approved therapies shows that all products depend on the molecular properties of the drug or prodrug to penetrate the BBB. Novel technologies, capable of enhancing BBB permeation, are also discussed relative to improving CNS therapies for these disease states.

Carbon nanotubes might improve neuronal performance by favouring electrical shortcuts

Carbon nanotubes have been applied in several areas of nerve tissue engineering to probe and augment cell behaviour, to label and track subcellular components, and to study the growth and organization of neural networks. Recent reports show that nanotubes can sustain and promote neuronal electrical activity in networks of cultured cells, but the ways in which they affect cellular function are still poorly understood. Here, we show, using single-cell electrophysiology techniques, electron microscopy analysis and theoretical modelling, that nanotubes improve the responsiveness of neurons by forming tight contacts with the cell membranes that might favour electrical shortcuts between the proximal and distal compartments of the neuron. We propose the 'electrotonic hypothesis' to explain the physical interactions between the cell and nanotube, and the mechanisms of how carbon nanotubes might affect the collective electrical activity of cultured neuronal networks. These considerations offer a perspective that would allow us to predict or engineer interactions between neurons and carbon nanotubes.

Optical detection of brain cell activity using plasmonic gold nanoparticles

Metal nanoparticles are being actively explored for applications that use localized surface plasmon (LSP) resonance for optical sensing. Here we report an electrostatic field sensing technique which has been applied to detection of mammalian brain cell activity, by optically measuring the cellular potential induced shift in the SP resonance mode of an adjacent planar gold nanoparticle array. An experimental scheme was first devised which enables a quantitative calibration of the field-induced plasmon resonance modulation in air. Hippocampal (brain) neural cells were then grown onto the nanoparticle template and cellular level individual transient signals were detected optically when the chemically triggered neurons switched their potential. Experimental data are compared with calculations using the Drude model for the dielectric response of gold and the Stern model for the metal-electrolyte junction, with good agreement.

Nanotechnology approaches to crossing the blood-brain barrier and drug delivery to the CNS

Nanotechnologies are materials and devices that have a functional organization in at least one dimension on the nanometer (one billionth of a meter) scale, ranging from a few to about 100 nanometers. Nanoengineered materials and devices aimed at biologic applications and medicine in general, and neuroscience in particular, are designed fundamentally to interface and interact with cells and their tissues at the molecular level. One particularly important area of nanotechnology application to the central nervous system (CNS) is the development of technologies and approaches for delivering drugs and other small molecules such as genes, oligonucleotides, and contrast agents across the blood brain barrier (BBB). The BBB protects and isolates CNS structures (i.e. the brain and spinal cord) from the rest of the body, and creates a unique biochemical and immunological environment. Clinically, there are a number of scenarios where drugs or other small molecules need to gain access to the CNS following systemic administration, which necessitates being able to cross the BBB. Nanotechnologies can potentially be designed to carry out multiple specific functions at once or in a predefined sequence, an important requirement for the clinically successful delivery and use of drugs and other molecules to the CNS, and as such have a unique advantage over other complimentary technologies and methods. This brief review introduces emerging work in this area and summarizes a number of example applications to CNS cancers, gene therapy, and analgesia.